利用生态池净化玉泉景点富营养化水的研究

在人工湿地的基础上建立生态池，来净化杭州植物园玉泉观鱼景点观鱼池富营养化水质。结果表明该生态池在每年的不同季度内对总氮（TN）、氨氮（NH3-N）、总磷（TP）、化学需氧量（CODMn）、五日生化需氧量（BOD5）、溶解氧（DO）、浊度（TURB）、电导率（COND）均有较好的改善和净化效果，对硝态氮（NO3-N）的净化能力稍弱；总氮和氨氮的去除率在夏季最高，分别达到26．6％和87．7％，总磷在春季的去除率最高，为56．3％，硝态氮、CODMn和BOD5在秋季去除率最高，分别为8．05％、65．9％和73．9％。生态池的净化出水水质略低于地下水，但可以替代地下水来给养鱼池换水，为解决景区富营养化水质提供了一个好的途径。     

混凝沉淀SBR活性炭过滤处理垃圾渗滤液

采用沉淀-SBR-活性炭过滤复合工艺对城市垃圾渗滤液进行处理，确定混凝、SBR和活性炭过滤的最佳参数。结果表明，当进水CODcr 2500mg／L、氨氮在900mg／L的条件下，经该系统处理后，出水CODcr均在300mg/L以下，氨氮在20mg/L以下。CODcr去除率达90％以上，氨氮去除率达98％以上，达到去除有机物和氨氮的较好效果。     

优化生物倍增工艺提高除氮效率

对某厂丙烯晴生产过程中产生的废水进行分析,根据其特点采用生物法进行处理。为降低丙烯腈污水预处理池出水氨氮的浓度,在原有池体即生物倍增池末端增加反硝化工艺去除氨氮,节省了投资成本、减少了改造时间。污水池改造,氨氮、COD去除率分别为87%,77%,TN、CN去除率分别为66%,93%,达到了去除出水大部分氨氮的预期效果。     

催化氧化复合生物技术处理油气田压裂返排液

针对油气田压裂返排液处理难度大的问题,以四川某气田井组压裂返排液为研究对象,通过对其水质特征和治理技术现状的分析,提出催化氧化复合生物处理工艺并进行了现场实验。实验结果表明:该技术对于压裂返排液COD去除效果明显,最终出水COD浓度均降至100mg/L以下,COD去除率达到98%以上;G-BAF生化系统进水盐度在0.5%~5%时,系统适应性非常好,有机物去除率达93%以上;当盐度提高到8%时,有机物去除率仍能保持在84%左右,G-BAF生化系统适合高盐度压裂返排液的处理;压裂返排液出水主要污染指标COD浓度、氨氮浓度、SS浓度、pH值均达到GB 8978—1996《污水综合排放标准》一级标准,出水可用于油田及污水处理站设备清洁、钻井岩屑清洗等,实现废水综合利用。     

分层填料土地毛管渗滤系统脱氮作用研究

对土壤煤渣分层的土地毛管渗滤系统的脱氮效果和机理进行了研究。氮的静态吸附试验和土壤全氮含量分析表明,填料对氮的去除作用有限。植物对总氮的去除贡献率只占0.47%,作用不明显。温度和总氮去除率的相关分析表明,温度对总氮去除效果影响不显著。提高出水水位30 cm以创造适合反硝化菌生长的还原环境,总氮去除率由39.1%下降到30.0%,可见氧化还原条件不是系统反硝化反应的限制条件。投加葡萄糖作为碳源,使C/N〉3,有机物去除率保持在80%以上,总氮的去除率上升到52.4%,较高的C/N比能有效提高土地毛管渗滤系统的总氮去除效果。     

玻璃蚀刻液废水中氨氮和氟去除研究

研究了MAP法(Magnesium Ammonium Phosphate磷酸铵镁结晶法)和化学沉淀法对玻璃蚀刻液废水中氨氮和氟的去除效果,获得了最佳工艺参数并形成了一套玻璃蚀刻液废水处理工艺。采用N/P/Mg投加比例为1∶1∶1的两级MAP法和Ca/F投加比为1. 8的两级化学沉淀法,并在两级氨氮和氟去除反应后分别添加PAC-PAM (聚合氯化铝-聚丙烯酰胺)为40 mg/L、2mg/L和20 mg/L、1mg/L进行絮凝沉淀,最终出水氨氮和氟的去除率分别可以达到96. 8%和99. 9%;对出水进行折点加氯处理,氨氮最终去除率可达99. 9%,出水可达到国家污水综合排放标准。     

