氢自养脱氮法去除污染地下水中硝酸盐氮的模拟研究

针对硝酸盐氮污染地下水,利用含水层介质培养驯化氢自养脱氮菌,借助静态实验,开展氢自养脱氮的室内研究,考察了初始NO3--N浓度、C/N、P/N、溶解氧（DO）和腐殖酸（HA）对脱氮能力的影响。结果表明,当初始NO3--N浓度为11 mg·L-1时,反应7 d后去除率为97.0%;当初始值分别为22和44 mg·L-1时,13 d后去除率为97.9%和60.7%。在C/N ≤ 2：1时,生成的NO2--N峰值达3.45 mg·L-1。当C/N=15：1~20：1时,去除率增加至97.1%~97.8%,NO2--N为0.12~0.35 mg·L-1。当P/N由0.03：1增加至0.29：1时,去除率由76.5%上升至98.1%。当DO≤1.98 mg·L-1时,去除率为93.7%~96.8%;当DO≥3.87 mg·L-1时,去除率降低至84.1%~88.5%。当HA由0.05 mg·L-1增加至38.75 mg·L-1时,去除率为96.8%~98.1%,同时与初始HA相比残留HA呈降低趋势。初始NO3--N浓度、C/N、P/N和DO显著影响氢自养脱氮性能。HA抑制自养脱氮性能,且HA存在时部分NO3--N被异养脱氮去除。     

NO模拟烟气水净化实验研究

通过模拟实验研究了在NO=120～480mL/Nm3低浓度和含氧量55%、60%和20%体积浓度及常压与≤36℃条件下,以纯水净化难溶有害污染成分NO构成的模拟烟气。在相同的NO配气体积浓度10%,NO被净化吸收量随其流量的增加而增加,而吸收率ηLENO却下降了。常压大气中吸收率值为56%～206%;55%O2时的吸收率值为13%～46%;添加少量氧化剂使O2达60%时的吸收率值为13%～167%。     

溶解氧和有机碳源对同步硝化反硝化的影响

利用SBR反应器,探讨了溶解氧(DO)和有机碳源(COD)对同步硝化好氧反硝化的影响.结果表明,DO范围在0.5～0.6 mg/L时最适合于同步硝化好氧反硝化脱氮.在同步硝化反硝化过程中出现了亚硝酸盐氮的积累,推断经由短程硝化反硝化途径.总氮的去除率随着COD/N(碳氮比)的增加而增加,当COD/N为10.05时,总氮去除率最高可达70.39%.继续增加碳氮比时,总氮去除率增加不多,并且还会导致硝化作用不完全.当存在足够的易降解有机碳源时,能发生完全的好氧反硝化作用.     

生物脱氮在污染治理中的应用

生物脱氮作为一种新兴技术,已经在国内外开展了广泛的研究和应用,为环境领域的脱氮处理提供了一个实用而节能的新途径,因此,集中对生物脱氮技术在废气和废水中的应用进行了介绍,分别介绍了这两个方面的进展,并简单比较了各种技术的优缺点,还探讨了生物脱氮技术的今后发展方向。     

生物滤池外加碳源脱氮研究

以葡萄糖、甲醇、乙醇、乙酸4种有机物为碳源,以中试二沉池出水为原水,研究了生物滤池的反硝化效能,并分析了水温和水力负荷对反硝化效果的影响.结果表明,投加4种碳源后生物滤池均能有效脱氮,对NO-3-N的去除率达67.1％～83.7％.乙酸为碳源时,NO-3-N在生物滤池内浓度下降最快;甲醇为碳源时,NO-3-N浓度下降最...     

