环境条件对上海蕴藻浜水体沉积物Ni释放影响的研究

通过改变环境条件(温度、pH、溶解氧),并采用Tessier五步连续提取法,研究了温度、pH和溶解氧对蕴藻浜沉积物中Ni的释放的影响,并对不同条件下的沉积物释放前后Ni的形态进行了对比分析.结果表明:随着温度的升高,沉积物对Ni的释放通量升高,可交换态、铁锰氧化物结合态以及有机物结合态在沉积物中所占百分比均上升;随着pH的增加,沉积物对Ni的释放通量下降,可交换态、碳酸盐结合态、铁锰氧化物结合态以及有机结合态所占百分比均有不同程度的增加;而溶解氧高的水体比溶解氧较低的水体更不容易释放Ni.     

南随塘河pH值超标原因分析和解决方法

自2007年以来,每年夏季某石化_丁业区南随塘河水质经常出现pH值碱性超标。经试验证实了其原因之一是循环水场排污水质pH值较高,加上夏天气温高,河水蒸发浓缩和河水流速缓慢,致使水处理剂有机结构打破,产生更多的碱性物质;原因之二是循环水场排污水和沿岸各排口排放的清下水均含有不少有机物,使水体富营养化,从而河水中藻类大量繁殖,藻类的光合作用引起了溶解氧浓度的升高,影响了水中的碳酸盐平衡,从而导致pH值的升高。对原有的pH值与溶解氧的关系式进行了修正,建立了更符合实际情况的新关系式。建议循环水场排污水采用微滤膜和反渗透膜的双膜法处理,处理后的回用水电导率小于300μS／em时送回循环水系统．剩余浓缩污水可排至生化装置进一步处理。对于藻类繁殖问题．建议通过磁处理法灭藻、控制营养和及时捞取等方法解决。     

比表面积促进水体过饱和溶解氧释放的试验研究

水坝高流速、大流量泄水伴随的强掺气作用导致下游水体中溶解气体过饱和,致使鱼类患气泡病甚至死亡。而水体中固体介质的存在可以促进过饱和溶解气体的释放,从而减小过饱和气体对鱼类的影响。对此,以活性炭为固体吸附介质,试验研究了介质不同比表面积对过饱和溶解氧释放过程的影响。结果表明,随着活性炭比表面积的增大,其对过饱和溶解氧释放的促进作用显著。研究结果为利用固体介质加快水体内过饱和气体释放提供了科学依据,亦可据此提出工程上减缓过饱和溶解气体对鱼类影响措施。     

太湖沉积物中有效态砷的释放

近年来,水体砷(As)污染逐渐加重,沉积物作为水体污染物的内源,其释放的As可能是造成水体As污染的重要原因。利用ZrO-Chelex薄膜梯度扩散技术(ZrO-Chelex DGT)原位、同步获取太湖沉积物中有效态As和Fe的高分辨垂向信息,并考察两者之间的关系。结果发现,太湖北部湖区上覆水总As和溶解态As的浓度较高,4个采样点总As均超过中国的生活饮用水标准(10μg/L);沉积物中As的赋存形态主要为Fe结合态。沉积物中DGT有效态As和Fe随深度有升高趋势,部分样点有效态As在升高后出现降低;有效态As和Fe在3个样点分布相似,呈现显著相关,表明沉积物As的释放受Fe还原过程的控制;但在另外3个样点分布不同,表明存在其他主导机制控制沉积物中As的释放,需做进一步研究。     

摇蚊幼虫扰动对富营养化湖泊沉积物—水微界面磷释放的影响

为探讨摇蚊幼虫扰动对富营养化湖泊沉积物—水微界面磷释放的影响,以大纵湖湖心区域为研究对象,通过室内培养试验,模拟摇蚊幼虫扰动下沉积物中磷的释放情况。即利用微电极系统和高分辨率的渗析平衡技术(HR-Peeper),获取摇蚊幼虫扰动沉积物中的溶解氧(DO)和pH值,并同步获取间隙水中的溶解态反应性磷(SRP)和溶解态二价铁(Fe2+),分辨率分别为μm、mm级。结果表明,摇蚊幼虫扰动增加了沉积物中DO的渗透深度及pH值,降低了间隙水中60.7%的SRP及42.1%的溶解态Fe2+的浓度,增加了沉积物中铁结合态磷(Fe-P)的浓度,其他结合态的磷(TP、IP、OP、AP)无显著变化。说明摇蚊幼虫扰动沉积物间隙水中的SRP与Fe2+显著相关,因此摇蚊幼虫扰动沉积物中SRP的释放主要受Fe2+的氧化还原所控制。     

汽油清净剂对发动机沉积物生成影响的试验研究

在M111发动机台架上,采用GB/T 19230.6-2003中所规定的试验方法,研究了不同油品对发动机进气阀、燃烧室等部位沉积物的影响.研究结果表明:使用清净性不同的车用汽油,所产生进气阀沉积物数量差别很大,平均每阀沉积物重量超过10倍;如果采用合适的汽油清净剂,可以有效控制进气阀沉积物的数量,能降低80～90%以上;加清净剂的汽油在减少进气阀积炭的同时增加了燃烧室的积炭;我国车用汽油的清净性能与国外相比差距较大.     

