FAQs: Faecal sludge and septage management

Empty faecal sludge drying bed (Image: Lars Schoebitz)
Empty faecal sludge drying bed (Image: Lars Schoebitz)

This primer provides the basics related to most aspects of faecal sludge and septage management. Please click on a topic to view more detailed information.

What is faecal sludge and septage management?

What is the difference between greywater and blackwater?

What is the difference between sewage, faecal sludge and septage?

What considerations need to be kept in mind while designing septic tanks and sanitary toilets?

Why is faecal sludge and septage management important?

What are the objectives of faecal sludge and septage treatment?

Does India have a faecal sludge and septage management policy?

What are the steps needed to prevent manual scavenging in FSSM?

What does Goal 6 of Sustainable Development Goals recommend about FSSM?

What are the broad options for faecal sludge and septage treatment/disposal?

What do you mean by faecal sludge treatment (FST)? Is it different from decentralised waste water treatment (DWWTs)?

What are the common processes and treatment technologies used at faecal sludge treatment plants?

What care should be taken for conveyance of faecal sludge to the disposal site?

What is a decanting facility?

What is co-treatment of faecal sludge/septage and sewage?

What is the final stage of faecal sludge management?

What is faecal sludge and septage management?

Sewerage networks serve parts of our large cities but are yet to reach smaller towns, hence, faecal sludge i.e., a mixture of human excreta, water and solid wastes (such as toilet paper and menstrual hygiene materials) gets collected in onsite sanitation systems. These solids may get collected in the system with time, leading to poor performance and overflows from septic tank and pit latrines. The unsafe emptying and indiscriminate disposal on open grounds and water systems, contributes to disease burden and pollution of water bodies. This is highly unhygienic and unsafe, and can lead to both surface and ground water pollution, and has associated public health and environmental impacts.

Cities need to mandatorily adopt safe practices in collection, transport, treatment of septage and faecal waste and appropriate options in disposal and safe reuse of treated black water.

Faecal sludge and septage management (FSSM) refers to the management of all stages of the sanitation value chain such as collection, emptying, transport, treatment, disposal and reuse of faecal sludge from pit latrines, septic tanks or other onsite sanitation systems. The term FSSM is not just about creating infrastructure for each stage, it also includes creating enabling environment for the system to run smoothly and sustainably.

Figure: Value chain of faecal sludge management

Source: Guidelines for faecal sludge and septage management in Bihar, Government of Bihar, 2018 

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What is the difference between greywater and blackwater?

Grey water is the wastewater from kitchen and bathrooms i.e. from sinks, bathtubs, showers, dishwashers, and clothes washers and does not contain excreta. Wastewater from a community, containing solid and liquid excreta, is known as black water, as per the Central Public Health and Environmental Engineering Organization (CPHEEO). Black water is generated from the toilet, which contains human excreta whereas grey water can be generated from other activities like cooking, washing cloths and dishes. 

Sources of generation of black and grey water

Source: From Liquid Waste Management presentation made by NIUA, CDD Society and BORDA quoted in NIUA (2018) “Faecal Sludge and Septage Management: An Orientation Module”

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What is the difference between sewage, faecal sludge and septage?

Sewage is untreated domestic/municipal waste water, which contains mostly of greywater and blackwater and gets conveyed through the sewerage system or into an onsite sewage facility. Sewage is characterized by its rate of flow, physical condition, chemical and toxic constituents, and its bacteriological status. The biochemical oxygen demand (BOD) of sewage ranges from 150-350 mg/l and sewage treatment plants are designed for this load. Sewerage refers to the infrastructure that conveys sewage.

Faecal sludge is the mixture of human excreta, water and solid wastes (such as toilet paper and menstrual hygiene materials) that gets collected in onsite sanitation systems.

Septage is a specific type of faecal sludge and refers to the partially digested faecal solids that accumulate in septic tanks. Faecal sludge and septage is emptied out of pits or septic tanks and is much more concentrated than sewage; for example, BOD of septage ranges from 1,000-20,000 mg/l.

Estimates indicate that a truck of faecal sludge and septage carelessly dumped equals to 5,000 people defecating in open. A gram of faeces may contain 100 parasite eggs, 1000 protozoa, 10 lakh bacteria and 1 crore virus (Chary and Srinivas, 2017).