氯离子对过一硫酸盐法处理垃圾渗滤液的研究

为探究氯离子(Cl^-)对过一硫酸盐法(PMS)去除垃圾渗滤液中氨氮和难降解有机物的影响，通过改变Cl^-浓度和氨氮浓度，采用常规水质指标分析及三维荧光光谱分析，对比了Cl^-对PMS体系处理垃圾渗滤液中活性氯的累积生成情况、氨氮的转化影响和难降解有机物的去除效果。结果表明，在无氨氮时，Cl^-可以增强垃圾渗滤液中有机物的降解效果；当初始氨氮浓度为60 mg/L,反应60 min时，垃圾渗滤液中氨氮的去除率可达90%以上，但UV₂₅₄去除率从22.96%大幅下降9.27%,说明了Cl^-的存在可以促进渗滤液中氨氮的转化但会影响芳香性有机物的去除效果。三维荧光分析结果进一步证明了Cl^-可以降低PMS体系处理后垃圾渗滤液中有机物的腐殖化程度，但氨氮的存在会削弱高含氯垃圾渗滤液中腐殖质的去除效果。本文研究结果可为优化过一硫酸盐法处理高含Cl^-垃圾渗滤液中氨氮与有机物提供理论基础。     

采用生化-化学技术处理吗啉生产废水

针对吗啉生产废水的特点,制定处理工艺路线,通过生化试验和化学氧化试验,研究该工艺对废水COD和氨氮的处理效果,并确定生化各段停留时间及氧化剂投加量等工艺参数,最终开发出一套处理吗啉生产废水的工艺路线。试验结果表明:生化段试验进水COD平均7 725 mg/L,平均出水COD为168 mg/L,COD平均去除率为97.7%;进水氨氮平均浓度489 mg/L,出水氨氮平均浓度为2.3 mg/L,氨氮平均去除率为99.5%。最后经化学氧化处理后,出水COD60 mg/L,氨氮5 mg/L,达到GB 8978—1996《污水综合排放标准》一级标准。     

荒漠土壤渗滤系统中再生水典型污染物变化规律研究

土壤渗滤系统具有处理效果好、投资少等优点,适合再生水或经过预处理农村生活污水的处理,逐步成为国内外的研究热点。采用新疆准噶尔盆地边缘的荒漠-绿洲交错地带的土壤,利用室内土柱装置,研究城市再生水在荒漠土壤中渗滤后进出水水质与土壤污染物含量的变化特征,探讨土壤性质对再生水氨氮去除率和土壤污染物浓度变化的影响。结果表明,荒漠土壤对再生水氨氮等有显著的去除作用,且再生水经过土柱渗滤后,在60 cm处的出水氨氮浓度逐渐趋于稳定,但氨氮去除率随时间并不十分稳定,且不同土壤质地、组分与性质不同,对氨氮的去除效果有明显差异。同一土柱,对不同污染物去除作用也有很大差异。通过相关性分析可知,土壤中的CO_3~(2-)、HCO_3~-、Na~+、SO_4~(2-)、总磷、碱解氮与硝酸盐氮等指标含量对再生水氨氮的去除率及土壤中污染物浓度变化有明显的影响。研究结果为进一步研究荒漠土壤渗滤系统去除污染物机理、新疆再生水安全利用以及荒漠土壤渗滤系统的实践应用提供基础。     

好氧颗粒污泥同时脱氮除磷技术研究

采用序批式活性污泥法(SBR)处理新疆油田公司准东石油基地污水,作为生物膜的一种特殊形式,介绍了该工艺的优点,在适宜的运行条件下进行实验。讨论了好氧颗粒污泥脱氮以及除磷的过程,分析了该工艺对氮、磷的去除率及好氧颗粒污泥在好氧、缺氧条件下的吸磷情况,当进水氨氮、磷和乙酸碳浓度分别为38.2 mg/L、27.7 mg/L和134.6 mg/L,MLSS和MLVSS分别为7.0 mg/L、6.4 mg/L时,氨氮、总无机氮、磷、乙酸碳的平均去除率分别达到98.8%、90.2%、98.9%、97.2%.     

