Aerobic treatment – August 2019

Organization : IFRC

 

Location of the case study


Cox's Bazar - Bangladesh [get_field_info_custom field='location' type='placeholder']

Main treatment objectives


Pathogen reduction [get_field_info_custom field='main-treatment-objectives' type='placeholder']

Capex per design input flow


9191 USD/m3/day

Opex per real input flow


5 USD/m3

Required space


0.02 [get_field_info_custom field='required-space' type='placeholder']

Description of the treatment process

 

Short description of the emergency context

Main treatment objectives

Pathogen reduction

Design population

20000 Persons

Design input flow

10 m3/day

Design life

Long term (years)

Source of sludge

Pit latrines affected by groundwater infiltration

Types of output

Effluent, Sludge

Required space

0.02 [get_field_info_custom field="required-space" type="placeholder"]

Local constraints

Flood prone area

Capex per design input flow

9191 USD/m3/day

Real input flow

2.2 [get_field_info_custom field="real-input-flow" type="placeholder"]

Opex per real input flow

5 USD/m3

TS reduction

78[get_field_info_custom field="ts-reduction" type="placeholder"]

COD reduction

88[get_field_info_custom field="cod-reduction" type="placeholder"]

Faecal coliforms reduction

100[get_field_info_custom field="faecal-coliforms-reduction" type="placeholder"]

The anaerobic baffled reactor is used as pretreatment, to remove solids from the waste stream. The waste then moves to two reactor tanks in series. The aeration of the incoming faecal sludge in the a reactor tanks leads to the breeding of bacteria that metabolize the organic content (COD/TOC (Total Organic Content)) together with the oxygen, turning the organic content into a gas (carbon dioxide).

The supernatant from the two reactor tanks is transferred to a settling tank, where the remaining solids are separated. The supernatant of the settling tank is then passed through a glass bead filter, which is regularly backwashed, for the removal of parasites and parasite eggs. Finally, the liquid is disinfected by chlorine or UV. Sludge from the settling tank is added to the reactor tank. Reactor tank sludge is treated by anaerobic digestion or lime treatment.

The plant is located next to a creekline that has been widened. The site has yet to be flooded, however potential flooding could occur in large rainfall event (e.g. 1 in 50 years).

The unit does not produce strong odours or attract insects but it should be as far from settlement as possible while still allowing for efficient delivery of faecal waste.

Fencing and security are needed for health and safety and theft prevention.

A fully functional faecal sludge quality laboratory is a requirement for this unit.

The cost is $180,000 per treatment line ($9.00 per person) excluding works, plus local materials (e.g.fencing, gravel). It includes genset rather than renewable energy source.

The skills required for set up and oversight is aerobic treatment expertise.

The construction lasts 2-5 days and the inception time is about 4 weeks or more depending on waste characteristics.

Equipment package comes with 12 kVA genset and wiring for connection to renewable energy. Water is needed for inception and backwash.

An estimated 0.1 m3 of dried sludge and 10 m3 of treated wastewater is discharged per day (wastewater can safely be used for irrigation or added to a surface waterway).

There is a 2.2m3 inflow every day, and 2.5m3 of output is produced every 3 days, with a 10% solids (100 kg / m3).

The COD average influent concentration is 23,600 mg/L and the COD average effluent concentration is 1,100 mg/L.

The faecal coliforms are fully removed due to current chlorination dosage.

The average TS influent concentration is 22 g/kg and the outlet concentration is 5 kg//kg.

The average pH for influent is 8.1 and the average pH for effluent is 7.9.

The helminth eggs average influent concentration is 266 eggs/g and the helminth eggs average effluent concentration is 3 eggs/g.

The cost is $5 per m3 treated, reduced with use of renewable energy. It excludes sludge transport cost.

The skills required for daily operation and maintenance is basic mechanical and electric skills and low skill labour.

The aerator and oloid are coming from Germany, the oxfam tanks are also imported from abroad.

Strengths

  • Odour and solid reduction
  • Low land use
  • Effective and efficient

Weaknesses


NC

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Location

Definition of the indicator

Country, state and town where feacal sludge management activities are taking place.

References, tips, examples

Bangladesh, Cox’s Bazar
Myanmar, Rakhine State, Sittwe camps

Why is it important to measure it

The case studies are gathered and sorted by location on the website.

Main treatment objectives

Definition of the indicator

The objectives are the main desired treatments or modifications of the input sludge before disposal or reuse.

Unit/value

Solid/liquid separation
Pathogen reduction
BOD/COD reduction
TSS and TDS reduction
Nutrient reduction
Biogas production
Compost production
Other

How to measure or calculate it

Review the design documents or ask the design team or consultant: the objectives are considered to design the faecal sludge treatment site. Usually, the objectives are related to the quality of input sludge and the environmental conditions of disposal sites or the desired output reuse.

References, tips, examples

If the aim is to reuse the wastewater outlet in agriculture, the treatment objectives are solid/liquid separation and pathogen reduction.

Why is it important to measure it

It is a requirement to design the faecal sludge treatment plant and to evaluate the efficiency of the treatment of the wastes by the plant.

Capex per design input flow

Definition of the indicator

This indicator defines the total cost the construction works, including:

– Preliminary and general items (Office and transport contractor and supervisors, security, insurance, electricity supply connection, etc.)
– Purchase of land if relevant
– Civil works
– Electromechanical works: pumps, GenSet, etc.
– Design (typically 5% of Civil & Electromechanical costs)
– Supervision of implementation (typically 5-15% of Civil and Electromechanical costs)

divided by the design input flow.

Unit/value: USD/m3/day

How to measure or calculate it

Review the purchase documents and include the HR costs related to construction. All the expenditure for the construction and installation of a sludge faecal treatment system has to be considered and divided by the design flow (see indicator).

References, tips, examples

Capital expenditure per design flow for faecal sludge treatment sites differs from place to place and depends mostly on transport costs. A treatment plant in inaccessible areas where cement bags need to be flown in can be 10 times more expensive than the same plant in areas where cement can be purchased ‘off the shelf’.

Why is it important to measure it

This indicator is useful to know the cost of construction of a treatment solution, in relation to the volume of sludge treated. This enters in the decision-making process to choose a treatment solution as the amount of money available for construction can be limited.

Opex per real input flow

Definition of the indicator

Operation expenditure includes the daily average of:

– Staff costs
– Energy costs (especially high when electricity needs to be generated separately)
– Chemical costs
– Transport costs
– Administration costs
– Water for cleaning / operating costs
– Personal Protection Equipment costs
– Etc.

divided by real input flow.
This doesn’t include the desludging costs.

Unit/value: USD/m3

How to measure or calculate it

Review the operation and maintenance SOPs, the purchase documents and ask the staff. All the expenditure for operation has to be considered and divided by the real input flow (see indicator). Expenditure for daily, weekly and monthly operation, as well as yearly and extraordinary maintenance should be considered as a daily average. It includes the cost of human resources involved in the operation and maintenance of the plant, but it doesn’t include the costs related to desludging activities.

References, tips, examples

Typical O&M costs for faecal sludge treatment plants around the world are 6-10 USD/m3.

Why is it important to measure it

This indicator is useful to know the economical efficiency of a faecal sludge treatment system.

Required space

Definition of the indicator

This is the space occupied by the faecal sludge treatment site in relationship with the design beneficiary population (see indicator).

Unit/value: m2/person

How to measure or calculate it

Measure in the field (on site) or in the project designs, the total area of the faecal sludge treatment site and divide it by the design population (see indicator).

References, tips, examples

Example:
If the total area of the plant is 500 m2, and the design population is 1600 persons, the required space is 500/1600 = 0,31 m2/person.

Why is it important to measure it

This indicator is useful to know the amount of land needed to implement treatment technologies depending on the design population. In humanitarian contexts, where the population is often obliged to settle in crowded areas with unfavourable environmental conditions, the space available for faecal sludge treatment sites may be limited.

Design population

Definition of the indicator

Number of people to benefit from the faecal sludge treatment service that was used for the design of the treatment plant.

Unit/value: Persons

How to measure or calculate it

Analyse the current population, its growth and movement trends. In a stable growing population, population to be served can be calculated as follows:
Pn = P0 * (1+i)^n
Pn = Population in year ‘n’
n = design period (refer to design life indicator)
P0 = Population in year 0
i = annual growth of the population
However in humanitarian context, this will usually depend on the security context (forecast of the population affected by the crisis).

References, tips, examples

n = design period = 5 years
P0 = Population in year 0 = 1,000 persons
i = annual growth of the population = 10% influx per year
P5 = 1,000 * (1+0.1)^5 = 1,610 persons, say 1,600

Why is it important to measure it

It is necessary to know the size of the population that needs to be served in order to design the treatment plant correctly and accordingly. It is important to forecast the population growth to better size the facility (tanks, pumps, drying beds, etc.) so that it can answer to the future needs of the population. If the facilities are not designed according to the needs, the construction and operation costs can end up being unnecessarily increased (plant overdesigned) or the treatment results can be poorer (plant underdesigned).

Design input flow

Definition of the indicator

This indicator defines the quantity of sludge per day that the facility can receive according to the design.