The line between septage and faecal sludge is thin. Septage is the combination of scum, sludge and liquid that accumulates in septic tanks. Septage is limited to septic tanks, and has already undergone partial digestion, whereas faecal sludge includes contents from other onsite technologies, such as pit latrines, and may or may not be digested. Faecal sludge from pit latrines may have a lower water content compared to septage and may contain more solid waste. The physical, chemical and biological qualities of faecal sludge are influenced by the duration of storage, temperature, soil condition, and intrusion of groundwater or surface water in septic tanks or pits, performance of septic tanks, and tank emptying technology and pattern. (AMRUT, Ministry of Housing and Urban Affairs, 2017)

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What considerations need to be kept in mind while designing septic tanks and sanitary toilets?

As per the Central Public Health and Environmental Engineering Organization (CPHEEO) the following points need to be taken care of:

  • To eliminate contact with human faeces, seal the air vent of septic tanks with mosquito fly traps. A septic tank should have at least two lined chambers with a flow vent in between at the required height and size outlined by CPHEEO. The outflow should be passed through a soak pit. The septic tank design specification also includes an openable flap for regular cleaning and a vent exhaust pipe equipped with a mesh capping.
  • To eliminate the contamination of ground using a pit latrine system, toilets should be located at a safe distance from a drinking water source. The groundwater table should not be high.
  • A two pit latrine system is safer to adopt when compared to a single pit latrine system.

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Why is faecal sludge and septage management important?

Indian cities are characterised by low levels of sewerage system coverage (over 7,000 smaller towns do not have centralised sewerage systems) and high population densities. Sewerage systems though comprehensive are expensive to build and operate considering their need for continuous power, skilled operators and extensive electromechanical maintenance. The issue of faecal waste continues to be a challenge and as per a study on Faecal Sludge Management conducted by WaterAid India in 2015 “only 30 percent of the sewage generated is actually treated”. There is a dearth of mandated institutions, lack of technical expertise and finances to implement successful FSSM initiatives.

As a result “decentralized faecal septage treatment plants (FSTPs) are emerging as solutions to the challenge of addressing safe treatment and disposal of septage.” (FSSM Orientation Module, NIUA, 2018).

On-site sanitation systems along with faecal waste and septage treatment plants have been successfully implemented in parts of India such as in Devanahalli. More and more cities need to adopt a set of safe practices, appropriate technology options and institutional arrangements for FSSM.

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What are the objectives of faecal sludge and septage treatment?

The faecal sludge collected from septic tanks has higher biochemical oxygen demand (BOD) as well as a higher solid content when compared to sewerage. Faecal sludge treatment entails separation of solid and liquid matter, their treatment, reuse and disposal. The objectives are to:

  • Reduce the water content of sludge, thus making it easier to work with and transport.
  • Reduce the oxygen demand and suspended solids content of the liquid fraction that is discharged to the environment.
  • Reduce pathogens from the liquid effluent, to allow its safe disposal or end use.
  • Reduce pathogen concentrations in sludge sufficiently to allow its safe end use (waste-to-energy and waste-to-compost) or disposal as part of the solid waste stream.

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Does India have a faecal sludge and septage management policy?

At the national level, the infrastructure driven approach towards sanitation is being increasingly replaced by a holistic, integrated, people centred approach with the coming up of the National Urban Sanitation Policy (NUSP) in 2008. The policy moves away from prescribing piecemeal infrastructure solutions such as construction of toilets or STPs towards planning and implementing measures on FSSM.

A national policy on FSSM was prepared by the Ministry of Urban Development in February 2017 with support and inputs from the National Faecal Sludge and Septage Management Alliance. The key features of the policy are: 

  • State level guidelines, framework, objectives, timelines and implementation plans to address septage management 
  • Formulating strategy on central level to initiate capacity building for training on FSSM
  • Sanitation benchmark framework to be used by urban local bodies (ULBs) to develop database, registry of certified on site sanitation system and robust reporting format
  • Funding for facilitation of FSSM projects and encouragement to increase public private partnerships (PPP) 
  • Achieving integrated citywide sanitation along with safe disposal
  • Revised service-level benchmarking for sanitation

The Septage Advisory issued by the MoUD focused primarily on the development of a septage management sub-plan as a part of the City Sanitation Plans. Each state was to have a FSSM policy directive and ULBs should have resolutions to implement this policy directive. The ULBs were to monitor planning, prepare detailed project reports (DPRs) and do tendering of services.

