NUTRIENT CONCENTRATIONS IN WASTEWATER TREATMENT PLANT EFFLUENTS,SOUTH PLATTE RWER BASIN1

ABSTRACT: Accurate data about nutrient concentrations in wastewater treatment plant effluents are needed for river basin water-quality studies. As part of the U.S. Geological Survey's National Water-Quality Assessment Program in the South Platte River Basin, nutrient data were requested from 31 wastewater-treatment plants located in the basin. This article describes the types of nutrient data available from the plants, examines the variability of effluent nutrient concentrations, and discusses methods for estimation of nutrient concentrations where data are lacking. Ammonia was monitored at 88 percent of the plants, nitrite plus nitrate was monitored at 40 percent of the plants, and organic nitrogen and phosphorus were monitored at less than 25 percent of the plants. Median total nitrogen concentrations and median total phosphorus concentrations were small compared to typical literature estimates for wastewater-treatment plants with secondary treatment. Nutrient concentrations in effluent from wastewater-treatment plants varied widely between and within plants. For example, ammonia concentrations varied as much as 5 mg/L during a day, as much as 10 mg/L from day to day, and as much as 30 mg/L from summer to winter within a plant. In the South Platte River Basin, estimates of median annual ammonia and nitrite plus nitrate concentrations can be improved based on plant processes; and nitrite plus nitrate and organic nitrogen concentrations can be estimated based on ammonia concentrations. However, to avoid large estimation errors, more complete nutrient data from wastewater-treatment plants are needed for integration into river basin water quality studies. The paucity of data hinders attempts to evaluate the relative importance of point source and nonpoint source nutrient loadings to rivers.     

NUTRIENT CONCENTRATION CRITERIA AND CHARACTERIZATION OF PATTERNS IN TROPHIC STATE FOR RIVERS IN HETEROGENEOUS LANDSCAPES1

ABSTRACT: A method is demonstrated for the development of nutrient concentration criteria and large scale assessment of trophic state in environmentally heterogeneous landscapes. The method uses the River Environment Classification (REC) as a spatial framework to partition rivers according to differences in processes that control the accrual and loss of algae biomass. The method is then applied to gravel bed rivers with natural flow regimes that drain hilly watersheds in New Zealand's South Island. An existing model is used to characterize trophic state (in terms of chlorophyll a as a measure of maximum biomass) using nutrient concentration, which controls the rate of biomass accrual, and flood frequency, which controls biomass loss. Variation in flood frequency was partitioned into three classes, and flow data measured at 68 sites was used to show that the classes differ with respect to flood frequency. Variation in nutrient concentration was partitioned at smaller spatial scales by subdivision of higher level classes into seven classes. The median of flood frequency in each of the three higher level classes was used as a control variable in the model to provide spatially explicit nutrient concentration criteria by setting maximum chlorophyll a to reflect a desired trophic state. The median of mean monthly soluble reactive phosphorus and soluble inorganic nitrogen measured at 68 water quality monitoring sites were then used to characterize the trophic state of each of the seven lower level classes. The method models biomass and therefore allows variation in this response variable to provide options for trophic state and the associated nutrient concentrations to achieve these. Thus it is less deterministic than using reference site water quality. The choice from among these options is a sociopolitical decision, which reflects the management objectives rather than purely technical considerations.     

Sustainability of Current Agricultural Practices in The Cameron Highlands, Malaysia

Cameron Highlands is a mountainous region with steep slopes. Gradients exceeding 20^∘ are common. The climate is favourable to the cultivation of tea, sub-tropical vegetables and flowers (under rain-shelter). Crop production is sustained by high fertiliser and manure applications. However, agriculture in this environment is characterised by high levels of soil erosion and environmental pollution. A study on the sustainability of these agro-ecosystems was conducted. Results indicated that soil loss was in the range of 24–42 ton/ha/yr under vegetables and 1.3 ton under rain-shelter. Sediment load in the vegetable sub-catchment reached 3.5 g/L, 50 times higher than that associated with flowers under rain-shelter and tea. The sediments contained high nutrient loads of up to 470 kg N/ha/yr. The N, P and K lost in runoff from cabbage farms was 154 kg/season/ha, whereas in chrysanthemum farms it was 5 kg. In cabbage farms, the N, P, and K lost through leaching was 193 kg/season/ha. The NO₃–N concentration in the runoff from the cabbage farms reached 25 ppm but less than 10 ppm in runoff from rain-shelters. Inorganic pollution in the rivers was within the acceptable limit of 10 ppm. The sustainability of the agro-ecosystems is in the order of tea { > } rain–shelter ≫ vegetables.     

蠡河底泥中反硝化复合菌群富集及菌群结构研究

从无锡市滨湖区蠡河底泥中富集培养反硝化复合菌群,研究其在不同富集培养阶段TN、NO-3-N、NO-2-N、NH+4-N和COD动态变化,分析反硝化过程中气体释放总量、释放速率和成分,通过构建全长16S r DNA克隆文库研究其菌落结构.结果表明,反硝化复合菌群富集在阶段4时脱氮效果最佳,仅在9 h内,330 mg·L-1的TN负荷下,TN去除率达90.9%,NO-3-N去除率达100%,中间产物NO-2-N和NH+4-N积累量最少,分别为3.39 mg·L-1和16.64 mg·L-1,COD去除率达85%;释放气体260m L,气体主要成分为N2,同时还有少量的CH4和CO2等.富集培养反硝化复合菌群细菌属于Pseudomonadaceae科和Rhodocyclaceae科,为Proteobacteria门,OUT丰度分别为57.8%和31.6%,Pseudomonadaceae科是优势类群.     

