Re ECF Project: 2012-29

Project Title: An in-depth investigation of the microbial community underpinning renewable biogas production from North East New Territories landfill

Applicant: Prof Frederick C.C. Leung, School of Biological Science, The University of Hong Kong

Total Approved Grant: $498,150

Duration: 1/5/2014 to 31/10/2015

Project Status/Remarks: Completed

Scope:
This project aims to unravel the microbial mystery and identify key interactions in biogas production from landfill sites. This knowledge could transform into technical innovations to provide green waste disposal strategy with renewable energy generation.

Summary of the Findings/Outcomes:
The raw leachate microbial consortia of the four phases of the North East New Territories landfill was monitored through monthly sampling, total genomic DNA extraction and 16S rRNA amplicon deep sequencing, a bacterial and archaeal diversity marker gene. The three most dominant phyla, across all four phases, were Bacteroidetes, Firmicutes and Proteobacteria. Methanogens, responsible for methane biogas production, represented <2% of the total microbial abundance. Aside from phase status, open/closed to waste feeding, environmental factors influenced the composition and/or abundance of the microbial community. Waste decomposition at a landfill can be classified into four stages: hydrolysis, acidogenesis, acetogenesis and methanogenesis. Microbes increasing in abundance with a raised temperature included the hydrolytic Parabacteroides [Bacteroidales] and acetogenic Gracilibacteraceae [Clostridiales]; from increased rainfall, the hydrolytic/acidogenic Actinomycetales, several Bacteroidales, Oxalobacteraceae [Burkholderiales] and several acetogenic Clostridiales increased in abundance. With the microbial composition now known and its variation with climate conditions, depending on what stage of decomposition a particular phase is at, active intervention e.g. removing the pond cover to collect rainwater or sunlight exposure can be carried to enhance decomposition and improve biogas yield. Select listed microbes here can be assayed with variable sunlight and rainfall to determine optimal conditions of microbial activity.