Effect of adding cold-adapted microbial agent on the decomposition and microbial community diversity of human faecal compost

Abstract

This study tackled the challenges posed by arid and cold climates on human faeces treatment technology. Three strains of faecal degrading bacteria were previously isolated and purified from cold environments using a gradient dilution method. Rice husk powder was used as a carrier to prepare cold-adapted microbial agent (CAMA). To study the effect of CAMA, a 35-day composting experiment was conducted at 5°C–10°C using wood chips as a conditioning agent. The experiment was divided into two groups: the experimental group (S), which contained CAMA, and the control group (CK), which did not contain CAMA. Inoculation with CAMA caused the compost heap to warm up rapidly, which significantly reduced the composting duration. At the end of composting, the water content was 53.03 %, pH was 8.1, electrical conductivity was 3.18 mS/cm, organic matter content was 46.10 % and seed germination index was 87.02 %, indicating the decomposition of the composting materials. Furthermore, CAMA significantly modified microbial community succession and increased community diversity. In total, seven major categories of biometabolic pathways were obtained by using PCRUSt2 software, and the metabolic abundance of the experimental group was higher than that of the control group, suggesting that the addition of CAMA can effectively promote faecal degradation. These findings provide novel insights into addressing the issue of human faeces accumulation in arid and cold climates.