The key objective of the urban FSSM policy is to –

  • Set the context, priorities, and direction for, and to facilitate, nationwide implementation of FSSM services in all ULBs such that safe and sustainable sanitation becomes a reality for all in each and every household, street, town and city. 
  • Ensure that all benefits of wide access to safe sanitation accrue to all citizens across the sanitation value chain with containment, extraction, transportation, treatment, and disposal or re-use of all faecal sludge, septage and other liquid waste and their by-products and end-products. 
  • Suggest and identify ways and means, including the methods and resources, towards creation of an enabling environment for realising safe and sustainable FSSM in India.
  • Define the roles and responsibilities of various government entities and agencies, and of other key stakeholders such as the private sector, civil society organisations and citizens for effective implementation of FSSM services throughout the country.
  • Enable and support synergies among relevant Central Government programs such as Atal Mission for Rejuvenation and Urban Transformation (AMRUT) and Swachh Bharat Mission (SBM) and the Smart Cities Mission to realise safe and sustainable sanitation for all at the earliest.
  • Mitigate gender-based sanitation insecurity directly related to FSSM, reducing the experience of health burdens, structural violence, and promote involvement of both genders in the planning for and design of sanitation infrastructure.

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What are the steps needed to prevent manual scavenging in FSSM?

A study by Urban Management Centre in the Ahmedabad Municipal Corporation indicates that manual scavenging may occur due to cleaning of open defecation spots, emptying onsite sanitation systems, cleaning of sewer lines and manholes, cleaning of pit latrines, and cleaning of excreta from insanitary latrines. “Manual scavenging in FSSM can be avoided if cities have adequate suction based vacuum trucks to empty the wastewater from onsite sanitation systems as Manual Scavenging Act clearly states wastewater emptying should be done in a mechanical way. The ULBs could either have these trucks themselves or should empanel private agencies for emptying onsite sanitation systems. Safety gears should be given to the workers engaged in wastewater emptying and disposal system, and capacity building of the workers and staff engaged in FSSM services should be done.” (FSSM Orientation Module, NIUA, 2018)

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What does Goal 6 of Sustainable Development Goals recommend about FSSM?

  • Improve the functioning of onsite sanitation systems and to reduce the potential for human contact with faecal-borne pathogens;
  • Minimize odors and nuisances, and the uncontrolled discharge of organic matter from overflowing tanks or pits;
  • Support the upgrading of onsite sanitation upgrading programs;
  • Safeguard public health against indiscriminate disposal of collected faecal sludge;
  • Derive agricultural products, including soil conditioner from composting or co-composting materials and energy products such as biogas, charcoal pellets, industrial powdered fuel etc.
  • Stimulate economic development, and job creation and livelihood opportunities, while addressing the issues of the social stigma and operator health and safety that continue to impact informal workers.

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What are the broad options for faecal sludge and septage treatment/disposal?

  • Independent septage treatment is done where there is lack of sewer networks and sewage treatment.
  • Co-treatment of faecal sludge with sewage is done where there is an existing or planned sewer network. This is generally preceded by septage pre-treatment (some form of digestion) to separate solids from liquid and reduce odours. For co-treatment, it is important to ensure that the load generated by faecal sludge and septage (as it is higher) is assessed in relation to the capacity of wastewater treatment facilities to accept that load. This assessment ideally covers both the organic and suspended solids load carried in the liquid fraction of separated sludge/septage and the volume of separated solids.
  • Land disposal of untreated septage where septage is discharged to agricultural and forest land may contaminate watercourses, adversely affecting their condition. Deep trench burial of faecal sludge in a suitable location is a viable option for disposal provided contamination of surface soil is prevented.

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What do you mean by faecal sludge treatment (FST)? Is it different from decentralised waste water treatment (DWWTs)?

A facility where the septage and/or faecal sludge is received (by vacuum trucks or otherwise) as an input and gets fully treated to allow for safe reuse or disposal of generated output (both solid and liquid). Faecal sludge can also be treated along with sewage (co-treatment) at a STP. There are a number of “treatment options: gravity based biological treatment, mechanical centrifugal, chemical flocculants treatment, membrane-based and filtration systems, electrical heat and drying, incinerators etc. Treatment for wastewater and liquid content of faecal waste matter can also be biological plant based systems, membrane and filtration, chlorination, ultra violet, among others.” (FSSM Orientation Module, NIUA, 2018)

Decentralised waste water treatment is a facility where domestic wastewater (both black and grey water) is treated close to the source at community or institutional scale to allow for safe local reuse or disposal of generated effluent.

