Influence of Electric Fields on the Maturity and Microbial Communities During Sludge and Straw Composting

Numerous challenges including low temperatures, extended fermentation durations, and inadequate material degradation hinder the compost maturity during the aerobic sludge composting. In order to improve the compost maturity, 2 V and 5 V electric fields were introduced and compared with the composting without electric field. The application of electric fields, particularly at 5 V, significantly increased compost temperatures and extended the duration of the thermophilic phase, enhancing pathogen reduction and compost maturity. 5 V electric fields could demonstrate a better performance (such as the electrical conductivity, volatile solid, dissolved organic carbon, NH₄⁺-N, NO₃⁻, C/N) and it was also found that the germination index increased by 13.38%. Proteobacteria (15.9-62.0%), Firmicutes (5.0-60.6%), Bacteroidetes (1.0-29.6%), and Actinobacteria (3.7-28.3%) emerged as the dominant phyla during composting, and electric fields enhanced the relative abundance of Proteobacteria and Bacteroidetes. At the genus level, the application of electric field enriched the compost with key bacterial genera such as Pseudoxanthomonas, known for their role in organic matter decomposition, and promoted the succession of beneficial microbial communities. These crucial bacterial species were significantly influenced by physicochemical parameters (p < 0.05). These results offer valuable insights and a theoretical framework for the application of electric fields in accelerating the composting process, thereby contributing significantly to its optimization.