A simulation experiment on the effectiveness of tree and pasture filter strips to remove NO3-N in lateral soil water flow

The impact of vegetative filter strips to reduce the delivery of nonpoint source pollutants from agricultural land to inland water systems is now recognized as an important element in overall agro-ecosystem management. A glasshouse experiment was undertaken to measure the effectiveness of tree (Eucalyptus camaldulensis Dehnh. and Casuarina cunninghamiana Mq.) and pasture filter strips to intercept lateral movement of NO(3)-N in soil water. Tree treatments retained significantly more NO(3)-N associated with shallow soil water movement (between the A and B soil horizons) than bare ground. Nitrate-N removal was not significantly different between trees and pasture, and among the tree treatments. However, uptake and accumulation of NO(3)-N by pastures was significantly (P < 0.001) greater than the trees. The average rates of N accumulation were 0.82 g m(-)(2) and 1.52 g m(-2) wk(-1) for the tree plots and the pasture plots, respectively. The experiment also showed that the efficiency of NO(3)-N removal from soil solutions by trees was greater when NO(3)-N concentrations were relatively higher in the soil (81.4% removal at 20 mg L(-1) compared to 68.1% at 10 mg L(-1)).     

Comparing carbon substrates for denitrification of subsurface drainage water

Nitrate in water from tile drained corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] fields in the U.S. Midwest contributes to nitrate contamination of surface waters. Denitrification-based biofilters are a promising strategy for reducing nitrate concentrations, but these systems require an external carbon supply to sustain denitrification. The ability of four organic materials to serve as carbon substrates for denitrification biofilters was evaluated in this laboratory study. Wood chips, wood chips amended with soybean oil, cornstalks, and cardboard fibers were mixed with subsoil (oxidized till) and incubated anaerobically for 180 d. Periodically, 15NO3-N was added to maintain nitrate N concentrations between 10 and 100 mg L-1. All of the materials stimulated NO3-N removal and the degree of removal from highest to lowest was: cornstalks, cardboard fibers, wood chips with oil, and wood chips alone. Analysis of 15N showed that immobilization and dissimilatory nitrate reduction to ammonium accounted for <4% of NO3-N removal in all treatments, therefore denitrification was the dominant NO3-N removal process. Cardboard fibers, wood chips and oil, and wood chips alone did not support as much denitrification as cornstalks, but their rates of NO3-N removal were steady and would probably continue longer than cornstalks. The addition of soybean oil to wood chips significantly increased denitrification over wood chips alone.     

Monitoring nitrate leaching from submerged drains

Monitoring nitrate N (NO3-N) leaching is important in order to judge the effect that agricultural practices have on the quality of ground water and surface water. Measuring drain discharge rates and NO3-N concentrations circumvents the problem of spatial variability encountered by other methods used to quantify NO3-N leaching in the field. A new flow-proportional drainage water sampling method for submerged drains has been developed to monitor NO3-N leaching. Both low and high discharge rates can be measured accurately, and are automatically compensated for fluctuations in ditch-water levels. The total amount of NO3-N leached was 10.6 kg N ha(-1) for a tile-drained silt-loam soil during the 114-d monitoring period. The NO3-N concentrations fluctuated between 5 mg L(-1) at deep ground water levels and 15 mg L(-1) at shallow levels, due to variations in water flow. A flow-proportional drainage water sampling method is required to measure NO3-N leaching accurately under these conditions. Errors of up to 43% may occur when NO3-N concentrations in the drainage water are only measured at intervals of 30 d and when the precipitation excess is used to estimate cumulative NO3-N leaching. Measurements of NO3-N concentrations in ground water cannot be used to accurately estimate NO3-N leaching in drained soils.     