固体碳源生物膜处理地下水硝酸盐污染的脱氮性能研究

采用聚己内酯(PCL)为固体碳源和生物膜载体,研究填充率和水力停留时间(HRT)对生物膜反应器脱氮的影响。结果表明:(1)40%(体积分数)的填充率较合适,4h为最佳HRT。此时反应器硝酸盐氮去除率为88%,出水硝酸盐氮质量浓度平均值为8.80mg/L。(2)丛毛单胞菌属(Comamonas)、热单胞菌属(Thermomonas)、固氮螺菌属(Azospira)和长绳菌属(Longilinea)为反应器的主要菌属,且填充率40%的反应器以上菌属相对丰度总和最高(70%)。     

微污染水源水脱氮的强化混凝工艺

通过对机械搅拌桨桨板结构优化改造,实现在絮凝池内同步进行强化混凝及生物脱氮反应,分析桨板长度梯度、板间间距及其与固定挡板间夹角对絮凝池内溶解氧浓度梯度产生影响,设计出了一种搅拌时池内可以形成厌氧-缺氧-好氧环境的新型机械搅拌桨,Fluent流场分析进一步验证了池内横向、纵向都会产生溶解氧浓度梯度。新型搅拌桨与传统搅拌桨生物脱氮对比实验表明,当采用新型搅拌桨时,絮凝池对${\rm{NH}}_4^ + $-N、TN去除效果远优于传统搅拌桨。进一步进行模拟微污染水源水的强化混凝生物脱氮应用实验,出水浊度为0.47 NTU,COD、${\rm{NH}}_4^ + $-N和TN的浓度分别为10.54、5.01和5.84 mg·L−1,表现出良好的处理效果。对污泥粒径的研究表明,PAC投加可有效改善污泥絮体结构,为微污染水源水的处理提供了新思路。     

EVO(乳化油)-Mg(OH)2双功能缓释剂强化修复三氯乙烯污染地下水

氯代烃污染地下水在外加有机质(电子供体)进行强化还原脱氯时,存在有机质消耗快、pH持续降低等影响脱氯效率的问题。利用乳化油(EVO)与胶体氢氧化镁复配的方法,制备了一种兼具电子供体缓释性和OH-缓释性的双功能缓释剂EVO-Mg(OH)2;成功制备了不同EVO∶Mg(OH)2配比的EVO-Mg(OH)2试剂,并对其稳定性、分散性及粒径分布进行了研究;向模拟砂柱中注入不同体积的EVO-Mg(OH)2,考察试剂的迁移性能以及试剂注入对三氯乙烯(TCE)迁移的影响;开展了EVO-Mg(OH)2强化TCE还原脱氯摇瓶实验,考察了该试剂对脱氯效果的影响。结果表明：不同EVO∶Mg(OH)2配比的试剂稳定性及分散性良好,粒径无明显差异;EVO-Mg(OH)2可以有效地在多孔介质中迁移并实现部分滞留;注入量对EVO-Mg(OH)2的迁移性有一定的影响;EVO-Mg(OH)2可以促进TCE溶解和迁移从而减小EVO-Mg(OH)2和TCE之间的传质阻力;EVO-Mg(OH)2能够实现电子供体及OH-的双重缓释,有效促进脱氯微生物的生长,提高TCE的降解速率(k=0.128 d-1),同时抑制pH的降低(pH=7.5)。     

生物流化床处理垃圾渗滤液的硝化强化实验研究

采用厌氧/好氧/硝化耦合生物流化床反应器处理高浓度难降解垃圾渗滤液,通过摇瓶富集与开放体系扩大培养得到高浓度的硝化菌液,用于硝化生物流化床反应器的挂膜启动、驯化与动态运行实验。结果表明,扩培菌液中亚硝化细菌与硝化细菌的浓度分别达到9 .0×107 和3. 5×107 MPN/mL。硝化生物流化床的强化挂膜启动与驯化约历时30d,实际废水动态运行的结果显示,当进水垃圾渗滤液平均氨氮浓度为284 .4mg/L时,出水氨氮浓度为14. 3mg/L,达到了GB16889 1997一级排放标准,经过硝化生物强化的流化床反应器处理高浓度垃圾渗滤液的硝化速率高达28. 1gNH+4 N/m3·h,与未经生物强化的同类系统相比高出近1倍。     