溶解氧浓度对多级接触氧化系统的影响研究

采用多级接触氧化系统对经过物化工艺预处理后的实际汽车涂装废水进行生化处理小试验,考察了溶解氧浓度对多级接触氧化系统整体除碳脱氮效果的影响,并通过正交试验确定了在生化反应器不同位置的溶解氧浓度最优组合。     

pH值调控对发酵产氢的影响

利用厌氧活性污泥作产氢接种物，发酵有机质产生氢气，一般是在酸性条件下进行的。以厌氧活性污泥作接种物，有机酸为基质，在厌氧、恒温25℃、不同的pH值下，启动发酵产氢，以及监测产氢过程中的pH值变化，得出pH值过高时，有大量的甲烷生成，pH值过低时，则对产氢细菌不利，难于产氢。启动发酵产氢时，pH值不宜底于4．3，较为适宜的产氢pH值范围4．5～5．5。     

河流沉积物与悬浮颗粒物的重金属来源及风险差异

为明确河流沉积物与悬浮颗粒物重金属来源与风险的差异,2018年12月采集海河流域缓流河流子牙河与快速流河流滦河沉积物及悬浮颗粒物样品,采用ICP-MS及ICP-OES分析其重金属(Cr、Ni、Cu、Zn、As、Cd、Pb)含量并利用多种分析方法对比两条河流沉积物与悬浮颗粒物的来源与风险的差异性.结果表明,子牙河与滦河悬...     

汽油机燃烧沉积物对发动机性能影响的研究

本介绍了作在一台４９２Ｑ型汽油机上进行燃烧沉积物对发动机性能影响的研究结果，发现燃烧沉积物导致发动机压缩比提高，废气排放中ＮＯｘ、ＨＣ排放增多并导致发动机充气效率下降，此外还分析了燃烧沉积物影响发动机性能的主要原因。     

Cu-Mn复合载氧体释氧反应性及动力学研究

载氧体作为化学链转换技术的核心与关键,其性能决定了反应过程的经济性和稳定性。采用石墨成孔浸渍法制备了4种不同含量Cu修饰的Cu-Mn复合载氧体,对其进行了表征和抗磨损性能实验。在热重分析仪上研究了载氧体的释氧特性和循环反应特性,并采用Model-free method分析了载氧体的释氧动力学特性。结果表明,载氧体制备过程中活性组分CuO和Mn2O3并未与惰性载体MgO发生化学反应。Cu修饰对载氧体具有拓孔作用,可以显著提高载氧体比表面积和总释氧量,降低释氧所需温度,缩短释氧时间,降低释氧活化能。但随着Cu含量的增加,载氧体抗烧结性能和抗磨损性能逐渐降低,且随着循环次数增加,载氧体循环反应性能降低。     

预处理对河道底泥固化效果的影响

为了通过预处理改变底泥的理化性质,增加底泥固化后抗压强度,实现底泥的资源化利用,比较了3种底泥预处理方法(Fenton氧化、热处理、淋洗)对底泥中有机质的质量分数、重金属总质量、重金属形态分布,特别是对底泥固化后抗压强度的影响。结果表明:固化后抗压强度与底泥中有机质的质量分数直接相关;可降低底泥中有机质的质量分数的预处理方法(Fenton氧化、热处理)对提高底泥固化后抗压强度效果较好,底泥固化后抗压强度高达2.7 MPa;鼠李糖脂淋洗虽然能够有效去除底泥中的重金属,但是淋洗剂中的有机物反而使底泥中有机质的质量分数增加,对固化不利。因此,Fenton氧化和热处理均可用作提高底泥固化强度的预处理方法,且固化后试样重金属浸出毒性低,对环境影响小。     

Effects of pH value and substrate concentration on hydrogen production from the anaerobic fermentation of glucose

A series of batch experiments were conducted to investigate the effects of pH and glucose concentrations on biological hydrogen production by using the natural sludge obtained from the bed of a local river as inoculant. Batch experiments numbered series I and II were designed at an initial and constant pH of 5.0–7.0 with 1.0 increment and four different glucose concentrations (5.0, 7.5, 10 and 20 g glucose/L). The results showed that the optimal condition for anaerobic fermentative hydrogen production is 7.5 g glucose/L and constant pH 6.0 with a maximum H₂ production rate of 0.22 mol H₂ mol⁻¹ glucose h⁻¹, a cumulative H₂ yield of 1.83 mol H₂ mol⁻¹ glucose and a H₂ percentage of 63 in biogas.     

