The treatment of reclaimed water (treated wastewater) and its reuse has become an important area of interest due to its potential to address many pressing urban challenges. Indian cities are grappling with a sharply increasing demand for fresh water due to rapid urbanization and exponential population growth. Treating the resulting wastewater proved equally difficult; much of it ends up polluting urban water bodies.
In addition, the discharge of untreated wastewater triples the carbon emissions compared to reclaimed water. This is particularly relevant now in light of the IPCC’s Sixth Assessment Report on Climate Change Mitigation, released on April 4. Studies have shown that emissions from remediation and their management can play a key role in reducing greenhouse gases, including methane. Making these improvements early can reduce long-term climate impacts.
But institutional arrangements and regulations alone are not enough to achieve the kind of step change needed for the integrated management of urban water that is essential to building more resilient cities. Acceptance by end users, especially city residents, is a big part of this equation.
Research with apartment dwellers in Bengaluru found that the ‘yuck factor’ is a major barrier to widespread use of reclaimed water, despite its demonstrable safety. How can their legitimate concerns be allayed? What role can technology play in facilitating this shift in perception?
Bangalore makes wastewater reuse mandatory
Cities like Bengaluru have made great strides towards implementing more efficient wastewater management systems in the domestic context, i.e. apartment buildings. Recognizing the limitations of upgrading the existing centralized infrastructure, the Bangalore Water Supply and Sanitation Board (BWSSB) mandated in 2016 that all apartments larger than 20 units must install decentralized STPs and adhere to the Zero Liquid Discharge policy ( ZLD). Decentralized treatment uses off-grid wastewater treatment technology to treat wastewater at the source of production. There are now more than 3,250 decentralized STPs in the city, according to the state’s Pollution Control Board (PCB), and yet there is little progress on the reuse mandate.
Wastewater reuse is hampered by lack of trust
Decentralized sewage treatment plants in Bengaluru provide residents with a huge opportunity to replace fresh water with activities that require non-potable quality water, such as cleaning floors, cleaning surfaces and vehicles. The bottleneck is trust. Residents have a negative perception of reclaimed water that needs to be addressed.
Interviews with Resident Welfare Associations (RWAs) in Bengaluru revealed that residents rated water quality based on visual markers, i.e. whether the water was clear and odorless . Related to this, residents feel a lack of confidence in water quality reports in relation to the color of the water (which may be yellowish or contain suspended particles). Their distrust is also reinforced by the fact that the operations and maintenance of treatment plants are not carried out regularly or by workers with the expertise to do so.
There are fixes to the trust issue
Better STP Technology
One way to build user confidence is to make technological changes that improve and promote the reuse of treated water. This can range from retrofitting faulty STPs, then installing sensors that provide real-time data on the quality of the water produced by the STP, to installing systems that treat gray water separately ( water from shower pipes, kitchen sinks) and black water (toilet water). .
Clear standards and protocols
Defining clear water quality parameters and economically viable testing mechanisms can help establish appropriate treated wastewater monitoring protocols. The standards may vary depending on the purpose for which the reclaimed water is used. The multi-barrier approach used in Israel is an example of using wastewater of different qualities for different purposes, which meets prescribed reuse standards.
Studies have shown that residents give a lot of credit to what they can actually see and observe in determining water quality. Even if the water is clear and not visibly polluted, a “yuck factor” remains. Here, sensors that clearly display real-time water quality indicators at the STP itself and on the tankers that transport wastewater can play a pivotal role in quality assurance and confidence building. .
These technical fixes cannot accomplish a widespread change in perception without systematic outreach programs to educate the public on the safety of using reclaimed water and its multiple benefits. It is important to demonstrate successful case studies, as in Singapore and Israelwhich show that fresh water can be saved by replacing it with waste water.
There are cases in Bangalore alone, such as T-Zed Apartments in Whitefield, which treats and reuses all of its water. They also conducted “blind” behavioral experiments, under the supervision of health professionals, to convince residents that the water was safe. T-Zed’s 95 units use treated greywater for toilet flushing, gardening and aquifer recharge through 44 on-site percolation wells.
Helping residents understand the potential savings and costs of fresh water is also an effective communication tool. Bengaluru and other major metropolitan cities in India need to build outwards in the outskirts. As growth far outpaces the provision of essential services like piped water, people in these new areas depend on water tankers. It’s already expensive, and as fuel prices reach record highs, that expense is likely to increase. There is therefore an economic incentive to consider reusing reclaimed water.
Capacity building and certification
Finally, state support and regulation are essential to link these many considerations. But the capacity to implement the regulations is lacking. Currently, most apartment STPs are not monitored by trained professionals who can detect problems early on and ensure proper maintenance. State-run PCB training programs and third-party STP certifications can help fill this gap.
Investing in wastewater is “investing in our planet”
The multiple factors and stakeholders mentioned above highlight the complexity of this area. The theme for Earth Day this year is “Investing in our planet” with the message that “we must act (boldly), innovate (widely) and implement (fairly).” This is a call that resonates strongly with the kind of approach needed to understand and establish appropriate wastewater treatment and reuse systems in our cities.
The opinions expressed above are those of the author.
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