Energy recovery from wastewater treatment plants through sludge anaerobic digestion: effect of low-organic-content sludge
- 349 Downloads
During anaerobic digestion, low-organic-content sludge sometimes is used as feedstock, resulting in deteriorated digestion performance. The operational experience of conventional anaerobic digestion cannot be applied to this situation. To investigate the feature of low-organic-content sludge digestion and explain its intrinsic mechanism, batch experiments were conducted using designed feedstock having volatile solids (VS) contents that were 30–64% of total solids (TS). The results showed that the accumulative biogas yield declined proportionally from 173.7 to 64.8 ml/g VS added and organic removal rate decreased from 34.8 to 11.8% with decreasing VS/TS in the substrate. The oligotrophic environment resulting from low-organic-content substrates led to decreased microbial activity and a switch from butyric fermentation to propionic fermentation. A first-order model described the biogas production from the batch experiments very well, and the degradation coefficient decreased from 0.159 to 0.069 day−1, exhibiting a positive relation with organic content in substrate. The results observed here corroborated with data from published literature on anaerobic digestion of low-organic-content sludge and showed that it may not be feasible to recover energy from sludge with an organic content lower than 50% through mono digestion.
KeywordsAnaerobic digestion Biogas Energy Organic content Sludge Volatile fatty acid
This work was supported by the China Major Science and Technology Program for Water Pollution Control and Treatment (grant number 2011ZX07302); the Natural Science Foundation of China (grant number 51478239); and the Shenzhen Science and Technology Project (grant number JCYJ20170307152224920).
- Anthonisen AC, Loehr RC, Prakasam T, Srinath EG (1976) Inhibition of nitrification by ammonia and nitrous acid. JWater Pollut Control Fed 48:835–852Google Scholar
- Dai X, Zhao Y, Sha C, Dai L, Dong B (2014) Investigation on the status and causes of sludge sand content of wastewater treatment plants in China. Water Wastewater Eng75-78, 79Google Scholar
- Lowry OH, Rosebrough NJ, Farr AL, Randall RJ (1951) Protein measurement with the folin phenol reagent. J Biol Chem 193:265–275Google Scholar
- Ministry of Environmental Protection, China. Standard methods for the examination of water and wastewater. Beijing: China Environmental Science Press, 2002Google Scholar
- Rice EW, Baird RB, Eaton AD, Clesceri LS (2012) Standard methods for examination of water and wastewater. APHA AWWA WEF, Washington, DCGoogle Scholar