Wastewater treatment plants shift from energy consumers to producers
by Ruth Cooper
With the right technology, wastewater treatment plants can move from a focus on biosolids disposal to become energy-positive biofactories that produce a valuable product.
This is something SUEZ Innovation Project Manager Marlene Choo-Kun is passionate about.
“We are looking for ways to use the resources that are in our wastewater,” she said.
“We want to turn biosolids into a valuable product, either as a fertiliser or a new source of energy. This includes producing a biochar that could partly replace the use of fossil fuels.”
Choo-Kun is based in Paris and played a key role in the development of Dehydris Ultra, a new technology from SUEZ that performs ultra-dewatering on sewage sludge.
The aim of Dehydris Ultra was to develop a more energy-efficient treatment for biosolids that also offers improved resource recovery.
It mimics the natural process of coal generation from organic matter by applying hydrothermal carbonisation (HTC) to biosolids, which Melbourne-based SUEZ Technical Support Manager Veronique Bonnelye said maximises liquid-solid separation.
“With Dehydris Ultra, we are able to reach 70% dryness while using two to three times less energy than thermal drying,” she said.
“If you move from conventional treatment, you can reduce the amount of biosolids by 75%.”
Bonnelye, who will discuss the Dehydris Ultra process at Ozwater’19 in May, said utilities with significant biosolids disposal costs would benefit most from the technology, along with those that want to create an energy-positive plant.
“The process leaves you with less biosolids to dispose of, which means fewer trucks on the road and less carbon emissions,” she said.
“From an operational perspective, you significantly reduce the cost of biosolids disposal.”
For Choo-Kun, the technology is a step towards creating the wastewater treatment plant of tomorrow. This includes turning waste into energy by producing more biogas and making energy from biochar.
“We want to help people think about sludge as a final product with an additional value, instead of thinking about it as waste,” Choo-Kun said.
“We also want to close the loop in terms of energy. Wastewater treatment plants can produce a product that can be used to produce energy.”
View the full Ozwater'19 program here.
