Focus: Jebel Ali sewage treatment plant
Why bother with tankers when you can treat waste directly on site?
When 4000 people live a long way from centralised services, there will be challenges involved with providing basic necessities. These challenges involve dealing with their waste too.
Without a connection to a municipal sewage system, operators of the labour camp housing workers building the Jebel Ali sewage treatment plant, needed an efficient way to deal with daily waste water. The initial method was to transport it off site using tankers. But with up to 360m3/day of waste to deal with, this process was time consuming and expensive compared to the alternative – treating the waste on site.
The first obvious thing that is obvious in the chosen solution is that there’s no smell. The second is the size; the waste water treatment plant installed at the boundary of the camp is surprisingly small, with a footprint of around 1200m2. Designed and developed by Huber Technology, the plant combines screening with activated sludge and membrane technology to treat the black water from the camp.
The end product of the three-stage treatment process is a small bin of ‘screenings’ – dry solid waste – and treated water, suitable for irrigation, which, disregarding a slight mustiness, is more or less odourless. Reaching this point required some technical ingenuity on the side of the treatment team.
“The best point is the challenge,” said Faisal Dawood, project manager for Huber. “With waste you are always dealing with something unusual, because waste is never the same. From one location to another, waste and its characteristics can be completely different, but you have to get the same end result. So the question is how to convert the waste into something useable once again.”
Huber has come up with a number of answers to this question and can apply them on an industrial or municipal scale.
In the case of the Jebel Ali camp site – a project started in October last year and completed in just a few months – the pre-treatment technology was particularly significant. Separating solids from liquids was both important and difficult because of the amount of grease going down the drain from the camp kitchens.
“Using pre-treatment we separate out the insoluble waste,” said Dawood. “The physical separation is achieved using a screening machine (with a 3mm fine screen) to remove grit and grease. Soluble waste needs different treatment, so to purify the water and remove the soluble pollutants we use a biological treatment process.”
This process employs bacteria to digest and consume the soluble pollutants and is carried out in an aeration tank. It’s the aerobic stabilisation on the process that eliminates the odours. Once the stabilised activated sludge has done its work, the purified liquid is separated off using membrane modules, returning the bacteria to do its dirty work.
This is a key part in the completely automated process, which turns the liquid into useable irrigation-quality water. The membranes rotate in the aerated liquid, perpetually cleaned by the scouring action of the bubbles, taking the sludge off the membranes. Since the development of the membrane technology this has been unnecessary. Huber uses its own ultra-filtration membranes, which have a pore size of 0.038 microns.
“This small porosity is to achieve high-quality water,” said Dawood. “A wide range of bacteria and viruses cannot penetrate this barrier. The result is pure water that can be used for irrigation. Further steps after that can improve its quality and can finally convert waste water to useable water.”
While employing its own technology for the water treatment processes, Huber also acts as an integrator, using well-known brands such as KSB, Siemens and ABB, to provide the running equipment.
The technology behind the plant is scaleable and can be applied to population concentrations of up to 50000 people. This is the size window the company concentrates on operating in.
“Beyond that [size] we are not concentrating our efforts,” said Peter Brechtelsbauer, managing director of Huber in the Middle East. “There too many competitors and the investment side is much bigger. Faster and more secure jobs come from municipalities at the moment, industries right now seem a bit shy of investing.”
Brechtelsbauer said the market for its technology was worth 15 million euro to the company last year and that it is looking for 17-18 million euro worth of sales in 2009. Given the current climate, any expectation of growth shows dealing with waste is a solid business to be in.