活性污泥中硝化螺菌(Nitrospira)的富集及其动力学参数

采用连续进水的进水方式对污水处理厂活性污泥系统中的Nitrospira富集培养并对其相关动力学参数进行研究.结果表明,在控制反应器亚硝酸盐浓度不高于2 mg·L~(-1)的条件下可以成功富集出以Nitrospira为优势种属的活性污泥,其最大比亚硝酸盐氧化速率(以N/VSS计)为48.72 mg·(g·h)~(-1).荧光原位杂交结果显示Nitrospira占活性污泥总微生物量的75%左右,而Nitrobacter仅占总微生物的0.1%.此外通过对Nitrospira在20℃时的动力学参数进行测定,结果表明Nitrospira的最适生长温度为30~35℃,温度修正系数τN为1.046,其基质半饱和常数KS和氧半饱和常数KO分别为(0.32±0.03)mg·L~(-1)和(1.52±0.09)mg·L~(-1).Nitrospira动力学参数的研究为污水处理厂的设计运行及工艺优化提供理论参考.     

西大海湖沉积物营养盐垂直分布特征变化分析

通过对西大海湖心柱状沉积岩芯有机质(OM)、总氮(TN)、总磷(TP)、磷形态和粒度指标的测试和分析,探讨其垂向分布特征及影响因素.结果表明,营养盐中OM、TN和TP的含量分别为0.633%~2.756%、0.150%~0.429%和648.00~1 480.67 mg·kg-1.Ca-P是TP的主要部分,占TP含量66.04%.1843~1970年间,Ca-P、IP、OM含量变化较小,Fe/Al-P、OP、TP、TN含量波动较大;1970~1996年间,Ca-P、IP、TP含量变化均呈减小趋势,Fe/Al-P、OP、OM含量不同程度上先减少后增加,TN波动较大;1996~2009年营养元素含量相对波动较大,Fe/Al-P、OP和OM的平均含量是3个阶段中最高的.西大海湖沉积岩芯营养元素污染来源以工业废水、生活污水和化肥农药的流失为主.沉积物中C/N比值显示有机质主要来源于水生生物.沉积物粒度组成以黏土和细粉砂为主.相关性研究表明,Ca-P、IP与TP均呈显著的正相关关系,表明Ca-P对IP、TP的增长贡献大.     

香溪河沉积物-水界面的营养盐交换特征

为研究香溪河库湾沉积物-水界面的营养盐交换特征,于2016年6月采集香溪河库湾上覆水和沉积物间隙水样品,分析不同形态氮、磷的空间分布特征并进行相关性分析,计算沉积物-水界面氮、磷的释放通量.结果表明:香溪河库湾上覆水和沉积物间隙水中ρ（TP）的变化范围分别为0.484~0.927和0.511~2.220 mg/L,ρ（TN）的变化范围分别为0.739~4.302和3.571~14.011 mg/L;上覆水和沉积物间隙水中氮、磷质量浓度在沿程和垂向上具有一定的变化规律,上游区域沉积物间隙水中氮、磷质量浓度大于下游区域,沉积物间隙水中氮、磷质量浓度明显大于上覆水;香溪河沉积物总体上表现为PO₄3--P和NH₄+-N的"源",中下游区域沉积物表现为NO₃--N的"源",而中上游区域表现为NO₃--N的"汇";PO₄3--P的释放通量范围为0.129~0.339 mg/（m2·d）,NH₄+-N的释放通量范围为0.213~1.415 mg/（m2·d）,NO₃--N的释放通量范围为-1.109~3.446 mg/（m2·d）.研究显示,上覆水的环境条件对于沉积物-水界面营养盐交换存在一定的影响,但影响程度各有不同.      

75t/h燃煤锅炉汞迁移转化规律研究

通过对2台75 t/h循环流化床锅炉烟气中汞排放浓度、燃煤和其他固体副产物中的汞含量进行测试,分析了燃煤大气汞的排放因子,并建立了燃煤汞的质量平衡。结果表明:燃煤锅炉中,大部分汞主要存在于烟气和脱硫副产物中,燃烧后进入炉渣、飞灰中的汞含量较少,低于5%。燃煤汞排放去向与脱硫除尘控制技术有关,不同控制技术协同除汞的效果差异较大,而单质汞是燃煤锅炉汞污染防治的重点和难点。     

杭州湾表层海水营养盐分布特征及富营养化状况研究

根据2015年3月和8月杭州湾的海水质量监测数据,分析了该海域的营养盐分布特征以及富营养化状况,结果表明:杭州湾表层海水无机氮变化范围为0.36~4.22 mg/L,活性磷酸盐的含量范围为0.014~1.51 mg/L,化学需氧量含量范围为0.56~3.18 mg/L.该海域无机氮和活性磷酸盐超标严重,表层海水已处于重度富营养化状态,调查站位EI均大于1.该海域表层海水无机氮、活性磷酸盐、化学需氧量和富营养化指数高值区均与陆源入海口、养殖区、排污口等人类活动影响较大的区域有关.     

长春市春季PM2.5中金属污染与潜在生态风险评价研究

2014年春季采集了长春市大气PM2.5样品,测定了PM2.5及其17种金属元素的含量.PM2.5质量浓度为175.2±75.1μg/m3,变异系数为0.44,环境重污染日与优良日空气质量差异较大.PM2.5中金属元素平均含量顺序为Ca>Fe>K>Mg>Al>Zn>Ti>Mn>Pb>As>Cu>V>Ni>Cr>Co>Ba>Cd.采用富集因子法和潜在生态风险指数法对PM2.5中金属进行了评价.其中Cd、As、Zn、Pb、Cu富集因子大于100.金属综合潜在生态风险等级为极强生态风险,Cd的贡献率为83.2%,受人类活动干扰严重.