镉、铬复合污染水源水的处理技术研究

重金属引起的给水污染是威胁人体健康的元凶首恶之一,也为传统给水处理工艺提出更大的挑战.本文以强化混凝沉淀的方法处理铬、镉复合污染的水源水,旨在通过优化原工艺应对突发污染.研究表明,针对铬和镉的初始污染浓度分别为0.170 0 mg/L和0.030 0 mg/L的复合污染水源水,采用分段工艺,只需在原水的pH值的条件下,投加混凝剂(FeCl3)20.0 mg/L,混凝剂(PAFC)的投加量为2mg/L,出水即可以达到国家出水标准.处理过程模拟水厂现有工艺,无需新增设备,易于操作.     

零价铁-四钛酸钾晶须处理铀矿山废水

以四钛酸钾晶须作为处理材料去除废水中的铀,考察了四钛酸钾晶须投加量、溶液pH值、铀初始质量浓度、反应时间和温度等因素对去除效果的影响。结果表明:在温度为25℃、pH=8.0、反应时间为120 min的条件下,四钛酸钾晶须对初始质量浓度为100 mg/L的含铀废水中铀去除率达97.4%。在此基础上开展零价铁和四钛酸钾晶须联合处理含铀废水研究,二者在实验所设的8种投加量情况下均可将初始铀浓度为100 mg/L的废水降至GB 23727—2009《铀矿冶辐射防护和环境保护规定》规定值0.05 mg/L以下。在增加投加量的基础上,二者联合处理,可使铀浓度约为50 mg/L的实际铀矿山废水中铀含量降至0.1 mg/L左右,去除率达99.8%。     

锐态型纳米TiO_2光催化处理含镉废水的研究

采用溶胶-凝胶法制备锐态型纳米TiO2,用XRD、SEM对粉体进行表征。在紫外光的作用下将自制纳米TiO2光催化处理废水中的Cd2+。考察反应时间、pH值、废水负荷、催化剂用量等因素对去除率的影响。实验结果表明:纳米TiO2光催化处理含镉废水的去除率高,含镉废水pH值、废水负荷、纳米二氧化钛浓度以及反应时间等因素影响含镉废水去除率。在优化的处理条件中:废水镉浓度为30mg/L,纳米TiO2投加量为3mg/L,含镉废水的pH为10,反应时间为2.5h,废水中镉的去除率可达99.52%。     

化学沉淀法处理葫芦岛锌厂含镉废水的研究

采用化学沉淀法对葫芦岛锌厂含镉废水进行处理,分别考察了反应pH值、添加絮凝剂种类、反应时间、沉淀剂种类等因素对模拟含镉废水处理的影响,并在最佳条件下对葫芦岛锌厂含镉废水处理进行了研究。结果表明,采用化学沉淀法处理含镉废水时的合适pH值为11;当采用浓度为5%的FeSO4作为絮凝剂,浓度为10%的Ca（OH）2作为沉淀剂时,对含镉浓度为20mg/L的模拟含镉废水的最佳沉淀时间为15min;对含镉浓度为1200mg/L的实际废水处理后废水中镉离子浓度平均值为0.086mg/L,可以实现达标排放。     

利用莱茵衣藻去除污水中氮磷的研究

对莱茵衣藻去除废水中氮磷的性能进行了研究,考察了初始氮磷浓度、氮磷比、光照条件、pH值和细胞固定化等因素对去除效率的影响.结果表明,莱茵衣藻对氮磷的去除率在初始氮磷浓度分别在55 mg·L-1和7 mg·L-1以下时接近100%,但初始氨氮浓度进一步升高至75 mg·L-1以上时会导致氨氮去除率急剧下降至50%.当氮磷比为5∶1和10∶1时,衣藻在3 d内完全吸收水体中的氨氮,而当氮磷比为25∶1时则需要6 d;3种氮磷比下衣藻基本上4 d内能完全去除水体中的磷.2种光照条件下(L/D为24 h∶0 h和12 h∶12 h)衣藻对氮磷的去除率都能达到100%,但L/D为24 h∶0 h时的去除速率更快.衣藻去除氮磷的最适pH范围为6～7.藻细胞固定化后对氨氮的去除能力显著提高,在初始氨氮浓度为75 mg·L-1时去除率由游离细胞的50%提高到100%;对磷的去除率不变,但速率有所减慢.     

巯基重金属捕集剂脱除电镀废水中低浓度Ni的效能及机理研究

以某电镀厂经Na2S预处理后的废水作为研究对象,选用Na OH、Na2S和有机巯基类化合物(EDTC)作为重金属捕集剂,对废水中低浓度Ni进行深度脱除.通过处理效果对比,最终选用EDTC作为Ni理想的捕集剂,重点考察了加药方式、p H、EDTC投加量、反应时间、PAC投加量及不同含Ni电镀废水对Ni去除效果的影响并探讨了EDTC去除Ni的机理.结果表明,Ni初始浓度为6.41 mg·L-1时,最佳工艺条件依次为:p H为7.0,EDTC投加量为摩尔比nEDTC/nNi=4,反应时间为15 min,PAC投加量为100 mg·L-1,PAM投加量为2.5 mg·L-1,此时出水Ni2+浓度为1.08 mg·L-1,去除率达83.15%.在此基础上,针对3种不同含Ni电镀废水,经EDTC处理后Ni去除率均在80%以上,部分废水出水Ni2+浓度低于0.1 mg·L-1,达到了《电镀污染物排放标准(GB21900-2008)》中关于Ni污染物特别排放限值的要求(0.1 mg·L-1).红外光谱图和有机元素分析结果表明,EDTC与Ni会发生螯合反应,即EDTC巯基中硫捕捉Ni2+并趋向成键,生成难溶的螯合产物,从而有效地去除废水中Ni.     

