Dr Amy Tan is an Assistant Professor at the Department of Architecture and Civil Engineering (ACE), The City University of Hong Kong (CityU). She holds a PhD degree in Civil and Environmental Engineering and a Bachelor degree in Biological Sciences from Nanyang Technological University (NTU), Singapore.

Dr Tan’s research focus lies in waste-to-energy and waste-to-resource (bio)technologies. Specifically, environmental microbiology and biotechnologies for sustainable organic waste management and waste up-cycling (bio-energy and high-value bio-products). She is particularly interested in the underlying metabolic mechanisms and exploiting them to address existing environmental and industrial problems. To date, Dr Tan’s research has led to more than 20 research publications in peer-reviewed journals including Water Research, Nature Scientific Report and Waste Management. She has also received several awards including the Environmental Paper Award from The Hong Kong Institution of Engineers in 2019 and the Hong Kong Institution of Engineers Outstanding Paper Award for Young Engineers/Researchers in 2016.

Abstract

Bioenergy Recovery from Chemically Enhanced Primary Sludge

Establishing the water-energy nexus is pivotal for sustainable water management. Energy sustainability is a top priority for Hong Kong with targets to reduce energy intensity by 40% by 2025. These days, sewage treatment works (STWs) are no longer viewed as just simply facilities for waste treatment, but also for bioenergy recovery as part of the local government’s efforts to achieve greater energy sustainability among the municipalities.

The predominant chemically-enhanced primary treatment (CEPT) process generates large sludge volume, which is currently incinerated and landfilled. Nevertheless, CEPT sludge contains >75% of total influent organics, presenting an untapped potential for bioenergy recovery. However, under typical anaerobic conditions, saline CEPT sludge is biodegradation-resistant and produces toxic hydrogen sulfide due to high cellulosic/recalcitrant and sulfate contents. The introduction of sub-nanomolar oxygen levels is expected to facilitate micro-aerobic degradation of CEPT sludge, maximizing biomethane yield from recalcitrant organics and increasing digested sludge settleability. This presentation will introduce the concept of micro-aeration and illustrates its benefits for bioenergy recovery from CEPT sludge waste management.