Journal of Environmental Engineering Technology•2026•DOI: 10.13205/j.hjgc.202606018
Swine wastewater, a high-strength organic effluent, offers a viable substrate for anaerobic biohydrogen production, aligning with clean energy recovery. This study compared hydrogen production in three anaerobic sequencing batch reactors (ASBRs) treating: raw wastewater (R1), supernatant after MAP (magnesium ammonium phosphate) precipitation for nitrogen and phosphorus recovery (R2), and the same supernatant with anaerobic sludge heat-treated at 75°C for 0.5 h (R3). Without pH adjustment, hydrogen production in R1 remained below 0.50 mmol/(kg·d). At an influent COD of 1800 mg/L, R2 and R3 achieved hydrogen production rates of 48.17 and 71.44 mmol/(kg·d), respectively. At COD 2400 mg/L, methane concentrations in R1, R2, and R3 were 10.8%, 14.2%, and 9.1%, respectively, indicating MAP pretreatment enhanced both hydrogen and methane production. As COD increased, R1's methane concentration rose to 14.6%, while average COD removal efficiencies for R1, R2, and R3 were 78.9%, 70.8%, and 52.5%, respectively. Under pH adjustment, all reactors peaked at pH 4.0, with hydrogen production rates of 0.10, 7.74, and 8.83 mol/(kg·d) for R1, R2, and R3, respectively. These findings demonstrate that MAP pretreatment combined with sludge heat treatment significantly enhances biohydrogen production, offering a promising strategy for swine wastewater valorization.
Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2025042103
This study investigated the spatiotemporal distribution, ecological risk, and sources of seven heavy metals (Cr, Cd, Cu, Ni, Pb, Zn, As) in surface sediments of Ranwu Lake, Xizang. Twelve samples were collected during the glacial ablation period (July 2024) and late glacial ablation period (November 2024). Concentrations were determined and analyzed using inverse distance weighting (IDW) for spatial patterns, geo-accumulation index (Igeo) and potential ecological risk index (RI) for risk assessment, and correlation analysis (CA), principal component analysis (PCA), and absolute principal component score-multiple linear regression (APCS-MLR) for source apportionment. Results showed that during glacial ablation, mean Cr, Cd, Pb, and As exceeded Xizang soil background values, while in the late ablation period only Cd, Pb, and As remained elevated. Spatial distribution varied between periods, with high concentrations in the middle and lower lake during ablation, shifting to the lower lake in the late period. Igeo and RI indicated overall low ecological risk, with Cd as the primary risk factor; mean RI values were 81.79 and 98.30 for the two periods, respectively. Source apportionment revealed that heavy metals mainly originated from natural and transportation sources, with traffic emissions being the major contributor to ecological risk. Specifically, Cr, Ni, and As were predominantly natural, Cd and Pb were mainly traffic-related, and Cu and Zn were influenced by both natural and traffic sources.