Unit/value: m3/day

How to measure or calculate it

Review the design documents or ask to the design team or consultant: the input flow is considered to design the faecal sludge treatment plant. It is based on the design population, knowing that an average individual produces between 0.12 – 0.40 litres of faeces and 0.6 – 1.5 litres of urine per day. For small networks (small bore sewerage, solids free sewerage) where domestic drinking water network is available: it is estimated that 80% of the drinking water supply ends up in the sanitation system.

Why is it important to measure it

This indicator is important to know what inlet flow the plant can receive (mean and maximum). It is used to design the whole facility (tanks, pumps, drying beds, etc.).

Design life

Definition of the indicator

This indicator defines how long the faecal sludge treatment site was designed to last and cover the population needs.

Unit/value:

Short term (months)
Long term (years)

How to measure or calculate it

Identify for how long the plant will cover the population’s needs (see Design population indicator). It depends on immediate and long term needs, population growth and movement trends, donors and implementing actors’ commitments for the future.

Why is it important to measure it

The design life determines the appropriate building material to use and helps planning for upgrades of the plant.

Source of sludge

Definition of the indicator

It defines the type of sanitation infrastructures which the sludge comes from.

Unit/value

Public toilets
Flush latrines
Dry latrines
Septic tanks
Unlined pit latrines
Lined pit latrines
Pit latrines affected by groundwater infiltration
Health facilities
Pits or tanks connected to greywater
Urine diversion toilets
Other

How to measure or calculate it

If they exist, analyse the documents on desludging which report this information, otherwise observe the desludging activities and the sanitation infrastructures which the sludge comes from. Talk with people in charge of desludging.
It is possible to select several answers.

References, tips, examples

For example, the sludge can come from different types of latrines – lined and unlined pit latrines, all being dry latrines and some being public toilets. All four responses need to be ticked.

Why is it important to measure it

This indicator is important to estimate the sludge’s characteristics as it varies depending on the origin of the infrastructure (flush vs dry latrines, affected by groundwater or not, from health facilities, etc.). The design of the plant should be based on the sludge characteristics. For example, the sludge from hospitals is likely to be more hazardous and will need a special treatment.

Types of output

Definition of the indicator

The indicator defines what the main outputs of the faecal sludge treatment site are:
Sludge is a mixture of solids and liquids, containing mostly excreta and water, in combination with sand, grit, metals, trash and/or various chemical compounds.
Effluent is the general term for a liquid that leaves a technology, typically after blackwater or sludge has undergone solids separation or some other type of treatment.
Biogas is the common name for the mixture of gases released from the anaerobic digestion of organic material.
Compost is decomposed organic matter that results from a controlled aerobic degradation process, and is an earth-like, odourless, brown/black material.

Unit/value

Sludge
Effluent
Biogas
Compost

How to measure or calculate it

Review the design documents or observe what the different outputs of the plant are. Several responses can be selected.

References, tips, examples

For example, if there is a solid/liquid separation of the sludge with drying beds followed by a constructed wetland for the liquid outlet treatment, the outputs of the plant are sludge (from the dewatered sludge of the drying beds) and effluent (from the outlet of the constructed wetland).

Why is it important to measure it

Knowing the different outputs enables the creation of specific disposal or end-use systems.

Local constraints

Definition of the indicator

This indicator defines the constraints faced in the area where the treatment plant is located.

Unit/value

High water table
Rocky ground
Flood prone area
Earthquakes
Mountainous topography
Only locally available material
Other

How to measure or calculate it

High water table: check, at the end of rainy season, the groundwater table at the faecal sludge site by digging a pit and/or checking dug wells nearby (in the early morning before water is taken and water level drops). If it’s not possible to do it at the end of the rainy season, ask for information from the local population about the water level in the wells during the year. If there is less than 1m between the water table and the ground level, consider that it is a high water table.
Rocky ground: check if the ground is rocky where the plant is located, thanks to local knowledge of the population, reference documents or by digging a hole next to the treatment plant.
Flood prone area: verify with litterature and local knowledge if a flood occurred in the area next to the faecal sludge treatment site, in the last period equivalent to the design life (see indicator).Take in consideration only the faecal sludge treatment site and not the access to it or the latrines.
Earthquakes: verify with litterature and local knowledge if an earthquake occurred in the area next to the faecal sludge treatment site, in the last period equivalent to the design life (see indicator). Take into consideration only the faecal sludge treatment site and not the access to it or the latrines.
Mountainous topography: the area where the plant is implemented is not flat, there are hills or mountains.
Only locally available material: analyse the purchase documents for the faecal sludge treatment site and identify if only locally available material and equipment were used. Don’t tick the box if material and equipment from abroad were used.
Other: indicate any other constraints faced locally.

Why is it important to measure it

All these constraints will influence the chosen technologies for the treatment plant: construction in areas with a high ground water table requires more complex structures as faecal sludge is composed of contaminants that spread easily and quickly in water; rocky ground will make digging work more complex and expensive; plants in flood prone areas will need extra work to be protected against flooding, as flooding may stop operations for several weeks and/or spread faecal contamination out of the faecal sludge treatment site; plants in earthquake-prone areas will need extra work and consolidation in order to be resistant to earthquakes; a mountainous topography may determine the type of treatment facilities to be built and may influence the transportation and pumping costs; plants contructed and operated only with locally available material reduce costs and are easier to replicate in the same area.

Real input flow

Definition of the indicator

This indicator is required to know how much sludge is currently treated at the faecal sludge treatment site. It can differ from the design flow and be lower.

Unit/value: m3/day

How to measure or calculate it

Calculate the real input flow by measuring the sludge volume in transport tanks arriving to the faecal sludge treatment site or by measuring the pump flow rates and their time of use (duration of usage) during desludging. Consider an average value including also the days the faecal sludge treatment activities are not running.
If it’s not possible to measure in the field, the input flow is estimated as follows:
For emergency simple pit latrines emptied at regular intervals and with poor pit infiltration: it is estimated to 2.2 lcd (litres per capita per day) (1 for anal cleansing and toilet cleaning + 1.2 for faeces)
For emergency simple pits where effluent can infiltrate and latrines are emptied at regular intervals consider the following sludge accumulation rates:
– Wastes retained in water where water is used as anal cleansing material: 25 litres per capita per year (lcy);
– Wastes retained in water where degradable anal cleansing materials are used: 40lcy;
– Wastes retained in water where non-degradable anal cleansing materials are used: 60lcy;
– Wastes retained in dry conditions where degradable anal cleansing materials are used: 60lcy;
– Wastes retained in dry conditions where non-degradable anal cleansing materials are used: 90lcy.
For pour-flush facilities where water cannot infiltrate and be emptied at regular intervals: it is estimated at 4.2 lcd (2 for additional flush water),
For small networks (small bore sewerage, solids free sewerage) where domestic drinking water network is available: it is estimated that 80% of the drinking water supply ends up in the sanitation system.

References, tips, examples

Examples:
Simple pit latrines emptied at regular intervals and with poor pit infiltration: only water used for anal cleansing and cleaning the toilet enters the receptacle together with the volume of urine and faeces. Typical volume for anal cleansing is 1 litre per person per day (lcd or litres per capita per day). Typical volume of fresh urine and faeces is 1.2 lcd. Hence, for 1.000 people: 1.000 * (1+1.2) = 2,200 litres or 2.2 m3/day;
Pour-flush facility where water cannot infiltrate, emptied at regular intervals: water used for anal cleansing and for manually flushing the toilet enters the receptacle. A typical volume for pour-flush is 2-3 lcd. Hence, for 1,000 people: 1,000 * (3+1.2) = 4,200 litres or 4.2 m3/day;
Small network (small bore sewerage, solids free sewerage) where domestic drinking water network is available: when wastewater is collected, conveyed and treated, usually 80% of the drinking water supply ends up in the system. Hence, if for example drinking water is 25lcd, wastewater is 25 * 0.8 = 20lcd. Hence, for 1,000 people: 1,000 * 20 = 20,000 litres or 20 m3/day.

Why is it important to measure it

The real input flow can be compared with the design flow and upgrades or flow increases can be planned accordingly.

TS reduction

Definition of the indicator

Total solids is the measurement of the concentration of particulate solids that can dissolve or suspend in wastewater. It is commonly expressed as mass of solids in comparison to volume of solution  (% weight-volume).
The reduction is related to the total solids concentration of the effluent exiting the faecal sludge treatment site in comparison to the total solids concentration of the influent entering the faecal sludge treatment site.

Unit/value: %

How to measure or calculate it

The reduction is calculated as a relative percentage of the average total solids value of the effluent exiting the faecal sludge treatment site over the average total solids value of the influent entering the faecal sludge treatment site in the same period.
% = (1-Ce/Ci) x 100
with Ce = effluent TS concentration (mg/l)
Ci = influent TS concentration (mg/l)

The laboratory test protocol can be found at:
The STeP Global Testing Protocols & Parameters – A best practices guide for testing sanitation technologies in the field
http://stepsforsanitation.org/?smd_process_download=1&download_id=4171

References, tips, examples

Septage (contents of a septic tank) usually has a low percentage of solids (typically 1-2 %) and faecal sludge from pit latrines usually has a high percentage of solids (typically 10-15%). Example values from Zambia: 7-15% for pit latrines and 1-2% for septic tanks.
For example if the influent TS concentration of the treatment plant is 1000 mg/l and the effluent TS concentration is 400 mg/l:
(1-400/1000) x 100 = 60% of TS reduction.

