34 / 2021-06-28 20:48:21

Effects of urease inhibitors on enzymatic activities and fungal communities during the biosolids composting

Urease inhibitors; N transformation; Enzymatic activities; Fungal communities; Composting

This study evaluated the effects of urease inhibitors (UIs) on nitrogen conversion, enzyme activities, and fungal communities during aerobic composting. Three treatments were designed using the same mixture of sludge-sawdust with different contents of UI (0.3% and 0.6% on a dry weight basis; denoted U1 and U2, respectively) and treatment without adding UI as a control (CK). The results showed that the addition of UI reduced NH₃ emissions by 22.2% and 21.5% and increased the total nitrogen (TN) content by 9.7% and 14.3% for the U1 and U2 treatments, respectively, relative to CK. The addition of UI inhibited enzyme activity during the thermophilic phase but increased enzyme activity at the end of composting. Ascomycota, Basidiomycota and unclassified fungi were the main phyla, and Ascomycota increased significantly during the maturity period. UI addition significantly increased the diversity of fungi during the maturity stage, and network analysis showed that Aspergillus, Penicillium, Trichoderma, Talaromyces, Peseudeurotium, and Exophiala were the main “connecting” genera. The redundancy analysis (RDA) showed that the fungal community was mainly influenced by temperature, DOC, pH, and urease. The results suggested that UI addition was a feasible way to reduce nitrogen loss and promote enzyme activity during the sewage sludge composting.