渗滤液的反渗透浓缩液回灌研究

反渗透处理渗滤液会产生一定量浓缩液,浓缩液的污染物浓度远高于渗滤液。对浓缩液回灌于填埋垃圾体进行实验,结果表明:浓缩液回灌对有机污染物有很好的去除效果,厌氧条件下COD去除率为81.56%,BOD5去除率为82.5%,NH3-N去除率为60%～70%;浓缩液回灌的最佳水力负荷为32.38mL/(L·d),此时回灌浓缩液COD浓度<75000mg/L时,COD去除率达85%以上;回灌的浓缩液pH为9时,COD去除率最高;而pH为11时,NH3-N去除率最高。     

准好氧填埋渗滤液水质与COD降解拟合研究

在成都市长安垃圾填埋场内开展了规模为10m×10m×5m的准好氧填埋实验,分别对渗滤液pH值、COD和NH4+-N进行了研究,结果表明:渗滤液COD经过697d后从最初的65324mg/L降低到2013mg/L,下降96.92%;由于渗滤液收集管直径较小,进入垃圾体的氧气量受到限制,所以NH4+-N的降解效果较差。通过Excel和Lingo软件对渗滤液COD的降解趋势进行拟合,结果表明Lingo拟合的效果更佳。     

间歇式生物反应器回灌量对渗滤液水质的影响研究

通过两套间歇式生物反应器填埋模拟装置开展实验,对不同回灌量下的垃圾降解前期渗滤液pH值、CODcr、NH4^＋-N、VFA以及渗滤液产生量的变化规律进行了对比研究,实验结果表明：间歇式生物反应器填埋方式能够有效抑制填埋初期渗滤液pH值的快速下降,渗滤液采取部分回灌能有效降低NH4^＋-N浓度的积累,回灌量为70％较50％能够更好地改善渗滤液的水质。     

碱渣与生活垃圾混合填埋的实验研究

以碱渣(白泥)和生活垃圾按不同比例混合填埋,模拟真实垃圾填埋场的垃圾降解条件,进行垃圾降解实验以探索白泥存在对垃圾填埋场垃圾降解过程的影响。通过21周的室内模拟实验,垃圾填埋时填加白泥可以提高渗滤液出水的pH值和电导率DS值,降低出水的COD值。得出垃圾填埋时加入适量白泥是经济有效的固体废弃物处理处置方法的结论。     

暴雨径流对非常规水源补给城市河流水质冲击研究

选择北运河流域典型非常规水源补给城市河流(凉水河)为研究对象,阐述暴雨径流对非常规水源补给城市河流水体物理化学特征的影响.结果表明,非暴雨期间,凉水河水体p H和DO平均值分别为7.67和3.88 mg·L-1;耗氧物质COD和氨氮(NH+4-N)平均质量浓度分别为47.41 mg·L-1和8.39 mg·L-1;富营养化元素总氮(TN)和总磷(TP)平均质量浓度分别为16.34 mg·L-1和1.45 mg·L-1.暴雨期间,雨水径流汇入收纳水体后,COD、NH+4-N、TP平均质量浓度明显上升,最高值分别达到108、14.24、3.02 mg·L-1.在空间分布上,COD、NH+4-N、TN和TP质量浓度变化趋势随土地利用类型变化特征趋于一致,从城镇区至农村区,均呈逐渐上升趋势.     

铁离子循环电解法处理垃圾填埋场晚期渗滤液

使用箱式电化学反应器,采用铁离子循环电解工艺处理垃圾填埋场晚期渗滤液,确定了硫酸铁的剂量,考察了该工艺去除污染物的效率与主要因子对污染物去除的影响.实验结果表明,铁离子循环电解工艺对垃圾填埋场晚期渗滤液具有良好的处理效果,在电压3.80V、pH值为3.0、电解时间40min条件下,电解后的渗滤液满足二级排放标准的要求;硫酸铁的合理浓度为1000mg·L-1;电解电压不宜超过4.0V,电解时间不宜超过40min;渗滤液中氯离子的浓度对COD和NH 4-N的去除有显著影响,浓度越高COD和NH 4-N去除效果越好,且其对NH 4-N去除的影响大于对COD去除的影响.     

