异养与硫自养反硝化协同处理高硝氮废水特性研究

在异养反硝化反应器中添加单质硫,实现硫自养与异养反硝化联合处理NO_3~-废水,探讨异养和硫自养反硝化协同过程中的p H恒定及污泥减量化的特性.结果表明,硫自养反硝化菌在异养反硝化反应器内能够实现快速生长.经过65d的运行,控制进水TOC/N为0.65~0.75时,协同反硝化在无额外碱添加的情况下,厌氧反硝化产生的碱度满足自养反硝化的需求;运行至116d时,协同反硝化的总氮去除率为85%以上,脱氮效能稳定在2.5 kg·(m~3·d)~(-1).通过与完全异养反硝化相比,协同反硝化的污泥产量仅为完全异养反硝化的60%,极大地降低了污泥产量.但是利用协同自养反硝化处理高浓度NO_3~--N废水时,存在NO_2~--N累积的现象,即使是最终稳定期也有20 mg·L~(-1),需进行深度处理.     

海水异养硝化-好氧反硝化芽孢杆菌SLWX2的筛选及脱氮特性

从分离自刺参养殖环境的7株候选菌株中筛选出1株具有较强异养硝化和好氧反硝化能力的菌株SLWX_2,通过形态学特征、生理生化特性和16S rRNA基因测序分析鉴定其为花津滩芽孢杆菌(Bacillus hwajinpoensis).该菌株脱氮特性研究结果表明,SLWX_224 h对氨氮、亚硝酸氮和硝酸氮的去除率分别达到100%、99.5%和85.6%;当3种无机氮源同时存在时,菌株优先利用氨氮,再利用NO_2~--N和NO_3~--N,72 h 3种无机氮的质量浓度均降至0.013 mg·L~(-1)以下,表明该菌株能同时进行异养硝化和好氧反硝化完成脱氮;在氨氮负荷500 mg·L~(-1)、亚硝酸氮负荷100 mg·L·~(-1)和硝酸氮负荷200 mg·L~(-1)范围内,该菌的脱氮能力不受明显抑制,对3种形态的氮均有良好去除效果,96 h最多可去除180 mg NH_4~+-N、30 mg NO_2~--N和120 mg NO_3~--N,并且在硝化过程中没有亚硝酸氮积累.该菌株在海水养殖和高盐高氮工业废水的脱氮处理方面具有更大潜力.     

耦合厌氧氨氧化反应的高氮负荷型双室MFC性能研究

实验针对厌氧氨氧化反应在双室型MFC阳极和阴极2种形式的耦合,将厌氧氨氧化菌分别接种于a、b-双室型MFC的阳、阴极,并探究其产电、脱氮性能及脱氮机理.结果表明,2种类型的MFC均可在NH+4-N、NO-2-N浓度分别为400 mg·L-1和528 mg·L-1的高氮浓度模拟配水条件下稳定启动.与开路状态下的线性关系曲线不同,2类MFC在闭路状态下氨氮、亚硝态氮浓度均呈单指数关系衰减曲线,脱氮效率显著提高,周期内氨氮、亚硝态氮去除率均分别达到99%和85%以上.另外a、b-MFC平均容积氮去除负荷分别为0.417 kg·m-3·d-1和0.516 kg·m-3·d-1.在外阻1500Ω条件下,a-MFC最高输出电压48.0 m V,b-MFC最高输出电压可达到502.2 m V,b-MFC稳定输电周期约2170 min.     

黄土高原磷湿沉降特征及其对坝系流域磷输出影响-以羊圈沟为例

对黄土高原坝系流域磷(P)的湿沉降过程进行动态监测,分析了降雨-径流过程中各形态磷的输出变化,探讨了黄土高原坝系流域磷湿输出分异特征及其对水体的影响.结果表明:2015年湿季(7、8月)共11场降雨,产生的磷湿沉降负荷为30.8 kg,磷湿沉降通量为0.16kg·hm~(-2),干季(9月)共3场降雨,产生的磷湿沉降负荷为20.51 kg,磷湿沉降通量为0.11 kg·hm~(-2),干湿季磷湿沉降负荷呈现出明显差异性;选取3场降雨过程(降雨量从小到大)进行动态分析发现,流域磷湿沉降负荷分别为3.33、7.51和6.35 kg,相应的本地区磷湿沉降通量依次为0.02、0.04、0.03 kg·hm~(-2),3场降雨总磷(TP)的输出负荷为1.5×10-3kg,溶解性总磷(DTP)的输出负荷为1.24×10~(-3)kg,PO_4~(3-)-P的输出负荷为7×10-4kg,表明该地区磷湿沉降以可溶性磷为主.根据单因子评价方法中的标准指数法,发现流域水质不能满足Ⅴ类水质标准,应对流域水体加强管理.     

