Anaerobic co-digestion of food waste and chemically enhanced primary-treated sludge under mesophilic and thermophilic conditions.
Anaerobic co-digestion of food waste with primary sewage sludge is beneficial for urban centers, while the optimized conditions reported in the literature are not locally suitable for Hong Kong. Therefore, the present study was aimed to develop an optimized mixing ratio of food waste to chemically enhanced primary-treated sewer sludge (CEPT) for co-digestion using batch tests under mesophilic (37°C) and thermophilic (55°C) conditions. The mixing ratios of 1:1, 1:2, 1:3, 2:1 and 3:1 (v v(-1)) of food waste to CEPT sludge was tested under the following conditions: temperature - 35°C and 55°C; pH - not regulated; agitation - 150 rpm and time - 20 days. The thermophilic incubations led a good hydrolysis rate and 2-12-fold higher enzyme activities than in mesophilic incubations for different mixing ratios. While the acidogenesis were found retarded that leading to 'sour and stuck' digestion for all mixing ratio of food waste to CEPT sludge from thermophilic incubations. The measured zeta potential was most favourable (-5 to -16.8 mV) for methane production under thermophilic incubations; however the CH4 recovery was less than that in mesophilic incubations. The results suggested that the quick hydrolysis and subsequent acid accumulation under thermophilic incubation lead to inhibited methanogenesis at the early stage than in mesophilic systems. It is concluded that buffer addition is therefore required for any mixing ratio of food waste to CEPT sludge for improved CH4 recovery for both mesophilic and thermophilic operations.
a Sino-Forest Applied Research Centre for Pearl River Delta Environment , Hong Kong Baptist University , Kowloon Tong , Hong Kong SAR, People's Republic of China.|b Department of Biology , Hong Kong Baptist University , Kowloon Tong , Hong Kong SAR, People's Republic of China.
Parthiba Karthikeyan
PK
Obulisamy
a Sino-Forest Applied Research Centre for Pearl River Delta Environment , Hong Kong Baptist University , Kowloon Tong , Hong Kong SAR, People's Republic of China.|b Department of Biology , Hong Kong Baptist University , Kowloon Tong , Hong Kong SAR, People's Republic of China.
Debkumar
D
Chakraborty
a Sino-Forest Applied Research Centre for Pearl River Delta Environment , Hong Kong Baptist University , Kowloon Tong , Hong Kong SAR, People's Republic of China.|b Department of Biology , Hong Kong Baptist University , Kowloon Tong , Hong Kong SAR, People's Republic of China.
Ammaiyappan
A
Selvam
a Sino-Forest Applied Research Centre for Pearl River Delta Environment , Hong Kong Baptist University , Kowloon Tong , Hong Kong SAR, People's Republic of China.|b Department of Biology , Hong Kong Baptist University , Kowloon Tong , Hong Kong SAR, People's Republic of China.
Jonathan W C
JW
Wong
D000438:Alcohols / Q000378:metabolism; D000693:Anaerobiosis; D019149:Bioreactors; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005502:Food; D006868:Hydrolysis; D008697:Methane / Q000032:analysis / Q000378:metabolism; D010316:Particle Size; D010447:Peptide Hydrolases / Q000378:metabolism; D012037:Refuse Disposal / Q000379:methods*; D012722:Sewage; D000516:alpha-Amylases / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
D000438:Alcohols; D005232:Fatty Acids, Volatile; D012722:Sewage; D000516:alpha-Amylases; D001616:beta-Galactosidase; D010447:Peptide Hydrolases; D008697:Methane
Anaerobic co-digestion; food waste; iron; primary sludge; volatile fatty acids