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.
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.
<p>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 <a href="http://cdn.cseindia.org/attachments/0.11793200_1505299140_septage-management-a-practitioners-guide-update.pdf">not just about creating infrastructure for each stage</a>, it also includes creating enabling environment for the system to run smoothly and sustainably.</p>
Source: Guidelines for faecal sludge and septage management in Bihar, Government of Bihar, 2018
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.
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”
<p><h3>Faecal sludge</h3> 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.</p> <p><h3>Septage</h3> 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.</p>
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)
As per the Central Public Health and Environmental Engineering Organization (CPHEEO) the following points need to be taken care of:
<p>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 <a href="https://www.wateraidindia.in/sites/g/files/jkxoof336/files/an-assessment-of-faecal-sludge-management-policies-and-programmes-at-the-national-and-select-state-levels.pdf">study on Faecal Sludge Management</a> 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.</p>
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.
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:
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:
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 –
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)
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.
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.
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.
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.
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.
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.
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.