Waste oyster shell as a kind of active filler to treat the combined wastewater at an estuary

Estuaries have been described as one of the most difficult environments on Earth. It is difficult to know how to treat the combined wastewater in tidal rivers at the estuary, where the situation is very different from ordinary fresh water rivers. Waste oyster shell was used as the active filler in this study in a bio-contact oxidation tank to treat the combined wastewater at the Fengtang Tidal River. With a middle-experimental scale of 360 ma/day, the average removal efficiency of COD, BOD, NH3-N, TP and TSS was 80.05%, 85.02%, 86.59%, 50.58% and 85.32%, respectively, in this bio-contact oxidation process. The living microbes in the biofilms on the waste oyster shell in this bio-contact oxidation tank, which were mainly composed of zoogloea, protozoa and micro-metazoa species, revealed that waste oyster shell as the filler was suitable material for combined wastewater degradation. This treatment method using waste oyster shell as active filler was then applied in a mangrove demonstration area for water quality improvement near the experiment area, with a treatment volume of 5 × 10^3 m^3/day. Another project was also successfully applied in a constructed wetland, with a wastewater treatment volume of 1 ×10^3 m^3/day. This technology is therefore feasible and can easily be applied on a larger scale,     

Formation of THMs and HANs during bromination of Microcystis aeruginosa

Bromine-contained disinfectants and biocides are widely used in swimming pools, recreational waters and cooling towers. The objective of this study was to evaluate the formation of thrihalomethanes (THMs) and haloacetonitriles (HANs) and their cytotoxicity in algae solutions during free bromine disinfection. Disinfection by-products formation potential experiments were conducted using model solutions containing 7 mg/L (as total organic carbon) Microcystis aeruginosa cells. Effects of free bromine dosage, pH and ammonia were investigated. The results showed that brominated disinfection by-products were the major products when free bromine was applied. The total THMs formed during bromination was much as that formed during chlorination, whereas HANs were elevated by using bromination instead of chlorination. Dibromoacetonitrice (C2H2NBr2 ) and bromoform (CHBr3 ) were the only detected species during free bromine disinfection. The production of C2H2NBr2 and CHBr 3 increased with disinfectant dosage but decreased with dosing ammonia. CHBr3 increased with the pH changing from 5 to 9. However, C2H2NBr2 achieved the highest production at neutral pH, which was due to a joint effect of variation in hydrolysis rate and free bromine reactivity. The hydrolysis of C2H2NBr2 was base-catalytic and nearly unaffected by disinfectant. Finally, estimation of cytotoxicity of the disinfected algae solutions showed that HANs formation was responsible for the majority of toxicity. Considering its highest toxicity among the measured disinfection by-products, the elevated C2H2NBr2 should be considered when using bromine-related algaecide.     

Eutrophication development and its key regulating factors in a water-supply reservoir in North China

Yanghe Reservoir is an important source of drinking water for Qinhuangdao City,North China;however,in recent decades this water source has been eutrophic with recurrent summer cyanobacterial blooms.The trophic grade of the system in summer was mesotrophiceutrophic in 1990 and became hypertrophic in 2011.The nutrient availability is extremely high during the entire year,and the water temperature should be the primary driver of the summer blooms.In May-October of 2010 and 2011,abrupt variations were observed in the Secchi depth(SD) and chlorophyll a(Chl-a),and both the correlated analysis of Chl-a-SD and trophic status indices(TSI) deviation(TSI Chl-a-TSI SD) showed that algal cell density dominated light attenuation.During the algal bloom outbreak,the microcystin concentration was found to vary between 0.35-2.12 μg/L in 2010 and 0.11-1.86 μg/L in 2011.The maximum microcystin content was more than two times the safety limit required for drinking water.Inflow discharges were most concentrated in the summer,with periods of lower residence time and the largest water level fluctuation over the entire year.When a high availability of nutrients promoted a high Chl-a concentration in the whole system,it appeared that the instability caused by the decrease in residence time could not produce effective changes in the cyanobacterial abundance.The results indicated that nutrient enrichment in the aquatic systems of Yanghe Reservoir is the most serious problem and that the status would not been modified effectively by increasing hydrological fluctuations(e.g.,decreasing the residence time).Therefore,decreasing the nutrient concentrations is the only route to improve the water quality of this reservoir.     

Speciation of organic phosphorus in a sediment profile of Lake Taihu II. Molecular species and their depth attenuation

The understanding of organic phosphorus(P) dynamics in sediments requires information on their species at the molecular level,but such information in sediment profiles is scarce.A sediment profile was selected from a large eutrophic lake,Lake Taihu(China),and organic P species in the sediments were detected using solution phosphorus-31 nuclear magnetic resonance spectroscopy(31 P NMR) following extraction of the sediments with a mixture of 0.25 mol/L NaOH and 50 mmol/L EDTA(NaOH-EDTA) solution.The results showed that P in the NaOH-EDTA extracts was mainly composed of orthophosphate,orthophosphate monoesters,phospholipids,DNA,and pyrophosphate.Concentrations of the major organic P compound groups and pyrophosphate showed a decreasing trend with the increase of depth.Their half-life times varied from 3 to 27 years,following the order of orthophosphate monoesters > phospholipids DNA > pyrophosphate.Principal component analysis revealed that the detected organic P species had binding phases similar to those of humic acid-associated organic P(NaOH-NRP HA),a labile organic P pool that tends to transform to recalcitrant organic P pools as the early diagenetic processes proceed.This demonstrated that the depth attenuation of the organic P species could be partly attributed to their increasing immobilization by the sediment solids,while their degradation rates should be significantly lower than what were suggested in previous studies.     