Nitrate removal in riparian wetlands: interactions between surface flow and soils

Riparian wetlands containing springs are thought to be ineffective at removing nitrate because contact times between the upwelled ground water and the underlying microbially active soils are short. Tracer experiments using lithium bromide (LiBr) and nitrate (NO3-N) injected at the surface were used to quantify residence times and NO3-N removal in a riparian swale characteristic of New Zealand hill-country pasture. An experimental enclosure was used with collecting trays at the downstream end to measure flow and concentration, shallow wells to measure subsurface concentrations, and an array of logging conductivity probes to monitor tracer continuously. The majority of added tracer reached the outlet more slowly than could be explained by surface flow, but more quickly than could be explained by Darcy seepage flow. There was evidence from the wells of tracer diffusing vertically to a depth of at least 5 cm into the surface soil layer, which was permanently saturated and highly porous. During dry weather 24 +/- 9% of added NO3-N was removed over a distance of 1.5 m largely by denitrification. The net uptake length coefficient for this wetland (K = 0.08 +/- 0.03 m(-1)) is slightly higher than the range (K = 0.01-0.07 m(-1)) measured in a small stream channel infested with macrophytes. Nitrate removal is expected to decrease with increasing flow. Seepage flow is estimated to have removed only 7 +/- 4% of the added NO3-N and we hypothesize that vertical diffusion substantially increases NO3-N removal in this type of wetland. Riparian wetlands with springs and surface flows should not be dismissed as having low NO3-N removal potential without checking whether there is significant vertical mixing.     

Upflow reactors for riparian zone denitrification

We used permeable reactive subsurface barriers consisting of a C source (wood particles), with very high hydraulic conductivities ( approximately 0.1-1 cm s(-1)), to provide high rates of riparian zone NO3-N removal at two field sites in an agricultural area of southwestern Ontario. At one site, a 0.73-m3 reactor containing fine wood particles was monitored for a 20-mo period and achieved a 33% reduction in mean influent NO3-N concentration of 11.5 mg L(-1) and a mean removal rate of 4.5 mg L(-1) d(-1) (0.7 g m(-2) d(-1)). At the second site, four smaller reactors (0.21 m3 each), two containing fine wood particles and two containing coarse wood particles, were monitored for a 4-mo period and were successful in attenuating mean influent NO3-N concentrations of 23.7 to 35.1 mg L(-1) by 41 to 63%. Mean reaction rates for the two coarse-particle reactors (3.2 and 7.8 mg L(-1) d(-1), or 1.5 and 3.4 g m(-2) d(-1)) were not significantly different (p > 0.2) than the rates observed in the two fine-particle reactors (5.0 and 9.9 mg L(-1) d(-1), or 1.8-3.5 g m(-2) d(-1)). A two-dimensional ground water flow model is used to illustrate how permeable reactive barriers such as these can be used to redirect ground water flow within riparian zones, potentially augmenting NO3- removal in this environment.     

Transport and fate of nitrate in headwater agricultural streams in Illinois

Nitrogen inputs to the Gulf of Mexico have increased during recent decades and agricultural regions in the upper Midwest, such as those in Illinois, are a major source of N to the Mississippi River. How strongly denitrification affects the transport of nitrate (NO(3)-N) in Illinois streams has not been directly assessed. We used the nutrient spiraling model to assess the role of in-stream denitrification in affecting the concentration and downstream transport of NO(3)-N in five headwater streams in agricultural areas of east-central Illinois. Denitrification in stream sediments was measured approximately monthly from April 2001 through January 2002. Denitrification rates tended to be high (up to 15 mg N m(-2) h(-1)), but the concentration of NO(3)-N in the streams was also high (>7 mg N L(-1)). Uptake velocities for NO(3)-N (uptake rate/concentration) were lower than reported for undisturbed streams, indicating that denitrification was not an efficient N sink relative to the concentration of NO(3)-N in the water column. Denitrification uptake lengths (the average distance NO(3)-N travels before being denitrified) were long and indicated that denitrification in the streambed did not affect the transport of NO(3)-N. Loss rates for NO(3)-N in the streams were <5% d(-1) except during periods of low discharge and low NO(3)-N concentration, which occurred only in late summer and early autumn. Annually, most NO(3)-N in these headwater sites appeared to be exported to downstream water bodies rather than denitrified, suggesting previous estimates of N losses through in-stream denitrification may have been overestimated.     

