Water and wastewater treatment specialist Veolia Water Solutions & Technologies South Africa (VWS South Africa) has designed, supplied and commissioned a number of modular sewage treatment plants to reduce the reliance on municipal wastewater treatment plants in Africa and South Africa.

“It is a known fact that wastewater treatment works are under immense pressure and solutions are needed to assist government and local water authorities.

“We have noted government’s involvement in the issuing of tenders to upgrade sewerage infra- structure, but upgrades are expensive and we are not sure if government has sufficient funds to provide for this,” says VWS South Africa Engineered Systems GM Wayne Taljaard.

The company says its affordable and effective modular wastewater plant solutions have been supplied for use mainly in the mining sector.

The plants have been supplied locally to a mine camp in Mpumalanga, and across the border to mines in the Democratic Republic of Congo (DRC), Zimbabwe and Uganda, as well as to mining projects in central Mozambique and Tanzania.

Domestic Wastewater Treatment
One of the most recent projects awarded to VWS South Africa is a 70 m3/d containerised plant for a mining camp in the DRC. The contract, which was awarded at the beginning of this month, is an early works supply contract and is still in the engineering phase.

Another project undertaken by VWS South Africa is the design and installation of two 70 m3/d modular civil construction sewage treatment plants for a mine camp site in Mpumalanga. The plants are currently under construction.

Further, it was awarded a contract to supply a 40 m3/d civils-based modular sewage plant to a gold mine in Tanzania. The contract entails plant design, the supply of the mechanical, electrical and control equipment, as well as the commissioning of the plant.

It is due for completion in May.

Uniquely African Water Treatment Technology
VWS South Africa uses a biological treatment process known as trickling-filter technology, which was acquired from its Namibian subsidiary, Aqua Services & Engineering, in 2008, for the treatment of domestic wastewater.

This new-generation modular trickling- filter technology is more affordable for less privileged communities, enhancing its popularity in the South African and African wastewater treatment market.

The sewage treatment system screens and removes nondegradable particles from raw sewage. A biological digestion process further prepares sewage for a fixed-film trickling filter, where organic constituents are removed and nitrification and final water polishing occurs. Final solid separation, chlorination and disinfection leave the water ready for use in various processes.

When compared with the old trickling-filter technology using stones, the newer technology shows increased water flow, improved outlet water quality and a higher degree of control, states Taljaard.

He notes that the misconception that this technology is old-fashioned has led to a reluctance to establish trickling-filter technology as a highly effective small-scale wastewater treatment solution.

To overcome this problem, the company is focused on educating the market on the technology and its benefits. This includes low energy consumption, low maintenance requirements and its simple operation, he says.

An Energy Solution
One of the main objectives of the global Veolia Water Group is to turn wastewater into a valu- able energy resource.

One of the ways in which it aims to achieve this is through the combination of the Exelys thermal hydrolysis sludge process and digestion, where biogas, heat and energy can be recovered from sludge in a cleaner and more environment-friendly recycling process.

The Exelys process breaks down the long chain molecules typical of sludge to enable the digestion to release larger quantities of biogas for energy generation, while reducing overall sludge quantities, explains VWS South Africa municipal engineering director Laurent Schmitt.

The energy generated from biosolids makes it possible for wastewater treatment works to become independent of grid supply and can even enable the supply of surplus clean power to the grid.

Moving Forward
VWS South Africa hosted a seminar in October last year to update its clients on the latest global Veolia Water Solutions & Technologies division’s innovations in biological wastewater treatment, nitrate and phosphorus removal and clarification technologies.

The presentations focused on the possibilities of creating value from wastewater for more sustainable resource management throughout the African continent by using modular trickling-filter technology to effectively treat wastewater produced by communities of under 50 000 residents.

One of VWS South Africa’s goals is to focus on energy efficient solutions and securing large-scale municipal treatment works upgrade contracts.

The company suggests that municipalities use the new-generation tricking-filter technology solution as an economical way of upgrading similar existing infrastructure and, in so doing, treating their effluent and overcoming the country’s sewerage infrastructure backlog.

The Exelys sludge processing technology can further help overcome energy shortages and reduce sludge quantities in future.

Standards Association
Meanwhile, Taljaard points out that nonprofit organisation the Sewage Package Plant Sup- pliers Association (Sewpacksa), which is affi- liated to the Water Institute of Southern Africa (WISA), is in the process of establishing a technical standards committee to ensure the quality of packaged plants.

The standards will include specific criteria for after-sales service and plant production capacity.

Sewpacksa was established in Nov- ember 2010 with the aim of improving the quality and standards within the packaged sewage plant industry.

It regulates the quality of supply, design, installation and performance in the industry and, as an ultimate goal, would like to see all suppliers abide by the Sewpacksa standards with professionalism and integrity.

Association members are currently adhering to standards outlined in the Water Research Commission’s (WRC’s) guideline document for package plants for the treatment of domestic wastewater.

VWS South Africa reports that Sewpacksa’s aim is to have all its members ensuring that their clients are compliant with the Department of Water Affairs’ Green Drop certification requirements.

The Green Drop certification programme for wastewater treatment works is an initiative to ensure that these wastewater treatment works progressively improve their operations. Green Drop status is achieved if the water service authority complies with wastewater legislation and other best practice requirements.

WISA and WRC member Valerie Naidoo states there is a R2-billion demand for modu- lar sewage treatment plants in Africa.

The advantage of being a Sewpacksa member will become obvious during the tendering process for this work in that it will level the playing field, as everyone will be working within the same parameters, says Naidoo.

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