Why is it important to measure it

Faecal sludge characteristics vary widely between cities, types of on-site sanitation systems and types of emptying system used. Samples taken from the same pit latrine can have significant variations in standard physio-chemical testing, which impacts how sludge must be treated.
Suspended solid can lead to the development of sludge deposits and anaerobic conditions when untreated wastewater is discharged in the aquatic environment.
Moreover, as an example, solids content is an important parameter to estimate the volume of dried sludge to be removed from the drying beds of sludge treatment plants.

COD reduction

Definition of the indicator

Chemical oxygen demand (COD) is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution. It is commonly expressed in mass of oxygen consumed over volume of solution  (mg/L) and is composed principally of proteins, carbohydrates and fats.
The reduction is related to the COD concentration of the effluent exiting the faecal sludge treatment site in comparison to the COD concentration of the influent entering the faecal sludge treatment site.

Unit/value: %

How to measure or calculate it

The reduction is calculated as a relative percentage of the average COD value of the effluent exiting the faecal sludge treatment site over the average COD value of the influent entering the faecal sludge treatment site in the same period.
% = (1-Ce/Ci) x 100
with Ce = effluent COD concentration (mg/l)
Ci = influent COD concentration (mg/l)

The laboratory test protocol can be found at:
The STeP Global Testing Protocols & Parameters – A best practices guide for testing sanitation technologies in the field
http://stepsforsanitation.org/?smd_process_download=1&download_id=4171

References, tips, examples

If the influent COD concentration of the treatment plant is 3000 mg/l and the effluent COD concentration is 1000 mg/l:
(1-1000/3000) x 100 = 66% of COD reduction.
Influent values example from Zambia: 50,000-100,000mg/l for pit latrines and 10,000-20,000mg/l for septic tanks

Why is it important to measure it

Faecal sludge characteristics vary widely between cities, types of on-site sanitation systems and types of emptying system used. Samples taken from the same pit latrine can have significant variations in standard physio-chemical testing, which impacts how sludge must be treated.
The COD parameter monitors the available oxygen which has a direct impact on aquatic life. If biodegradable organics are discharged untreated to the environment, their biological stabilisation can lead to the depletion of natural oxygen resources and to the development of septic conditions.

Faecal coliforms reduction

Definition of ithe ndicator

Faecal coliforms are pathogenic organisms that can transmit diseases. They include genera that originate in feces (e.g. Escherichia) as well as genera not of faecal origin (e.g. Enterobacter, Klebsiella, Citrobacter). It is an indicator of faecal contamination, indicating the presence of other pathogens. E.Coli are part of the feacal coliforms that can be tested. They are commonly expressed in colony forming units over 100mL volume of solution  (CFU/100mL), or in Log (1 log = 1000 CFU/100mL).
The reduction is related to the faecal coliforms concentration of the effluent exiting the faecal sludge treatment site in comparison to the faecal coliforms concentration of the influent entering the faecal sludge treatment site.

Unit/value: Log Reduction

How to measure or calculate it

The reduction is calculated as COMPLEMENTARY PERCENTAGE of the average faecal coliforms of effluent exiting the faecal sludge treatment site over the average faecal coliforms of influent entering the faecal sludge treatment site in the same period.

References, tips, examples

If the number of faecal coliforms in the influent of the treatment plant is 1*10^6 and the number of faecal coliforms in the effluent is 1000:
log10(1*10^6)-log(1000) = 3  Log Reduction.
Example values from Zambia: 2*107 CFU/100ml for pit latrines and 1*105 CFU/100ml for septic tanks

Why is it important to measure it

Faecal sludge characteristics varies widely between cities, types of on site sanitation systems and type of emptying system used. Even samples taken from the same pit latrine have been shown to have significant variation in standard physio-chemical testing.  Such characteristics impact how sludge can be processed following removal. Stabilised sludge is very poor in terms of gas release in an anaerobic digester.

Objective

Definition of indicator

The objective, in this case, is the desired treatment or modification of the input sludge before disposal or reuser.

How to measure or calculate it ?

If possible, revise design  document and ask to the design team or consultants: the objective should have been considered to design and dimension the faecal sludge treatment site. Usually, the objective is related to the quality of input sludge and the environmental conditions of disposal sites or the desired reusing methodology.

Why it is important to measure it

This is very important to design the faecal sludge treatment site and to evaluate the efficacy of the treatment.

Skills level

Definition of the indicator

This indicates if the knowledge and experience level of an FSM specialist is required to be able to design, contruct, operate and maintain the faecal sludge treatment site successfully.
Communitarian operation means the faecal sludge treatment system is operated exclusively by the beneficiary community without constant external support.

Unit/value: 

FSM specialist for design
FSM specialist for construction
FSM specialist for operation and maintenance
Communitarian operation

How to measure or calculate it

For design: the indicator is determined by assessing the design process and understanding if specialists were involved or not.
For construction: the indicator is determined by assessing the construction process (including selection of contractors or construction staff) and understanding if specific contractors and specialists for special supervision, know-how, equipment use were involved or not.
For operation and maintenance: analyse the CV of the manager of the O&M of the faecal sludge treatment site and identify if he/she has completed higher education related to FSM and if this education is strictly necessary for his/her role.
For community operation: analyse responsibilities and tasks of the faecal sludge treatment site management. Identify if they are covered by the beneficiary community. If there is occasional external support, still consider that the site is completely operated by the community.

References, tips, examples

Example of different design skills in the same context: the design of Oxfam’s large scale faecal sludge treatment site in Cox’s Bazaar was implemented in collaboration with Borda (sanitation experts); Oxfam’s small lime stabilization faecal treatment site was implemented by WASH officers (not FSM specialists).

Why is it important to measure it

This indicator is important to know what kind of skills are needed to have a properly functioning treatment plant, to be able to hire the right people for the task and to select the technologies according to the local skills available.

Risque d’inondation

Définition de l’indicateur

L’indicateur précise si la zone où se situe le site de traitement de boues de vidange est sujette aux inondations.

Comment le mesurer ou le calculer ?

En vous appuyant sur la documentation et les connaissances locales, vérifiez à quand remonte la dernière inondation du site de traitement de boues de vidange. L’indicateur précise si la zone où se situe le site de traitement a déjà été inondée pendant une période antérieure égale à la durée de vie du projet (voir indicateur) et si rien n’a été fait pour éviter les inondations dans la zone pendant la construction. L’indicateur prend en considération uniquement le site de traitement de boues de vidange, sans tenir compte des routes d’accès ou des latrines.

Pourquoi c’est important de le mesurer

Les boues de vidange sont des matières potentiellement dangereuses : les inondations peuvent provoquer l’arrêt de l’exploitation pendant plusieurs semaines et/ou répandre la contamination fécale en dehors du site de traitement de boues de vidange.

Réduction de la DBO

Définition de l’indicateur

La Demande Biochimique en Oxygène (DBO) est la quantité d’oxygène dissoute requise (c.-à-d. exigée) par les organismes biologiques aérobies pour pouvoir décomposer les matières organiques présentes dans un échantillon d’eau donné à une certaine température pendant une période de temps spécifique. La valeur de la DBO s’exprime le plus souvent en milligrammes d’oxygène consommés par litre d’échantillon pendant 5 jours d’incubation à 20°C (mg/l).
La réduction fait référence à la DBO de l’effluent sortant du site de traitement de boues de vidange par rapport à la DBO de l’influent entrant dans le site de traitement de boues de vidange.

Comment le mesurer ou le calculer ?

TLa réduction se calcule comme un POURCENTAGE COMPLÉMENTAIRE de la DBO moyenne de l’effluent sortant du site de traitement de boues de vidange, divisé par la DBO moyenne de l’influent entrant dans le site de traitement de boues de vidange pendant la même période.

Pourquoi c’est important de le mesurer

Les caractéristiques des boues de vidange varient beaucoup selon la ville de provenance, le type de système d’assainissement sur place et le système de vidange utilisé. Dans des échantillons issus de la fosse d’une seule latrine, on a même constaté des variations significatives lors des analyses physico-chimiques standards. La DBO dans les latrines à fosse peut baisser avec la profondeur (avec l’augmentation de l’âge des boues), ce qui démontre une stabilité croissante des boues et donc une diminution de la dégradation microbienne. De tels caractéristiques influent sur la méthode de traitement des boues après leur enlèvement. Les boues stabilisées ont un rendement très faible de gaz dans un digesteur anaérobie.

Réduction de la DCO

Définition de l’indicateur

La Demande Chimique en Oxygène (DCO) sert à mesurer, à titre indicatif, la quantité d’oxygène qui peut être consommée par des réactions dans une quantité de solution donnée. Elle s’exprime généralement en masse d’oxygène consommée par rapport au volume de solution (mg/l).
La réduction fait référence à la DCO de l’effluent sortant du site de traitement de boues de vidange par rapport à la DCO de l’influent entrant dans le site de traitement de boues de vidange.

Comment le mesurer ou le calculer ?

