In India, and most other developing countries of Asia and Africa, the urban, peri-urban and rural communities suffer from serious lack of sustainable wastewater and sanitation facilities. Unlike in the developed countries, the standard practice of human excreta and wastewater disposal system (sewerage) is not functional in most urban communities. The Western model sewerage system is largely unaffordable for most communities. The problem is extremely serious and critical, in small and medium towns. The septic tank system, tried in many urban localities, also faces serious problems in operation and maintenance. This paper reviews the Indian scenario in respect of urban wastewater and sanitation management, with particular reference to the problems of small and medium towns, and describes an alternative approach for sustainable human excreta and wastewater disposal systems that could be affordable and sustainable for small and medium towns in India.

Every year, 1,500 km3 of wastewater are produced globally. While waste and wastewater can be reused productively for energy and irrigation, this is not usually done. In developing countries more than 80% of all waste is discharged untreated, because of lack of regulations and resources. Population and industrial growth add new sources of pollution and increased demand for clean water. Deterioration of water quality occurs when existing municipal and industrial water treatment and/or sanitation infrastructure are overloaded, or the relevant infrastructure is absent or outdated and waste and wastewater are discharged directly into the environment, and find their way into surface- or ground- water. Enhancing and expanding infrastructure can be very costly and is not generally keeping up with rapid development. Wastewater management is thus emerging as a major global challenge. In addition, agricultural and industrial production result in new pollution problems and these have become one of the biggest challenges facing water resources in many parts of the world (Nath K. J. 2011).

There has been a steady rise in the urban population in India. At independence, India was a predominantly rural society. Since then there has been intense urbanization and industrialization all over the country. As per the National Census in 2011, India's urban population was 388,524,900, about 31% of the total for the country. The character of urban habitations can classified as:

  1. Million plus cities: 35.

  2. Class I towns (population 100,000 to 1 million): 414.

  3. Class II towns (population 50,000 to 100,000): 489.

  4. Class III towns (population 20,000 to 50,000): 1,738.

The balance of the urban population lives in Class IV (population 10,000 to 20,000), Class V (5,000 to 10,000) and Class VI (below 5,000) towns. The level of urbanization varies within these categories. While the million plus cities, including megacities (population more than 5 million), are characterized by high degrees of urbanization and modern urban facilities, towns in Class III and categories are characterized by semirural and peri-urban features.

In India, and many countries in Asia and Africa, urban, peri-urban and rural communities suffer from lack of sustainable wastewater and sanitation facilities. The western model of flush toilets, with sewerage and sewage treatment plants, is capital intensive, and needs large amounts of water for toilet flushing and maintaining self-cleansing velocities in the sewerage systems. It is largely unaffordable for most Indian communities. In India, Calcutta was the third city in the world with sewerage, receiving it in 1870. Since then, only about 250 Indian cities and towns have received even partial sewerage systems. Even where sewerage/sewage treatment has been provided, the systems often do not work properly because of poor operation and maintenance. Apart from institutional and financial hurdles, most urban local bodies lack skilled manpower with adequate operator training. Recently, under a program for cleaning the River Ganga, attempts were made to install sewage treatment plants in cities and towns without sewerage, by intercepting surface drains and pumping the wastewater to treatment plants at the pipe ends. This failed to prevent riverine pollution and the treatment plants functioned poorly because the hydraulic loading was inadequate and erratic. The urban wastewater management situation is situation grim, and serious environmental problems are arising due to poor management of sewage, grey-water and storm water. In rural areas, 53% of the population still practices open defecation (All India Institute of Hygiene and Public Health, 1995; Centre for Science and Environment 2014).

The poor status of wastewater and excreta disposal systems has serious impacts on public health. The burden of infectious diseases related to fecal pollution of the environment, as well as vector borne diseases, is high. The health sector finds it difficult to prevent and control infectious diseases. In India, diarrheal diseases alone cause more than 0.6 million deaths annually. Figure 1 shows the disease burden in India terms of infectious diseases, which are mostly related to lack of safe disposal of human excreta and fecal wastewaters.
Figure 1

Disease Burden Map. The disease map of India: Mail Today, Published: 20:51 GMT, 12 August 2014, Updated: 22:52 GMT, 12 August 2014; http://www.dailymail.co.uk/indiahome/indianews/article-2723168/VISUAL-EDIT-The-disease-map-India.html.

