Ambient air temperature effects on the temperature of sewage sludge composting process

Article type: Research Article

Authors: HUANG, Qi-fei | CHEN, Tong-bin | GAO, Ding | HUANG, Ze-chun

Affiliations: Chinese Research Academy of Environmental Sciences, Beijing 100012, China | Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China

Note: [] Corresponding author. E-mail: [email protected]

Abstract: Using data obtained with a full-scale sewage sludge composting facility, this paper studied the effects of ambient air temperature on the composting temperature with varying volume ratios of sewage sludge and recycled compost to bulking agent. Two volume ratios were examined experimentally, 1:0:1 and 3:1:2. The results show that composting temperature was influenced by ambient air temperature and the influence was more significant when composting was in the temperature rising process: composting temperature changed 2.4–6.5°C when ambient air temperature changed 13°C. On the other hand, the influence was not significant when composting was in the high-temperature and/or temperature falling process: composting temperature changed 0.75–1.3°C when ambient air temperature changed 8–15°C. Hysteresis effect was observed in composting temperature's responses to ambient air temperature. When the ventilation capability of pile was excellent (at a volume ratio of 1:0:1), the hysteresis time was short and ranging 1.1–1.2 h. On the contrary, when the proportion of added bulking agent was low, therefore less porosity in the substrate (at a volume ratio of 3:1:2), the hysteresis time was long and ranging 1.9–3.1 h.

Keywords: sewage sludge, composting, ambient air temperature, hysteresis

Journal: Journal of Environmental Sciences, vol. 17, no. 6, pp. 1004-1007, 2005