Emergency Faecal Sludge Management – Lime Treatment

04 April 2023

Geographic location

Bentiu
South Sudan

Main treatment objectives

BOD / COD Reduction
Pathogen reduction

Technologies employed

Lime treatment
Unplanted drying beds

Design population

102 811 persons

Design input flow

120 m²/day

Source of sludge

Dry toilet
Lined pit latrines
Septic tank connected by greywater

Final outputs

Effluent
Sludge

Skills level

FSM specialist for design
Geographic location

Bentiu
South Sudan

Main treatment objectives
BOD / COD Reduction
Pathogen reduction
Technologies employed
Lime treatment
Unplanted drying beds
Design population
102811 persons
Source of sludge
Dry toilet
Lined pit latrines
Septic tank connected by greywater
Final outputs
Effluent
Sludge

Time construction and commissioning

Design input flow
120.00 m²/day
Skills level
FSM specialist for design

Description of the emergency context

Bentiu IDP camp located in Unity state, South Sudan hosts a population of 102,811 as of October population count. The camp has been in existence since 2014 as a Protection of civilian Site (PoC) established after the conflict displacement. In March 2021, the PoC transited to and IDP camp. In 2021, Unity state experienced severe flooding and in September 2021, the flood water reached Bentiu with water levels picking significantly around mid-November 2021 to an average water level of 1.2m. The rising water levels forced residents to flee their homes to nearby higher grounds, destroyed livelihoods and infrastructure, disrupted service delivery, and cut-off the supply chain; leaving displaced population overcrowded in temporary sites and to protect human lives form the flood treats dykes were constructed around Bentiu.

Description of the treatment process

IOM with support from MSF established an emergency faecal sludge management plant (FSM) within the IDP camp in order to manage liquid waste in the camp to avert any public health hazard since the access to the oxidation ponds was cut off by the floods. The operation of the emergency FSM plant started from the 13th October 2022 until 22 January 2023.

IOM used lime to treat and ensure pathogen reduction of the influent by raising of the pH levels to high alkaline conditions.

Assessment & design (feasibility)

Construction

Operation and maintenance

Lessons learned

• Lime powder is corrosive and can affect the skin and respiratory system, and this calls for training of the staff to ensure safety protocols and proper PPE to the operators.
• Weather affects the drying period of the sludge from the dry beds, longer time to dry during the rainy days and 5-7 days during dry periods of temperature above 30oC.
•Adequate mixing of sludge is an important aspect to ensure effective lime treatment and to achieve this, lime to be mixed first with raw water, form a slurry after which is mixed with the sludge.

Strengths

• FSM plant easy to set up and start treatment operations for emergency settings to avert public health challenges.

Weaknesses

Even though the Lime treatment plant is easy to set up, in the case of Bentiu, there is need for prepositioning of lime. In Bentiu, the cost of lime procurement and transportation is high upto $67.17/ bag.
Road access is a challenge with only a short window per year to use the road, living air transport as the main option. In Bentiu, the FSM plant can only be effective for a shorter period (emergency) considering the daily treatment needs and high operational cost.

Sharable project files

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