Abstract: In order to investigate the composting effect of the thermophilic microbial agent combined with hydrochloric acid in the micro-reactor, the aerobic composting method was used under the condition of micro-reactor composting. Four treatments were set up, which were conventional fermentation agent at 1.5% of fresh material weight (CK), conventional fermentation agent at 1.5% of fresh material weight with 0.03 mol H⁺ per kilogram of material (CKA), thermophilic microbial agent at 2.0% of fresh material weight (TMF), and thermophilic microbial agent at 2.0% of fresh material weight with 0.03 mol H⁺ per kilogram of material (TMFA). The fermentation period was 21 days to explore the nitrogen transformation characteristics and maturity effect of the thermophilic microbial agent combined with hydrochloric acid composting. The results showed that the thermophilic microbial agent could increase the temperature of the pile, up to 55.35 ℃, and increase the moisture content of the pile. At 17 d, the seed germination index of each treatment was greater than 70%, reaching a completely decomposed state. Compared with CK, TMFA significantly reduced the pH and electrical conductivity of the pile, and significantly increased the nitrate nitrogen content by 55.52% (P<0.05), but the total nitrogen and total carbon losses were significantly increased by 42.59% and 42.19%, respectively(P<0.05). The addition of hydrochloric acid under the conventional fermentation agent increased the total nitrogen content by 8.35%, while the addition of hydrochloric acid under the thermophilic microbial agent increased the total nitrogen content by 2.99% and significantly increased the total carbon content by 15.36% (P<0.05). There was no significant difference in the cumulative emission of ammonia in each treatment (P>0.05).

Key words: composting, livestock manure, thermophilic microbial agent, additive, hydrochloric acid, micro-reactor, carbon and nitrogen loss, maturation