ALGAE PROVES A HIT IN THE TREATMENT OF WASTEWATER
Ageing infrastructure, insufficient technical skills and limited financial resources have posed significant challenges at some of the country’s wastewater treatment plants. Inefficiently treated wastewater which is released into rivers poses a risk to the environment and human health in downstream communities.
Globally an increase in water pollution is pushing scientists and environmental care specialists to seek best practice in preserving and maintaining sources of safe drinking water. In South Africa areas such as the greater Sekhukhune District Municipality in Limpopo are experiencing huge water quality and sanitation challenges.
The 2014 Green Drop Report noted a digressive trend of the 16 Waste Water Treatment Works (WWTWs) assessed in the area with 3 plants in high risk and 13 plants in critical risk positions. Effluent discharged from WWWs pollutes receiving water bodies, weakening ecosystem services and presenting high risks to the health of communities living downstream. Local communities bear the brunt of poor WWTWs, since they depend on drinking water from the same rivers and streams that are contaminated by these waste waters.
In a bid to address this challenge the Department of Science and Technology (dst), in partnership with the Council of Scientific and Industrial Research (CSIR) and Water Research Commission (WRC) implemented an innovative algae-based wastewater treatment solution at the Motetema wastewater treatment works in the Sekhukhune District Municipality. The Algal Based Ponding Water Treatment initiative is aimed at facilitating the effective and efficient removal of nutrients and pathogens in wastewater treatment works.
Algae are plants that can be grown using water resources such as brackish-, sea-, and wastewater unsuitable for cultivating agricultural crops. When using wastewater, such as municipal, animal and even some industrial runoff, they can help in its treatment and purification, while benefiting from using the nutrients present.
The algae raceway was constructed at the Pretoria CSIR campus for the purpose of mass cultivation of microalgae to be introduced at the Motetema WWTWs. The R8 million infrastructure facilitates growth of algae over a period of approximately 4 weeks using water, fertilisers and algal reactors that were installed in Motetema. On maturation the last two ponds of the 12 are inoculated with algae. Due to the fact that the pond system is based on natural overflow, the inoculated algae will move from one pond to another naturally.
David Mailula, a process controller at Motetema WWTWs welcomed,the project:
“We are now certain when the water from the algae inoculated ponds flows outside and to the nearby rivers , it is safe for animals and human beings to drink. The safety of water was tested using fish. If the fish survives in the algae inoculated ponds then the water is safe.”
The Motetema WWTWs is in the Elias Motsoaledi Local Municipality, one of the five sub-districts that form Greater Sekhukhune District that was identified for the pilot study. Communities from the area previously had no access to safe water. The WRC and CSIR reported that 90% of the water in the Elias Motsoaledi Local Municipality was polluted. Today, more than 300 000 residents are enjoying the health benefits of using recycled water from the sewerage ponds. Well-managed wastewater is a valuable resource and its use could lead to improved food security, health and economy, said the CSIR’s Dr Marius Claassen. He believes the project will play a significant role in growing the economy in the area. Sekhukhune District is one of the areas in the country with extreme poverty levels. If wastewater is treated properly it can be used to create new resources. The sludge removed from wastewater treatment ponds can produce saleable products such as bricks, artificial rocks and compost,w said Claassen. The Algal Based Ponding Water Treatment is a project of the dst’s flagship programme, the Innovation Partnerships for Rural Development Programme (IPRDP). The principal objective of the project is to achieve a significant improvement in the quality of the effluent discharged at Motetema WWTWs.
Other objectives of the project include:
Facilitate the effective and efficient removal of nutrients and pathogens in WWTWs effluent, which a risk to downstream communities and water resources; Establish biotic communities that consume algae and residual pathogens in the final stage with the added benefit of establishing an aquaculture venture. Implement a self-sustaining system that is independent of electricity or expensive chemicals and can be effectively managed by a semi-skilled workforce. Apply a Quantitative Microbial Risk Assessment to confirm the reduction of health risks and Improve community awareness, knowledge sharing and capacity development through an associated community and stakeholder programme
Algae reactors installed in Motetema
David Mailula, leads stakeholders on a site visit to an algae based Waste Water Treatment plant in Motetema.