不同填埋结构渗滤液中的氮动态变化特性

建立了准好氧和厌氧的垃圾填埋模拟试验装置,研究了渗滤液中ρ(NH₄＋-N),ρ(NO₃－-N),ρ(NO₂－-N)和ρ(TN)的动态变化特性. 结果表明:装入模拟装置的城市生活垃圾,经过12个月的降解后,准好氧填埋结构渗滤液中的ρ(NH₄＋-N)和ρ(TN)显著下降,分别降至945和986 mg/L,下降率(分别为79.2%和77.3%)远远大于厌氧填埋结构;ρ(NO₃－-N)和ρ(NO₂－-N)变化波动较大,在第25～31周时,NO₃－-N与NO₂－-N都有一个累积的过程;厌氧填埋结构中,ρ(NH₄＋-N)由初始的4 599 mg/L降至2 812 mg/L,ρ(TN)则降至2 859 mg/L,其降解效果远不如准好氧填埋,而ρ(NO₃－-N)和ρ(NO₂－-N)较低,波动不大.      

好氧填埋技术对渗滤液水质变化的影响

垃圾填埋场产生大量渗滤液,而一般厌氧型填埋场产生渗滤液中含有很高浓度的有机物。因此,渗滤液成为填埋场的难题。通过试验模拟垃圾的好氧填埋过程,并在此过程中对垃圾产生渗滤液中的COD、BOD5和NH 4+-N进行连续监测,通过试验初步得出:在好氧填埋条件下,垃圾堆体产生渗滤液中有机物和NH 4+-N浓度得到较大程度降低。渗滤液中COD、BOD5和NH 4+-N的降解率分别高达98.99%、99.94%和99.78%。     

间歇式曝气生物滤池对焚烧垃圾渗滤液深度脱氮的研究

为了提高焚烧垃圾渗滤液深度处理的脱氮效率,构建并启动了间歇式曝气生物滤池(IABF).在曝气阶段停止进水、停曝阶段进水的运行方式下,考察了曝气停曝时间比、运行周期、水力停留时间、碳氮比和气水比对反应器脱氮效率的影响.结果表明,在曝气停曝时间比为1:1,运行周期为1h,水力停留时间8h,COD/TN为4:1,气水比5:1的条件下,IABF取得最佳脱氮效率,平均出水TN可达到19.39 mg·L-1,NH4+-N为9.48 mg·L-1.TN和NH4+-N的平均去除率分别为87.5％和84.1％,出水水质达到《生活垃圾填埋场污染控制标准(GB16889-2008)》.     

垃圾填埋场生化降解指标测试及液气产量评估

以上海某综合垃圾填埋场作为研究对象,钻取不同龄期的生活垃圾测试固液气生化降解指标,并对全场的渗滤液产量以及填埋气产量进行评估.经过测试和计算,该处区域已开始稳定产甲烷,进入慢速降解阶段.其中,固相垃圾样的C/L（纤维素与木质素的比值）大部分集中在0.72~1.53之间;渗滤液pH值介于7.91~8.92,BOD介于1050~5780mg/L,COD介于2640~15200mg/L,NH₃-N介于2110~4360mg/L.引入固相、液相以及气相归一化指标β₁、β₂、β₃,用于评估填埋场降解阶段.其中,β₁介于0.56~0.83,β₂介于0.65~0.76,β₃介于0.97~1.02.β₁与β₂能够作为判定垃圾场降解阶段的指标,但β₃只能作为判定垃圾场是否处于稳定产甲烷阶段的指标.另外,建立考虑垃圾压缩-渗流耦合作用的渗滤液产量计算方法,垃圾自身渗滤液产率在70%~80%左右;采用垃圾两阶段降解模型计算填埋气产量,随着垃圾停止入场填埋,填埋气可收集量快速降低,至2025a降至峰值的3.88%,至2040a降至峰值的0.08%.     

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.     

Evaluation of phytoextracting cadmium and lead by sunflower, ricinus, alfalfa and mustard in hydroponic culture

Soil contaminated with heavy metals cadmium(Cd)and lead(Pb)is hard to be remediated.Phytoremediation may be a feasible method to remove toxic metals from soil,but there are few suitable plants which can hyperaccumulate metals.In this study,Cd and Pb accumulation by four plants including sunflower(Helianthus annuus L.),mustard(Brassica juncea L.),alfalfa(Medicago sativa L.), ricinus(Ricinus communis L.)in hydroponic cultures was compared.Results showed that these plants could phytocxtract heavy metals, the ability of accumulation differed with species,concentrations and categories of heavy metals.Values of BCF(bioconcentration factor)and TF(translocation factor)indicated that four species had dissimilar abilities of phytoextraction and transportation of heavy metals.Changes on the biomass of plants,pH and Eh at different treatments revealed that these four plants had distinct responses to Cd and Pb in cultures.Measurements should be taken to improve the phytoremediation of sites contaminated with heavy metals,such as pH and Eh regulations,and so forth.     

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.