July 22, 2016

Scientists at the ongoing Africa Water Week have pointed out different innovative techniques which have succeeded elsewhere in the world, in which waste water can be converted into a useful resource for African countries.

“We have documented up to 150 different case studies in which waste water has been turned into a meaningful resource,” said Dr Kala Vairavamoorthy, the Practice Leader for Applied Research and Knowledge at the International Water Management Institute (IWMI). “All we need is to change our perspectives, and create opportunity to do things differently,” he told participants at the AWW.

Dr Vairavamoorthy explained that flowing waste water can easily be used to rotate micro-turbines to generate hydro-electric power, and in the same energy sector, the water can be used in bio-digesters to produce biogas, which can be sold for income generation.

“Crop nutrients can also be extracted from waste water to be used for different purposes, and it can still be recycled for other purposes,” he said.

However, for this to happen, said Sarantuya Zandaryaa of UNESCO said that African countries need to put in place relevant policies to provide an enabling environment for reuse of the waste water. She gave examples of regulations in different countries, which have provided an enabling environment for companies to convert waste water into a resource. She gave an example of regulations governing the California use of waste water as a successful case study where policies have provided enabling environment for waste water use.

A farmer using sewage water on his farm in Nairobi,  Kenya
A farmer using sewage water on his farm in Nairobi, Kenya

So far, the California Water Recycling Criteria (encoded in Title 22 of the California Code of Administration) allow 43 specified uses of recycled water – including irrigation of all types of food crops. These criteria include different water quality requirements for irrigation of each type of crop; those eaten raw, those receiving processing before consumption, and those not involving any human contact before industrial processing.

However, the regulations are among the most stringent in the world and have been used as a model for many other countries’ guidelines and water reuse regulations. It is in the same regard that Zandaryaa pointed out that for such policies to work for Africa, there must be very reliable monitoring, reliable enforcement of the regulations and appropriate technology.

These regulations, said Zandaryaam, must be developed with close involvement of local communities, and there is need for capacity building at all levels, from the government moving down to the people. She said that the countries can start by improving the existing legal frameworks, but should develop guidelines for waste water reuse. In a different forum elsewhere, Dr Paramjit Singh Minhas, an Indian research scientist gave a different perspective on how waste water can be used meaningfully.

In a study titled ‘Potential of tree plantations for wastewater disposal: Long term use in Eucalyptus,’ the researchers argue that trees with high transpiration rate (‘thirsty’ trees) such as eucalyptus can be easily used to clean the environment of wastewater. The trees grown in wastewater will also produce fuel-wood and timber for income generation, and as well sequester carbon from the atmosphere.

The Eucalyptus trees have long been blamed for their ‘thirst’ for ground water, owing to their long tap roots, and there is scientific evidence that the species could dry up water bodies. According to Dr Vairavamoorthy, waste water has always been a burden particularly in Africa. But with new evidence based studies, it can now be put to use, thus supplementing the clean water, which is scarce in many African countries.

Water Journalists Africa

Water Journalists Africa (WJA) is the largest network of journalists reporting on water in the African continent. It brings together some 700 journalists from 50 African countries. It was established in...

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