Figure 1

Disease Burden Map. The disease map of India: Mail Today, Published: 20:51 GMT, 12 August 2014, Updated: 22:52 GMT, 12 August 2014; http://www.dailymail.co.uk/indiahome/indianews/article-2723168/VISUAL-EDIT-The-disease-map-India.html.

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In the 7,000 or so Indian cities and towns, some 234 (5%) have sewage treatment plants (STPs). Most were developed in the 1980s and 90 s, and are located on the banks of major rivers. Among the various STP technologies, activated sludge, bio-filters and oxidation ponds are the commonest process train, accounting for 60% of total installed capacity. This is followed by Up-flow Anaerobic Sludge Blanket (UASB) technologies, at 26% of installed capacity. Waste stabilization ponds are also used and account for about 6% of installed capacity. Per capita wastewater generation in class-I and II cities/towns, representing 72% of India's urban population, has been estimated at around 98 lpcd, while Delhi alone discharges 3,663 MLD of wastewaters, 61% of which is treated, amounting to more than 220 lpcd. Estimates by the Central Pollution Control Board (CPCB) indicate that total wastewater generation from the 414 Class I cities and 489 Class II towns is around 26,164 and 2,965 MLD respectively. The corresponding sewage treatment capacity installed is just 6,047 and 200 MLD, respectively (see Table 1 and Figure 2), leading to a gap of 22,939 MLD in capacity (CPCB 1999; CPCB 2005a).
Table 1

Sewage generation and treatment in Class I and II cities and towns (2001 population basis)

City category & populationNumberSewage generation, MLDInstalled sewage treatment capacity, MLDCapacity gap in cities having STPs, MLD (A)Sewage generation in cities having no STPs, MLD (B)Total capacity gap, MLD (A + B)
Class I cities 414** 26,164 (100%) 6,047 (23.1%) (In 112 cities) 8,605 (32.9%) 11,512 (44%) 20,117 (76.9%) 
Class II towns 489** 2,965 (100%) 200 ( > 143*) (4.8%) (In 22 towns) Nil 2,822 (95.2%) 2,822 (95.2%) 
Totals (Classes I and II) 893** 29,129 (100%) 6,190 (21.3%) 8,605 (29.5%) 14,334 (49.2%) 22,939 (78.7%) 
City category & populationNumberSewage generation, MLDInstalled sewage treatment capacity, MLDCapacity gap in cities having STPs, MLD (A)Sewage generation in cities having no STPs, MLD (B)Total capacity gap, MLD (A + B)
Class I cities 414** 26,164 (100%) 6,047 (23.1%) (In 112 cities) 8,605 (32.9%) 11,512 (44%) 20,117 (76.9%) 
Class II towns 489** 2,965 (100%) 200 ( > 143*) (4.8%) (In 22 towns) Nil 2,822 (95.2%) 2,822 (95.2%) 
Totals (Classes I and II) 893** 29,129 (100%) 6,190 (21.3%) 8,605 (29.5%) 14,334 (49.2%) 22,939 (78.7%) 
Figure 2

Sewage generation and treatment capacity in 414 Class I cities and 489 class II towns in India. (CPCB 2009).

Figure 2

Sewage generation and treatment capacity in 414 Class I cities and 489 class II towns in India. (CPCB 2009).

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Figure 3

Sulabh Public Toilet Complexes.

Figure 3

Sulabh Public Toilet Complexes.

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Figure 4

Complete Recycling & Reuse of Human Excreta from Public Toilets – Sulabh Effluent Treatment Technology.

Figure 4

Complete Recycling & Reuse of Human Excreta from Public Toilets – Sulabh Effluent Treatment Technology.

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Existing treatment capacity is thus just 18.6% of sewage generation but another 5.2% is being added. As the actual capacity utilization of STPs is only 72.2%, however, only 13.5% of the sewage is treated. This clearly indicates the dismal position of sewage treatment, and is the main cause of pollution in rivers and lakes. There is an urgent need to increase sewage treatment capacity and optimize its utilization, to improve water quality.

