INDUCED OXIDATION OF STREAMS AND WATER QUALITY CONTROL INSTITUTIONS1

The proof is rapidly mounting that instream aeration is a technically and economically feasible supplement to secondary treatment of wastes, an alternative to tertiary waste treatment. Some phenomena remain unexplained; and competing technologies, especially those employing molecular oxygen, are being explored vigorously. However, there are convincing arguments in favor of aeration on theoretical grounds, proved technology is available; and the first installations have already been made. While remaining questions are being further investigated, it is time to consider in more detail the broader aspects, as to the institutional, legal, and political hurdles to be overcome before advantage can be taken of the new technology. This paper first summarizes the state-of-the-art as far as technology is concerned; and then outlines the institutional problem.     

Uncertainty Analysis In Dissolved Oxygen Modeling in Streams

Uncertainty analysis in surface water quality modeling is an important issue. This paper presents a method based on the first-order reliability method (FORM) to assess the exceedance probability of a target dissolved oxygen concentration in a stream, using a Streeter–Phelps prototype model. Basic uncertainty in the input parameters is considered by representing them as random variables with prescribed probability distributions. Results obtained from FORM analysis compared well with those of the Monte Carlo simulation method. The analysis also presents the stochastic sensitivity of the probabilistic outcome in the form of uncertainty importance factors, and shows how they change with changing simulation time. Furthermore, a parametric sensitivity analysis was conducted to show the effect of selection of different probability distribution functions for the three most important parameters on the design point, exceedance probability, and importance factors. Note: This version was published online in June 2005 with the cover date of August 2004.     

MODELING TO EVALUATE MACROPHYTE INDUCED IMPACTS TO DISSOLVED OXYGEN IN A TAILWATER RESERVOIR1

ABSTRACT: Effects of aquatic macrophytes are not considered in most standard water quality models. This study used field measurements and water quality models to help determine the effects of aquatic macrophytes on dissolved oxygen (DO) concentrations in a shallow tailwater reservoir. Installation of a hydropower plant and macrophytes (primarily Potamogeton and Chara) in a large shallow portion of the lake are possible causes of reduced DO levels in the tailwater reservoir. A water quality model (WASP5) was used to quantify the various DO sources and sinks and to evaluate the effects of the hydropower operations on DO levels in the lake. It was found that the macrophytes in Lake Ogallala had a significant effect on the DO levels in the lake. At an average macrophyte density of about 6,360 g/m² (wet weight) in 2000, the DO fluctuated daily from about 3 mg/l to about 12 mg/l. At an average macrophyte density of about 2,120 g/m² (wet weight) in 2002, the DO fluctuated from about 5 mg/l to about 9 mg/l daily. The model predicted that the DO would remain near 5 mg/l without macrophytes. The photo‐synthetic and respiration rates developed in the model (4.4 mg/g‐hr and 1.4 mg/g‐hr, respectively) agree well with literature values.     

密封法测定焦化厂废水的COD

介绍了用密封法测定焦化厂废水COD的方法，并与回流法进行了比较。试验结果表明，密封法与回流法有着很好的相关性，准确度高，用密封法测定焦化废水的COD，不仅工艺简单，费用低，而且可进行批量分析，提高工效5倍以上。     

MSBR法污水处理在线模糊控制的研究

MSBR法就其运行功能和效果而言,被认为是一种理想的污水处理工艺流程.由于运行过程变量多,它属于复杂的动态系统.目前采用的PID控制模式无法找到精确的模型来描述,故将模糊控制用于MSBR工艺系统控制中,对于处理效果有关的变量进行模糊控制,用模糊控制算法对处理效果的测试进行研究,并将该模糊控制算法在MATLAB上进行了仿真,结果表明系统具有较强的鲁棒性和自适应性及优良的控制性能.     

High Sediment Oxygen Demand Within an Instream Swamp in Southern Georgia: Implications for Low Dissolved Oxygen Levels in Coastal Blackwater Streams1

Todd, M. Jason, George Vellidis, R. Richard Lowrance, and Catherine M. Pringle, 2009. High Sediment Oxygen Demand Within an Instream Swamp in Southern Georgia: Implications for Low Dissolved Oxygen Levels in Coastal Blackwater Streams. Journal of the American Water Resources Association (JAWRA) 45(6):1493‐1507. Abstract: Sediment oxygen demand (SOD) is considered a critical and dominant sink for dissolved oxygen (DO) in many river systems including blackwater streams and is often poorly investigated or roughly estimated in oxygen budgets. The purposes of this study are to (1) characterize and document the magnitude and variability of SOD in representative instream swamps found on the Georgia Coastal Plain; (2) predict SOD from more readily measured parameters such as soil, sediment, and litter organic carbon; and (3) obtain an accurate representation of SOD values within this understudied habitat to help improve water quality models and the continued development of DO as an appropriate water quality standard. Results show SOD rates ranging from 0.491 to 14.189 g O₂/m²/day, up to 18 times higher than values reported for southeastern sandy‐bottomed streams and suggest that instream swamps are repositories of large amounts of organic matter and are thus areas of intense oxygen demand and a major factor in determining the oxygen balance of the watershed as a whole. These areas of intense oxygen demand in relatively unimpacted areas indicate that low DO concentrations may be a natural phenomenon. SOD rates were significantly correlated (alpha = 0.05) with a number of sediment parameters, with organic carbon and total organic carbon being the best predictors of SOD rate. When developing water quality models, managers should pay closer attention to the influence of SOD as it plays a critical role in determining DO levels within instream swamps and the river system.     

