Effects of Al3+ on pollutant removal and extracellular polymeric substances (EPS) under anaerobic,anoxic and oxic conditions

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 PO₄^3-.     

烟草对砷的吸收累积特征及其健康风险研究

以福建省主栽烟草品种翠碧1号、K326和云烟87为材料,在外源砷添加量为0、10、20、40、70和100 mg·kg~(-1)的土壤中进行盆栽试验,探讨砷对烟草的毒害效应以及砷在土壤-烟草体系中的迁移累积特征,并对植烟土壤中砷的安全临界值进行计算。结果表明,在砷毒害下,烟草生长受到抑制,且烟草根系生长受抑制程度最强。随着砷添加量的增加,土壤中有效砷含量和烟草各部位砷含量均显著提高(P 0.05),砷在根系中的含量最高,在茎中的含量最低。砷处理下各部位间的转移系数表现为TF_((茎-叶)) TF_((土-根)) TF_((根-茎)),且外源砷的增加促进砷从茎到叶片中转移。38.28%～74.37%的砷富集在烟草根部,上部叶中砷的富集量最少(4.61%～11.7%),且所研究的3个烟草品种中翠碧1号对砷的富集能力最强。根据通过吸烟进入人体砷的限量以及土壤有效砷含量与烟草中部叶砷含量的回归模型,推算出翠碧1号、K326和云烟87的植烟土壤有效砷的安全临界值分别为14.17、14.31和11.86 mg·kg~(-1)(磷酸二氢钠浸提)。并将福建省植烟土壤有效砷的安全临界值拟定为11.86 mg·kg~(-1)(磷酸二氢钠浸提)。本研究结果为福建省烟草安全生产提供一定技术指导。     

The influence of slope collapse on water exchange between a pit lake and a heterogeneous aquifer

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.     

基于全生命周期管理的固体废物分类资源化利用研究

梳理我国固体废物资源化利用现状,剖析当前固体废物在处理机制、管理思路和方式、协同处置等方面问题,基于全生命周期理论、绿色循环及低碳发展思路和方法,开展固体废物分类资源化全生命周期优化管理,提出工业生产制造环节须开展绿色生态设计、推行清洁生产;流通消费环节须构建绿色供应链、倡导绿色消费生活方式;回收处置环节须探索新型商业模式、加大重点领域重点品种固体废物资源化科技创新。     

资源产业集聚对资源型城市经济增长的影响--基于夜间灯光数据的实证研究

在资源依赖背景下,发挥好资源产业集聚的正向作用,是资源型城市实现经济可持续增长的关键。基于2005—2017年山西省11个地级市面板数据,采用校正整合的夜间灯光数据度量城市经济增长,并运用系统广义矩估计法(SYS-GMM)检验了资源产业集聚对城市经济增长的影响。结果表明:资源产业集聚对资源型城市经济增长影响显著,呈“先上升,后下降”的倒“U”型关系,在资源产业集聚初期将推动城市经济增长,但过度集聚反而会抑制经济增长。     

多参量综合指标冲击地压预测技术研究

提出了"全局-区域-局部"多参量综合指标冲击地压预测技术,多种预测方法相互协调与配合、优势互补,形成空间上层次化全方位的预测体系,可极大提高冲击地压预测准确性。结合老虎台矿冲击地压发生机理与影响因素,提出利用微震法对采区全局范围内微震事件进行实时监测,划分具有冲击危险区域,全局范围预测冲击地压;利用电磁辐射法监测工作面及巷道近场围岩的应力场和煤岩变形破坏变化状况,确定近场围岩高冲击危险区域,局部范围预测冲击地压;采用矿压监测法和钻屑法对确定具有冲击危险的区域进行重点监测,判断冲击危险程度,对采取防治措施后的防冲效果进行检测;采用采空区气体分析法预测电磁辐射法和矿压观测法等无法监测到的采空区的冲击地压。实践证明:全局-区域-局部"多参量综合指标预测技术的各种预测方法在功能上表现出明显的互补特征,在老虎台矿的冲击地压预报中取得良好效果。     