沸石强化A/O生物脱氮工艺氨氮去除机理研究

沸石强化A/O生物脱氮实验研究表明,沸石对配水氨氮具有良好的吸附性能,其吸附特征可以通过Frend lich和Langmu ir吸附等温线表征,但对污水中氨氮的吸附较配水吸附要复杂。由于沸石能与微生物构成沸石-生物复合体,从而增加了系统的硝化细菌和反硝化细菌数量,改善了A段的反硝化作用和O段的硝化作用。吸附饱和的铵沸石在硝化细菌和电导率的协同作用下,经好氧曝气4.5 h,能再生69.8%。在A段,进水氨氮浓度较高,沸石吸附氨氮,提高污水碳氮比,促进生物反硝化;进入O段,在盐度和微生物的协同作用下,混合液氨氮浓度因为生物降解而逐渐降低,不断打破铵沸石的吸附-脱附平衡,铵沸石不断释放氨氮而得到充分的再生。     

纳米铁系双金属-微生物体系去除地下水NO-3-N研究

采用不同液相还原法制备纳米Fe0、Fe/Ni和Fe/Cu粒子,将其与反硝化细菌混合应用于地下水NO3--N去除研究。考察3种体系对NO3--N去除速率的影响,并对其脱氮产物及RNA水平上纳米铁系双金属对反硝化细菌的毒性效应进行了分析和讨论。结果表明,9 d内纳米Fe0体系可完全将NO3--N去除,过程中伴随NO2--N先升高后降低的生成趋势,NH 4+-N生成52%;纳米Fe/Ni体系脱氮速率最快,6 d内可将NO 3--N完全去除,几乎未检测到NO 2--N的生成,而NH 4+-N的转化率高达69%;纳米Fe/Cu体系7 d内可将NO3--N去除完全,NH4+-N的生成率降低,仅39%,但是出现33%NO2--N积累。从反应前后反硝化细菌总RNA浓度变化看,3种纳米粒子对反硝化细菌的毒性大小为纳米Fe/Ni﹥纳米Fe/Cu﹥纳米Fe0。     

Effects of macrophytes and external carbon sources on nitrate removal from groundwater in constructed wetlands

Several microcosm wetlands unplanted and planted with five macrophytes (Phragmites australis, Commelina communis, Penniserum purpureum, Ipomoea aquatica, and Pistia stratiotes) were employed to remove nitrate from groundwater at a concentration of 21-47 mg NO3-N/l. In the absence of external carbon, nitrate removal rates ranged from 0.63 to 1.26 g NO3-N/m2/day for planted wetlands. Planted wetlands exhibited significantly greater nitrate removal than unplanted wetlands (P<0.01), indicating that macrophytes are essential to efficient nitrate removal. Additionally, a wetland planted with Penniserum showed consistently higher nitrate removal than those planted with the other four macrophytes, suggesting that macrophytes present species-specific nitrate removal efficiency possibly depending on their ability to produce carbon for denitrification. Although adding external carbon to the influent improved nitrate removal, a significant fraction of the added carbon was lost via microbial oxidation in the wetlands. Planting a wetland with macrophytes with high productivity may be an economic way for removing nitrate from groundwater. According to the harvest result, 4-11% of nitrogen removed by the planted wetland was due to vegetation uptake, and 89-96% was due to denitrification.     

固态碳源去除地下水硝酸盐的模拟实验

选取了5种研究较少的固体材料,棉花、丝瓜络、甘蔗渣、可降解餐盒、木屑作为去除地下水硝酸盐的外加碳源。在锥形瓶中进行反硝化对比实验,研究了不同固态碳源下NO3--N、NO2--N、NH4+-N及pH的变化情况,分析了NO3--N及总氮的去除率。研究结果表明,反硝化过程中pH呈升高趋势,在6.9～8.5范围内浮动。可降解餐盒和丝瓜络相对于其他的固态碳源来说,对NO3--N和总氮有较高的去除率,但丝瓜络的总氮去除率明显低于可降解餐盒。可降解餐盒的硝酸盐去除率达到98.28%,总氮去除率达到93.48%。可降解餐盒能够有效地去除地下水硝酸盐,达到以废治废的效果,是经济有效的最佳固态碳源。     