Irrespective of the technologies adopted, the operation and maintenance of most sewage treatment plants is poor. Most do not function properly and many are non-functional. To meet the National Guideline (Ref. CPHEEO, Ministry of Urban Development, Govt. of India) , STPs are designed to produce effluents with less than 30 mg-BOD/l, but the fecal coliform content of their effluents is very high (>105 MPN/100 ml). This is the principal reason behind the high fecal coliform count in Indian rivers, which makes them unfit for bathing (CPCB 2007a; CPCB 2009).

Sludge removal, treatment and handling are largely neglected in most Indian STPs. The conventional wastewater treatment processes are extensive, requiring complex operation and maintenance beyond the capabilities of most local urban bodies. Thus, due to poor design and maintenance, irregular power supplies and lack of technical manpower, wastewater treatment facilities in India do not function properly and remain closed most of the time. It is also true of wastewater treatment that none of the technologies available provides a direct economic return. Thus, local authorities are not generally interested in wastewater treatment.

The situation is particularly critical in the small and medium towns. The large metropolitan and mega cities have adequate financial capacity and technical manpower to operate sewerage systems with treatment plants. Small and medium municipal towns have inadequate financial resources and cannot afford them. Even if central or state government installs facilities in such towns, they cannot be maintained by the municipality. It has been noted before that, even after such projects have been completed, the municipalities have refused to take over their management.

Some 72% of the Indian urban population lives in Class I and II cities/towns. Most small and medium towns are in Class II, and their combined, installed wastewater collection and treatment capacity is less than 10% of that needed. As a result, most wastewater goes via open surface drains leading to natural receiving bodies (rivers and lakes). The surface drains, carrying storm water; sullage and grey-water, are contaminated with fecal waste. Many urban households in small/medium towns, where there is no sewerage system, use septic tank toilets for excreta disposal. Such systems are expensive and require large volumes of water for flushing. Further, most septic tanks function without soakage pits and thus discharge highly polluting effluents to the surface drains. Septic tanks have other problems, too, like the periodic need for cleaning and disposal of sludge. Inadequate effluent disposal is a source of foul smells, as well as mosquito breeding and related health hazards.

From the above, it is obvious that Western-style wastewater disposal, comprising sewerage networks and STPs, is neither affordable nor technically feasible in countries like India. In particular, small and medium towns Class II III – are not in a position to install, operate and maintain them, either now or in the near future. This is because, among other things:

  • The capital and O&M costs are prohibitive.

  • Water requirements are high.

    Large amounts of water are needed for flushing toilets and to maintain self-cleansing velocities in the sewerage system. Analysis of water resource issues indicates increasing problems, with reduced fresh water availability but increased demand for them.

  • Skilled manpower is needed.

    Class II and III towns have not got the infrastructure, institutional set up or manpower required to construct and/or maintain sewerage and sewage treatment plants.

In this context, urban development policy makers must consider alternative, decentralized wastewater and excreta disposal systems. This could be a combination of onsite management of human excreta and a decentralized system of wastewater disposal.

Most Class II and III towns have no sewerage or underground drainage system. While storm water, grey-water and sullage are removed via open surface drains, the human excreta from toilets go to septic tank systems or pit latrines. In under-served or un-served urban areas like slums, people often recourse to open defecation. On the whole, the status of sanitation is low, resulting in serious environmental pollution.

Sulabh International Social Service Organization (SISSO) has developed two technologies that, if combined judiciously, could largely deal with the management problems of wastewater and human excreta. Individual household toilets could be connected to double pit systems, popularly known as two-pit pour-flush toilets. These are characterized by low water consumption, total recycling of the excreta as organic manure, and eco-friendly and cost-effective operation and maintenance – see below.

It is suggested that, for towns without sewerage systems, on-site sanitation should be supported by community toilet complexes, to take care of the excreta and wastewater loads from the isolated and floating populations. The effluent from the community toilet complexes and the sewage collected from isolated population groups like high rise buildings, housing colonies, etc. could be treated in a decentralized system also developed by SISSO. In this, the sewage effluent from isolated toilet complexes is stored and digested in biogas plants, while multi-stage treatment is provided for the effluent, using sand filtration followed by activated charcoal and UV irradiation. The BOD of the final effluent is below 10 mg/l and the fecal coliform count very low, so it is safe for discharge into rivers or reuse for agriculture, horticulture or industry.