Recirculating sand filters for treatment of synthetic dairy parlor washings

Land-spreading and spray irrigation are the most widely used practices for the disposal of dairy wastewaters in Ireland but in some cases there can be problems due to contamination of surface and ground water. The use of intermittent sand filtration has been suggested as an alternative treatment process. However, a single pass through a sand filter limits denitrification because of the absence of reducing conditions following nitrification and the lack of an available carbon source. This leads to poor total nitrogen (TN) reduction and an effluent that is high in nitrate nitrogen (NO3-N). This paper follows a previous paper in which two instrumented stratified sand filter columns (0.9 and 0.425 m deep, and both 0.3 m in diameter) were intermittently loaded with synthetic dairy parlor washings at a number of hydraulic loading rates, leading to a TN reduction of 27 to 41%. In the present study, under a chemical oxygen demand (COD) of 23.4 g m(-2) d(-1), the TN was reduced by 83.2% when three-quarters of the sand filter effluent was recirculated through an anoxic zone. This produced an effluent NO3-N concentration of 60 mg L(-1). With recirculation, the improvement in the removal of organic matter and ammonia N (NH4-N) is minimal. Recirculating sand filters appear to offer a mechanically simple and effective method for the removal of nitrogen from dairy parlor effluents and are a significant improvement over a single-pass sand filter.     

Evaluation of simulated strategies for reducing nitrate-nitrogen losses through subsurface drainage systems

The nitrates (NO(3)-N) lost through subsurface drainage in the Midwest often exceed concentrations that cause deleterious effects on the receiving streams and lead to hypoxic conditions in the northern Gulf of Mexico. The use of drainage and water quality models along with observed data analysis may provide new insight into the water and nutrient balance in drained agricultural lands and enable evaluation of appropriate measures for reducing NO(3)-N losses. DRAINMOD-NII, a carbon (C) and nitrogen (N) simulation model, was field tested for the high organic matter Drummer soil in Indiana and used to predict the effects of fertilizer application rate and drainage water management (DWM) on NO-N losses through subsurface drainage. The model was calibrated and validated for continuous corn (Zea mays L.) (CC) and corn-soybean [Glycine max (L.) Merr.] (CS) rotation treatments separately using 7 yr of drain flow and NO(3)-N concentration data. Among the treatments, the Nash-Sutcliffe efficiency of the monthly NO(3)-N loss predictions ranged from 0.30 to 0.86, and the percent error varied from -19 to 9%. The medians of the observed and predicted monthly NO(3)-N losses were not significantly different. When the fertilizer application rate was reduced ~20%, the predicted NO(3)-N losses in drain flow from the CC treatments was reduced 17% (95% confidence interval [CI], 11-25), while losses from the CS treatment were reduced by 10% (95% CI, 1-15). With DWM, the predicted average annual drain flow was reduced by about 56% (95% CI, 49-67), while the average annual NO(3)-N losses through drain flow were reduced by about 46% (95% CI, 32-57) for both tested crop rotations. However, the simulated NO(3)-N losses in surface runoff increased by about 3 to 4 kg ha(-1) with DWM. For the simulated conditions at the study site, implementing DWM along with reduced fertilizer application rates would be the best strategy to achieve the highest NO(3)-N loss reductions to surface water. The suggested best strategies would reduce the NO(3)-N losses to surface water by 38% (95% CI, 29-46) for the CC treatments and by 32% (95% CI, 23-40) for the CS treatments.     

Removal of bis (2-ethylhexyl) phthalate from reject water in a nitrogen-removing sequencing batch reactor

Reject water from sewage sludge processing may contain high concentrations of nutrients and organic pollutants and cause internal pollution load at a sewage treatment plant (STP) if circulated to the headworks of an STP. In the present study removal of nitrogen and bis (2-ethylhexyl) phthalate (DEHP) from reject water was studied in two sequencing batch reactors (SBRs) with different aerobic/anoxic periods during a 6-h total cycle period. Ammonia-nitrogen (NH(4)-N) was almost totally removed in both reactors, apparently by nitrification throughout the run, while denitrification declined with decreasing SCOD in the influent resulting in an increase in the effluent nitrate-nitrogen (NO(3)-N) concentration. DEHP removals from the water phases were above 95% in both reactors, while the average total removals were 36 and 42%, calculated on a mass basis. Much higher removals occurred in the experiment where one of the systems was spiked with a given amount of DEHP. The spiking experiment suggested that SBRs had the potential to remove DEHP biologically from reject water but that the removal was restricted by the poor bioavailability of DEHP as a result of sorption to solids. This study showed that SBR has the potential to cut the internal load of nitrogen and hydrophobic organic pollutants in cases where reject water is circulated to the headworks of an STP.