温度对好氧颗粒污泥处理纤维素乙醇废水脱氮效能的影响

采用SBR反应器,考察了温度对好氧颗粒污泥处理纤维素乙醇废水脱氮性能的影响.研究结果表明,当进水为纤维素乙醇废水原水时,稳定阶段不同温度(10、20、30℃)条件下体系对COD的去除率分别为10.2%、12.7%、13.7%;总无机氮的去除率分别为42.8%、53.6%、70.5%,温度的升高明显地提高了硝化菌的活性和生长速率,进而促进了脱氮效果.当进水为纤维素乙醇废水经IC工艺处理后的厌氧出水时,3个温度条件下系统对废水中有机物的去除效果无较大差异,去除率均低于15%,主要因为纤维素乙醇废水的厌氧处理出水中的有机物很难被微生物利用;而温度对脱氮效果影响较大,30℃下NH_4~+-N去除率达到60.9%,分别是10℃和20℃时的2.0和1.3倍,并且,随着温度的升高总无机氮的去除率增强,NO_3~--N的去除量增加.由于体系COD去除率低说明反硝化可利用的碳源不足,因此,系统内可能存在内碳源反硝化作用,而且内碳源反硝化作用也随着温度的升高而增强.通过氮平衡计算可知,3个温度条件下氮损失分别为37.6%、45.0%、53.6%,说明温度的升高不仅提高了硝化菌活性,还促进了内碳源反硝化,进而提高了对氮素的去除.     

纳米TiO2添加剂对DMDF发动机大负荷燃烧及PM排放影响的试验研究

在一台电控增压中冷四缸柴油机的进气道上加装一套电控喷射装置,使其运行柴油/甲醇双燃料(DMDF)模式.研究了甲醇中Ti O_2添加剂的添加量及同一添加剂添加量在不同甲醇分散系喷射量时对发动机大负荷工况的燃烧和颗粒物(PM)排放的影响.结果表明,在甲醇中添加适量(30和100 mg·kg~(-1))的纳米Ti O_2能够使爆发压力升高,对燃烧有一定的促进作用,但添加过量(100 mg·kg~(-1))会对燃烧产生不利影响.加入纳米Ti O_2后,干炭烟烟度排放和积聚态颗粒数明显降低,在添加剂添加量为1000 mg·kg~(-1)时,最大降幅分别达到26.8%和29.4%,而核态颗粒物排放变化不大.在相同添加剂添加量下,增加甲醇分散系替代率R_m会使放热始点后移,放热更加集中,爆发压力增大,干炭烟烟度和颗粒物排放均大幅度降低.在添加剂添加量为100 mg·kg~(-1)时,与R_m=10%相比,R_m=40%时爆发压力增加0.94 MPa,放热率峰值增加53.5%,烟度、核态颗粒数、积聚态颗粒数和颗粒物总数的降幅分别达66.9%、42.3%、67.0%和58.0%.     

Comparison among model estimates of critical loads of acidic deposition using different sources and scales of input data

The critical load (CL) of acidic atmospheric deposition represents the load of acidity deposited from the atmosphere to the earth’s surface at which harmful acidification effects on sensitive biological receptors are thought to occur. In this study, the CL for forest soils was estimated for 27 watersheds throughout the United States using a steady-state mass balance approach based on both national and site-specific data and using different approaches for estimating base cation weathering. Results suggested that the scale and source of input data can have large effects on the calculated CL and that the most important parameter in the steady-state model used to estimate CL is base cation weathering. These results suggest that the data and approach used to estimate weathering must be robust if the calculated CL is to be useful for its intended purpose.     

