Gravity-fed wastewater system could aid developing world

A gravity-powered mobile wastewater system that cuts energy use by more than 90 per cent could help rural communities in the developing world.

The Extreme Separator (ExSep) recently won a Bloomberg New Energy Pioneer award for reducing energy and chemical use and solid waste output in remote communities such as oil-industry worker camps.

Its creators at the Luxembourg-based firm Epuramat, of which cleantech investment firm I2BF is a shareholder, are now working with several partners to create a sewage system for villages in developing countries.

The ExSep, which makes wastewater easier to treat by removing 99 per cent of solid matter, has also been used on digestate waste from bio-gas plants and to remove water from oil once it is extracted from the ground.

For use as a mobile technology, the ExSep has been packaged with an ultra-filtration unit that makes the separated wastewater safe to release into the environment inside a 20 or 40ft container called the Box4Water.

‘We have a very compact solution that is very appropriate to be used in remote locations where you don’t have any infrastructure of sewage canals or pumping stations,’ said Epuramat’s sales and marketing director, Dirk Martin.

‘The water can be treated there and then, and reused or discharged without causing any impact to the environment. The resulting sludge can be used as compost or disposed of in a landfill, but the volume is reduced compared with conventional sludge.’

He added: ‘The majority of turnover for big water companies is in selling chemicals and our system doesn’t require any chemicals at all. So this is quite disruptive.’

The ExSep is able to reduce the energy used to separate liquid and solid waste by 92 per cent compared with conventional equipment by using a gravity-fed design that only needs electricity if pumps are used to feed the waste in.

The water enters the system at high speed through a small pipe and is then decelerated as it passes upwards into a larger tube. This causes most of the suspended solid particles to separate from the water, removing the need for large sediment tanks.

The resulting sludge then has more water removed so that the waste has a much lower volume than products from conventional equipment, reducing the need to empty the solid tank so often.

The water is passed through a membrane bioreactor that uses bacteria and ultra-filtration membranes to purify it to a level where it can be safely released into the environment for use as non-drinking water.

Box4Water is already being used in Canada by mobile camps for workers in the oil industry. It has also been used to relieve pressure on an overloaded treatment plant in Luxembourg that accepts sewage from 3,000 people.

The containers make the system modular and easily enlarged, but it is only cost effective for settlements with fewer than 15,000 people.

In the industrial world, the ExSep has been tested by oil companies in Mexico and Germany, where it was combined with another of Epuramat’s technologies — a specially designed membrane — to remove water from extracted oil.

Epuramat is also working with a UK university spin-out firm to market the technology to biogas plants around Europe as a way of treating the solid organic matter left over from the anaerobic digestion process.