Reimagining Urban Sanitation through Decentralised Systems of Waste-Water Management
"Decentralized wastewater systems help the community reach the triple bottom line of sustainability: Good for Environment, Good for Economy and Good for the People" - United States' Environmental Protection Agency
The national urban footprint growth in India has been about 40% in the last 11 years, national average population living in slums stand at 23% and is as high as over 50% in cities like Mumbai; with 7000+ towns and cities; only about 250 of them have sewerage systems, 60% of these underperform or are closed. Indian cities are dumping a volume of untreated sewerage to the tune of approximately 1,60,00,000 Olympic size swimming pools directly into the environment; daily (Rath, 2020). These figures are astounding in the wake of being one of the most water stressed countries in the world.
Waste water flowing into Mithi River, Mumbai; environment pollution and the contrast of understanding a holistic need for Urban Sanitation.
Image source: (Team, 2020)
It has been over half a decade to the launch of the national Swatch Bharat Mission that has been successful in generating awareness and providing sanitation solution through public toilets. However, it still remains a grassroots level initiative, without catering to the other side of the same coin that deals with the discharge of fecal waste and waste water reuse. It remains un-scalable to the policies of Indian cities due to the lack of a larger vision incorporated to look at the potential of urban sanitation solutions from both top down and bottom up approaches. The next level of the program really calls for understanding integrated water and sanitation reuse strategies as waste water really is only second to the most dangerous environment problem of plastic as a single use resource.
Developing countries are going to continue to see an enlargement of their urban footprint. With the current sanitation and water management regime in most cities in India; both are provided by the government. The enlarging footprint of cities is continually going to add infrastructure and maintenance burden both financially and administratively to local governing bodies. Cities like Mumbai, Pune, Delhi are already drawing water and disposing their waste hundreds of kilometers away. The capital cost of providing these services are as high as INR 25000/capita and construction of these systems actually account for 90% of the costs. We are essentially looking at projects of INR 1000-4000 Cr to provide safe sanitation facilities and long time frames of 8-10 years of construction time. Meanwhile, conventional gravity sewers are large networks of underground pipes that convey black-water, grey-water and, in many cases, storm water from individual households to a (Semi-) Centralized Treatment facility, using gravity (and pumps when necessary). As pumps may be necessary if the landscape is very flat, or in hilly regions, they are mostly found in urban areas. They require high capital and operation cost which becomes a huge burden for cities, that is difficult and costly to extend as a community changes and a city grows. Leakages pose a risk of wastewater exfiltration and groundwater infiltration and are difficult to identify.
Does this mean that we stop urbanising? Or can we look at more sustainable systems to provide and manage such services to urban population with decentralized solutions that can be easy to construct, more economical with respect to service provision and environmentally more sustainable. However, decentralization shall require a paradigm shift for administration due to the complexity of large numbers compared to 10 STPs in cities today. Decentralization at neighbourhood level reduces the load on large capex and time required to build. Also the treated water can go back to the system. Most importantly it needs to be understood that the more urbanised a city becomes, it creates a greater need for an integrated system across with a holistic approach towards the lifecycle of an asset like water.
Water Infrastructure in Mumbai.
Image Source: (Cole)
We draw in water from hundreds of miles and then pump out waste to hundreds of miles away. Can we look at creating circular loops engaging the individual, community, service providers and government through more holistic models? Can we look at financial models with other industries that can use and create accountability to the use of locally treated water that they have been traditionally purchased through Public Private Partnership (PPP), Design-Build-Finance-Operate-Transfer (DBFOT), Hybrid Annuity Model (HAM), etc. The lack of awareness of innovative technologies of decentralized systems being developed for waste discharge and treatment and the policies supporting them is the reason for the age old installations of septic tanks in the building industry. The sludge from these septic tanks is also one of the most common reasons of underground water contamination. Technologies like MBR, MBBR, DEWATS, coupled with dual piping systems and affordable automation, etc can help in creating integrated water and waste management systems at the neighbourhood level. Contrary to this, decentralized sanitation systems do not require such huge investments, can be managed effectively and provision can be done to all the remote areas and satellite towns, making it manageable for the cities to operate.
Innovative sanitation systems developed by BORDA with integrated with systems of dual piping for reuse of waste water and landscape strategies.
Image Source: (Rath, 2020)
Sanitation revolutions (plague, malaria, dengue) have been the most critical life saving solutions than any medical advancements in the world by their sheer number. Projects like the revitalization of Lake Geneva on the Swiss-French border in Europe show how regions can turn around when they manage their water bodies through federal laws and collaborative efforts of enforcement policies, scientists, urban administrators. Decentralised systems need to be looked from the neighbourhood level - administratively and economically; however zooming out the lens to the land use planning level at the municipal level is also necessary where land parcels are reserved in Development plans integrated with urban parks where and water retention areas created an integrated loop to transform water from waste to a resource.
Cole, B. WATER PIPES NEAR THE DHARAVI SLUM, MUMBAI, INDIA. Brett-Cole-India-01909.
Rath, M. (2020, October 16). Wastewater Management & Reuse. (P. Cities, Interviewer)
Team, M. L. (2020). Retrieved 2020, from Mumbai Live: https://www.mumbailive.com/en/civic/mumbai-rains-update-still-have-huge-garbage-in-mithi-river-of-mumbai-51836
For more information, watch the Master Class 10 “Wastewater Management and Reuse” on the link:
About the Speaker
Manas Rath is a Senior Advisor at BORDA/CDD that focuses on natural wastewater treatment solutions and decentralized sewerage management--to improve health, sanitation and water security through re-use of treated water.
He has worked extensively with social startups and NGOs in urbanization and sanitation including CDD Society and Shelter Associates, and is helping set up a $100 million water, sanitation and waste management-focused urban impact investment fund.
Earlier, Manas was a Director at Dasra, and advised on private equity and M&A transactions at Avendus Capital. He is co-founder of the Blue Water Company and is a graduate of MIT and the Sloan School of Management.
About the Writer
Enakshee Bhatia is a practicing Architect, Urban Designer and Academician from Mumbai who is passionate about exploring inter-disciplinary approaches towards urban transformation. She believes that writing is a crucial medium of engaging with society to better the practice of architecture and urbanism.