Buffering phosphate mitigates ammonia emission in sewage sludge composting: Enhanced organics removal coupled with microbial ammonium assimilation. (1st August 2019)

• Record Type: Journal Article
• Authors: Shou, Zongqi; Zhu, Nanwen; Yuan, Haiping; Dai, Xiaohu; Shen, Yanwen
• Is Part Of: Journal of cleaner production. Volume 227(2019)
• Page Start: 189
• Page End: 198
• Publication Date: 2019-08-01
• Subjects: Waste activated sludge -- Composting -- Ammonia emission -- Phosphate buffer -- Microbial ammonium assimilation; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2019.04.197
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: Ammonia emission is a challenge for sewage sludge composting, causing odor issues, indirect greenhouse gas emission and nitrogen loss in the mature compost. This study investigated the effectiveness of applying K2 HPO4 KH2 PO4 buffer to mitigate ammonia emission in sewage sludge composting. During the 34-day aerated composting experiment, adding 7.5 mg P·g −1 DM (dry matter) K2 HPO4 KH2 PO4 buffer reduced the ammonia emission and total nitrogen loss by 45.4% and 41.8%, respectively. The enhanced nitrogen conservation by phosphate additive resulted from two complementary mechanisms: (1) phosphate buffering effect and (2) accelerated sludge extracellular polymeric substance (EPS) decomposition, thus improving microbial ammonium assimilation to convert ammonia-N to cell-protein. The extent of nitrogen conservation was found to be positively associated with activities of the key enzymes for microbial ammonium assimilation and relative abundance of the ammonium-assimilating Bacillus . In a summary, K2 HPO4 KH2 PO4 addition was proved as an effective strategy to reduce ammonia emission, promote organics removal and conserve nitrogen nutrients in the final compost product. Graphical abstract: Image 1 Highlights: KH2 PO4 K2 HPO4 buffer enhanced organic matters removal during sludge composting. Buffer addition accelerated sludge EPS solubilization to provide carbon resources. Enhanced buffering capacity mitigated NH3 emission for nitrogen conservation. Microbial ammonia assimilation was observed as a biotic mechanism in composting.