Wastewater Management as a Tool for Sustainable Development
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Each year, approximately 56% of the 4000 km3 of freshwater extracted globally for human use is released as municipal and industrial wastewater into the water system, with the numbers in litres increasing every year with the growth of urban areas. Still, a large gap remains between the amount of wastewater generated and the amount treated, with even lower numbers for the amount reused.
Amongst the Sustainable Development Goals (SDGs) defined by the UN, target 6.3 deals with improving water quality through wastewater management, eliminating dumping, halving the proportion of untreated wastewater and increasing recycling and safe reuse globally. In a study conducted by UN ESCAP, this target holds the strongest impact upon SDG 6 (on water), with the most number of inter-linkages with other goals and targets. The analysis concluded that most of these linkages are positive and mutually reinforcing. For example, by promoting proper wastewater management and thoughtful use and reuse, the risk of waterborne diseases and malnutrition will drop, positively affecting education and the economy, which in turn contributes to the reduction of poverty and inequalities. This shows a direct influence on SDG 3 (on human health and well-being), on SDG 11 (on cities and human settlements), on SDG 14 (on sustainable use of oceans, seas and marine resources) and on SDG 15 (on sustainable use of terrestrial ecosystems).
The extremely low level of wastewater treatment in low-income and lower-middle-income countries reveals an urgent need for implementing low-cost solutions and safe water reuse options to support the achievement of target 6.3. The Twelfth Five Year (2012–17) Planning Commission (NITI Aayog) Report on Urban Development highlights that 4861 cities and towns in India lack even a partial centralised sewerage network, and almost 50% of households in some metropolitan cities do not have any sewerage connections whatsoever. As mentioned earlier, there is a large gap between the wastewater generated and actually treated. Out of about 61754 million litres per day (MLD) of sewage generated, treatment capacity exists for only 32% (about 22963 MLD). As per the CPCB report, Status of Sewage Treatment in India, municipal wastewater generated in 35 metropolitan cities shows that all these cities collectively generate 15,644 MLD of sewage. But, these cities have sewage treatment capacity of only 8040 MLD. This highlights the need for better infrastructure, either by increasing the number of treatment plants or by increasing the efficiency and capacity of the existing system in the country.
In India, the wastewater sector has been a slow-moving market driven by compliance with regulations instead of demand, with the cost-factor being the driving force behind most decision making. After the signing of the Paris Agreement in 2016, the driving forces have moved towards environmental goals - water security in times of need and reuse of treated wastewater. Water security ranks as a high priority for many policymakers in India, with several cities facing water shortage and high dependency on seasonally unreliable freshwater resources. In most cities, decentralised wastewater treatment systems (DEWATS) have shown greater potential as compared to high-investment centralised treatment plants as the way forward for achieving the above mentioned goals. Yet, for a long-lasting impact on policy-making, what remains to be demonstrated through all these projects is how the costs of improved wastewater management can be outweighed by the benefits in terms of human health, socio-economic development and environmental sustainability. According to the UN World Water Development Report 2017, for every USD 1 spent on sanitation, the estimated return to society is USD 5.5. With adequate treatment and safe application, wastewater can be considered as a reliable and sustainable source of regular water supply, trace elements, phosphorus and other useful by-products. This will, in turn, also reduce the stress on the depleting groundwater resources and freshwater extractions which can offset the growing water scarcity and demands, leading to water security. Competitive pricing for wastewater and appropriate pricing of water from other sources can be implemented to reflect the costs and impact on the environment. This will enable future investments in wastewater treatment, which can result in affordability for all.
Wastewater is projected to play a key role in the move towards creating a circular economy. However, wastewater’s potential as a source of profitable by-products and services in India remains an uncharted territory. Energy recovered by using wastewater in the form of biofuel, biogas, heat and electricity generation has significant potential for wastewater management systems in terms of reducing the energy use of the system itself, and its operational costs. This shows potential for all wastewater treatment systems to transition towards net neutrality or even energy production units.
An important aspect that needs consideration in the application of treatment systems in India is that not all wastewater needs to be treated to the level of drinking water quality. Non-potable quality water can be safely used in agriculture, industries and municipalities for a variety of purposes – irrigation, cleaning, cooling etc. As the cost for advanced treatment methods is increasing, treating wastewater to the level most appropriate for its intended ‘safe’ use (known as ‘fit-for-purpose’ treatment) is essential for maintaining the system’s affordability.
There is also a need to make wastewater treatment and reuse in India a people-centric system with the use of decentralised wastewater treatment plants. On an industrial level, many such projects have been implemented; yet there are currently two major roadblocks in the adoption of treated wastewater for municipal and domestic purposes. First is the requirement of setting up a third water utility: a pipeline network for distribution of treated/reclaimed water to households, in addition to the wastewater and freshwater systems. Second is the hesitation by domestic users, who have a negative perception of the phrase “reused water” and concerns over the efficacy of the toilet-to-tap system. Barriers to the use of reclaimed wastewater and recovered by-products are, thus, more economic, regulatory and social, rather than technical.
The environmental benefits of wastewater treatment are widely known and understood. To move forward with action, demonstrating its long-term socio-economic benefits and the steps required to integrate it into the Indian systems is imperative and needs further exploration. Efforts towards this, and overcoming the previously mentioned barriers, is essential for Indian cities to address the complex challenges for towards achieving the 2030 Agenda for Sustainable Development. ■