La réduction se calcule comme un POURCENTAGE COMPLÉMENTAIRE de la DCO moyenne de l’effluent sortant du site de traitement de boues de vidange, divisé par la DCO moyenne de l’influent entrant dans le site de traitement de boues de vidange pendant la même période.

Pourquoi c’est important de le mesurer

Les caractéristiques des boues de vidange varient beaucoup selon la ville de provenance, le type de système d’assainissement sur place et le système de vidange utilisé. Dans des échantillons issus de la fosse d’une seule latrine, on a même constaté des variations significatives lors des analyses physico-chimiques standards. De tels caractéristiques influent sur la méthode de traitement des boues après leur enlèvement. Les boues stabilisées ont un rendement très faible de gaz dans un digesteur anaérobie.

Gestion exclusive de l’exploitation par la communauté

Définition de l’indicateur

Cet indicateur précise si le système de traitement de boues de vidange est gérée exclusivement par la communauté bénéficiaire sans aucun soutien extérieur régulier.

Comment le mesurer ou le calculer ?

Étudiez les tâches et les responsabilités liées à la gestion du site de traitement de boues de vidange. Déterminez si elles sont toutes couvertes par la communauté bénéficiaire ou une partie de celle-ci. Si on fait appel à des soutiens extérieurs ponctuels, il faut néanmoins considérer que le site est entièrement géré par la communauté.

Pourquoi c’est important de le mesurer

Il est important de reconnaître la complexité des opérations par rapport aux compétences de la communauté afin de planifier la gestion du site de traitement de boues de vidange et de prévoir la pérennité du projet dans la durée.

Dépenses d’investissement par rapport au flux actuel (hors coûts de terrain)

Définition de l’indicateur

Cet indicateur désigne le total des coûts suivants :

– Dépenses préliminaires et générales (entreprises de transport/services généraux et supervision, sécurité, assurance, connexion à l’alimentation électrique, etc.)
– Travaux de génie civil
– Travaux électromécaniques : pompes, GenSet (group électrogène)
– Conception (en général, 5 % des coûts électromécaniques et de génie civile)
– Supervision de la mise en œuvre (en général, 5-15 % des coûts électromécaniques et de génie civile)

divisé par le flux actuel.

Comment le mesurer ou le calculer ?

Tous les investissements nécessaires pour construire et mettre en place le système de traitement de boues de vidange (HORS L’ACHAT DE TERRAIN) doivent être pris en compte et divisés par le flux entrant réel (voir indicateur). Cela inclut également une part des ressources humaines impliquées dans la conception et la construction, qui peuvent également effectuer d’autres tâches.

Pourquoi c’est important de le mesurer

Le ratio des dépenses d’investissement au flux actuel pour un site de traitement de boues de vidange sera différent d’un endroit à un autre, essentiellement en fonction des coûts de transport.

Dépenses d’investissement par rapport au flux actuel (y compris les coûts de terrain)

Définition de l’indicateur

Cet indicateur désigne le total des coûts suivants :

– Dépenses préliminaires et générales (entreprises de transport/services généraux et supervision, sécurité, assurance, connexion à l’alimentation électrique, etc.)
– Achat de terrain
– Travaux de génie civil
– Travaux électromécaniques : pompes, GenSet (group électrogène)
– Conception (en général, 5 % des coûts électromécaniques et de génie civile)
– Supervision de la mise en œuvre (en général, 5-15 % des coûts électromécaniques et de génie civile)

divisé par le flux actuel.

Comment le mesurer ou le calculer ?

Tous les investissements nécessaires pour construire et mettre en place le système de traitement de boues de vidange doivent être pris en compte et divisés par le flux entrant réel (voir indicateur). Cela inclut également une part des ressources humaines impliquées dans la conception et la construction, qui peuvent également effectuer d’autres tâches.

Pourquoi c’est important de le mesurer

Le ratio des dépenses d’investissement au flux actuel pour un site de traitement de boues de vidange sera différent d’un endroit à un autre, essentiellement en fonction des coûts de transport.

Population bénéficiaire considérée pour la conception

Définition de l’indicateur

Nombre de personnes pouvant bénéficier du service de traitement de boues de vidange.

Comment le mesurer ou le calculer ?

Etudiez la population actuelle et ses tendances de croissance et de déplacement. A l’intérieur d’une population stable croissante, la population à desservir peut être calculée de la manière suivante :
Pn = P0 * (1 + i)^n
Pn = la population en année ‘n’ (consulter l’indicateur de durée de vie)
n = la période d’exploitation prévue
P0 = la population en année 0
i = la croissance annuelle de la population
Par contre, dans un contexte humanitaire, ce chiffre a tendance à évoluer selon le contexte de sécurité (estimation de la population affectée par une catastrophe naturelle/d’origine humaine).

Pourquoi c’est important de le mesurer

Lorsqu’on connaît la population, on dispose d’une base solide pour dimensionner le site de traitement : dimensionnement des réservoirs ET dimensionnement des éventuels pompes, lits de séchage, etc.

Flux entrant considéré pour la conception

Définition de l’indicateur

Cet indicateur précise le flux de boues pour lequel le site de traitement a été conçu.

Comment le mesurer ou le calculer ?

Si possible, passez en revue le document de calcul du projet et demandez conseil à l’équipe ou aux consultants en charge de la conception. Le flux entrant aurait dû être pris en considération pour dimensionner le projet. De manière générale, si ce n’est pas possible de le mesurer sur le terrain, on estime le flux entrant de la manière suivante :
Pour des latrines à fosse simples en contexte d’urgence, vidangées à intervalles régulières avec peu d’infiltration dans le sol : on estime 2,2 l/p/j (1 l pour le nettoyage anal et le nettoyage des toilettes + 1,2 l de fèces),
Pour des fosses simples en contexte d’urgence où l’effluent peut s’infiltrer, vidangées à intervalles régulières, il faut envisager les taux d’accumulation de boues suivants :
 Déchets résiduels dans l’eau lorsque l’eau est utilisée pour le nettoyage anal : 25 litres par personne par année (l/p/a) ;
 Déchets résiduels dans l’eau lorsque des matières biodégradables sont utilisées pour le nettoyage anal : 40 l/p/a ;
 Déchets résiduels dans l’eau lorsque des matières non-biodégradables sont utilisées pour le nettoyage anal : 60 l/p/a ;
 Déchets résiduels en milieu sec lorsque des matières biodégradables sont utilisées pour le nettoyage anal : 60 l/p/a ;
 Déchets résiduels en milieu sec lorsque des matières non-biodégradables sont utilisées pour le nettoyage anal : 90 l/p/a ;
Pour des installations à chasse d’eau manuelle où l’eau ne peut s’infiltrer, vidangées à intervalles régulières, on estime 4,2 l/p/j (2 l pour l’eau de chasse additionnelle),
Pour les petits réseaux (égouts de faible diamètre, égouts sans matières solides) et lorsqu’il y a également un réseau d’eau potable domestique : on estime que 80% de l’eau potable distribuée se retrouve dans le système d’assainissement.
Dans certaines conditions environnementales et pour certaines infrastructures, on doit tenir compte de l’infiltration des eaux souterraines à l’intérieur des installations d’assainissement.

Pourquoi c’est important de le mesurer

Lorsqu’on connaît le flux entrant consideré pour la conception, on dispose d’une base solide pour dimensionner le site de traitement : dimensionnement des réservoirs ET dimensionnement des éventuels pompes, lits de séchage, etc. La quantité de boues peut largement excéder le volume d’urines et de fèces, ce qui aura un impact important sur le dimensionnement. Si on néglige cet aspect, les infrastructures seront trop petites, ce qui raccourcira les temps de rétention/traitement et produira des résultats médiocres.

Réduction des coliformes fécaux

Définition de l’indicateur

Les coliformes fécaux sont des bactéries anaérobies facultatives, de forme allongée, non-sporulantes, à Gram négatif. Les bactéries coliformes proviennent généralement des intestins des animaux à sang chaud. Les coliformes fécaux sont capables de se développer en présence de sels biliaires ou d’autres tensioactifs similaires. Ils sont oxydase négative et fermentent le lactose avec production d’acide et de gaz à 44 ± 0,5°C en 48 heures. Le terme ‘coliforme thermotolérant’, plus exact, gagne progressivement du terrain sur ‘coliforme fécal’.
Les bactéries coliformes comprennent des genera provenant des fèces (ex. Escherichia) ainsi que des genera qui ne sont pas d’origine fécale (ex. Enterobacter, Klebsiella, Citrobacter). L’analyse vise à indiquer une contamination fécale ; en particulier par E. coli, un micro-organisme indicateur d’autres pathogènes pouvant être présents dans les fèces. Les coliformes fécaux s’expriment généralement en unités formant des colonies (UFC) par rapport à 100 ml de solution (UFC/100 ml).
La réduction fait référence aux coliformes fécaux présents dans l’effluent sortant du site de traitement de boues de vidange par rapport aux coliformes fécaux présents dans l’influent entrant dans le site de traitement de boues de vidange.

Comment le mesurer ou le calculer ?

La réduction se calcule comme un POURCENTAGE COMPLÉMENTAIRE de la moyenne des coliformes fécaux dans l’effluent sortant du site de traitement de boues de vidange, divisé par la moyenne des coliformes fécaux dans l’influent entrant dans le site de traitement de boues de vidange pendant la même période.

