The highest removal efficiencies of COD and TN were achieved under 10 mg/L of Al3+.The highest TP removal efficiency occurred under 30 mg/L of Al3+.EPS, PS and PN concentrations increased with the addition of Al3+.Sludge properties significantly changed with the addition of Al3+. Aluminum ions produced by aluminum mining, electrolytic industry and aluminum-based coagulants can enter wastewater treatment plants and interact with activated sludge. They can subsequently contribute to the removal of suspended solids and affect activated sludge flocculation, as well as nitrogen and phosphorus removal. In this study, the effects of Al3+ on pollutant removal, sludge flocculation and the composition and structure of extracellular polymeric substances (EPS) were investigated under anaerobic, anoxic and oxic conditions. Results demonstrated that the highest chemical oxygen demand (COD) and total nitrogen (TN) removal efficiencies were detected for an Al3+ concentration of 10 mg/L. In addition, the maximal dehydrogenase activity and sludge flocculation were also observed at this level of Al3+. The highest removal efficiency of total phosphorus (TP) was achieved at an Al3+ concentration of 30 mg/L. The flocculability of sludge in the anoxic zone was consistently higher than that in the anaerobic and oxic zones. The addition of Al3+ promoted the secretion of EPS. Tryptophan-like fluorescence peaks were detected in each EPS layer in the absence of Al3+. At the Al3+ concentration of 10 mg/L, fulvic acid and tryptophan fluorescence peaks began to appear, while the majority of protein species and the highest microbial activity were also detected. Low Al3+ concentrations (<10 mg/L) could promote the removal efficiencies of COD and TN, yet excessive Al3+ levels (>10 mg/L) weakened microbial activity. Higher Al3+ concentrations (>30 mg/L) also inhibited the release of phosphorus in the anaerobic zone by reacting with PO43-. 相似文献
Slope collapse will reduce the water exchange.Slope collapse will affect the spatial distribution of the water exchange.Precipitation have the most impact on the dynamics of the water exchange. Due to the increase in open pit mining, pit lakes have become common surface water features, posing a potential risk to subsurface aquifer. In this study, a pit lake–groundwater interaction model is built based on the general program MODFLOW with the LAK3 package. For the first time, the effects of lake-slope collapse and aquifer heterogeneity on pit lake–groundwater interactions are analyzed by dividing the lake into six water exchange zones based on the aquifer lithology and groundwater level. Our investigation and simulations reveal a total water exchange from groundwater to the lake of 349000 m3/a without collapse of the pit lake slope, while the total net water exchange under slope collapse conditions is 248000 m3/a (i.e., a reduction of 1.40-fold). The monthly net water exchange per unit width from groundwater to the lake reaches the largest in April, shifting to negative values in zone IV from June to August and in zone V in June and July. Moreover, the monthly net water exchange per unit width decreases from north to south, and the direction and magnitude of water exchange are found to depend on the hydraulic gradients between the lake and groundwater and the hydraulic conductivity of the slope collapse. 相似文献
• PM2.5-related deaths were estimated to be 227 thousand in BTH & surrounding regions.• Local emissions contribute more to PM2.5-related deaths than PM2.5 concentration.• Local controls are underestimated if only considering its impacts on concentrations.• Rural residents suffer larger impacts of regional transport than urban residents.• Reducing regional transport benefits in mitigating environmental inequality. The source-receptor matrix of PM2.5 concentration from local and regional sources in the Beijing-Tianjin-Hebei (BTH) and surrounding provinces has been created in previous studies. However, because the spatial distribution of concentration does not necessarily match with that of the population, such concentration-based source-receptor matrix may not fully reflect the importance of pollutant control effectiveness in reducing the PM2.5-related health impacts. To demonstrate that, we study the source-receptor matrix of the PM2.5-related deaths instead, with inclusion of the spatial correlations between the concentrations and the population. The advanced source apportionment numerical model combined with the integrated exposure–response functions is used for BTH and surrounding regions in 2017. We observed that the relative contribution to PM2.5-related deaths of local emissions was 0.75% to 20.77% larger than that of PM2.5 concentrations. Such results address the importance of local emissions control for reducing health impacts of PM2.5 particularly for local residents. Contribution of regional transport to PM2.5-related deaths in rural area was 22% larger than that in urban area due to the spatial pattern of regional transport which was more related to the rural population. This resulted in an environmental inequality in the sense that people staying in rural area with access to less educational resources are subjected to higher impacts from regional transport as compared with their more resourceful and knowledgeable urban compatriots. An unexpected benefit from the multi-regional joint controls is suggested for its effectiveness in reducing the regional transport of PM2.5 pollution thus mitigating the associated environmental inequality. 相似文献
• The source of DOM in surface water and sediment is inconsistent.• The DOC content changes differently in surface water and sediment.• The content of DOC in the surface water is lower than that in the sediment.• The DOM in the surface water had higher photodegradation potentials than sediment. Dissolved organic matter (DOM) in rivers is a critical regulator of the cycling and toxicity of pollutants and the behavior of DOM is a key indicator for the health of the environment. We investigated the sources and characteristics of DOM in surface water and sediment samples of the Wei River, China. Dissolved organic carbon (DOC) concentration and ultraviolet absorbance at 254 nm (UV254) increased in the surface water and were decreased in the sediment downstream, indicating that the source of DOM in the water differed from the sediment. Parallel factor (PARAFAC) analysis of the excitation-emission matrices (EEM) revealed the presence of terrestrial humus-like, microbial humus-like and tryptophan-like proteins in the surface water, whereas the sediment contained UVA humic-like, UVC humic-like and fulvic-like in the sediment. The DOM in the surface water and sediment were mainly derived from microbial metabolic activity and the surrounding soil. Surface water DOM displayed greater photodegradation potential than sediment DOM. PARAFAC analysis indicated that the terrestrial humic-like substance in the water and the fulvic-like component in the sediment decomposed more rapidly. These data describe the characteristics of DOM in the Wei River and are crucial to understanding the fluctuations in environmental patterns. 相似文献