Abstract:

Odor emissions have become a critical bottleneck restricting the sustainable development of municipal wastewater treatment plants. Biological trickling filters (BTFs) are widely adopted because of their low energy consumption and ease of maintenance, yet their deodorization performance depends greatly on the characteristics of the packing material. Using bamboo charcoal as the control, this study systematically evaluated the deodorization performance of municipal sludge pyrolysis char (sludge char) as a BTF packing material and compared the removal efficiencies of NH₃, H₂S, and odor concentration under ambient (25℃) and relatively low (15℃) temperatures. Utilizing high-throughput sequencing analysis, the microbial mechanism of sludge char deodorization was revealed. The results showed that, the removal rates at 25℃ of NH₃, H₂S, and odor concentration by the sludge-char BTF reached 88.4%, 96.1%, and 87.8%, respectively, which were essentially equivalent to the rates of bamboo charcoal. When the temperature was decreased to 15℃, the deodorization efficiency of the sludge-char BTF was reduced by an average of 6.3% compared to that of bamboo charcoal. Furthermore, microbial analysis indicated that denitrifying sulfur-oxidizing bacteria enriched in the sludge char, such as Massilia and Microvirga, synergistically degraded odor components through the glutamate synthesis pathway driven by gln and glt genes, coupled with the sulfur-autotrophic denitrification pathway mediated by dsr and sox genes. The comprehensive analysis demonstrates that sludge char can replace high-cost bamboo charcoal as a BTF packing materia, providing not only a new perspective for low-cost deodorization in BTFs but also a novel approach for the resource utilization of municipal sludge.

Key words: biotrickling filter, sludge char, deodorization, microbial community structure, functional gene