富营养化湖泊藻华腐解产生的溶解性有机质动态变化及其环境效应

富营养化和有害藻华是湖泊面临的主要环境问题,富营养化湖泊藻华在后期会发生衰亡和腐解并产生大量藻源溶解性有机质（DOM）,影响水体DOM的质量和活性,并对关键元素的生物地球化学循环产生重要调控作用.为探究不同富营养化程度湖泊水体藻华腐解过程,对藻华腐解过程中水体DOM总量、生物有效性、相对分子质量和组分的动态变化进行分析,并探讨了藻华腐解引发的环境效应.结果表明,藻华腐解显著提高DOM浓度、生物有效性和各荧光组分强度.随着腐解的进行,DOM浓度逐渐降低,而相对分子质量逐渐增大.在分子水平上,超高分辨率质谱结果显示腐解过程中不饱和烃和脂肪族化合物优先被微生物利用,并生成木质素、缩合烃和高O/C值的单宁酸等惰性分子.藻华腐解过程中细菌群落主要优势种从变形菌门（46%）逐渐变为拟杆菌门（42%）.此外,藻华腐解还导致水体CO₂和CH₄排放显著升高1.2~5倍,且排放量可以由DOM光学指标a₂₅₄预测.该结果为全面揭示藻华腐解过程中DOM特征的动态变化,以及湖泊富营养化治理和环境效应预测提供理论依据和科学支撑.     

溶解有机质对生物富集因子计算的影响:以东江鱼体中多溴联苯醚的生物富集为例

准确获取化合物的生物富集因子(BAF)对于判定化合物是否属于潜在毒害性污染物、评价其生态环境风险都具有重要的意义。为探究水体中溶解有机质(DOM)对BAF值的影响,以东江三角洲流域为研究区域,以多溴联苯醚(PBDEs)为目标化合物,研究了PBDEs各单体在3种鱼体中的富集特征。结果表明,PBDEs在3种鱼体中的浓度范围为42~825 ng·g-1脂肪,log BAF值位于5.0~7.4之间。由于脱溴代谢的种间差异,3种鱼类表现出2种PBDE的组成模式。在缺乏脱溴代谢途径的鱼体内,log BAF与化合物辛醇/水分配系数(log KOW)之间存在统计意义上的抛物线关系。但当BAF进行DOM的校正之后,二者之间抛物线形式的相关性消失,而呈现出显著的正线性相关性。以往研究对BAF值在化合物的log KOW达到一定程度后(7~8附近)出现下降的解释是高KOW化合物较大的分子体积降低了其穿过生物膜的可能性,但我们的研究结果表明,这种下降很可能是由于忽视了水体中DOM影响的结果。     

Forecasting of dissolved oxygen in the Guanting reservoir using an optimized NGBM (1,1) model

An optimized nonlinear grey Bernoulli model was proposed by using a particle swarm optimization algorithm to solve the parameter optimization problem. In addition, each item in the first-order accumulated generating sequence was set in turn as an initial condition to determine which alternative would yield the highest forecasting accuracy. To test the forecasting performance, the optimized models with different initial conditions were then used to simulate dissolved oxygen concentrations in the Guanting reservoir inlet and outlet (China). The empirical results show that the optimized model can remarkably improve forecasting accuracy, and the particle swarm optimization technique is a good tool to solve parameter optimization problems. What's more, the optimized model with an initial condition that performs well in in-sample simulation may not do as well as in out-of-sample forecasting.     

KMnO4-PAC对高原喀斯特湖库DOM的DBPsFP控制

以云贵高原典型喀斯特湖库红枫湖取水口溶解性有机质（DOM）为研究对象,调查不同组合方式下高锰酸钾-聚合氯化铝（KMnO₄-PAC）对消毒副产物的生成潜能（DBPsFP）变化和平均组成分布,并通过红外光谱（FTIR）和三维荧光光谱（3D-EEM）对部分样品进行化学表征,推断其影响机制.结果表明：在0.1,0.2,0.4mg/L KMnO₄投加量下,DBPsFP降低17.5~73%,DOM的卤代活性化学结构和官能团部分被有效钝化;PAC的网捕和卷扫效应使DBPsFP进一步减少27.9~86.1%,组合工艺对DBPs的生成潜能影响大小为：三卤甲烷（THM₄） > 卤乙酸（HAA₉） > 卤乙腈（HAN₄）/卤代酮（HK₂）/三氯硝基甲烷（TCNM）.FTIR的结果表明预氧化后3300cm^-1处的透过率降低,指纹区1000~1300cm^-1处的峰频提升,表明分子中的O-H、COOH和C-O官能团增加,共轭不饱和结构在KMnO₄作用下部分消失.3D-EEM验证了外源有机物（腐殖酸）在DOM中占比随KMnO₄浓度梯度升高而下降,同时类蛋白结构的吸收峰强度增加,说明最终DBPs贡献可能源于DOM中剩余的小分子类蛋白（氨基酸）.