树脂吸附法处理采矿塌陷区废水的研究

文章采用ND-90型超高交联吸附树脂吸附处理采矿塌陷区废水.原废水COD质量浓度为200～230mg·L-1,经沉淀-树脂吸附法处理,处理量20BV,吸附流出液COD质量浓度为40～50 mg·L-1,COD去除率≥80.23%,树脂经过碱液脱附后可重复利用且运行稳定.该处理工艺投资少、操作简便,为解决采矿塌陷区水体修复问题提供了一种新的方法.     

固定化菌体吸附矿山废水中重金属的研究

研究了固定化菌体对矿山废水重金属的吸附性能.结果表明,固定化菌体对重金属有良好的富集性能,投加15g·L-1的固定化菌体,对100 mg·L-1 Cu、50 mg·L-1 Zn的去除率分别可达94.4%、80.6%.废水pH、菌体投加量对固定化菌体的处理效果影响较大,其最佳值分别为3.5、15 g·L-1.经4轮吸附-解吸循环实验,显示固定化菌体可重复利用3次,固定化菌体在使用第3次时,对100 mg·L-1 Cu、50mg·L-1 Zn的去除率分别为67.4%、46.5%.用固定化菌体的流化床工艺处理废水最佳参数为曝气量4.02 L·min-1,处理2h.用固定化菌体的流化床工艺处理矿山废水取得了较好的效果,对于浓度低于10 mg·L-1的重金属,去除率达到了100%,对浓度为579.2 mg·L-1 Fe的去除率也达到了56.6%,表明该工艺具有较好的工业化前景.     

超声技术强化处理制革废水中的有机物

采用超声波强化混凝沉淀法处理制革废水,考察了超声波的作用时间和施加方式、混凝剂投加量等因素对降低废水中有机物的影响.实验结果表明:只用超声波作用废水60s,COD去除率为40.6%;混凝剂总浓度为100mg/L时COD去除率最高;先施加超声波60s,再投加混凝剂,COD去除率最高可达73.2%,比不用超声波时提高10%以上.因此,超声技术用于混凝沉淀法处理制革废水有明显的强化作用.     

PAC和PAFC对内循环连续砂滤器处理石化二级出水的影响

采用PAC（聚合氯化铝）和PAFC（聚合氯化铝铁）作为絮凝剂,探讨不同絮凝剂及其投量对于内循环连续砂滤器处理效果和滤料板结潜在趋势的影响.结果表明,PAC和PAFC投量由5mg/L升至30mg/L时,COD和SS的去除率随着投加量的增大均呈现出先升高后降低的趋势.10mg/L为试验水质下的最佳投量,在该投量下,PAC对SS和COD去除率为分别为49.7%和12.9%;PAFC对SS和COD去除率分别为50.6%和13.8%.内循环连续砂滤器主要去除的是相对分子量在3k以上的溶解性有机物,但对相对分子量1k以下的溶解性有机物去除效果不好,总DOC去除率低于5%,需进一步深度处理以满足最新的排放标准.PAFC混合液比PAC混合液黏度低,有利于缓解滤料板结.总体来看,更适合于石化二级出水的混凝剂为PAFC,最佳投量为10-15mg/L,可保障对SS高效去除同时并使内循环连续砂滤器运行更加稳定.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter （NOM）. A relatively higher molecular weight （MW） of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.     

Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on Al,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.     

Simultaneous removal of ammonium and phosphate by zeolite synthesized from coal fly ash as influenced by acid treatment

Zeolite synthesized from fly ash （ZFA） without modification is not efficient for the purification of NH4＋ and phosphate at low concentrations that occur in real effluents, despite the high potential removal capacity. To develop an effective technique to enhance the removal efficiency of ammonium and phosphate at low concentrations, ZFA was modified with acid treatment and the simultaneous removal of ammonium and phosphate in a wide range of concentration was investigated. It was seen that when compared with untreated ZFA, only the treatment by 0.01 mol/L of H2SO4 significantly improved the removal efficiency of ammonium at low initial concentrations. The behavior was well explained by the pH effect. Treatment by more concentrated H2SO4 led to the deterioration of the ZFA structure and a decrease in the cation exchange capacity. Treatment by 0.01 mol/L H2SO4 improved the removal efficiency of phosphate by ZFA at all initial P concentrations, while the treatment by concentrated H2SO4 （≥0.9 mol/L） resulted in a limited maximum phosphate immobilization capacity （PIC）. It was concluded that through a previous mild acid treatment （e.g. 0.01 mol/L of H2SO4）, ZFA can be used in the simultaneous removal of NH4＋ and P at low concentrations simulating real effluent.