垃圾渗滤液与城市污水同时处理系统优化运行策略探讨

采用倒置A2/O工艺处理垃圾渗滤液与城市污水的混合污水.模型试验结果表明,水力停留时间是影响混合污水氮和有机物去除的控制因素;水温为23～30℃、泥龄为20 d时,最优运行参数为:水力停留时间9h、DO2 mg/L、外回流比80％、内回流比200％,此时COD、NH3-N和TN去除率分别为76.4％～78.2％、95....     

Reopening abandoned forest roads in northern Idaho,USA: Quantification of runoff,sediment concentration,infiltration, and interrill erosion parameters

This study measured runoff and sediment concentration from the tire track and from the non-tire track to determine infiltration, interrill erodibility, and vegetative cover impacts of reopening an abandoned forest road. Runoff was lowest on the non-track portion of the abandoned road and highest on the reopened road. Sediment concentrations were significantly higher on the reopened road. Increased sediment concentrations were attributed to decreased vegetative cover, rather than traffic-induced changes in the physical soil properties of the reopened road. Thirty years of no traffic and vegetation regrowth was not sufficient to allow recovery of infiltration to values similar to an undisturbed forest. The study also found a significant dynamic behavior in interrill erodibility with respect to antecedent rainfall. Forest road erosion models that fail to account for this change will overestimate sediment yields.     

地面注浆控制井壁破裂变形的理论与实践

阐述地面注浆控制井壁破裂变形的机理,并就具体工程进行分析。根据对井壁混凝土应变、地表变形、注浆帷幕测试结果,注浆前、第一阶段注浆、第二阶段注浆、注浆后的4个阶段内,井壁竖向附加应变分别经历了增加100με、缓释200με、再缓释200με、最终缓释200με的变化过程。与此同时,工业广场地表经历了抬升(对应与第一阶段注浆)、稳定(对应于间歇期)、再抬升(对应于第二阶段注浆)和稍降(对应于注浆后)的过程,地面最终抬升约稳定在70~80mm之间。利用高频应力波检测注浆体,笔者认为注浆帷幕交圈闭合较好,平均厚度近7.6m。研究表明,地面注浆加固能有效地改善井壁的受力状态,对井壁既有应变有显著缓释作用,对矿井疏排水造成的井壁附加应变的增长有明显抑制作用,从而起到维护井筒安全的作用。     

侧沟式膜泥法一体化OCO工艺中水力停留时间对脱氮除碳的影响

在传统OCO工艺基础上设计了一体化OCO工艺,在厌氧区放置填料,将二沉池和生物反应器合建,并就水力停留时间(HRT)对生物反应器脱氮除碳的影响进行研究。在进水COD为260～360 mg/L,好氧区DO为2 mg/L左右,缺氧区<0.5 mg/L,MLSS为4 500 mg/L左右时,分别研究了不同HRT下的脱氮除碳效果。研究结果表明：随着HRT的逐渐增大,出水COD值无明显波动,COD去除率达到90%以上,出水氨氮随着HRT的增大而降低;但仅当HRT为12 h左右时,氨氮和总氮均有良好的去除效果,去除率分别可达到93%和80%。     

Factors affecting nitrate distribution in shallow groundwater under a beef farm in South Eastern Ireland

Groundwater contamination was characterised using a methodology which combines shallow groundwater geochemistry data from 17 piezometers over a 2 yr period in a statistical framework and hydrogeological techniques. Nitrate–N (NO₃-N) contaminant mass flux was calculated across three control planes (rows of piezometers) in six isolated plots. Results showed natural attenuation occurs on site although the method does not directly differentiate between dilution and denitrification. It was further investigated whether NO₃-N concentration in shallow groundwater (<5 m below ground level) generated from an agricultural point source on a 4.2 ha site on a beef farm in SE Ireland could be predicted from saturated hydraulic conductivity (K_sat) measurements, ground elevation (m Above Ordnance Datum), elevation of groundwater sampling (screen opening interval) (m AOD) and distance from a dirty water point pollution source. Tobit regression, using a background concentration threshold of 2.6 mg NO₃-N L⁻¹ showed, when assessed individually in a step wise procedure, K_sat was significantly related to groundwater NO₃-N concentration. Distance of the point dirty water pollution source becomes significant when included with K_sat in the model. The model relationships show areas with higher K_sat values have less time for denitrification to occur, whereas lower K_sat values allow denitrification to occur. Areas with higher permeability transport greater NO₃-N fluxes to ground and surface waters. When the distribution of Cl⁻ was examined by the model, K_sat and ground elevation had the most explanatory power but K_sat was not significant pointing to dilution having an effect. Areas with low NO₃ concentration and unaffected Cl⁻ concentration points to denitrification, low NO₃ concentration and low Cl⁻ chloride concentration points to dilution and combining these findings allows areas of denitrification and dilution to be inferred. The effect of denitrification is further supported as mean groundwater NO₃-N was significantly (P < 0.05) related to groundwater N₂/Ar ratio, redox potential (Eh), dissolved O₂ and N₂ and was close to being significant with N₂O (P = 0.08). Calculating contaminant mass flux across more than one control plane is a useful tool to monitor natural attenuation. This tool allows the identification of hot spot areas where intervention other than natural attenuation may be needed to protect receptors.     

