Envis Centre, Ministry of Environment & Forest, Govt. of India

Printed Date: Friday, May 27, 2022

Low-Cost Sanitation

Unsanitary conditions and contaminated drinking water exact a crippling toll on both the health of the human population and the environment. Approximately 40 percent of the world’s population does not have access to improved sanitation. In addition to the indignity suffered by those lacking sanitation facilities, millions of people in the developing world die each year from diseases contracted through direct and indirect contact with pathogenic Bactria found in human excreta. Infectious diseases such as cholera, hepatitis, typhoid and diarrhea are waterborne, and can be contracted from untreated wastewater discharged into water bodies. More than half of the world’s rivers, lakes, and coastal waters are seriously polluted from wastewater discharge. The cost of inadequate sanitation translates into significant economic, social, and environmental burdens. As the world attempts to realize these goals, we must reassess the lessons learned, evaluate new technologies, identify research gaps, and critically discuss ways forward. Since 2 billion of the 2.6 billion people lacking sanitation live in rural areas, we must complement large-scale urban investments with low-cost, on site technologies that target rural communities. Low cost sanitation options have significantly improved, especially for the reuse of sewage for agriculture or aquaculture.

 

The Centrally Sponsored Scheme of Low Cost Sanitation for Liberation of Scavengers started from 1980-81 initially through the Ministry of Home Affairs and later on through the Ministry of Welfare. From 1980-90, it came to be operated through the Ministry of Urban Development and later on through Ministry of Urban Employment and Poverty Alleviation now titled Ministry of Housing & Urban Poverty Alleviation. The main objectives of the Scheme are to convert the existing dry latrines into low cost pour flush latrines and to construct new ones where none exist. The scheme has been continued in the 12th plan period with the intention of converting the remaining latrines serviced by human identified by the Census of India 2011 in urban areas.

 

The objective of the Scheme is to convert/ construct low cost sanitation units through sanitary two pit pour flush latrines with superstructures and appropriate variation to suit local conditions (area specific latrines) and construct new latrines where EWS household have no latrines and follow the inhuman practice of defecating in the open in urban areas. This would improve overall sanitation in the towns. The Scheme also encourages adoption of new technologies like bio-digesters and ecosan toilets by the implementing agencies.

 

SULABH SAUCHALAYA – LOW COST SANITATION

 

Sulabh flush compost toilet is eco-friendly, technically appropriate, socio-culturally acceptable and economically affordable. It is an indigenous technology and the toilet can easily be constructed by local labour and materials. It provides health benefits by safe disposal of human excreta on-site. It consists of a pan with a steep slope of 25°-28° and an especially designed trap with 20 mm waterseal requiring only 1 to 1.5 litres of water for flushing, thus helping conserve water. It does not need scavengers to clean the pits. There are two pits of varying size and capacity depending on the number of users. The capacity of each pit is normally designed for 3 years’ usage. Both pits are used alternately. When one pit is full, the incoming excreta is diverted into the second pit. In about two years, the sludge gets digested and is almost dry and pathogen free, thus safe for handling as manure. Digested sludge is odourless and is a good manure and soil-conditioner. It can be dug out easily and used for agricultural purposes. The cost of emptying the pit can be met partially from the cost of manure made available. Sulabh toilet can also be constructed on the upper floors of buildings. It has a high potential for upgradation, and can later be easily connected to sewers when introduced in the area. Sulabh has so far constructed over a million individual household toilets in different parts of the country.

 

Operation and Maintenance

 

  • Operation and maintenance of a Sulabh flush compost toilet is very easy and simple:
  • Before use, wet the pan by pouring only a little quantity of water.
  • After defecation, pour 1.5 to 2 litres of water in the pan for flushing.
  • Pour about half litre of water in the pan after urination.
  • The pan should be cleaned once a day with a brush or a broom and with soap powder periodically.
  • One of the pits is to be used at a time by plugging the drain for the other pit.
  • Kitchen, bathroom waste water or rain water should not be allowed to enter the pits.
  • Other solid wastes like kitchen waste, rags, cotton, sweepings etc. should not be thrown in the pan, this could block the toilet.

 

When the first pit in use is full, the flow should be diverted to the second pit and the filled up pit should be desludged after 1.5 to 2-year rest period. The first pit can then be put to reuse, when the second pit fills up.

 

Prevention of Pollution

 

To check pollution of drinking water sources, the pits in fine soils (effective size 0.2mm or less) should be located at a minimum distance of 3 metres from open wells and shallow hand pumps provided ground water table throughout the year is 2 metre or more below the bottom of the pit; if water table is higher, the distance should be increased to 10 metres. In coarser soils (effective size more than 0.2mm), the same safe distances can be maintained by providing 500mm thick sand envelope of 0.2mm sand all round the pit and sealing the pit bottom by some impervious material like puddled clay, polythene sheet, lean cementconcrete or cement stabilised soil.

 

Normally bacteria do not move beyond 3 metres horizontally in homogeneous soil and vertically they do not permeate more than 1 metre, however there can be marginal deviations depending upon the types and compaction of the soil. It may be noted that chances of ground water occur due to higher hydraulic load. Since in this system hydraulic load is only 1.5 to 2 litres per use, there is no such chance of ground water pollution.

 

Manure from Human Excreta

 

One of the major difficulties for the use of human excreta as manure is the presence of bacterial and other pathogens. Human excreta contain a full spectrum of pathogens causing various infections. It should be free from pathogens before being used as manure. Another problem is psychological/chamber (250mm x 500mm internal size) should be constructed at the place from where the pipe is bifurcated to connect the two pits. The pipes of drains should have a minimum gradient of 1:15.

 

Cost of Sulabh Flush Compost Toilet

 

The cost of Sulabh flush composting toilets varies widely to suit people of every economic stratum. The cost ranges from US$ 10 to US$ 1000 per unit. It depends upon materials of construction of pits and seat as well as of the superstructure. The pits can be constructed with bricks or any locally available materials like stones, wood logs, burnt clay rings, concrete rings or even used coaltar drums. Similarly, the quality of superstructure ranges from simple gunny bag sheets, or thatch to well finished tiles with R.C.C. roof, doors, wash basin, etc. Cost varies also due to size and capacity of the pits, varying from 2 years to 20 years capacity for each pit. Keeping the basic design unchanged, Sulabh has a number of such toilet models for demonstration.

 

Manure from Human Excreta One of the major difficulties for the use of human excreta as manure is the presence of bacterial and other pathogens. Human excreta contains a full spectrum of pathogens causing various infections. It should be free from pathogens before being used as manure. Another problem is psychological/ religious taboos associated with it. The studies carried out by the Sulabh have revealed that the content of a Sulabh toilet pit is almost free from pathogens when taken out after two years of resting period. To make it completely pathogen free, digested sludge is sun dried for 2 to 3 weeks. During drying of sludge big lumps are formed making it difficult to mix in soil homogeneously. Sulabh developed a technology to granulate such dried lumps into small size graded granules which look like processed tea leaves. Before granulating, it is processed in a ball mill to break it into small pieces. Then it is passed through the mass mixer where the moisture content of manure is regulated by adding water. Such manure has a good percentage of plant nutrients. Besides, it increases humus and water holding capacity of the soil. The Institute has carried out experiments to monitor its manurial effects on different vegetables and flowering plants. In all the cases tested, the effect of manure on the growth of plants was very encouraging.