Soil properties and habitats determine the response of bacterial communities to agricultural wastewater irrigation

Increasing temperatures and variability of precipitation events due to climate change will lead in the future to higher irrigation demands in agroecosystems.However,the use of secondary treated wasterwater(TWW)could have consequences for the receiving soil environment and its resident microbial communities.The objective of this study was to characterize the importance of soil properties and habitats to the response of soil bacteria and archaea to irrigation with TWW.Two agricultural soils with contrasting textures(loamy sand or silt loam)and,for each,three variants differing in soil organic carbon and nitrogen,as generated by long-term fertilization,were analyzed.For each of these six soils,prokaryotic communities from two habitats,i.e.,root-free bulk soil and the rhizosphere of developing cucumber plants in the greenhouse,were characterized.Communities were analyzed by the quantity and diversity of their polymerase chain reaction(PCR)-amplified 16S rRNA genes.To account for TWW-associated nutrient effects,potable water(PW)served as a control.Amplicon sequence analysis showed that prokaryotic communities mainly consisted of bacteria(99.8%).Upon irrigation,regardless of the water quality,prokaryotic diversity declined,p H increased,and no bacterial growth was detected in bulk soil.In contrast,the growth of cucumbers was stimulated by TWW,indicating that plants were the main beneficiaries.Moreover,strong responses were seen in the rhizosphere,suggesting an indirect effect of TWW by altered rhizodepositions.The main bacterial responders to TWW were Proteobacteria,Bacteroidetes,Actinobacteria,and Planctomycetes.Changes in bacterial communities due to TWW were less pronounced in all variants of the silt loam,indicating the importance of clay and soil organic carbon for buffering effects of TWW on soil bacterial communities.Hence,soil organic carbon and soil texture are important parameters that need to be considered when applying TWW in agriculture.     

NaCl浓度对SBBR同步脱氮及N2O释放的影响

盐度是影响生物脱氮过程的重要因素。盐度增加会导致生物硝化和反硝化过程中N_2O的产生并释放。该文以添加NaCl的生活污水为研究对象,采用固定填料序批式生物膜反应器(sequencing batch biofilm reactor,SBBR),考察了不同NaCl浓度(0、5、10、15和20g/L)对SBBR脱氮性能及N_2O释放的影响。结果表明,试验NaCl浓度范围内,SBBR出水COD稳定在40～60mg/L。硝化过程NO_2~-/NO_3~-随NaCl浓度增加而增加。NaCl浓度≤10g/L时,NH_4~+-N去除率大于95%,N_2O产率由4.08%(NaCl浓度为0)增至6.72%(NaCl浓度为10 g/L)。NaCl浓度为20 g/L时,驯化后SBBR内平均NH_4~+-N去除率为70%,平均N_2O产率为13.60%。无添加NaCl时,N_2O主要产生于硝化阶段的AOB好氧反硝化过程,SBBR内缺氧区有助于减少N_2O释放;高NaCl浓度条件下,N_2O主要产生于AOB好氧反硝化过程和内源同步反硝化过程,高盐度加剧内源反硝化阶段NO_2~-和N_2O之间电子竞争,抑制N_2O还原,其活性抑制性能与电子受体和初始C/N有关。与硝态氮还原速率和亚硝态氮还原速率相比,氧化亚氮还原速率受NaCl抑制最为明显,是导致高盐度条件下N_2O释放量增加的重要因素。     

Carbon dioxide and gaseous nitrogen emissions from biochar‐amended soils under wastewater irrigated urban vegetable production of Burkina Faso and Ghana

To quantify carbon (C) and nitrogen (N) losses in soils of West African urban and peri‐urban agriculture (UPA) we measured fluxes of CO₂‐C, N₂O‐N, and NH₃‐N from irrigated fields in Ouagadougou, Burkina Faso, and Tamale, Ghana, under different fertilization and (waste‐)water regimes. Compared with the unamended control, application of fertilizers increased average cumulative CO₂‐C emissions during eight cropping cycles in Ouagadougou by 103% and during seven cropping cycles in Tamale by 42%. Calculated total emissions measured across all cropping cycles reached 14 t C ha^?1 in Ouagadougou, accounting for 73% of the C applied as organic fertilizer over a period of two years at this site, and 9 t C ha^?1 in Tamale. Compared with unamended control plots, fertilizer application increased N₂O‐N emissions in Ouagadougou during different cropping cycles, ranging from 37 to 360%, while average NH₃‐N losses increased by 670%. Fertilizer application had no significant effects on N₂O‐N losses in Tamale. While wastewater irrigation did not significantly enhance CO₂‐C emissions in Ouagadougou, average CO₂‐C emissions in Tamale were 71% (1.6 t C ha^?1) higher on wastewater plots compared with those of the control (0.9 t C ha^?1). However, no significant effects of wastewater on N₂O‐N and NH₃‐N emissions were observed at either location. Although biochar did not affect N₂O‐N and NH₃‐N losses, the addition of biochar could contribute to reducing CO₂‐C emissions from urban garden soils. When related to crop production, CO₂‐C emissions were higher on control than on fertilized plots, but this was not the case for absolute CO₂‐C emissions.     