Characterization and microbial utilization of dissolved organic carbon in groundwater contaminated with chlorophenols

The aim of this study was to characterize the labile part of dissolved organic carbon (DOC) present in groundwater by identification of natural organic carbon substrates and to assess their microbial utilization during aeration of the groundwater. The studied chlorophenol (CP) contaminated groundwater contained 60-2650 micromoll(-1) of DOC of which up to 98.0% were CPs; 1.7% were low-molecular weight organic acids and 0.2% were dissolved free amino acids. Traces of following natural organic carbon substrates were identified: L-alanine, L-isoleucine, L-leucine, L-serine, L-threonine, L-tyrosine, L-valine, L-aspartic, acetic, citric, formic, lactic, malic and oxalic acid. Dissolved oxygen concentration inside the CP-plume was lower (mean 25 micromoll(-1)) than outside of the plume (mean 102 micromoll(-1)). Over a monitoring period of four years the concentrations of CPs, Fe(II) and NH4+ were higher inside than outside of the CP-plume. Oxygen availability within the CP-plume limits in situ biological oxidation of CPs, DOC, NH4+ and Fe(II). The microbial enzymatic hydrolysis rates of 4-methylumbelliferyl and 7-amino-4-methylcoumarin-linked substrates varied from 0.01 to 52 micromoll(-1)h(-1) and was slightly higher inside than outside the plume. Microbial uptake rates of 14C-acetate, 14C-glucose and 14C-leucine were on average 28, 4 and 4 pmoll(-1)h(-1) outside and 17, 25 and 8 pmoll(-1)h(-1) inside the plume, respectively. The indigenous microorganisms were shown able of hydrolysis of dissolved organic matter, uptake and utilization of natural organic carbon substrates. Therefore, the labile part of DOC serves as a pool of secondary substrates beside the CP-contaminants in the groundwater and possibly help in sustaining the growth of CP-degrading bacteria.     

Hydraulic constraints on the performance of a groundwater denitrification wall for nitrate removal from shallow groundwater

Denitrification walls are a practical approach for decreasing non-point source pollution of surface waters. They are constructed by digging a trench perpendicular to groundwater flow and mixing the aquifer material with organic matter, such as sawdust, which acts as a carbon source to stimulate denitrification. For efficient functioning, walls need to be permeable to groundwater flow. We examined the functioning of a denitrification wall constructed in an aquifer consisting of coarse sands. Wells were monitored for changes in nitrate concentration as groundwater passed through the wall and soil samples were taken to measure microbial parameters inside the wall. Nitrate concentrations upstream of the wall ranged from 21 to 39 g N m(-3), in the wall from 0 to 2 g N m(-3) and downstream from 19 to 44 g N m(-3). An initial groundwater flow investigation using a salt tracer dilution technique showed that the flow through the wall was less than 4% of the flow occurring in the aquifer. Natural gradient tracer tests using bromide and Rhodamine-WT confirmed groundwater bypass under the wall. Hydraulic conductivity of 0.48 m day(-1) was measured inside the wall, whereas the surrounding aquifer had a hydraulic conductivity of 65.4 m day(-1). This indicated that during construction of the wall, hydraulic conductivity of the aquifer had been greatly reduced, so that most of the groundwater flowed under rather than through the wall. Denitrification rates measured in the center of the wall ranged from 0.020 to 0.13 g N m(-3) day(-1), which did not account for the rates of nitrate removal (0.16-0.29 g N m(-3) day(-1)) calculated from monitoring of groundwater nitrate concentrations. This suggested that the rate of denitrification was greater at the upstream face of the wall than in its center where it was limited by low nitrate concentrations. While denitrification walls can be an inexpensive tool for removing nitrate from groundwater, they may not be suitable in aquifers with coarse textured subsoils where simple inexpensive construction techniques result in major decreases in hydraulic conductivity.     