Pourquoi c’est important de le mesurer

Les caractéristiques des boues de vidange varient beaucoup selon la ville de provenance, le type de système d’assainissement sur place et le système de vidange utilisé. Dans des échantillons issus de la fosse d’une seule latrine, on a même constaté des variations significatives lors des analyses physico-chimiques standards. De tels caractéristiques influent sur la méthode de traitement des boues après leur enlèvement. Les boues stabilisées ont un rendement très faible de gaz dans un digesteur anaérobie.

Durée de vie et fiabilité

Définition de l’indicateur

Cet indicateur précise la durée prévue de fonctionnement du site de traitement de boues de vidange au moment de sa conception.

Comment le mesurer ou le calculer ?

Définissez les besoins immédiats et à long terme. Étudiez les tendances de croissance et de déplacement de la population (voir l’indicateur de population bénéficiaire considérée pour la conception), ainsi que les engagements des donateurs et des acteurs impliqués à l’avenir.

Pourquoi c’est important de le mesurer

Il est important de connaître la période d’exploitation prévue pour aider à calculer la population bénéficiaire considérée pour la conception (voir indicateur) du site de traitement de boues de vidange. En outre, il est important de connaître la durée de vie requise du site de traitement afin de choisir des matériaux de construction appropriés.

Utilisation de matériaux disponibles sur place

Définition de l’indicateur

Les matériaux disponibles sur place sont des matériaux qui n’ont pas besoin d’être importés.

Comment le mesurer ou le calculer ?

Vérifiez si une clôture a été installée sur tout le périmètre du site de traitement de boues de vidange. Identifiez les points faibles où des personnes, animaux ou véhicules non impliqués dans le processus de traitement pourraient entrer sur le site.

Pourquoi c’est important de le mesurer

Une clôture adéquate est obligatoire en toutes circonstances, ainsi que la présence d’agents de sécurité 24 h sur 24 : les boues de fosses septiques, les eaux usées et les boues de vidange sont des matières dangereuses qui peuvent facilement être utilisées pour contaminer une communauté entière. Pensez au vandalisme en perçant un trou dans un réservoir souple plein de boues.

Objectifs de la solution

Définition de l’indicateur

Dans ce cas, l’objectif est le traitement ou la modification souhaité des boues entrantes, avant leur élimination ou réutilisation.

Comment le mesurer ou le calculer ?

Si possible, passez en revue le document de conception et demandez conseil à l’équipe de consultants en charge de la conception: l’objectif aurait dû être pris en considération pour concevoir et dimensionner le site de traitement de boues de vidange. De manière générale, l’objectif fait référence à la qualité des boues entrantes et aux conditions environnementales des sites d’élimination ou à la méthodologie de réutilisation souhaitée.

Pourquoi c’est important de le mesurer

C’est très important pour concevoir le site de traitement de boues de vidange et pour évaluer l’efficacité du traitement.

Flux entrant réel

Définition de l’indicateur

Cet indicateur est nécessaire pour connaître le volume réel de boues traitées actuellement au site de traitement de boues de vidange.

Comment le mesurer ou le calculer ?

Calculez le flux entrant réel soit en mesurant le volume de boues dans les citernes transportées vers le site de traitement, soit en mesurant le débit des pompes et leur temps de fonctionnement pendant le vidange des boues. Prenez une valeur moyenne qui tient également compte des jours d’inactivité du site de traitement de boues de vidange.

Pourquoi c’est important de le mesurer

Lorsqu’on connaît le flux entrant réel, on peut le comparer avec le flux entrant considéré pour la conception et la production de boues sortant pour donner des indications importantes sur une mise à niveau éventuelle.

Surface nécessaire

Définition de l’indicateur

Il s’agit de la surface occupée par le site de traitement de boues de vidange par rapport à la population considérée pour la conception (voir indicateur).

Comment le mesurer ou le calculer ?

Mesurez, soit sur le terrain, soit au niveau des plans du projet, la superficie totale du site de traitement de boues de vidange et divisez-le par la population considérée pour la conception (voir indicateur).

Pourquoi c’est important de le mesurer

Dans un contexte humanitaire, les populations sont souvent obligées de s’installer dans des zones surpeuplées où les conditions environnementales sont défavorables. Cela impacte également l’espace disponible pour des sites de traitement de boues de vidange et des infrastructures d’assainissement en général.

Niveau de compétences requis pour la construction

Définition de l’indicateur

Cet indicateur précise le niveau de connaissances et d’expérience nécessaires pour mener à bien la construction d’un site de traitement de boues de vidange.

Comment le mesurer ou le calculer ?

On obtient cet indicateur en évaluant le déroulement de la construction (y compris la sélection des entreprises ou du personnel de construction) pour déterminer si on a fait appel ou non à des entreprises spécifiques ou à des spécialistes pour apporter une supervision, des savoir-faire ou des équipements particuliers.

Pourquoi c’est important de le mesurer

Les boues de vidange sont des matières potentiellement dangereuses : une simple erreur dans la construction des infrastructures peut provoquer l’arrêt de l’exploitation pendant plusieurs semaines et influer sur la pérennité du traitement des boues de vidange.

Provenance des boues

Définition de l’indicateur

Cet indicateur précise le type d’infrastructure d’assainissement d’où proviennent les boues.

Comment le mesurer ou le calculer ?

S’ils existent, étudiez les rapports de vidange de boues où ces informations sont enregistrées. Sinon, observez les activités de vidange de boues et les infrastructures d’assainissement d’où proviennent les boues. Parlez avec les personnes responsables de la vidange de boues.

Pourquoi c’est important de le mesurer

Il est important de connaître la provenance des boues pour pouvoir évaluer leurs caractéristiques et déterminer la probabilité qu’elles soient contaminées par des pathogènes (bien entendu toutes les boues de vidange doivent être traitées comme des matières dangereuses mais les déchets hospitaliers risquent d’être encore plus dangereux et nécessitent une attention particulière).

Réduction des MS

Définition de l’indicateur

Les Matières Sèches (MS) regroupent les Solides Dissous Totaux (SDT) + les Matières En Suspension (MES). Elles s’expriment généralement en masse de matières solides par rapport au volume de solution (% poids-volume).
La réduction fait référence aux matières sèches dans l’effluent sortant du site de traitement de boues de vidange par rapport aux matières sèches dans l’influent entrant dans le site de traitement de boues de vidange.

Comment le mesurer ou le calculer ?

La réduction se calcule comme un POURCENTAGE COMPLÉMENTAIRE de la moyenne des matières sèches dans l’effluent sortant du site de traitement de boues de vidange, divisé par la moyenne des matières sèches dans l’influent entrant dans le site de traitement de boues de vidange pendant la même période.

Pourquoi c’est important de le mesurer

Les caractéristiques des boues de vidange varient beaucoup selon la ville de provenance, le type de système d’assainissement sur place et le système de vidange utilisé. Dans des échantillons issus de la fosse d’une seule latrine, on a même constaté des variations significatives lors des analyses physico-chimiques standards. De tels caractéristiques influent sur la méthode de traitement des boues après leur enlèvement. Les boues stabilisées ont un rendement très faible de gaz dans un digesteur anaérobie.
La teneur en substance solide est un paramètre important pour estimer le volume de boues séchées qu’il faudra enlever des lits de séchage des stations de traitement de boues.

Type de produits issus du traitement

Définition de l’indicateur

Cet indicateur précise si les principaux produits issus du site de traitement de boues de vidange se composent uniquement de boues, d’effluent, ou des deux.

Comment le mesurer ou le calculer ?

Observez si on peut distinguer deux produits différents suite aux mécanismes de séparation des matières solides/liquides, en se basant sur leur densité et leur teneur en substance solide.

Pourquoi c’est important de le mesurer

Savoir s’il y a des produits sortants différents permet de prévoir la création de chaînes de traitement et de mécanismes d’élimination spécifiques et différenciés.

Indicators notice

Definition of indicator

The objective, in this case, is the desired treatment or modification of the input sludge before disposal or reuser.

How to measure or calculate it ?

If possible, revise design  document and ask to the design team or consultants: the objective should have been considered to design and dimension the faecal sludge treatment site. Usually, the objective is related to the quality of input sludge and the environmental conditions of disposal sites or the desired reusing methodology.

Why it is important to measure it

This is very important to design the faecal sludge treatment site and to evaluate the efficacy of the treatment.

Definition of Indicator

This indicator defines at the moment of design how long the faecal sludge treatment site should be operational..

How to measure or calculate it ?

Identify immediate and long term needs. Analyse population growth and movements trends (see design beneficiary indicator), donors and implementing actors commitments.

References, tips, examples

The size of the population today might be 1,000 persons (often referred to as ‘capita’), but in 1 year this may double and in 5 years this might increase ten-fold; moreover it is important to know how long the facility will need to last to determine the building materials to use.

Why it is important to measure it ?

It is important to know the design period as this will help to calculate the designed beneficiary population (see indicator) of the faecal sludge treatment site. Moreover, it is important to know how long the facility will need to last to determine the building materials to use.

