For people across the developing world, there is often no escape from water pollution. Tens of millions live alongside rivers choked with sewage, lakes filled with farm run-off and canals brimming with industrial toxins.
That is a byproduct of a global wastewater crisis. Just 20 percent of water used in homes, farms and factories is treated, in large part because many communities cannot afford the complex sanitation systems needed to make dirty water clean.
But in some places, like Dar es Salaam, Tanzania, innovative, low-cost, decentralized water treatment systems – some of which don’t even need electricity – are offering hope for the future.
Following World Water Week, we spoke to Riccardo Zennaro, a wastewater expert with the United Nations Environment Programme (UNEP), about those innovative systems and the challenges of managing wastewater.
UNEP: Why is water contamination so widespread and what effect does it have on communities?
Riccardo Zennaro: In the developing world water contamination is due to human activities, both domestic and industrial, population pressure, weak governance and poor management. Slums are often the only place newly arrived city-dwellers can afford to stay, and they generally don’t have safe and effective sewage systems. In most big cities in Africa, for instance, huge volumes of wastewater are dumped untreated in the environment. This increases the risk of diseases, the contamination of fish and irrigated crops, and the loss of livelihoods, with devastating effects on communities. COVID-19 has shown that we need to pay far greater attention to environmental health if we are to secure human health.
UNEP: Around one-third of all rivers in Latin America, Africa and Asia suffer from severe pollution, and there is serious pollution in around one-seventh of all rivers. What are the main challenges for policymakers when it comes to wastewater treatment?
RZ: I would say the main challenges are financial and capacity-related. Unsustainable consumption and a lack of awareness about the impact of pollution are also part of the problem. The fashion industry, for instance, generates about 20 per cent of the world’s wastewater, releasing 500,000 tons of synthetic microfibres into the ocean annually. Also, the benefits of reusing wastewater and investing in sustainable wastewater management and sanitation – such as improving food security, alleviating pressure on water resources and creating green jobs – are sometimes not understood. However, mindsets are shifting. And we see inspiring waves of social mobilization by young people.
UNEP: Poor sanitation is a huge problem in big cities in many parts of the world. How is UNEP helping to change that?
RZ: UNEP is the global voice for the environment and healthy people require a healthy planet. UNEP has been working with various partners to gather data on water quality and develop innovative sewage treatment solutions, such as in Malaysia. We like to think of ourselves as conveners, bringing together willing partners to curb pollution and enhance sustainable development. In the past few years UNEP has worked on wastewater projects in Egypt, Ghana, Morocco and Namibia. In our work we are seeking to spread the use of low-cost, alternative technologies, raise awareness and build capacity. UNEP’s membership in the One Health Alliance is a further opportunity to raise awareness about the health impacts of wastewater pollution.
UNEP: Can you tell us more about a new UNEP initiative in Tanzania to bring affordable sewage systems to non-sewered parts of the country?
RZ: Yes. UNEP is working with the Bremen Overseas Research and Development Association (BORDA), a member of the Global Wastewater Initiative, as well as with local stakeholders from Tanzania, to disseminate the December 2018 Guidelines on Decentralized Wastewater Treatment Systems. The guidelines were developed by UNEP, BORDA, UN-Habitat and the Ministry of Water of Tanzania and have been translated into Swahili – no easy task as many of the technical terms do not exist in Swahili. BORDA is also engaged in capacity-building. It recently held a three-day training session for 42 local specialists to scale up a low-cost, decentralized wastewater treatment systems (known as DEWATS).
UNEP: What are the benefits of these systems?
RZ: They are small-scale treatment plants developed and tested primarily in low-income countries. They give people access to basic sanitation, reduce environmental contamination, and turn wastewater into reusable by-products for agriculture and energy. Typically, they treat up to 1,000 cubic metres of wastewater per day, operate with zero or minimal power, require minimal maintenance, reuse resources wherever possible, and recover energy and nutrients. Investment and operating costs are much lower than centralized systems.
UNEP: To what extent is this a game-changer for, say, slum areas in Dar es Salaam? What has been achieved so far?
RZ: We and our partners are scaling up previous efforts and encouraging and implementing alternative and fit-for-context solutions for wastewater treatment. DEWATS is a game-changer not only for slum areas but for the entire country and beyond. The guidelines contain all the knowledge required to plan and implement DEWATS and build an enabling environment for large-scale replication.
UNEP: What are the barriers to scaling up efforts?
RZ: Barriers include limited resources, the low willingness of stakeholders to commit to change, wrong priorities, misconceptions about alternatives for wastewater treatment, lack of capacity and lack of enforcement of existing laws. However, this is why we are joining hands to develop sustainable solutions.
UNEP: Are climate change considerations built into DEWATS planning?
RZ: Yes. The DEWATS design must limit stormwater intrusion and we are careful to avoid installation in flood-prone locations. Also, DEWATS can reduce emissions of methane, a potent greenhouse gas, from pits and septic tanks and provide renewable energy in the form of biogas for heating and cooking.
For more information, please contact Riccardo Zennaro: riccardo.zennaro@un.org or Tim Fettback: fettback@borda.org.
