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Tuesday, April 25, 2017
- Tucked against the rolling hills of South Africa’s Eastern Cape province, a small rural school has been turning its kitchen scraps, and agricultural and human waste into methane gas for cooking, and nutrient-rich fertiliser, and is even recycling its water.
Using an integrated biogas system, the Three Crowns Rural School in Lady Frere District is teaching learners, the community, and engineers from around the country a new way of dealing with water, waste, and energy.
According to the Council of Scientific and Industrial Research, if a business as usual approach is followed, South Africa’s freshwater resources will be fully depleted by 2030, unable to meet the needs of people or industry. “The problems will be made worse by more frequent incidents of water pollution and increased costs of water treatment,” said the 2010 CSIR report author, Peter Ashton.
With over 40 percent of South Africa’s dams affected by eutrophication (the process by which water becomes too nutrient-rich and prone to toxic algae blooms), acid mine drainage threatening to poison the water table around heavily populated Gauteng Province, and, according to the Department of Water Affair’s 2010/11 Green Drop report, 56 percent of the nation’s 821 sewage works either in a “critical state” or delivering a “very poor performance,” arid South Africa must develop economical ways of effectively recycling its naturally scarce water resources.
Funded by the Development Bank of South Africa, the Chris Hani District Municipality’s Environmental Management System Programme has been doing just that in its two-year-old pilot project at the Three Crowns Rural School.
The school’s zero-waste system feeds organic waste from the school’s kitchen, gardens, and toilets into an anaerobic “digester” (an oxygen-limiting, gas-tight enclosed pit) where microbial action breaks down the waste, creating methane “bio-gas” in the process.
The digested effluent is sent to a series of ponds, where first the remaining pollutants combine with oxygen and are transformed into a nutrient-rich “algal slurry” that makes excellent fertiliser. The water that emerges from the first pond shuttles to another, where fish like tilapia can feed on remaining algal content. The fishpond eco-system produces another algal fertiliser, and the pond water is irrigation- ready.The final result is a system that transforms 100 percent of organic waste into biogas for cooking, pathogen-free algal fertiliser, and recycled pathogen-free water for irrigation of the school’s gardens. The project also provides an impressive life-science laboratory where learners daily witness and come to understand concepts like decomposition, aerobic and anaerobic biological action, and sustainability.
“It’s nothing new for the children to talk about digesters and bacteria and the algal pond and sterilisation. Hopefully these guys coming out of the school will help advance this type of thinking in the future,” said Mark Wells of People’s Power Africa (PPA), a consortium of environmental biotechnologies companies that was commissioned to install, manage, and monitor the system.
Francois Nel, head of environmental health and community services for Chris Hani District Municipality, emphasised the project’s ability to affect the way people think. “The first thing is the education of the children and changing the mindset in terms of energy, waste, and climate change. And the ownership – the children take ownership of the environment and the importance of protecting it.”
And it is not only the children who benefit. “This project is very, very important. First I can say to my own life, because I learned a lot of things about nature,” said Zothe, the school caretaker who oversees the feeding of the bio-digester. “We’ve learned how to use things that are connected to nature, like we have a solar cooker, bio-digester, wind power energy, so we don’t have to spend a lot of money, and we don’t waste.”
The Three Crowns project has been a great success, with four schools requesting installation of the same system, and the nearby communities of Intsikayethu and Engcobo planning to install the systems on a much larger scale.
It has also won numerous awards, including the 2011 Netherlands-sponsored Moolah for Amanzi award for best concept in water and sanitation projects, two Eskom ETA awards, and an Eastern Cape flagship project award.
Though adoption of the Three Crowns Project appears to be taking off, not far away in East London’s Buffalo City Municipality, another People’s Power Africa project is attempting to prove its worth to a sceptical municipality.
Like Three Crowns, PPA’s “eMonti Green Hub” is a one-stop shop to recover resources (e.g., nutrient- filled fertiliser, methane gas, and recycled water) from waste, but this time the “feed” includes municipal wastewater, sewage sludge, and the organic fraction of municipal solid waste including garden and abattoir refuse.
Currently 10 million litres of that “feed” in the form of raw sewage are dumped daily into the surf zone by Buffalo City’s defunct Second Creek Wastewater Treatment Works. The green hub proposes to use a large-scale anaerobic digester that is heated in continuously stirred reactors to more rapidly process that waste (woody garden refuse would fuel the heating).
Based on PPA’s feasibility study, the green hub is projected to produce methane biogas at a rate of 300 kilogrammes/hour (a head-high gas canister holds 40 kg), resulting in “green” methane gas, which can provide a sustainable source of income to run the hub. Mercedes Benz South Africa has already provided a letter of interest to purchase the biomethane for use in their paint shop air dryers and ovens.
Processing the daily “feedstock” (including eight million litres of industrial wastewater, eight million litres of domestic wastewater, two million litres of sewage sludge, 48 tonnes of food waste, 16 tonnes of abattoir waste, and 82 tonnes of garden refuse), the hub would yearly generate 5.8 billion litres of recycled water, 2,300 tonnes of biomethane gas, and 10,000 tons of bio-fertiliser, while diverting 30,000 tonnes of waste from landfills every year.
“That’s where it becomes so exciting,” Wells explained. “Especially when you look at what’s happening in the environment, the municipality needs to get its head around the huge amounts of bio-resources that they’re currently not using at all, that are just being thrown into landfill sites and into the sea. It just doesn’t make sense.”
Ultimately PPA wants the hub to benefit local communities, and so plans are for the plant to be held mostly in a joint community and municipal environmental trust, with additional private and public equity. Unfortunately getting the hub operational will involve cutting through extensive administrative red tape, which relies on changes in the attitudes of the city’s engineers and administrators.
“We know that everything is possible, but getting the city’s approval and endorsement has been a struggle. These projects are very difficult to put together because you’re talking about municipal resources and there’s all sorts of issues around that. Plus municipalities have to change the way they do things. We’re pushing the boundaries. We have the technical understanding, but now it’s the how to make it real,” Wells said.
Francois Nel agreed that PPA would face an uphill battle in getting the hub approved. “It’s a brilliant idea. The problem is that people don’t understand. They don’t understand the environment, and they don’t understand climate change,” Nel commented, recalling how even now he struggles to convince engineers to “come to the party,” despite the Three Crowns’ success.
Nonetheless, PPA and its partners anticipate that the hub’s environmental impact assessment will soon begin, and are working with the municipality on moving the public consultation process forward. They remain optimistic that by the end of 2013 the hub will begin producing the nutrients, energy, and recycled water.
“Essentially we see this as the people’s resources. Even if the municipality is in charge of it, they’re throwing it away, so we want to get the benefits from those resources back into community. Even if we don’t capitalise on it ourselves, the project will go forward. The main thing is to solve the problem and demonstrate these solutions,” said Wells.