Definition of indicator

This indicates the level of knowledge and experience required to be able to design faecal sludge treatment site successfully.

How to measure or calculate it ?

The indicator is determined by assessing the design process and understanding if specialists were involved or not.

References, tips and/or examples

Example of different design skills in the same context: Design of large scale faecal sludge treatment site of Oxfam in Cox Bazar was implemented in collaboration with Borda (sanitation experts). The small lime stabilization faecal treatment site of Oxfam was implemented by the ‘regular’ WASH officers.

However it’s always preferable to check designs with FSM specialists as in practice the law of Murphy rules: anything that can go wrong, will go wrong.
So for example also during the design of a simple facility such as a septic tank the following mistakes are common:
– inlet and outlet are mixed up;
– plans and cross-sections are mixed up;
– capacity of the facility is far too large;
– absence of ventilation pipes;
– absence of infiltration facilities;
– leaking tanks;
Etc., etc. etc.

Why it is important to measure it ?

Faecal sludge is a potentially dangerous material: a simple mistake impacts the lives of many people
This indicator is important for actors interested in implementing faecal sludge treatment for planning reasons.

Definition of indicator

The indicator defines if the technology also works well if ground-water is less than 1 metre from ground levelat least for a part of the year

How to measure or calculate it ?

Check, at the end of rainy season, the groundwater table at the faecal sludge site by digging a pit and/or checking dug wells nearby (in the early morning before water is taken and water level drops).
If it’s not possible to do it at the end of rainy season, ask for information from the local population about water level in the wells during the year.

References, tips, examples

In areas with high water tables, it might be a challenge to dig pits/ tanks as pumps for keeping the pit dry might be absent. Even if pumps are available, care must be taken to avoid floating of empty tanks. Floating can be avoided by adding enough weight (stones, concrete) to the tank to prevent floating. Hence, above ground / raised facilities are advised such as raised Oxfam tanks.

Why it is important to measure it ?

Faecal sludge is potentially dangerous material and when in contact with water, contaminants will spread easily and quickly. Moreover, construction in areas with high ground water table requires extra measures and more complex structures (expensive).

Definition of indicator

It defines the type of sanitation infrastructures from which the sludge comes from

How to measure or calculate it ?

If existing, analyse the documents of desludging which report this information, otherwise observe the desludging activities and the sanitation infrastructures from which the sludge comes from. Talk with people in charge of desludging.

References, tips, examples

Hospitainer has developed specific solutions for hazardous hospital waste in the framework of S(p) eedkits : https://hospitainer.com/add-ons/sanitation/ . Both IBBK and A-aqua have developed sludge pasteurizers: http://www.a-aqua.no/Products-Services/Humanitarian-Aid/Hygieniser100-Sludge-Pasteurising-Unit ;

Why it is important to measure it ?

It is important to know the source to estimate the characteristics of the sludge and likeliness of contamination with pathogens (of course, any faecal sludge needs to be treated as hazardous material but waste from hospitals is likely to be more hazardous and needs special attention.)

Definition of indicator

Number of people who can benefit from the faecal sludge treatment service.

How to measure or calculate it ?

Analyse current population, its growth and movement trends. In a stable growing population, population to be served can be calculated as follows:
Pn = P0 * (1+i)^n
Pn = Population in year ‘n’ (refer to life expectancy indicator)
n = design period
P0 = Population in year 0
i = annual growth of the population
However in humanitarian context, this will usually depend on the security context (forecast of the population affected by the natural /manmade disaster).

References, tips, examples

Example:
n = design period (say 5 years)
P0 = Population in year 0 (say 1,000)
i = annual growth of the population (say 10% influx per year)]
P5 = 1,000 * (1+0.1)^5 = 1,610 persons, say 1,600

Why it is important to measure it ?

When the population is known, there is a solid basis for sizing the facility: sizing of the tanks AND sizing of any pumps, drying beds, etc.

Definition of indicator

This is the space occupied by the faecal sludge treatment site in relationship with the design beneficiary population (see indicator).

How to measure or calculate it ?

Measure in the field, or in the project designs, the total area of the faecal sludge treatment site and divide it by the design beneficiary population (see indicator).

Why it is important to measure it ?

In humanitarian contexts, the population is often obliged to settle in crowed areas with unfavourable environmental conditions. This has a consequence also on the availability of space for faecal sludge treatment sites and sanitation facilities in general.

Definition of indicator

This indicator, in this case, defines the general slope of the area of the sludge treatment site.

How to measure or calculate it ?

If some types of topography are equally present, please provide multiple answers.

Why it is important to measure it ?

The topography may determine the type of treatment facilities to be built and may influence the transport and pumping costs.

Definition of indicator

This indicator defines for which sludge flow the facility has been designed.

How to measure or calculate it ?

If possible, revise design calculation document and ask the design team or consultants. The design input flow should have been considered for dimensioning. Usually, if it’s not possible to measure in the field, the input flow is estimated as follows:
For emergency simple pit latrines emptied at regular intervals and with poor pit infiltration: it is estimated 2.2 lcd (1 for anal cleansing and toilet cleaning + 1.2 for faeces)
For emergency simple pits where effluent can infiltrate and latrines are emptied at regular intervals consider the following sludge accumulation rates:
 Wastes retained in water where water is used as anal cleansing material: 25 litres per capita per year (lcy);
 Wastes retained in water where degradable anal cleansing materials are used: 40lcy;
 Wastes retained in water where non-degradable anal cleansing materials are used: 60lcy;
 Wastes retained in dry conditions where degradable anal cleansing materials are used: 60lcy;
 Wastes retained in dry conditions where non-degradable anal cleansing materials are used: 90lcy;
For pour-flush facilities where water cannot infiltrate, emptied at regular intervals: it is estimated 4.2 lcd (2 for additional flush water),
For small network (small bore sewerage, solids free sewerage) where domestic drinking water network is available: it is estimated 80% of the drinking water supply ends up in the sanitation system.
For some environmental conditions and infrastructures, groundwater infiltration inside the sanitation facilities should have been considered.

References, tips, examples

Example:
Simple pit latrines emptied at regular intervals and with poor pit infiltration: only water used for anal cleansing and cleaning the toilet enters the receptacle together with the volume of urine and faeces. Typical volume for anal cleansing is 1 litre per person per day (lcd or litres per capita per day). Typical volumes of fresh urine and faeces 1.2 lcd. Hence, for 1.000 people: 1.000 * (1+1.2) = 2,200 litres or 2.2 m3/day;
Pour-flush facility where water cannot infiltrate, emptied at regular intervals: water used for anal cleansing AND manually flushing the toilet enters the receptacle. Typical volume for pour-flush is 2-3 lcd. Hence, for 1,000 people: 1,000 * (3+1.2) = 4,200 litres or 4.2 m3/day;
Small network (small bore sewerage, solids free sewerage) where domestic drinking water network is available. When wastewater is collected and conveyed and treated, usually taken as 80% of the drinking water supply ends up in the system. Hence, if for example drinking water is 25lcd, wastewater is 25 * 0.8 = 20lcd. Hence, for 1,000 people: 1,000 * 20 = 20,000 litres or 20 m3/day.

Why it is important to measure it ?

When the design flow is known, there is a solid basis for sizing the facility: sizing of the tanks AND sizing of any pumps, drying beds, etc. Sludge can easily be much more than the volume of urine and faeces and has a big impact on the sizing. If this is neglected, the facilities are too small and retention / treatment times are shortened, resulting in poor results.

Definition of indicator

The indicator defines if the main outputs of the faecal sludge treatment site are composed only of sludge, effluent or both

How to measure or calculate it ?

Observe if two different outputs originating from solid/liquid separation mechanisms can be distinguished on the basis of their density and solids content.

References, tips, examples

For example, the ratio between the two in the simplest treatment system (sludge drying beds) has been assessed as following:
septage (contents of a septic tank) % of solids (typically 1-2 %)
faecal sludge from pit latrines with a high % of solids (typically 10-15%).
Solids content is an important parameter to estimate the volume of dried sludge to be removed from the drying beds of sludge treatment plants. After 2 weeks drying period the typical solids content is 40% dry solids. Hence, 1 m3 (1,000 litres) of septage containing 1% of dry solids has been decreased to 1,000 *1%/(40%) = 25 kg of biosolids. The remainder (typically 1,000-25 = 975 litres has partially evaporated, partially drained away. The drainage water, say max 975 litres, needs to be treated in a filter / pond system. Also, 1 m3 (1,000 litres) of faecal sludge containing 15% of dry solids has been decreased to 1,000 *15%/(40%) = 375 kg of biosolids. The remainder (typically 1,000-375 = 625 litres has partially evaporated, partially drained away. The drainage water, say max 625 litres, needs to be treated in a filter / pond system

Why it is important to measure it ?

Knowing if there are different outputs enables the creation of specific different treatment chains and disposal mechanisms.

Definition of indicator

Locally available material is material that doesn’t need to be imported.

How to measure or calculate it ?

Analyse the purchase documents for the faecal sludge treatment site and equipment and identify material imported from abroad.

References, tips, examples

Typical imported materials are the raised latrines discussed above, Oxfam tanks for sludge treatment (e.g. lime treatment) and a ‘plug-and-play’ wastewater treatment plant for a hospital.