Optimizing Bankfull Discharge and Hydraulic Geometry Relations for Streams in New York State1

Mulvihill, Christiane I. and Barry P. Baldigo, 2012. Optimizing Bankfull Discharge and Hydraulic Geometry Relations for Streams in New York State. Journal of the American Water Resources Association (JAWRA) 48(3): 449-463. DOI: 10.1111/j.1752-1688.2011.00623.x Abstract: This study analyzes how various data stratification schemes can be used to optimize the accuracy and utility of regional hydraulic geometry (HG) models of bankfull discharge, width, depth, and cross-sectional area for streams in New York. Topographic surveys and discharge records from 281 cross sections at 82 gaging stations with drainage areas of 0.52-396 square miles were used to create log-log regressions of region-based relations between bankfull HG metrics and drainage area. The success with which regional models distinguished unique bankfull discharge and HG patterns was assessed by comparing each regional model to those for all other regions and a pooled statewide model. Gages were also stratified (grouped) by mean annual runoff (MAR), Rosgen stream type, and water-surface slope to test if these models were better predictors of HG to drainage area relations. Bankfull discharge models for Regions 4 and 7 were outside the 95% confidence interval bands of the statewide model, and bankfull width, depth, and cross-sectional area models for Region 3 differed significantly (p < 0.05) from those of other regions. This study found that statewide relations between drainage area and HG were strongest when data were stratified by hydrologic region, but that co-variable models could yield more accurate HG estimates in some local regional curve applications.     

不同水力负荷下塘-湿地组合处理系统对再生水磷的净化效果

通过研究天津市空港经济区塘湿地组合处理系统对区内污水处理厂MBR出水（再生水）的净化过程,探讨再生水总磷（TP）及活性磷（SRP）的净化效果。研究表明：MBR出水SRP含量较高,SRP/TP高达84%。在3个水力负荷100、150及200 m³/d下,系统对磷均保持良好的处理效果,TP浓度由1.64 mg/L降至0.36 mg/L,SRP浓度由1.30 mg/L降至0.28 mg/L。同时,系统SRP/TP由进水的84%降至出水的54.5%,SRP去除效果显著。再生水中SRP含量较高的问题通过塘湿地组合处理系统得到了良好的解决,从而有效降低再生水回用景观水体所带来的藻华风险。     

加药量和水力搅拌速度对雨水混凝效果的影响

为降低分流制雨水中悬浮颗粒物及其他污染物浓度,减轻城市景观河道的水体富营养化程度,对取自泵站的雨水进行混凝沉淀工艺优化实验。以PAC为混凝剂,采用Zeta电位仪、激光粒度仪和iPDA在线监测技术对混凝过程进行监测,考察了混凝剂投加量和水力搅拌速度对絮体形成和分流制雨水处理效果的影响,结果表明,混凝剂投加量和混合水力搅拌速度直接影响絮体Zeta电位和聚沉特性;混合搅拌速度控制混凝反应速率,絮凝速度梯度影响絮体形成粒径。FI曲线特征参数对控制混凝工艺具有指导意义。PAC投加量为35 mg/L,混合阶段搅拌速度800 r/min,搅拌30 s,絮凝阶段采用150、108和60 r/min的转速各自搅拌5 min,沉后水中剩余颗粒总数最少,浊度、COD和总磷去除效果最佳。     

页岩气压裂返排液处理技术的研究进展

页岩气是一种重要的天然气资源,在其水力压裂开采过程中加入了多种有机添加剂,产生了大量具有高黏度、高COD、高含盐量特性的压裂返排液,常规处理技术难以实现其达标排放或回用。分析了页岩气压裂返排液的组分和特点,归纳总结了成熟的传统处理技术和新型处理技术的特点,提出了优化压裂返排液处理工艺、加强环境信息公开、研发节能环保的新型页岩气压裂技术的未来发展方向,为页岩气压裂返排液无害化、资源化处理技术的研发提供了思路和参考。     

水力停留时间对MBR中溶解性微生物产物生成的影响

考察水力停留时间(HRT)对MBR中膜污染的主要污染物——溶解性微生物产物(SMP)生成的影响。结果表明,在装置稳定运行期间,MBR中SMP随运行时间出现累积。与HRT为8 h相比,HRT为12 h时,SMP在MBR中平均累积量要少10.1%,SMP中多糖含量平均高7 mg/L左右,而蛋白质含量平均低45.6%。SMP的平均粒径随装置运行呈下降趋势,并且HRT较短有利于粒径较小的SMP生成,从而堵塞膜孔;HRT较长有利于粒径较大的SMP生成,从而形成凝胶层,两种情况导致膜污染的机制不同。