Saving water from waste in chemical plants
Producing chemicals and plastics indeed requires a lot of fresh water to cool down industrial processes, and this water is not always handy. Take a look on how new technologies can help recycle the water used in chemical plants to make these more environmentally friendly.
Our reporter Denis Loctier visited a Dow Benelux plastics plant on the southern coast of the Netherlands. This seaside plant cannot pump water from the ground: it must buy it from a supplier located dozens of kilometers away, uses it once and then pours it out into the sea.
“We need approximately 20 million cubes annually of fresh water. And that's a bit of a problem here, because the whole area is actually connected to the sea, and all the ground water is brackish or salty, even,” said Niels Groot, water specialist at Dow Benelux.
Salty or dirty water can damage installations, and for now it is cheaper for companies to buy fresh water than to recycle it. A European research project – called E4WATER – wants to change that.
An Evides pilot plant in the Netherlands is using various methods to cleanse water from salt and waste.
“First we try to remove the suspended solids; that’s done by the lamella separator. And then it goes to two different technologies for taking the salts out of the water,” explains Evides water treatment specialist Wilbert van den Broek.
Meanwhile at the VITO institute in Antwerp, Belgium, researchers are testing improved nano-filters and a new membrane technology that could make industrial water recycling much more efficient – and commercially viable.
“With conventional membrane filtration systems you can come up with water recovery of 50% to 70%. With this technology, you can expand the water recovery to 90-95%,” says Peter Cauwenberg, water technology specialist at VITO.
These membrane systems filter the water vapor and leave out the salt. They have a limited lifespan, so making them more efficient could get the industry to recycle more water, save costs, and help the environment.
“There are many advantages for the industry,” says Christina Jungfer, technical microbiologist at DECHEMA and E4WATER project coordinator. “First of all it's more environmentally friendly, because you can save water; it gives you independence from fresh water sources. And through new technologies, you can also save energy. So it's a win-win situation for the industry and for nature.”
So what is the best way to clean industrial water? There is no easy answer. Researchers say any plant can combine cleaning tools and methods in the way that's best suited to its particular production chain.
“Instead of cleaning the water at the end of the industrial process, the idea is to make recycling a part of it. So depending on the process, one facility will require a certain treatment system, another a completely different one,” says Carlos Negro, chemical engineer at the Complutense University of Madrid (UCM).
Belgian company Solvic runs a chlorine plant which receives from chemical companies nearby what can be considered as industrial waste. It tries various new technologies to recycle it into clean water and other usable materials. The stakes are high, says Sabine Thabert, chemical engineer and environmental coordinator for Solvic.
“We say – no, that's not waste, you have to reuse it, because it's very useful for other people. In the near future, water will be very expensive, so it's now that we have to try to find solutions for problems that we'll certainly get tomorrow,” she says.