'Change perception about wastewater'

Blanca Jimnez-Cisneros, director of the division of water sciences and secretary of International Hydrological Programme, Unesco, talks to Sushmita Sengupta on how a huge cultural change is required to treat wastewater as a valuable resource. Excerpts from an interview.

By Sushmita Sengupta
Last Updated: Thursday 22 March 2018

Do you think there will be more Cape Towns in the future?

There is a risk that several cities will face water shortage as they are witnessing rapid urban population growth. One of the factors behind population expansion is rural migration. People come to cities looking for employment opportunities. When population expands rapidly, water and sanitation infrastructure suffers a vast deal. Moreover, there is the issue of weak or almost non-existent policies on more efficient water usage. Also, water management plans are not based on demand, reuse and recycling. Wastewater is often not given much importance.

Which countries should immediately work on water management plans and practices to avoid stress?

Countries which are not already water stressed at present, those located in arid and semi-arid zones; having high population density; and, nations in temperate regions where the per capita water consumption surpasses the local renewable water availability, are the most vulnerable ones. One has to consider the climate change models to further prioritise countries in need of sound, science-based policies and plans for water resources management.

Why do you think cities should explore wastewater reuse at the policy level?

It is simply because cities represent a tiny fraction of land (less than 1 per cent of the total available land) where water demand is extremely high. At the same time, they are the source of high volumes of wastewater. On the one hand, it results in an unbalanced demand, as cities are incapable of sustainably collecting the amount of water needed in the geographical area they cover. They need water for their needs further away from their location. On the other, cities discharge waste that the local environment is incapable of absorbing. Thus, it is imperative that wastewater is used to ensure sustainable water provision in a city setting and relieve the environment from a source of pollution. By promoting wastewater use, a key component of circular economy, we turn waste into a valuable source of water and contribute to sustainably closing the water cycle. The benefits of wastewater reuse are multiple and go beyond its use as potable water, that for agriculture and industrial purposes.

Energy can be recovered in the wastewater treatment process and the sludge produced used as fertiliser post treatment. It is imperative to optimise the treatment stages and use wastewater for multiple purposes. I want to point out that the term wastewater reuse is not necessarily correct, as wastewater has to be used first in order to be reused. Most of the times, it is not the case.

Which water-stressed urban areas have the maximum potential for reuse of treated wastewater?

One has to aim for areas where there is high population density and where planners have made provision for green areas where wastewater can be used for irrigation. Also, there are cities where the infrastructure for wastewater treatment and reclamation do not exist, but can be constructed. This allows for proper design of the wastewater treatment process to optimise the results. In cities where wastewater treatment plants exist, other factors have to be taken into consideration such as the energy and infrastructure required to use wastewater.

What should be considered while developing a legislative and regulatory framework for treatment and reuse of wastewater at the municipal level?

The main thing is to consider wastewater as water source. We should move away from the concept that wastewater needs to be disposed of and embrace the idea that it consists of more than 99.99 per cent water.

It is important that legislative and regulatory framework recognises and promotes multiple uses of wastewater according to demand. It should be clear to legislators that not all consumption demands the same quality of water. For example, drinking water has to have high quality while the water used to flush toilets may be of inferior quality. If wastewater is to be used for irrigating green areas or for agriculture, the quality demand is again different. Various industrial uses require different degrees of water quality standards. All these need to be considered, as it would allow for a flexible policy, resulting in the utilisation of the resource in a financially optimal manner.

How can communities be made aware about treated wastewater and reuse?

Reuse of wastewater requires a cultural change. People are taught from a very young age that wastewater is a waste. Though partly true (as a number of water-borne diseases are attributed to dirty water), wastewater is a resource. For recognising it as valuable, we need to mainstream water education in the school curricula and educate future generations to accept its use and reuse without any hesitation. Furthermore, we need to organise awareness programmes to target certain groups of users: farmers for sure as agriculture is a major guzzler of water.

Which countries will achieve the Sustainable Development Goals if they include water conservation measures in their policies and actions?

All countries where water is scarce and where they understand the importance of efficient water use (that is using six to eight litres of water to flush toilets instead of 20-30 litres). Also, those countries will achieve the goals that are reusing water; employing water for a different use from which wastewater is produced; or recycling. Though water is one of the Sustainable Development Goals (SDG 6) and is linked to a number of other SDG targets related to water, it would be a mistake to believe that water conservation measures and policies would suffice for member states to achieve all the goals by 2030. However, I agree that they would definitely provide countries with solutions and support in achieving a few of them, but not all.

The interview was first published in March 16-31, 2018 issue of Down To Earth

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