Exploitation of extreme cavitation conditions for wastewater treatment

One of the most pressing global problems is the increasing pollution of surface and groundwater, which threatens the world's clean water supply and public health. Wastewater treatment plants (WWTPs), the last barrier between ever-increasing human activities and the environment, produce huge amounts, up to 13 million tonnes per year in the EU alone1, of unwanted semi-solid by-product - waste activated sludge (WAS). Therefore, upgrading wastewater (WW) processes with new circular economy approaches is crucial to achieve the goals of the EU Green Deal. Considering WAS as a resource rather than an unwanted end-product is the first step towards sustainable WW treatment. CAVIPHY will address this need directly by developing a unique device that exploits cavitation to pre-treat industrial or domestic WAS prior to anaerobic digestion (AD). However, this process, simple in its fundamentals, will never be sufficient to make a substantial contribution to current and future energy needs unless it is extensively modernized and refined to reach its full potential. Based on the knowledge gained within the ERC-CoG CABUM, we have developed a rotating generator for hydrodynamic cavitation (RGHC) - a scalable and cost-effective device that works simultaneously as a cavitation generator and a pump. With CAVIPHY, we will improve the disintegration, settleability and dewatering of WAS, resulting in synergistic effects in terms of lower costs associated with reduced volumes of WAS and environmental burden from its disposal, while producing methane – a renewable bioenergy source. This will have a direct impact on the economics of WWTPs, as the WAS associated costs already account for nearly half of the total WWTP operation expenses and will continue to increase.