Devanahalli faecal sludge treatment plant (Image: BORDA)

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What are the common processes and treatment technologies used at faecal sludge treatment plants?

It starts with faecal sludge reception where the truck unloads the sludge at the treatment plant. Preliminary treatment is done thereafter to remove garbage, sand, grit, fats, oil and grease. Primary treatment involves simple separation by physical means, or separation with microbial digestion. This is followed by liquid treatment using constructed wetlands, waste stabilization ponds, anaerobic digesters and solids processing.

Thermal processes, which can achieve cost effectiveness by eliminating the need for separate processes are considered to be an effective technology. They convert the faecal sludge along with certain fractions of sewage sludge or municipal solid waste to produce energy or fuel by using certain sewage sludge treatment technologies.

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What care should be taken for conveyance of faecal sludge to the disposal site?

Scheduled desludging is not being done in Indian cities and towns by the ULBs and private desludging agencies are called only when the septic tanks and soak-pits get filled. The data collected under Swachh Bharat Mission was not used to build a scheduled desludging regimen. Usually, faecal sludge collection services are made available on a call-for-service basis. Desludging vehicles or emptier trucks are used in order to safely transport faecal sludge and septage to the designated disposal site. There are a variety of desludging vehicles, which can be purchased from the market. The choice would depend on the volume of septic tanks to be emptied as well as the number of trips of an emptier truck. The options are - a tank and pump mounted on a flatbed truck or tractor; a small tank pulled by a motorcycle; or in containers on a hand cart. The pump is connected to a hose that is lowered down into the pit latrine or septic tank to pump the sludge out into the holding tank on the vehicle. These vaccum trucks are commonly used in Indian cities.

Transport of septage, Source: (Indian Institute for Human Settlements, 2017)

Suction-based vacuum trucks or emptier trucks with varying capacities of tanks (2,000 litres to 20,000 litres) are available in the market. ULBs should take cognisance of the average road width of the areas from where septic tanks need to be desludged. Not taking that into consideration while procuring emptier trucks has led to problems related to access to septic tanks.

There is a need for scheduled desludging programs by the local government or utility, where property occupiers are informed in advance about the planned emptying of septic tanks. Trucks move from neighbourhood to neighbourhood on a scheduled cycle, emptying pits on a regular 3-4 year cycle. A WSP study recommended that efforts to introduce scheduled emptying should focus first on areas where demand was greatest, moving on to other areas when the success of scheduled emptying had been demonstrated.

 

Emptying/Desludging: Septage is emptied from the septic tank by desludging operators using suction pipes in situations of septic tank overflowing or cleaning purposes. (Image: Indian Institute for Human Settlements, 2017)
Emptying/Desludging: Septage is emptied from the septic tank by desludging operators using suction pipes in situations of septic tank overflowing or cleaning purposes. (Image: Indian Institute for Human Settlements, 2017)

 

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What is a decanting facility?

Decanting stations are points where septage from on-site sanitation systems like pit latrines and septic tank is pumped into the underground sewerage systems, to be treated at the centralized treatment plant.

Decanting: Desludging trucks carry the desluged septage, and discharge it directly into the sewage or faecal sludge treatment plant or into decanting facilities of the sewage treatment plants. (Image: Indian Institute for Human Settlements, 2017)

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What is co-treatment of faecal sludge/septage and sewage?

Co-treatment of faecal sludge with sewage is done many a time at STPs, as most of them have ample spare capacity. But, care needs to be taken as septage and faecal sludge have high strengths and can lead to increased organic loading, leading to overloading and process failure in a STP. So, separate preliminary treatment and solids-liquid separation facilities are provided for septage and faecal sludge to reduce the overall load.

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What is the final stage of faecal sludge management?

Disposal or reuse is the final stage of FSSM where the treated human waste is either disposed of safely into the environment or can be reused as farm manure or biofuel. The pathogens are deactivated under the heat while the digestion process breaks down the organic matter into a humus-like material, which can be reused in agriculture. The treated water that is separated from septage can be used for agricultural or landscape irrigation. 

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