Why it is important to measure it ?

During the first few days of an emergency, it might be difficult to source local material. Hence, these need to be flown in. However, locally available material should as much as possible be sourced to reduce construction costs.

Definition of indicator

Barrier which doesn’t allow entrance to the faecal sludge treatment site for people, animals, vehicles who are not involved in the treatment operations.

How to measure or calculate it ?

Observe if a fencing is in place all along the perimeter of the faecal sludge treatment site. Identify if there are any weak points which allow people, animals, or vehicles who are not involved in the treatment operations to enter the site.

Why it is important to measure it ?

Adequate fencing is a must under all circumstances in conjunction with 24/7 guards: septage, wastewater and faecal sludge are hazardous material and can easily be used to contaminate the entire community. Think of vandalism by punching a hole in a bladder full of sludge.

Definition of indicator

Drainage are all the systems that avoid water logging and the entrance of run-off water to the faecal sludge treatment site.

How to measure or calculate it ?

Observe if there are specific infrastructures for drainage in the faecal sludge treatment site. Identify if there is any major waterlogging or water run-off which causes surface water contamination or makes the treatment operations difficult.

Why it is important to measure it ?

Adequate drainage is a must under all circumstances to prevent flooding and lead storm water away from the site without major contamination.

Definition of indicator

The indicator defines if the area of the faecal sludge treatment site is affected by flood.

How to measure or calculate it ?

Verify with literature and local knowledge when last flood occurred in the faecal sludge treatment site. The indicator defines if the area of the faecal sludge treatment site has been affected in the last period equivalent to the life expectancy (see indicator) and nothing has been done to avoid flood in the area during construction. The indicator takes in consideration only the faecal sludge treatment site and not the access to it or to latrines.

Why it is important to measure it ?

Faecal sludge is a potentially dangerous material: flooding may stop operations for several weeks and/or spread faecal contamination out of the faecal sludge treatment site.

Definition of indicator

This indicator defines the total of:

– Preliminary and general items (Office and transport contractor and supervisors, security, insurance, electricity supply connection, etc.)
– Purchase of land
– Civil works
– Electromechanical works: pumps, GenSet,
– Design (typically 5% of Civil & Electromechanical costs)
– Supervision of implementation (typically 5-15% of Civil and Electromechanical costs)

divided by current flow.

How to measure or calculate it ?

All the expenditure for the construction and put in place of sludge faecal treatment system have to be considered and divided by the real input flow (see indicator). It includes also a quota of human resources involved in the conception and construction, that can have been involved also in other tasks.

References, tips, examples

A treatment plant in inaccessible areas where cement bags need to flown is easily 10 times more expensive than the same plant in areas where cement can be purchased ‘of the shelf’.

Why it is important to measure it ?

Capital expenditure per real input flow on any faecal sludge treatment site differ from place to place and depends mostly on transport costs.

Definition of indicator

This indicator defines the total of:

– Preliminary and general items (Office and transport contractor and supervisors, security, insurance, electricity supply connection, etc.)
– Civil works
– Electromechanical works: pumps, GenSet,
– Design (typically 5% of Civil & Electromechanical costs)
– Supervision of implementation (typically 5-15% of Civil and Electromechanical costs)

divided by current flow.

How to measure or calculate it ?

All the expenditure for the construction and installation of the faecal sludge treatment system (EXLUDING PURCHASE OF LAND) has to be considered and divided by the real input flow (see indicator). It includes also a quota of human resources involved in the conception and construction, that can also have been involved in other tasks.

References, tips, examples

A treatment plant in inaccessible areas where cement bags need to be flown in is easily 10 times more expensive than the same plant in areas where cement can be purchased ‘off the shelf’.

Why it is important to measure it ?

Capital expenditure per real input flow on any faecal sludge treatment site differs from place to place and depends mostly on transport costs.

Definition of indicator

This indicator defines the level of knowledge and experience required to be able to build a faecal sludge treatment site successfully.

How to measure or calculate it ?

The indicator is determined by assessing the construction process (including selection of contractors or construction staff) and understanding if specific contractors and specialists for special supervision, know-how, equipment were involved or not.

References, tips, examples

Skill level for construction can be reduced by standardization, use of kits and clear and univocal instruction materials.

Why it is important to measure it ?

Faecal sludge is a potentially dangerous material: a simple mistake in infrastructures construction may stop operations for several weeks and affect the sustainability of faecal sludge treatment.

Definition of indicator

Operation expenditure includes the daily average of:

– Staff costs
– Energy costs (especially high when electricity needs to be generated separately)
– Chemical costs
– Transport costs
– Administration costs
– Water for cleaning / operating costs
– Personal Protection Equipment costs
– Etc.

divided by real input flow.
It doesn’t include desludging costs.

How to measure or calculate it ?

All the expenditure for operations has to be considered and divided by the real input flow (see indicator). Also expenditures for extraordinary operations as a daily average should be considered. It also includes a quota of human resources involved in the operations, that can also be involved in other tasks.

References, tips, examples

Typical O&M costs for faecal sludge treatment around the world are USD 6-10 /m3.

Why it is important to measure it ?

It represents the economical efficiency of the faecal sludge treatment systems by comparing daily operational costs with real input flow.

Definition of indicator

This indicator defines the skill level of the manager of the O&M tasks of the faecal sludge treatment site.

How to measure or calculate it ?

Analyse the CV of the manager of the O&M of the faecal sludge treatment site and identify if he/she has an education higher than the compulsory one (high school, university) and if this education is strictly necessary for his/her role.

Why it is important to measure it ?

This indicator provides information on the staff to be hired for the management of the faecal sludge treatment site.

Definition of indicator

This indicator is required to know how much sludge is currently really treated at the faecal sludge treatment site.

How to measure or calculate it ?

Calculate the real input flow by measuring the sludge volume in transport tanks to the faecal sludge treatment site or by measuring the pumps flow rates and their time of use during desludging. Consider an average value including also the days the faecal sludge treatment activities don’t run.

Why it is important to measure it ?

When the real input flow is known, it’s possible to compare it with design input flow and with the output sludge production and give important indications about possible upgrading.

Definition of indicator

This indicator defines how much sludge is produced daily by the faecal sludge treatment site in comparison to real input flow for an average operational period

How to measure or calculate it ?

Measure weight of the sludge produced daily before disposal or reuse out of the sludge treatment site. Divide it by real input flow (see indicator). Consider an average value including also the days faecal sludge treatment activities don’t run.

References, tips, examples

Output sludge production in comparison to sludge input flow can vary a lot according to treatment processes:
Chemical treatment like lime where the volume of sludge does not change (volume sludge in = volume sludge out);
Physical and biological treatment (separation of solids from fluids, aerobic or anaerobic digestion of sludge). Here the volume of sludge decreases drastically to 5-15% of the original volume (see examples).

Why it is important to measure it ?

The volume of sludge is an important parameter in sizing the transportation and disposal system of processed sludge from the faecal sludge treatment site.

Definition of indicator

Biochemical Oxygen Demand (BOD, also called Biological Oxygen Demand) is the amount of dissolved oxygen needed (i.e. demanded) by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. The BOD value is most commonly expressed in milligrams of oxygen consumed per litre of sample during 5 days of incubation at 20 °C (mg/L).
The reduction is related to the BOD of effluent exiting the faecal sludge treatment site in comparison to the BOD of influent entering the faecal sludge treatment site.

How to measure or calculate it ?

The reduction is calculated as COMPLEMENTARY PERCENTAGE of the average BOD of effluent exiting the faecal sludge treatment site over the average BOD of influent entering the faecal sludge treatment site in the same period.

References, tips, examples

The laboratory test protocol can be seen at:
The STeP Global Testing Protocols & Parameters – A best practices guide for testing sanitation technologies in the field
http://stepsforsanitation.org/?smd_process_download=1&download_id=4171
Influent example from Zambia: 25,000-40,000mg/l for pit latrines and 1,000-2,000mg/l for septic tanks
maximum concentration example of liquid effluent as per the ZEMA standard 50mg/l.

Why it is important to measure it ?

Faecal sludge characteristics vary widely between cities, types of on site sanitation systems and type of emptying system used. Even samples taken from the same pit latrine.

Definition of indicator

Chemical oxygen demand (COD) is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution. It is commonly expressed in mass of oxygen consumed over volume of solution (mg/L).
The reduction is related to the COD of effluent exiting the faecal sludge treatment site in comparison to the COD of influent entering the faecal sludge treatment site.

How to measure or calculate it ?

The reduction is calculated as COMPLEMENTARY PERCENTAGE of the average COD of effluent exiting the faecal sludge treatment site over the average COD of influent entering the faecal sludge treatment site in the same period.

References, tips, examples

The laboratory test protocol can be seen at:
The STeP Global Testing Protocols & Parameters – A best practices guide for testing sanitation technologies in the field
http://stepsforsanitation.org/?smd_process_download=1&download_id=4171
Influent example from Zambia: 50,000-100,000mg/l for pit latrines and 10,000-20,000mg/l for septic tanks
maximum concentration example of liquid effluent as per the ZEMA standard 50mg/l.

Why it is important to measure it ?