LNAPLs污染物在层状非均质多孔介质中的运移试验研究

文章通过室内试验研究层状非均质多孔介质中轻非水相液体(Light Non-Aqueous Phase Liquid,LNAPL)的运移机制与分布特性。首先,在二维砂槽上进行LNAPL的入渗试验,试验过程中用数码相机进行拍照,把LANPL的扩散过程以图像的形式记录下来;然后,用AutoCAD对图片进行分析处理,得出不同时刻LNAPL的入渗锋面变化图。结果发现,介质结构突变面改变了LNAPL的迁移模式。在LNAPL由中砂进入细砂层后,由于受到毛细作用的增强,其运移速度加快;而由中砂进入粗砂,受粗砂介质阻滞作用增强的影响,LNAPL运移速度变小。当LNAPL由干砂进入湿润砂体时,由于孔隙水浮托力增大,LNAPL先产生纵向运移,随后以横向迁移的形式在地下水位上部聚积。当达到一定厚度后,LNAPL的压头足以克服浮托力,驱替孔隙水进入砂土孔隙。另外,LNAPL的厚度足够大时,方可克服饱水层受到的浮托力,在地下水位上形成LNAPL池,并因孔隙水向周围砂体排泄,LNAPL池周围的水位上升。     

磁性多孔陶粒生物膜反应器处理焦化废水的试验研究

以磁性材料为原料,经过特定的工艺处理,对多孔陶瓷进行磁化改性获得磁性多孔载体,并将该载体应用于生物膜反应器中进行焦化废水处理试验。对不同类型的多孔陶粒载体进行对比试验,结果表明:磁性载体生物膜反应器对COD、NH3-N的去除率比普通活性污泥法高出25%³0%,比非载体生物膜反应器高出15%30%,比非载体生物膜反应器高出15%²0%左右。反应器的曝气量为1.5 L/h,曝气时间为10 h/d,温度为2520%左右。反应器的曝气量为1.5 L/h,曝气时间为10 h/d,温度为25³0℃。焦化废水经磁性载体生物膜反应器处理后,上清液中COD,NH3-N的去除率均在90%左右。出水浓度达到国家工业废水排放二级标准(GB18918-2002)。     

亚微米颗粒在Sierpinski海绵模型中热泳沉积研究

亚微米颗粒由于其特殊的粒径尺度,具有很多不同于与传统细颗粒的物理和化学性质,同时极易吸入人体,对人体造成很大危害。谢尔宾斯基海绵模型作为一种理想化的结构模型,具有内比表面积大、多通道等特点。通过建立可工程应用的谢尔宾斯基海绵模型通道,并结合热泳沉积相关数学模型开展计算,可以发现:随着谢尔宾斯基海绵阶数的上升,内部通道的增加是引起亚微米颗粒热泳沉积率上升的主要因素;在海绵通道中运动的亚微米颗粒较之其他粒径的颗粒,更容易受到热泳沉积的影响;同时温差对其热泳沉积影响较为剧烈,呈现线性变化。建立具有工程特征的谢尔宾斯基海绵模型通道,可为研究亚微米颗粒沉积及脱除开辟一条新途径。     

化学铁盐辅助除磷对生物除磷的影响研究

化学辅助除磷有助于污水厂实现磷达标,但其对生物系统存在潜在的影响。针对除磷药剂对生物除磷过程的影响展开研究,选用硫酸亚铁进行化学辅助除磷。药剂形成的化学污泥干扰生物除磷过程且成分复杂,故以磷酸铁、氢氧化铁模拟化学污泥,由钾离子、K/P摩尔比计算出同步除磷中的生物除磷,来探讨化学污泥对聚磷菌释磷/吸磷过程的影响。结果表明,连续投加硫酸亚铁使聚磷菌的释磷量、吸磷量降低;系统中磷酸铁含量0.075 mmol/L时聚磷菌的释磷和吸磷能力提高了约25%,磷酸铁含量0.15 mmol/L时对聚磷菌吸磷有抑制作用;氢氧化铁对聚磷菌释磷、好氧初期吸磷均有抑制作用。生物污泥与化学污泥存在交互作用。     

取代苯类化合物对斑马鱼急性毒性的QSAR研究

该文基于定量-构效关系(QSAR)原理,研究了26种取代苯类化合物与斑马鱼的48 h急性毒性(-lgLC50)之间的内在定量关系。利用AM1量子化学计算方法,首先计算了8种典型量子化学参数与斑马鱼48 h-lgLC50的相关性;然后通过逐步多元线性回归(MLR)方法建立了取代苯类化合物对斑马鱼48 h-lgLC50的QSAR模型,并对所建模型分别进行了内部验证和外部验证,所得复相关系数R2=0.942;最后利用QSAR模型,分析了取代苯类化合物量子化学参数对斑马鱼48 h-lgLC50的影响。结果表明:正辛醇—水分配系数(LogP)与-lgLC50的相关性最大,负电性[-(L+H)/2]与-lgLC50负相关。所得QSAR模型具有较高的稳定性及预测能力,可以用来预测取代苯类化合物对斑马鱼的急性毒性。     

上海市疏浚泥资源化可利用性分析

对上海市不同区域疏浚泥的颗粒粒径、化学成分、毒性、养分等理化性质进行测定,继而对其资源化可利用性进行了分析。结果表明,上海市疏浚泥可定性为粘质粉土和粉质粘土;3个采样区的样品均没有达到清洁疏浚泥的标准。内河航道疏浚泥养分充足但镉污染稍显严重,采取重金属预防措施后适宜作为农作地和湿地矿山修复用地;黄浦江码头前沿和长江码头前沿疏浚泥有机质严重不足,仅适于在绿地、绿化带、防护林等处使用;3处疏浚泥均可制陶粒和制砖,亦可用于围内吹填工程,但需事先对疏浚泥里的重金属成分进行固化。