Lime Stabilization

Organisation : NC

 

Objective

Reduction of pathogens

Construction cost without land

0.73 USD/m3/day

Required space

0.06 m2/person

Short description of the emergency context

The FSM site is situated in a densely populated refugee camp (Cox’s Bazar, Kutupalong-Balukhali extension area, camp 18) with hilly terrain and poor path conditions. The site can be reached on foot and is inaccessible for any type of motorised transport (tricycle, small truck, pick-up, vacuum truck) and non-motorized transport (bike, cart). Long rainfall periods during the monsoon and cyclone season worsened path conditions in the camp and desludging and sludge treatment had to be stopped.

The FSM site is particularly suitable for the relief phase and has a designed life expectancy of 6 – 12 months.

Objective

Reduction of pathogens

Life expectancy and reliability

Short term (months)

Skill level required for design

Low (easy design)

Source of sludge

From public toilet, From septic tank

Required space

0.06 m2/person

Topography

Mountains and hills, Valleys

Type of outputs

Sludge

Using locally available material

yes

Flood risk

No

Construction costs, Capex per current flow (excluding costs of land)

0.73 USD/m3/day

The area required for the FSM site is roughly 500 m2 (0.06m2/person). This includes all facility buildings, office and warehouse and ample free space but excludes the area needed for safe sludge disposal. An area of 90 m2 is directly occupied by drying beds.

On average 4m3 sludge is treated per day, which is in accordance with a target population of 10,000 people served with FSM activities and a sludge accumulation rate of 0.4 L/person/day.

Although desludging efforts seem to answer to the needs in 23 blocks (9,383 people), the actual number of people reached can be lower as 1) the desludging is done by the organisations that have constructed the latrines, 2) the desludging process is reactive rather than pro-active.

FSM actors state a two-week period between desludging, which calculates to a sludge accumulation rate of 2.9 L/cap/day (assuming full latrines, 0.8 m3, after two weeks).

Costs for construction of the FSM site are estimated at 0.73 USD/person. Construction costs include site preparation and construction of all facility buildings, with the exception of the office and warehouse building.

Daily operation and maintenance costs of the FSM site are estimated at 0.27 USD/person/month. One third of the operational and maintenance costs is requisition of hydrated lime. Another third consists of monetary incentives for community volunteers. Personal Protective Equipment, although of high importance, is only a small fraction of the running costs.

Strengths


NC

Weaknesses


NC

Gallery

Lime stablisation
IFRC lime stablisation (1)
Lime stablisation
IFRC lime stablisation (2)
IFRC sludge treatment
IFRC lime stablisation (3)

IFRC lime stablisation (4)

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Indicators notice

Unit/value

Excreta containment
Solid/liquid separation
Urine/faeces separation
Sludge drying
Stabilisation of sludge
Sludge volume reduction
Reduction of odour/flies
Reduction of pathogens
BOD reduction
TSS and TDS reduction
Nutrient removal
Nitrification
Nutrient recovery
Biogas recovery
Water recovery
Biomass production
Other

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

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

References, tips, examples

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

Unit/value
Short term (months)
Long term (years)

How to measure or calculate it ?

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

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) by 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

Unit / value

Low skilled: general WASH officer
Skilled: FSM specialist

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 as 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 potential 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.

Unit / value
yes
no

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 information to 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 contacts 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)

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