苏州河重金属污染特征及风险评价

沿苏州河水流方向设置 13个采样点进行3次采样,分析苏州河中As、Cd、Cr、Cu、Pb、Zn的分布,采用主成因分析和冗余分析,评价了苏州河水相及沉积相中微生物的稳定性以及重金属对微生物的影响。通过计算健康风险指数、内罗梅指数、地累积指数和重金属分配系数,评价了地表水中重金属对暴露人群存在的风险以及流域的生态危害。结果表明,水相中主要为Zn、Pb、Cu,沉积相中Zn质量浓度最高;研究流域的物种丰富度变化甚微;As和Cr对成人和儿童均存在不同程度的致癌风险,Cd的潜在生态危害最大。     

宝鸡市渭河市区段生态治理工程泥沙设计概述

宝鸡市在渭河主河床上兴建拦河闸,形成水面。泥沙淤积问题能否解决,是本工程是否可行的首要问题。本文经过分析,得出借助本工程的特殊地理位置,经过合理的运用,可以解决泥沙淤积问题。     

Effects of mediator producer and dissolved oxygen on electricity generation in a baffled stacking microbial fuel cell treating high strength molasses wastewater

The effects of Pseudomonas aeruginosa, pyocyanin, and influent dissolved oxygen (DO) on the electricity generation in a baffled stacking microbial fuel cell (MFC) treating high strength molasses wastewater were investigated. The result shows that the influent chemical oxygen demand (COD) of 500–1000 mg l⁻¹ had the optimal substrate-energy conversion rate. The addition of a low density of P. aeruginosa (8.2 mg l⁻¹) or P. aeruginosa with pyocyanin improved the COD removal and power generation. This improvement could be attributed to the enhancement of electron transfer with the help of redox mediators. Influent DO at a concentration of up to 1.22 mg l⁻¹ did not inhibit the electricity generation. Large proportions of COD, organic-N and total-N were removed by the MFC. The MFC effluent was highly biodegradable. Denaturing gradient gel electrophoresis analysis shows that the added pyocyanin resided in the MFC for up to 14 days. An analysis of anode voltage reveals that microbial proton transport to the cathode was importantly responsible for the internal resistance.     

Effect of dissolved oxygen concentration on nitrogen removal and electricity generation in self pH-buffer microbial fuel cell

A double-chamber self pH-buffer microbial fuel cell (MFC) was used to investigate the effect of dissolved oxygen (DO) concentration on cathodic nitrification coupled with anodic denitrification MFC. It was found that nitrogen and COD removal, electricity generation were positively correlated with DO concentration in the cathode chamber. When total inorganic nitrogen of influent was 202.51 ± 7.82 mg/L at DO 6.8 mg/L, the maximum voltage output was 282 mV and the maximum power density was 149.76 mW/m². After 82 h operation, the highest removal rate of total inorganic nitrogen was 91.71 ± 0.38%. Electrochemical impedance spectroscopy (EIS) test showed that the internal resistance of the reactor with different DO concentration was related to the diffusion internal resistance. The data of bacterial analysis in the cathode chamber revealed that there were not only ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), but also a large number of exoelectrogens. Compared with the traditional biological denitrification and related MFC denitrification research, this method does not need pH-buffer solution and external circulation device through the anion exchange membrane (AEM). It can generate electricity and remove nitrogen simultaneously, and the oxygen utilization rate in the cathode can also be enhanced.     

Kinetic study of the effects of pH on the photocatalytic hydrogen production from alcohols

Solution pH is an important parameter in photocatalytic reactions that substantially affects the process by changing photocatalyst agglomeration and substrate adsorption on photocatalyst surface. In this work, a kinetic study was performed on photocatalytic hydrogen production from alcohols and an intrinsic kinetic model was developed to predict the rate of hydrogen production from different alcohols as a function of pH. Glycerol, ethanol, and methanol were selected as representative substrates and tested in a pH range of 2–12. The very good agreement between model predictions and experimental data was confirmed by statistical analyses (R², R²_adj, RMS, AAD, and MAE). The results revealed that for all substrates investigated, the maximum hydrogen rate was obtained at a pH~8. A local minimum for hydrogen production was observed around pHzpc, as a result of catalyst agglomeration. The results of this study can be very useful in future investigations of the effects of pH on other aqueous phase photocatalytic processes.