Understand the local and regional contributions on air pollution from the view of human health impacts

• PM_2.5-related deaths were estimated to be 227 thousand in BTH & surrounding regions. • Local emissions contribute more to PM_2.5-related deaths than PM_2.5 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 PM_2.5 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 PM_2.5-related health impacts. To demonstrate that, we study the source-receptor matrix of the PM_2.5-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 PM_2.5-related deaths of local emissions was 0.75% to 20.77% larger than that of PM_2.5 concentrations. Such results address the importance of local emissions control for reducing health impacts of PM_2.5 particularly for local residents. Contribution of regional transport to PM_2.5-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 PM_2.5 pollution thus mitigating the associated environmental inequality.     

Identification of sources,characteristics and photochemical transformations of dissolved organic matter with EEM-PARAFAC in the Wei River of China

• 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.     

Using T-RFLP technology to analyze bacterial diversity in the rhizospheric soils of tea tree at different ages北大核心CSCD

The rhizospheric soils of Tieguanyin at different ages were used as the study materials, and terminal-restriction fragment length polymorphism (T-RFLP) was used to analyze the changes in bacterial diversity. The results showed that the number of T-RFs, Simpson index, and Shannon index decreased significantly with the age of the tea tree. Results of correlation analysis showed that 9 T-RFs from the bacterial community were significantly and positively correlated with the age of the tea tree, and included 34 species of microbes belonging to 10 classes. The 34 microbes were divided into 6 types according to their functional attributes, and included pathogenic bacteria, bacteria that improved soil texture or inhibited pathogenic bacteria, and bacteria associated with the carbon, nitrogen, or sulfur cycles, in which the percentage of pathogenic bacteria was 58.82%. Seventeen T-RFs were significantly and negatively correlated with the age of the tea tree, and included 38 species of bacteria belonging to 12 classes. The 38 bacterial species were divided into 5 types according to their functional attributes, and included pathogenic bacteria, bacteria that improved soil quality or inhibited pathogenic bacteria, and bacteria associated with the carbon cycle or nitrogen cycle, in which all the others, barring the pathogenic bacteria, accounted for 78.95% of the bacterial population. In brief, the diversity and function of bacteria in the rhizospheric soil of tea tree changed significantly with the age of the tea tree, which provides a theoretical basis for studying the interactions of bacterial communities. © 2018 Science Press. All rights reserved.     

Investigate of in situ sludge reduction in sequencing batch biofilm reactor: Performances,mechanisms and comparison of different carriers

Biofilm is an effective simultaneous denitrification and in situ sludge reduction system, and the characteristics of different biofilm carrier have important implications for biofilm growth and in situ sludge reduction. In this study, the performance and mechanism of in situ sludge reduction were compared between FSC-SBBR and SC-SBBR with constructed by composite floating spherical carriers (FSC) and multi-faceted polyethylene suspension carriers (SC), respectively. The variation of EPS concentration indicated that the biofilm formation of FSC was faster than SC. Compared with SCSBBR, the FSC-SBBR yielded 0.16 g MLSS/g COD, almost 27.27% less sludge. The average removal rates of COD and NH₄⁺-N were 93.39% and 96.66%, respectively, which were 5.21% and 1.43% higher than the average removal rate of SC-SBBR. Investigation of the mechanisms of sludge reduction revealed that, energy uncoupling metabolism and sludge decay were the main factors for sludge reduction inducing 43.13% and 49.65% less sludge, respectively, in FSC-SBBR. EEM fluorescence spectroscopy and SUVA analysis showed that the hydrolytic capacity of biofilm attached in FSC was stronger than those of SC, and the hydrolysis of EPS released more DOM contributed to lysis-cryptic growth metabolism. In additional, Bacteroidetes and Mizugakiibacter associated with sludge reduction were the dominant phylum and genus in FCS-SBBR. Thus, the effect of simultaneous in situ sludge reduction and pollutant removal in FSC-SBBR was better.

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