Multi-dimension analysis of volatile sulfur compound emissions from an urban wastewater treatment plant

Occurrence, characteristics, and microbial community of microplastics in anaerobic sludge of wastewater treatment plants

Wastewater treatment plants (WWTPs) usually contain microplastics (MPs) due to daily influents of domestic and municipal wastewater. Thus, the WWTPs act as a point source of MPs distribution in the environment due to their incapability to remove MPs completely. In this study, MPs occurrence and distribution in anaerobic sludge from WWTPs in different regions (Kaifeng "KHP", Jinan "JSP", and Lanzhou "LGP") were studied. Followed by MPs identification by microscopy and Fourier transform infrared (FTIR) spectrum. The microbial communities associated with anaerobic sludge and MPs were also explored. The results showed that MPs concentrations were 16.5, 38.5, and 17.2 particles/g of total solids (TS) and transparent MPs accounted for 49.1%, 58.5%, and 48.3% in KHP, JSP, and LGP samples, respectively. Fibers represented the most common shape of MPs in KHP (49.1%), JSP (56.0%), and LGP (69.0%). The FTIR spectroscopy indicated the predominance of polyethylene polymer in 1-5 mm MPs. The Proteobacteria, Chloroflexi, Actinobacteria, Bacteroidetes, and Planctomycetes were the abundant phyla in all anaerobic sludge. The bacterial genera in KHP and LGP were similar, in which Caldilinea (>23%), Terrimonas (>10%), and Ferruginibacter (>7%) formed the core bacterial genera. While Rhodococcus (15.3%) and Rhodoplanes (10.9%) were dominating in JSP. The archaeal genera Methanosaeta (>69%) and Methanobrevibacter (>10%) were abundant in KHP and LGP sludge. While Methanomethylovorans accounted for 90% of JSP. Acetyltransferase and hydratase were the major bacterial enzymes, while reductase was the key archaeal enzyme in all anaerobic sludge. This study provided the baseline for MPs distribution, characterization, and MPs associated microbes in WWTPs.

Release characteristics and risk assessment of volatile sulfur compounds in a municipal wastewater treatment plant with odor collection device

Due to the malodorous effects and health risks of volatile sulfur compounds (VSCs) emitted from wastewater treatment plants (WWTPs), odor collection devices have been extensively utilized; however, their effectiveness has rarely been tested. In the present investigation, the characteristics of VSCs released in a WWTP equipped with gas collection hoods are methodically examined by gas chromatography. The obtained results indicate that the concentration of VSCs in the ambient air can be substantially reduced, and the primary treatment unit still achieves the highest concentration of VSCs. Compared to WWTPs without odor collection devices, the concentration of H2S in this WWTP is not dominant, but its sensory effects and health risks are still not negligible. Additionally, research on the emission of VSCs from sludge reveals that the total VSCs emitted from dewatering sludge reaches the highest level. Volatile organic sulfur compounds play a dominant role in the component and sensory effects of VSCs released by sludge. This study provides both data and theoretical support for analyzing the effectiveness of odor collection devices in WWTPs, as well as reducing the source of VSCs. The findings can be effectively employed to optimize these devices and improve their performance.