It is proposed that covered surface drains, which would carry sullage, grey-water and storm water, would also receive the effluent from the community toilet-linked biogas system and carry the final effluent to the discharge point. Alternatively, depending on the local situation, effluent from the biogas system could be recycled for agriculture, horticulture, toilet flushing, etc, if it had low pollution potential. These alternative systems would be cost-effective, user-friendly and ecologically sustainable, and the system could be upgraded and connected to the sewerage system as and when that is installed.

The Sulabh flush compost toilet comprises an indigenous technology, and can be constructed by local labor with local materials. It consists of a pan with a steep slope of 25 to 28° and a specially designed trap with a 20 mm water-seal. This requires only 1.5 to 2 liters of water for flushing, thus helping conserve water. No scavengers are needed to clean the two pits, which have design capacities to suit the number of users. Each pit is normally designed for 3 years' use and the pits are used alternately. When one is full, the incoming excreta are diverted to the other. In about two years, the sludge is digested and is almost dry and pathogen free, and thus safe for handling as manure. Digested sludge, which can be dug out easily and used for agriculture, is odorless, and is a good manure and soil-conditioner. Pit emptying costs can be met partially by selling the composted manure (Figure 3).

The Sulabh toilet can be constructed on the upper floors of buildings and has a high potential for up-grading – it can be connected readily to sewers, in due course.

The provision of Sulabh public toilet complexes on a ‘pay-and-use basis' is an important landmark in public health, hygiene and environmental sanitation. In 1878, the Bengal Government enacted a law to set up toilet facilities in Calcutta, but such facilities could not be provided/maintained for the next 100 years. The concept of constructing public toilets and their maintenance on a pay-and-use basis, originated by Sulabh in 1974, was outstandingly successful. For some years the behavior and attitude of those not using the public toilets already available in cities/towns was studied. It was felt that the insanitary and filthy state of such toilets deterred use. It was also felt that, if facilities for bathing and washing clothes could be provided along with community toilets, people would like to use them and willing to pay to do so.

Up to 2015, more than 7,500 such public toilets have been constructed in India. The largest such toilet is in Shirdi, in Maharashtra State. It has 120 WCs, 108 bathrooms, 28 special toilets (separate for males and females) and 5,000 lockers for use by pilgrims. Others can be found in public places, bus stands, hospitals, markets and slums.

Recycling and reuse of human excreta for biogas generation is an important means of getting rid of potential health hazards. After a series of experiments, Sulabh developed an efficient biogas plant whose design has been approved by the Indian Ministry of Non-conventional Energy Sources for widespread implementation Figure 4.

  • The costs of sewage collection, and of system operation and maintenance, are low.

  • No manual handling of human excreta is required.

  • It is aesthetically and socially accepted.

  • Biogas has many potential uses.

  • The treated effluent is safe for use in agriculture and horticulture, or for discharge.

  • The treated effluent can be used for cleaning public toilet floors and the like.

  • If the effluent is discharged to sewer, this can reduce the load on the STP.

  • Conservation of water resources.

    Low flush toilets, like that described above, offer significant advantages in resource conservation.

  • Value of manure produced from twin pit toilets

    Humans excrete about 40 kg/a of dry solids. When multiplied by the total population of Class II and III towns in India, this represents significant value.

  • Bio-energy can be generated in bio-gas plants linked to community toilet complexes.

In countries like India, wastewater management is a critical concern, and is particularly challenging in small and medium towns. The challenge is to find a low cost, decentralized system for wastewater collection, transport and disposal, which is user-friendly and cost-effective. The system should be affordable for local urban bodies in these towns, and technically feasible. Compared to conventional treatment systems, it should require less materials and energy, consume less water, be more easily operated, present no sludge disposal problems and capable of operation by untrained personnel. The systems developed by SISSO and described here largely address these problems.

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