The recycling of wastewater on site by high water users in South Africa provides a cost-effective solution in managing water resources, says biological wastewater treatment solutions provider SewTreat business development manager Theunis Coetzer.

He notes that SewTreat was commissioned to supply a biological wastewater treatment plant to convert the existing septic tank system at Brakpan-based nonprofit organisation Siyabonga Africa’s headquarters to a fully functioning biological and ecofriendly system.

SewTreat carried out complete construction and testing of the new plant at the company’s 5 000 m2 manufacturing facility in Witbank, Mpumalanga.

The transportation of the plant to its final site and the full installation were completed in five days, with on-site civil and earth works conducted by local construction companies to the required design.

Coetzer further explains that the cost of vacuum and the disposal of sludge build-up was getting very high on a continual basis; the flow also increased and caused poor quality water to flow directly into the river adjacent to the property.

Septic tanks, he notes, are a rudimentary treatment in an anaerobic zone; therefore, contaminants, such as ammonia and nitrates, are not treated. Harmful bacteria are also released into the environment because the tanks are not disinfected.

SewTreat installed a 10 000 ℓ/d plastic high-density polyethylene above-ground add-on module, which includes an aerobic zone followed by a clarification zone, as well as disinfection.

“We have used Siyabonga’s current septic tank as an anaerobic zone, and a lifting station was installed at the outlet of the septic tank,” Coetzer explains.

He further adds that the activated sludge accumulated in the clarifier is then recycled to the septic tank for seeding, which eliminates the need for sludge removal, as all sludge is recycled and digested.

The configuration of the system, Coetzer enthuses, means that it can be effortlessly expanded in the future, as Siyabonga’s business and operations expand.

“This investment in SewTreat’s modular on-site wastewater treatment facility ensured that the responsible treatment and recycling of the collected waste achieves the highest possible water savin. Siyabonga will install holding tanks and reuse the treated water to flush toilets and use for irrigation,” he notes.

The facility will treat and reuse 3 650 000 ℓ/y of water (based on a treatment rate of 10 000 ℓ/d), he adds.

Future Focus

Coetzer enthuses that SewTreat is currently working on eight projects.

“We are also awaiting the adjudication of a bid that will revolutionise the wastewater treatment industry, especially the way we think of wastewater treatment. This entails the recycling of on-site wastewater for reuse as potable drinking water on the same site,” he notes.

He adds that technological developments in treating on-site wastewater to drinking- water quality are possible, in terms of delivering a controlled and constant quality of water, and return on investment.

SewTreat’s wastewater treatment solutions include its plants using naturally occurring bacteria to treat wastewater, which results in the production of clean, recycled water that can be used for nondrinking purposes.