Influences of the thermophilic period on biodegradation and nitrogen loss in stimulated vegetable waste composting

• Main Authors: Ruixue Chang, Yanming Li, Ji Li, Qing Chen, Hengyu Zhao, Zicheng Qi
• Format: Article
• Language: English
• Published: Elsevier 2019-04-01
• Series: Global Ecology and Conservation
• Online Access: http://www.sciencedirect.com/science/article/pii/S2351989418304517

Development of thermophilic composting with ultrahigh temperature (over 70 °C) would enable the vegetable wastes compost harmless, due to the inactivation of the potential viral pathogens. The present study respectively analyzed the influences of temperature (55 °C, 65 °C, and 75 °C), lasting time of temperature over 70 °C (12 h, 24 h, and 48 h), and duration over certain temperature (10 days over 50 °C, 5 days over 60 °C and 1 day over 70 °C), on biodegradation and nitrogen loss in composting, by controlling the temperature condition in stimulated composting system. The results showed that in the simulated condition, high temperature over 75 °C affected the microbial degradation of organic matter, but the activity of microorganisms could recover if the duration is no more than 24 h, which implied that the thermophilic stage of high temperature with short duration was able to inactivate the pathogenic organisms without affecting the composting process. More NH3 emission was observed in the stimulated composting of consistent 65 °C than 55 °C and 75 °C, while the TN loss rate was higher in the consistent 55 °C treatment. The NH3 emission amount was increased with the increase of the duration of 75 °C, while the TN loss rate was the lowest when the duration is 24 h. The results suggested that high temperature did not necessarily promote the emission of ammonia, and the influences on NH3 emission and TN loss rate did not always consistent. Furthermore, even the NH3 emission and TN loss rate were increased along with the temperature increase, the difference of the TN loss rate between the two treatments, over 60 °C 5 days and over 70 °C 1 day, was not significant. In conclusion, the thermophilic stage of the temperature over 70 °C with a short duration to inactivate the potential viral pathogens will not significantly increase the nitrogen loss and influence the composting process. Keywords: Composting, Thermophilic stage, Nitrogen loss, Ammonia, Vegetable wastes