多级跌水充氧式沟渠连通生态塘污水处理效果及优化模拟试验

针对农村污水流量小浓度高、排放不均匀及降雨冲击等特点,设计多级跌水充氧式沟渠连通生态塘组合工艺,进行水力负荷、运行方式、水量波动、降雨冲击等影响因素及参数优化试验。结果表明:随着水力负荷的增大,污染物的去除率逐渐降低;间歇运行的处理效果优于连续运行;水量的波动导致污染物的去除率也随之变化,其中化学需氧量和氨氮的去除率最大降幅接近20%;总氮去除率的降幅最大,约25%;总磷的去除率最大降幅最小,约15%左右;当降雨规模变大时,组合工艺对各污染物去除率分别从53.95%、52.44%、49.92%、71.64%下降到40.94%、43.75%、34.93%、53.84%。采取地表径流截流措施后,组合工艺对各污染物的去除效果有所改善,去除率的上升与截流倍数的增加近似呈现线性关系,当降雨为暴雨,采取截流倍数为5时,出水水质仍能达到城镇污水处理厂污染物排放标准(GB18918-2002)一级排放标准,对降雨期间农村污水的污染去除具有重要意义。     

Screening of bioflocculant-producing strains and optimization of its nutritional conditions by using potato starch wastewater

研究以开发微生物絮凝剂新产品及探索马铃薯淀粉废水资源化利用途径为目的。以活性污泥为材料,分离到100株菌株,通过液体发酵培养,以发酵液对高岭土悬浊液的絮凝率为评价指标,初筛到13株絮凝活性较高的菌株;根据菌株利用马铃薯淀粉废水发酵产絮凝活性能力,复筛得到一株高产絮凝物质的酵母菌F5,经26SrDNA鉴定为Candida anglica。再通过单因素试验和正交试验,确定了该菌株利用马铃薯淀粉废水发酵产絮凝剂的最佳营养条件。结果表明,当废水pH值5.6,接种量为10%（体积分数）,温度28 ℃,摇床转速为150 r/min条件下,废水不灭菌发酵48 h,C. anglica菌株利用马铃薯淀粉废水发酵产絮凝剂的最佳营养条件为：以 1 mL/100 mL甘油作为外加碳源,0.05 g/100 mL (NH4)2SO4为氮源,添加0.1 g/100 mL MgCl2和0.1 g/100 mL KH2PO4。验证试验表明,在该条件下,发酵液对高岭土悬浊液的絮凝率达到94.6%,使原废水化学需氧量（COD）去除率达到93.7%,絮凝活性提取物得率为1.36 g/L,研究结果可为马铃薯淀粉废水处理及生物再利用提供理论依据和参考。     

杭州灯塔养殖总场猪粪污水处理工程的设计与运行

采用厌氧—好氧(UASB—SBR)法处理技术对杭州灯塔养殖总场的高浓度猪粪污水进行处理，COD总去除率达98%，NH₃-N去除率达99%以上，出水COD浓度不大于150 mg/L ，NH₃-N浓度不大于15 mg/L，出水水质达到《污水综合排放标准》(GB8978-1996)的二级排放标准。     

园林地慢速渗滤系统处理农村分散式生活污水

针对农村分散式生活污水处理设施缺乏而面源污染严重的问题,该研究从土壤自净功能出发,结合传统土地慢速渗滤处理系统和澳大利亚FILTER系统技术特点,提出了园林地慢速渗滤农村生活污水处理系统,优化了污水处理工艺中的布水和排水系统,提高了系统的污水接纳与处理能力。试验结果表明该系统对TN(总氮)、TP(总磷)、COD(化学需氧量)、TOC(总有机碳)、NH4+-N(铵态氮)均有较好去除效果,平均去除率分别为80.7%、89.2%、89.5%、60.2%、85.7%,出水水质达到一级A类标准。该系统对农村生活污水处理效果良好,具有技术可行、成本有效和管理方便等特点,为中国现阶段农村生态环境建设提供参考。     

