Influence of spent mushroom substrate and molasses amendment on nitrogen loss and humification in sewage sludge composting

The present study included lab-scale sewage sludge (SS) composting amended by molasses and spent mushroom substrate (SMS) in 5 L composting reactor system. The influence of molasses and SMS amendment on nitrogen loss and humification of SS composting was evaluated. The results showed that SMS amendment, especially combination with molasses raised composting temperature, increased CO(2) volatilization, promoted organic matter degradation, improve germination index and humification process. The addition of SMS and molasses contain carbohydrates used as carbon source and energy substance by microorganisms could increase microbial activity and ammonia assimilation. In the SMS + molasses treatments, NH(3) volatilization was reduced by 33.1%–37.3% and N(2)O volatilization was only 17.8%–25.4% of that in the control treatment, furthermore, the nitrogen loss rate was reduced by 27.2%–32.2%. Consequently, the addition of SMS and molasses improved the compost maturity and reduced nitrogen loss in the SS composting process.