Engineering and environmental consultants SSI has devised a number of emergency projects to assist the municipalities of the southern Cape coastal belt, in light of the severe drought that the area is experiencing.

SSI communications manager Robin Hayes says that during December, tourists flood the region, swelling the resident population by up to five times, exacerbating the existing critical shortage of water.

SSI water sector head Francis Gibbons says that, in Sedgefield, the company specified a 1Ml/day mobile desalination reverse-osmosis plant, together with an upgraded membrane bioreactor wastewater treatment works (WWTW) that enables the indirect reuse of final effluent. New boreholes have also been installed to augment ground and surface water supplies.

SSI's medium term solution for Knysna and George also involves indirect effluent reuse, where final WWTW effluent is polished by an ultrafiltration process and then pumped into the towns' storage dams where it combines with fresh water from the rivers.

In Mossel Bay, national oil company PetroSA has in the past consumed about 15 Ml/day of potable water in the Mossgas process, which is about the average water demand the town draws from the Wolwedans dam for human consumption. SSI proposed that PetroSA make use of the same quantity of WWTW final effluent, polished through a reverse osmosis process, thus releasing the potable water to the municipality for human consumption.

Elsewhere, SSI is part of the consortium that is designing and supervising the construction of the R16-billion, 1 330 MW-Ingula pumped storage scheme for State-owned power utility Eskom, in the Little Drakensburg mountain range, on the border of the Free State and KwaZulu-Natal.

Gibbons explains that the scheme, which is currently in construction, will provide Eskom with vital ‘peaking power.' It will consist of two dams and an underground station. The upper dam will be connected to reversible pump/turbines through duplicate headrace tunnels, surge shafts, inclined pressure shafts and penstock bifurcations. The pumps/turbines will connect to a lower dam through draft tubes, extended draft tube tunnels, twin surge chambers and a single tailrace tunnel.

The underground powerhouse complex will consist of a combined machine and valve hall, a transformer hall and other ancillary tunnels and caverns. It will use excess power (conventionally generated) from the grid to pump water from the lower dam to the upper dam during periods of low electricity demand. During periods of peak demand, the water will flow back and generate hydroelectricity. The project is scheduled for completion in 2015.

Meanwhile, the company reports that its Nereda WWTW, which is installed in Gansbaai, in the Western Cape, operated in fully automated mode throughout December, with little problem. This is virtually unheard of in South Africa, says SSI principal specialist Paul Gaydon. The controls of the advanced programmable logic controller enables SSI, its Dutch parent company global consultancy and engineering services DHV, and the Overstrand municipality, to remotely monitor and control the plant's performance from SSI's Cape Town office and DHV's headquarters in Holland.

"While many WWTW's may fail over the Christmas period owing to a greater load from resident populations enlarged by tourists and a smaller staff contingent at the plants, this automated plant ran efficiently and SSI was able to monitor performance over an Internet interface," he says. "When a problem arises, such as a power failure, the control system immediately sends a SMS to the on-site operators, who can check it straight away." Although DHV has conducted pilot testing in the Netherlands, this is the first fully operational, demonstration-scale plant in the world, says Gibbons. The plant has been operational for over a year.

The plant has conventional head-of-works screening and degritting units, followed by a fine-screen unit. Gaydon explains that the Nereda works makes use of granulated activated sludge technology to remove biological nutrients, but what sets it apart is a super settling sludge. The process uses bacteria in the form of a ball or granule, which settles at the end of the process about ten times as fast as the conventional bacteria used in other WWTWs. Also, the plant is fully automated, smaller, simpler and easier to maintain, he says.

Gibbons says that there is a 75% saving in the land requirements for the plant and 40% on energy consumption because there are fewer moving parts than a conventional plant and the aeration is more efficient. The plant has only four moving parts, namely, two self contained blowers and two feed pumps in the buffer tank. The blowers self monitor continually and, in the event of a problem, the blower will power down automatically, with a ‘blue box' transmitting the problem to a remote site and automatically powering up a standby blower. In future, SSI would like to install online monitoring in plants but, unfortunately, it would come at a cost to municipalities that are already struggling financially, says Gaydon.

The plant produces effluent with very little ammonia and phosphates. SSI is monitoring the results with University of Cape Town             Prof George Ekama who is an international authority on activated sludge modelling and design. The company reports that there has been an increase in birdlife in the final effluent ponds at Gansbaai. It plans to persuade the local municipality to build walkways through the indigenous bush around the ponds for birdwatchers and to enlist a local birder to be at the site periodically.

Meanwhile, he says that the lack of maintenance in [water-related] infrastructure is a huge issue and that the civil engineering profession is trying to elevate the problem to avoid a similar situation in the water industry to that of the energy crisis. Hayes explains that in many cases South Africa's antiquated water and wastewater infrastructure has exceeded its life span and design specifications and is in need of replacement or upgrading to meet future demands.

Gaydon says that existing infrastructure, such as water works and wastewater works, requires a combination of refurbishment and upgrading when capacity is reached. "Unfortunately, despite government's intention to upgrade infrastructure across the board, there is a breakdown at the municipal level, owing to a lack of capacity," he says.

SSI has started a management, operations and maintenance unit, which will assist local municipalities in managing and maintaining their water infrastructure. The former Department of Water Affairs and Forestry instituted an accreditation system for water service authorities to encourage compliance with legislation and other best practice requirements, in the form of a blue drop status for water treatment plants and green drop accreditation for wastewater treatment plants. SSI offers assistance to water service authorities to obtain this accreditation and also helps them to raise finance and manage the tender process for refurbishments and upgrades.

The company is also involved in providing training to WWTW operators and water treatment plant operators. "The industry has to make the water industry attractive to young people, so that they will want to enter it, which then ensures the management of good quality water and waste water," concludes Gaydon.