木屑-硫磺填充床反硝化生物滤池强化硝酸盐去除

针对污水处理厂二级出水深度脱氮的需求,设计了以木屑与硫磺颗粒为填料（质量比1:1）的反硝化生物滤池,对碳氮比失衡的污水处理厂二级出水进行深度脱氮处理。结果表明,木屑释放碳源速率在10 d之后趋于稳定,COD中（40.6±10.0）%是反硝化菌可直接利用的VFA。反硝化生物滤池运行的最佳HRT为10 h,在此条件下,进水硝酸盐（以N计）浓度为30 mg·L-1时,出水硝酸盐浓度最低为11.5 mg·L-1,亚硝酸盐（以N计）浓度最低为1.4 mg·L-1,反硝化生物滤池内未发生硝酸盐异化还原（DNRA）作用,出水无氨氮积累。出水SO42-浓度最高为73.8 mg·L-1。反硝化生物滤池运行稳定后,出水中COD未超过30 mg·L-1,木屑释放的碳源与异养反硝化过程消耗的碳源持平,经反硝化生物滤池深度处理的出水中无过量残留有机物。出水pH稳定在6.9~7.4范围内,反硝化生物滤池无需外加碱类物质。     

外源性海藻糖强化好氧脱氮菌处理高盐废水的菌群特性

为提升高盐胁迫下好氧脱氮功能菌群的富集丰度及脱氮性能,解决高盐废水生物脱氮效率低的问题,助推好氧脱氮功能菌在高盐废水处理的工程应用,将海藻糖添加到已富集好氧脱氮功能菌的膜曝气生物膜反应器 (membrane aerobic biofilm reactor, MABR) 中,构建高盐废水的海藻糖生物强化处理系统,从反应器脱氮性能、菌群多样性以及脱氮功能基因丰度等方面探究高盐废水中海藻糖对好氧脱氮菌的强化机制。结果表明：实验组 (C₄₀、C₁₂₀、C₃₆₀和C_{1 080}) 中NH₄⁺-N、TN和COD去除率相较对照组 (C₀) 分别提高了10.70%、32.72%、27.36%、19.45%,8.32%、28.36%、22.53%、17.63%和12.09%、31.14%、25.27%、25.06%;外加海藻糖提高了菌群在高盐废水中的脱氮效率,浓度为120 μmol·L^-1时,NH₄⁺-N去除率最高可提升32.72%。高通量测序分析显示：在高盐环境胁迫下,海藻糖浓度对群落结构及丰度存在显著影响,C₄₀和C₁₂₀提高了异养硝化-好氧反硝化 (heterotrophic nitrification-aerobic denitrification, HN-AD) 菌 (Pseudofulvimonas、Rhodobacteraceae、 Paracoccus、Parapusillimonas和Flavobacterium) 的相对丰度,而C₃₆₀和C_{1 080}有利于异养反硝化菌 (heterotrophic denitrified bacteria, HDB) (Enterococcu、Nitrincola、Truepera、Fusibacter) 的富集;海藻糖浓度显著影响高盐废水中脱氮菌群的组成与丰度。PICRUSt1结果显示：添加海藻糖有效提高以HN-AD菌和HDB为主的脱氮菌群的反硝化活性,在C₄₀和C₁₂₀中,与HN-AD菌关联的硝化基因 (hao) 和反硝化基因 (nasA、napA和napB) 相对丰度提高,此时HN-AD途径得到增强;而与HDB关联的反硝化基因 (narG、narH和narI) 相对丰度在C₃₆₀和C_{1 080}增加,进一步说明加入高浓度海藻糖更有利于加强异养反硝化途径;海藻糖浓度为120 μmol·L^-1时,脱氮基因相对丰度最高,最大程度地加快了好氧脱氮菌群的硝化和反硝化进程。本研究结果可为好氧脱氮菌在高盐废水的好氧处理技术运用中提供参考。     

Molecular characterization of denitrifying bacteria isolated from the anoxic reactor of a modified DEPHANOX plant performing enhanced biological phosphorus removal