极大硬毛藻无性系对海水养殖废水中氮盐的去除效果

养殖水体中无机氮的高效去除是开展循环水养殖的重要保障条件之一。该论文研究了极大硬毛藻无性系(简称极大硬毛藻)对循环水养殖水体中无机氮盐的去除效率及特征。结果表明,当藻体密度为(10±1) g/L时,在一定浓度范围(氨氮:0～15 mg/L,亚硝酸盐氮:0～3 mg/L,硝酸盐氮:0～15 mg/L),极大硬毛藻对海水中3类无机氮盐的吸收速率随着时间变化即氮盐浓度降低而降低;其中藻类对氨氮的吸收速率变化较大,而对亚硝酸盐和硝酸盐的吸收速率相对稳定。当3种氮盐质量浓度为3 mg/L,极大硬毛藻首先选择吸收氨氮;当氨氮质量浓度降至1.5 mg/L时,藻开始吸收亚硝酸盐氮和硝酸盐氮。极大硬毛藻对人工模拟养殖废水中氨氮、亚硝酸盐氮和硝酸盐氮的15 h去除率可达到94.3%、100%、82.2%。该研究可为极大硬毛藻在循环水养殖水体净化的应用、养殖废水资源化利用和无害化处理技术的建立提供科学依据。     

Effect of Water Quality on Heavy Metal Redistribution and Mobility in Polluted Agricultural Soils in a Semi-Arid Region

Mornag Plain is a coastal area of the Mediterranean basin, which has undergone an agricultural industrial boom. The aim of this study was to investigate the different water qualities used for irrigation on heavy metal mobility in these polluted agricultural soils. The geo-accumulation indices for heavy metals (Ni, Cr, Pb, Cd, Cu, and Zn) revealed that industrial activities and used treated wastewater (TWW) contributed to soil pollution, and water irrigation always decreased this contamination. After long-term use of different water types, high perturbation of heavy metal redistribution has occurred. Groundwater use altered all heavy metal redistributions in the irrigated soil among various soil-solid and soil-solution fractions, as compared to the unirrigated soil. Slight acid water use transferred some metals from different solid phase components into water-soluble and exchangeable fractions. However, TWW use transformed some Ni, Cr, Cd, Cu, and Zn from water-soluble and exchangeable fractions to less labile fractions, particularly into organically bound fractions. Reuse of conventional water within the same soil decreased the whole soil redistribution index values, indicating tendency to return to the pattern of distribution of groundwater-irrigated soil.     

Na+和K+共存对A2/O工艺脱氮除磷效果及污泥性质的影响

为了揭示多种金属离子共存的含盐废水生物处理系统污染物的去除机制和污泥特性,考察Na~+、K~+共存对A~2/O工艺污染物去除率、污泥性质和微生物群落的影响,采用高通量测序技术分析了厌氧区、缺氧区和好氧区的微生物群落结构,结合脱氮除磷效果和污泥性质的变化,探讨不同Na~+/K~+摩尔比下A~2/O工艺优势种群的演替规律,以期从微生物角度明确Na~+、K~+共存对含盐废水污染物去除率的影响。结果表明:当进水Na~+/K~+摩尔比分别为2、1和0.5时,A~2/O工艺的COD去除率分别为80%、84%和86%,TN去除率分别为73%、77%和80%,K~+浓度的提高缓解了Na~+对COD和TN去除率的抑制作用;厌氧区释磷率分别为70%、73%和74%,缺氧区吸磷率分别为53%、55%和58%,好氧区吸磷率分别为70%、72%和75%。随着进水Na~+/K~+摩尔比的降低,厌氧区、缺氧区和好氧区微生物群落的丰富度和多样性降低,微生物群落差异显著,变形菌门的相对丰度均升高约30%,拟杆菌门和绿弯菌门相对丰度逐渐降低。陶氏菌属和固氮弧菌属作为优势菌属,其相对丰度逐渐增大,有利于氮磷污染物的去除。通过增加K~+的浓度有利于提高氮、磷去除率,增强污泥的生物絮凝性和反硝化聚磷菌的活性。