Periodic Reporting for period 1 - CAVIPHY (Exploitation of extreme cavitation conditions for wastewater treatment)
Reporting period: 2022-08-01 to 2024-01-31
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 alone, 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 modernised 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 WTPs, as the WAS associated costs already account for nearly half of the total WWTP operation expenses and will continue to increase.
The first aim of our activities was to fine tune our initial design. This was achieved by influencing the cavitation activity through the design features of the RGHC developed during the project. The results of the WAS treatments were in perfect agreement with our simplified CFD approach, where we used simulations to select optimal conditions among a range of RGHC geometry variants. We showed that besides the rotational speed, specifics of rotor geometry have the greatest influence on cavitation intensity and effectiveness, which is in perfect agreement with the biochemical methane potential. We have also shown that the surface roughness of the RGHC is less significant design parameter. This is one of the major achievements and goals accomplished in the Caviphy project as it clearly shows that the manipulation of cavitation conditions affects the energy required to operate RGHC, which is the critical factor in making WAS pretreatment economically feasible. We have developed a business plan and have begun to implement it. At the end of the project, we are in the negotiation phase of establishing a spin-out.
The optimization of waste-to-biogas conversion remains an ongoing challenge. Currently available technologies to enhance biogas production are complex and expensive. This is why the market for pretreatment technologies to improve anaerobic digestion is a completely undeveloped. Within ERC PoC CAVIPHY we developed a reactor for biogas pants that improves biogas production and quality. Compared to systems without pre-treatment, CAVI reactor increases biogas yields up to 30%, while being green – no chemical additives, robust, easy to operate, quiet and energy efficient.
Needs for further uptake and success: demonstration, access to markets and finance, commercialisation, IPR support.
Needs for further uptake and success: demonstration, access to markets and finance, commercialisation, IPR support.