Removal of trace sulfur odorants under adverse conditions in biotrickling filter: Performance enhancement, microbial adaptation, and functional improvement

Enhancement of sulfur odorants removal and microbial metabolism under adverse conditions (starvation and low temperature) are still a great challenge during the biotrickling filter (BTF) operation in wastewater treatment plants (WWTPs), especially when hydrophobic packing such as low-pressure drop structured polypropylene plastic (PP) in used. At the same time, surface modification may give such potential when combined with sodium dodecyl benzene sulfonate (SDBS). Herein, PP packing was first modified by plasma-chemical solution (PP@PC) and activated carbon (PP@AC), respectively, to improve its sulfur odorant removal by BTF. Results showed that the start-up time of PP@PC-BTF and PP@AC-BTF for H 2 S removal was shortened by approximately 7 days and 13 days, respectively. With the addition of 30 mg/L SBDS, the removal efficiency (RE) of H 2 S, dimethyl sulfide (DMS), and dimethyl disulfide (DMDS) increased by 14.5 %–20.5 %, 10.9 %–17.1 %, and 12.2 %–21.9 % on average, respectively, in surface-modified PP-BTFs during the starvation recovery phase. Furthermore, the DMDS removal was enhanced by 24.6 % and 28.2 % on average in PP@PC-BTF and PP@AC-BTF, respectively, at low temperature of 8 °C. PP@AC also improved bacterial diversity, sulfur metabolism, and functional stability of BTF under starvation and low-temperature conditions. The biofilm thickness in PP@AC was twice that of PP. Metagenomics results based on KEGG pathways confirmed that the gene expression related to sulfur metabolism and amino acid synthesis was improved in PP@AC-BTF. Additionally, the content of sulfur carrier protein in PP@AC was 2.5 times higher than in PP. Bacterial communities could adapt to adverse conditions by regulating biomarkers.