Faecal sludge characteristics vary widely between cities, types of on site sanitation systems and type of emptying system used. Even samples taken from the same pit latrine have been shown to have significant variation in standard physio-chemical testing. Such characteristics impact how sludge can be processed following removal. Stabilised sludge is very poor in terms of gas release in an anaerobic digester.

Definition of indicator

Faecal coliforms are facultatively anaerobic, rod-shaped, gram-negative, non-sporulating bacterium. Coliform bacteria generally originate in the intestines of warm-blooded animals. Faecal coliforms are capable of growth in the presence of bile salts or similar surface agents, are oxidase negative, and produce acid and gas from lactose within 48 hours at 44 ± 0.5°C.The term « thermotolerant coliform » is more correct and is gaining acceptance over « faecal coliform ».
Coliform bacteria include genera that originate in feces (e.g. Escherichia) as well as genera not of faecal origin (e.g. Enterobacter, Klebsiella, Citrobacter). The assay is intended to be an indicator of faecal contamination; more specifically of E. coli which is an indicator microorganism for other pathogens that may be present in feces. They are commonly expressed in colony forming units over 100mL volume of solution (CFU/100mL).
The reduction is related to the faecal coliforms of effluent exiting the faecal sludge treatment site in comparison to the faecal coliforms of influent entering the faecal sludge treatment site.

How to measure or calculate it ?

The reduction is calculated as COMPLEMENTARY PERCENTAGE of the average faecal coliforms of effluent exiting the faecal sludge treatment site over the average faecal coliforms of influent entering the faecal sludge treatment site in the same period.

References, tips, examples

The laboratory test protocol can be seen at:
The STeP Global Testing Protocols & Parameters – A best practices guide for testing sanitation technologies in the field
http://stepsforsanitation.org/?smd_process_download=1&download_id=4171
Influent example from Zambia: 2*107 CFU/100ml for pit latrines and 1*105 CFU/100ml for septic tanks
maximum concentration example of liquid effluent as per the ZEMA standard 2500CFU/100ml.

Why it is important to measure it ?

Faecal sludge characteristics varies widely between cities, types of on site sanitation systems and type of emptying system used. Even samples taken from the same pit latrine have been shown to have significant variation in standard physio-chemical testing. Such characteristics impact how sludge can be processed following removal. Stabilised sludge is very poor in terms of gas release in an anaerobic digester.

Definition of indicator

Total solids are the total dissolved solids (TDS) + total suspended solids (TSS). They are commonly expressed as mass of solids in comparison to volume of solution (% weight-volume).
The reduction is related to the total solids of effluent exiting the faecal sludge treatment site in comparison to the total solids of influent entering the faecal sludge treatment site.

How to measure or calculate it ?

The reduction is calculated as COMPLEMENTARY PERCENTAGE of the average total solids of effluent exiting the faecal sludge treatment site over the average total solids of influent entering the faecal sludge treatment site in the same period.

References, tips, examples

The laboratory test protocol can be seen at:
The STeP Global Testing Protocols & Parameters – A best practices guide for testing sanitation technologies in the field
http://stepsforsanitation.org/?smd_process_download=1&download_id=4171
Septage (contents of a septic tank) is much easier to pump and treat due to the low % of solids (typically 1-2 %) than faecal sludge from pit latrines with a high % of solids (typically 10-15%). Solids content is an important parameter to estimate the volume of dried sludge to be removed from the drying beds of sludge treatment plants. After 2 weeks drying period the typical solids content is 40% dry solids. Hence, 1 m3 (1,000 litres) of septage containing 1% of dry solids has been decreased to 1,000 *1%/(40%) = 25 kg of biosolids. The remainder (typically 1,000-25 = 975 litres has partially evaporated, partially drained away. The drainage water, say max 975 litres, needs to be treated in a filter / pond system. Also, 1 m3 (1,000 litres) of faecal sludge containing 15% of dry solids has been decreased to 1,000 *15%/(40%) = 375 kg of biosolids. The remainder (typically 1,000-375 = 625 litres has partially evaporated, partially drained away. The drainage water, say max 625 litres, needs to be treated in a filter / pond system;
Influent example from Zambia: 7-15% for pit latrines and 1-2% for septic tanks.

Why it is important to measure it ?

Faecal sludge characteristics vary widely between cities, types of on site sanitation systems and type of emptying system used. Even samples taken from the same pit latrine have been shown to have significant variation in standard physio-chemical testing. Such characteristics impact how sludge can be processed following removal. Stabilised sludge is very poor in terms of gas release in an anaerobic digester.
Solids content is an important parameter to estimate the volume of dried sludge to be removed from the drying beds of sludge treatment plants.

Definition of indicator

pH is a logarithmic scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the molar concentration, measured in units of moles per litre, of hydrogen ions. Indeed it doesn’t have unit measure.
The variation is related to the pH of effluent exiting the faecal sludge treatment site in comparison to the pH of influent entering the faecal sludge treatment site.

How to measure or calculate it ?

The variation is calculated as positive (when effluent pH is higher than influent pH) or negative (when effluent pH is lower than influent pH) difference of the average pH of effluent exiting the faecal sludge treatment site in comparison to the average pH of influent entering the faecal sludge treatment site in the same period.

References, tips, examples

The laboratory test protocol can be seen at:
The STeP Global Testing Protocols & Parameters – A best practices guide for testing sanitation technologies in the field
http://stepsforsanitation.org/?smd_process_download=1&download_id=4171
Influent example from Zambia: 7.5-7.8 for pit latrines and 7.0-7.5 for septic tanks
Example range of liquid effluent as per the ZEMA standard 6-9.

Why it is important to measure it ?

Faecal sludge characteristics vary widely between cities, types of on site sanitation systems and type of emptying system used. Even samples taken from the same pit latrine have been shown to have significant variation in standard physio-chemical testing. Such characteristics impact how sludge can be processed following removal. Stabilised sludge is very poor in terms of gas release in an anaerobic digester.

Definition of indicator

Parasitic worms, also known as helminths, are large macroparasites, which as adults can generally be seen with the naked eye. Many are intestinal worms that are soil-transmitted and infect the gastrointestinal tract. It is an umbrella term that includes many species of worm from different genera. Helminth eggs of concern in wastewater used for irrigation have a size between 20 and 90 μm. They are commonly expressed in number of eggs per gram of solution (n/g).
The reduction is related to the Helminth eggs in the effluent exiting the faecal sludge treatment site in comparison to the Helminth eggs in the influent entering the faecal sludge treatment site.

How to measure or calculate it ?

The reduction is calculated as COMPLEMENTARY PERCENTAGE of the average Helminths eggs in the effluent exiting the faecal sludge treatment site over the average Helminth eggs in the influent entering the faecal sludge treatment site in the same period.

References, tips, examples

The laboratory test protocol can be seen at:
The STeP Global Testing Protocols & Parameters – A best practices guide for testing sanitation technologies in the field
http://stepsforsanitation.org/?smd_process_download=1&download_id=4171
It is very difficult to inactivate helminth eggs, unless temperature is increased above 40 °C or moisture is reduced to less than 5%.

Why it is important to measure it ?

Helminth eggs (or ova) are a good indicator organism to assess the safety of sanitation reuse systems for resource recovery because they are the most environmentally resistant faecal pathogens and they can in extreme cases survive for several years in soil.

Definition of indicator

The indicator defines if the faecal sludge treatment system is operated exclusively by the beneficiary community without any constant external support.

How to measure or calculate it ?

Analyse responsibilities and tasks of the faecal sludge treatment site management. Identify if they are all cover by the beneficiary community or part of it. If there is occasional external support, still consider that the site is completely operated by the community.

Why it is important to measure it ?

It is important to know the complexity of operations in relation to the skills of the community in order to plan the faecal treatment site management and forecast long-term sustainability.

Definition of indicator

The indicator defines if washing capacities are available for the faecal sludge treatment workers.

How to measure or calculate it ?

Analyse if washing capacity (with adequate privacy and supplied with enough water and soap/chlore) are available and accessible at the key moments (before eating or drinking and before leaving the faecal sludge treatment site).

Why it is important to measure it ?

Washing capacity is key to protect the health of faecal sludge treatment workers and their family.

Definition of indicator

The indicator defines if Personal Protection Equipment (PPEs) are available for the faecal sludge treatment workers and potential visitors.

How to measure or calculate it ?

Analyse if Personal Protection Equipment (PPE) are available, accessible and frequently washed or replaced.

Why it is important to measure it ?

PPEs are key to protect the health of faecal sludge treatment workers and their family.

Definition of indicator

This indicator defines the level of knowledge and experience required to be able to upgrade or decommission the faecal sludge treatment site successfully.

How to measure or calculate it ?

The indicator is determined by forecasting an eventual upgrading or decommissioning phase taking lessons learnt from the construction process (including selection of contractors or construction staff). Should specific contractors and specialists be involved for special supervision, know-how, equipment?

Why it is important to measure it ?

Faecal sludge is a potential dangerous material: a simple mistake in infrastructures construction may stop operations for several weeks and affect the sustainability of faecal sludge treatment. For the same reason, decommissioning and disposal of faecal sludge treatment infrastructures and equipment can contaminate the environment and affect population living around the disposal site or dismissed faecal sludge treatment site.