Prediction of Streamflow Regime and Annual Runoff for Ungauged Basins Using a Distributed Monthly Water Balance Model1

Moore, R.D. (Dan), J.W. Trubilowicz, and J.M. Buttle, 2011. Prediction of Streamflow Regime and Annual Runoff for Ungauged Basins Using a Distributed Monthly Water Balance Model. Journal of the American Water Resources Association (JAWRA) 48(1): 32‐42. DOI: 10.1111/j.1752‐1688.2011.00595.x Abstract: Prediction of streamflow in ungauged basins is a global challenge, but is particularly an issue in physiographically complex regions like British Columbia (BC), Canada. The objective of this study was to assess the accuracy of a simple water balance model that can be run using existing spatial datasets. The model was developed by modifying an existing monthly water balance model to account for interception loss from forest canopy, glacier melt, and evaporation from lakes. The model was run using monthly climate normals from the ClimateBC application, which have a horizontal resolution of 400 m. Each ClimateBC grid cell was classified as forest, open land, glacier or water surface based on provincial scale digital maps of biogeoclimatic zones, glaciers, and water. The output was monthly mean runoff from each grid cell. These values were integrated within the catchment boundaries for streams gauged by the Water Survey of Canada. Annual runoff was predicted with modest accuracy: after updating the predicted runoff by interpolating errors from neighboring gauged streams, the mean absolute error was 25.4% of the gauged value, and 52% of the streams had errors less than 20%. However, the model appears to be quite robust in distinguishing between pluvial, hybrid, and melt‐dominated hydroclimatic regimes, and therefore has promise as a tool for catchment classification.     

湘江株洲段丰水期镉污染负荷总量测算及分配

以2010年8月湘江干流株洲段代表性断面水质与底泥监测资料以及其他资料为基础,采用WASP7模型模拟该江段丰水期镉浓度,并进行镉污染负荷测算与分配。研究结果表明,WASP7模型较好地重现了镉浓度的变化规律,8月份该河段上游镉入流量2 446.33 kg,下游出流量3 076.44 kg,区间增量630.12 kg,其中点源负荷量241.67 kg,占38.4%,面源负荷量304.49 kg,占48.3%,内源负荷量为83.96 kg,占13.3%。     

Incorporating Uncertainty Into the Ranking of SPARROW Model Nutrient Yields From Mississippi/Atchafalaya River Basin Watersheds1

Abstract: Excessive loads of nutrients transported by tributary rivers have been linked to hypoxia in the Gulf of Mexico. Management efforts to reduce the hypoxic zone in the Gulf of Mexico and improve the water quality of rivers and streams could benefit from targeting nutrient reductions toward watersheds with the highest nutrient yields delivered to sensitive downstream waters. One challenge is that most conventional watershed modeling approaches (e.g., mechanistic models) used in these management decisions do not consider uncertainties in the predictions of nutrient yields and their downstream delivery. The increasing use of parameter estimation procedures to statistically estimate model coefficients, however, allows uncertainties in these predictions to be reliably estimated. Here, we use a robust bootstrapping procedure applied to the results of a previous application of the hybrid statistical/mechanistic watershed model SPARROW (Spatially Referenced Regression On Watershed attributes) to develop a statistically reliable method for identifying “high priority” areas for management, based on a probabilistic ranking of delivered nutrient yields from watersheds throughout a basin. The method is designed to be used by managers to prioritize watersheds where additional stream monitoring and evaluations of nutrient‐reduction strategies could be undertaken. Our ranking procedure incorporates information on the confidence intervals of model predictions and the corresponding watershed rankings of the delivered nutrient yields. From this quantified uncertainty, we estimate the probability that individual watersheds are among a collection of watersheds that have the highest delivered nutrient yields. We illustrate the application of the procedure to 818 eight‐digit Hydrologic Unit Code watersheds in the Mississippi/Atchafalaya River basin by identifying 150 watersheds having the highest delivered nutrient yields to the Gulf of Mexico. Highest delivered yields were from watersheds in the Central Mississippi, Ohio, and Lower Mississippi River basins. With 90% confidence, only a few watersheds can be reliably placed into the highest 150 category; however, many more watersheds can be removed from consideration as not belonging to the highest 150 category. Results from this ranking procedure provide robust information on watershed nutrient yields that can benefit management efforts to reduce nutrient loadings to downstream coastal waters, such as the Gulf of Mexico, or to local receiving streams and reservoirs.