Enhanced Biological Phosphorus Removal (EBPR) under anoxic conditions was achieved using a Biological Nutrient Removal (BNR) system based on a modification of the DEPHANOX configuration. Double-probe Fluorescence in Situ Hybridization (FISH) revealed that Polyphosphate Accumulating Organisms (PAOs) comprised 12.3 +/- 3.2% of the total bacterial population in the modified DEPHANOX plant. The growing bacterial population on blood agar and Casitone Glycerol Yeast Autolysate agar (CGYA) medium was 16.7 +/- 0.9 x 10(5) and 3.0 +/- 0.6 x 10(5) colony forming units (cfu) mL(-1) activated sludge, respectively. A total of 121 bacterial isolates were characterized according to their denitrification ability, with 26 bacterial strains being capable of reducing nitrate to gas. All denitrifying isolates were placed within the alpha-, beta-, and gamma-subdivisions of Proteobacteria and the family Flavobacteriaceae. Furthermore, a novel denitrifying bacterium within the genus Pseudomonas was identified. This is the first report on the isolation and molecular characterization of denitrifying bacteria from EBPR sludge using a DEPHANOX-type plant.     

Bio-beads with immobilized anaerobic bacteria,zero-valent iron,and active carbon for the removal of trichloroethane from groundwater

Chlorinated hydrocarbons are the most common organic pollutants in groundwater systems worldwide. In this study, we developed bio-beads with immobilized anaerobic bacteria, zero-valent iron (ZVI), and activated carbon (AC) powder and evaluated their efficacy in removing 1,1,1-trichloroethane (TCA) from groundwater. Bio-beads were produced by polyvinyl alcohol, alginate, and AC powder. We found that the concentration of AC powder used significantly affected the mechanical properties of immobilized bio-beads and that 1.0 % (w/v) was the optimal concentration. The bio-beads effectively degraded TCA (160 mg L^?1) in the anaerobic medium and could be reused up to six times. The TCA degradation rate of bio-beads was 1.5 and 2.3 times greater, respectively, than ZVI + AC treatment or microbes + AC treatment. Measuring FeS produced by microbial reactions indicated that TCA removal occurred via FeS-catalyzed dechlorination. Analysis of clonal libraries derived from bio-beads demonstrated that the dominant species in the community were Betaproteobacteria and Gammaproteobacteria, which may contribute to the long-term stability of ZVI reactivity during TCA dechlorination. This study shows that the combined use of immobilized anaerobic bacteria, ZVI, and AC in bio-beads is effective and practical for TCA dechlorination and suggests they may be applicable towards developing a groundwater treatment system for the removal of TCA.     

基于Fe~0的PRB去除地下水中硝酸盐的模拟研究

由于地下水中硝酸盐污染的普遍性、难去除性和对人体健康的潜在危害性而引起人们的广泛关注。本研究通过柱实验,研究了不同条件(进水pH、砂/Fe0体积比和添加锯末)对基于Fe0的模拟渗透性反应墙(permeable reactivebarrier,PRB)去除地下水中硝酸盐的影响。结果表明,由于黄土的碱性和缓冲作用,进水pH的影响不显著;5~6∶1的砂/Fe0(S/Fe)体积比既可提高铁粉利用率,又有利于硝酸盐的还原并延长PRB的有效期;铁腐蚀产物引起铁粉粘固而导致PRB的渗透性和反应性降低,尤其在反应区的进水口端;虽然酸预处理Fe0有助于硝酸盐的还原,但更容易引起堵塞,而在Fe0体系中加入活性炭不仅可提高硝酸盐的去除率,还可延长PRB的有效期,是一种很好的辅助填料;同时添加锯末和Fe0的生物-化学联合法更有助于硝酸盐还原并提高出水水质,具有很好的应用潜力;不同条件下,出水中的氨和亚硝酸盐的浓度相差较大,但可溶性铁浓度均低于饮用水标准(0.3 mg/L)。Fe0的化学还原和锯末的生物反硝化是硝酸盐去除的主要机理。本研究表明,基于Fe0的PRB用于去除中性或偏碱性地下水中的硝酸盐污染具有很大的潜力。