The treatment of reclaimed water (treated wastewater) and its reuse has become a significant area of interest because of its potential to address many pressing urban challenges. Indian cities are grappling with steeply rising freshwater demand due to rapid urbanisation and exponential population growth. The treatment of the resultant wastewater has proved equally challenging; a lot of it ends up polluting urban water bodies.
Moreover, the release of untreated wastewater increases carbon emissions by three-fold compared to reclaimed water. This is particularly relevant now in light of the IPCC’s sixth Assessment Report on mitigating climate change, released on April 4. Studies have shown that emissions from sanitation and their management could play a vital part in reducing greenhouse gases, particularly methane. Making such improvements without delay can reduce long-term impacts on the climate.
But institutional arrangements and regulations are insufficient on their own to achieve the kind of sea change needed for integrated urban water management that’s key to building more resilient cities. Acceptance among end-users, particularly city residents, is a big part of this equation.
Research with apartment residents in Bengaluru revealed that the ‘yuck factor’ is a big hindrance to mainstreaming the use of reclaimed water – despite its demonstrable safety. How can their valid concerns be allayed? What role can technology play in easing this shift in perception?
Bangalore mandates wastewater reuse
Cities like Bengaluru have made great strides towards establishing more effective sewage management systems in the domestic context, i.e. apartment buildings. Recognising the limits of upgrading existing centralised infrastructure, the Bangalore Water Supply and Sanitation Board (BWSSB) mandated in 2016 that all apartments with more than 20 units have to install decentralised STPs and adhere to the Zero Liquid Discharge (ZLD) policy. Decentralised treatment uses off-grid wastewater treatment technology to treat sewage at the source of generation. There are now over 3,250 decentralised STPs in the city, according to the state Pollution Control Board (PCB), and yet there is little progress with regard to the reuse mandate.
Wastewater reuse is hampered by lack of trust
Bengaluru’s decentralised STPs offer residents a huge opportunity to substitute freshwater for activities that require water of non-potable quality such as mopping floors, cleaning surfaces and vehicles. The bottleneck is trust. Residents have a negative perception about reclaimed water that must be addressed.
Interviews with residents’ welfare associations (RWA) in Bengaluru found that residents gauged the quality of water based on visual markers, i.e. whether the water is clear and odourless. Connected to this is that residents feel a lack of trust in water quality reports when compared to the colour of the water (which could be yellowish or have suspended particles). Their distrust is also deepened by the fact that operations and maintenance of STPs 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 possibly build confidence among users is through technological modifications that enhance and promote the reuse of treated water. This can range from retrofitting malfunctioning STPs and then installing sensors that give real-time data about the quality of water that the STP produces to setting up systems that treat greywater (water from shower drains, kitchen sinks) and blackwater (water from toilets) separately.
Clear standards and protocols
Setting clear parameters about water quality and economically-viable testing mechanisms can help establish proper 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 found that residents give much credence to what they can tangibly see and observe to determine the quality of water. Even if the water is clear and not visibly polluted, a ‘yuck factor’ remains. Here, sensors that clearly show water quality indicators real-time at the STP itself and on water tankers that transport wastewater can play a pivotal role in quality assurance and trust building.
These technical fixes cannot accomplish widespread change in perception without systematic awareness-building programmes to educate the public about how reclaimed water is safe to use and has multiple benefits. It is important to demonstrate successful case studies, such as in Singapore and Israel, which show that freshwater savings can be achieved by replacing it with wastewater.
There are cases in Bengaluru alone, like T-Zed apartments in Whitefield, that treats and reuses all its water. They also conducted behavioural ‘blindfold’ experiments, with the supervision of healthcare professionals, to convince residents that the water is safe. The 95 units at T-Zed use the treated greywater for toilet flushing, gardening and recharging aquifers through 44 percolation wells onsite.
Helping residents understand the potential freshwater savings and cost is also an effective communication tool. Bengaluru and other big metropolitan cities in India are having to build outwards into the peripheries. As growth far outpaces the delivery of essential services like piped water supply, residents in these new areas depend on water tankers. This is already expensive and as fuel prices reach record highs, this expense will likely increase. Thus, there is an economic incentive to consider reusing reclaimed water.
Capacity building and certification
Finally, state support and regulations are key to tie these many considerations together. But capacity to implement regulations is lacking. Currently, most apartment STPs are not being monitored by trained professionals who can detect issues early on and ensure proper maintenance. Training programmes helmed by the state PCB and third-party STP certifications can help address this gap.
Investing in wastewater IS ‘investing in our planet’
The multiple factors and stakeholders mentioned above underline the complexity of this area. The theme of Earth Day this year is ‘Invest in our Planet’ with the message that ‘we need to act (boldly), innovate (broadly), and implement (equitably)’. This is a call that strongly resonates with the kind of approach needed to understand and establish proper wastewater treatment and reuse systems in our cities.
Views expressed above are the author’s own.
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