Prof Guanghao Chen obtained PhD degree in Environmental Engineering from Kyoto University in 1990. Currently he is a Chair Professor of Civil and Environmental Engineering at Hong Kong University of Science & Technology (HKUST), Hong Kong branch director of a CNERC (Chinese National Engineering Research Center) at HKUST, Director of Water Technology Center of HKUST, and an Associate Director of the Institute for the Environment of HKUST. Prof Chen was elected to a Distinguished Fellow of the International Water Association (IWA) in 2015, received four IWA awards including the Global Honor Award of IWA Project Innovation Awards (PIA) in 2012 and a bronze winner of IWA PIA of Breakthroughs in Research Development in 2018. He won the Chinese National Innovation Pioneer Awards in 2017 as the first Hong Kong researcher and the gold award of the Hong Kong Green Innovation Awards in 2019. Professionally he is a member of Strategic Council of IWA, an editor of Water Research, and an international mentor of the Global Sanitation Graduate School at IHE Delft.

Abstract

Low Energy Electrical Odour (LEEO) Control of Sludge

Low Energy Electrical Odour Control (LEEO), a HKUST innovative technology, targets for suppressing sludge mal-odour (particularly hydrogen sulfide). Batch operation was conducted with 40 L CEPT sludge at Siu Ho Wan Sewage Treatment Works (SHWSTW) was conducted for: i) confirming the capability of LEEO for sulfide control, ii) selecting the electrode materials, and iii) determining the effective input parameters.

Based on the above result, continuous operation was investigated with 700L sludge to evaluate the operation effects in different sludge mixing and pumping modes. Intermittent mixing and pumping modes significantly could halve the total energy consumption in comparison with the continuous mixing and pumping modes. We also found that total solids (TS) concentration of the CEPT sludge is varied daily, which strongly affects the LEEO efficacy. Simulation analysis of “TS-input energy” was conducted and the critical energy input at 0.2 kWh/kg TS was selected for LEEO’s long-term operation. During this long-term operation, the stability and impacts of LEEO on the whole SHWSTW process including sludge sulfide production, dewaterability, sludge cake heat value and supernatant toxicity were comprehensively analyzed. LEEO can not only completely suppress sludge sulfide production over 2 to 5 days under different weather conditions, but also enhance sludge dewaterability by 20~30% that improves sludge cake heat value potentially. Furthermore, LEEO does not increase sludge supernatant toxicity for operators and discharge, considering a dilution (~20 times) of effluent against receiving water volume.

Taking full-scale application of LEEO for sludge treatment at SHWSTW with a capacity of 817 m3 wet sludge as an example, a total daily saving of ~7.5 K HKD/day is estimated (need to be verified by client).