焦化废水原水中有机污染物的活性炭吸附过程解析

以焦化废水原水作为研究对象,采用粉末活性炭作为吸附剂,考察活性炭投加量、温度、pH及反应时间对废水中主要有机污染物去除的影响规律,结合UV-Vis吸收光谱及GC/MS对吸附过程中有机物组分的变化进行定性和半定量分析.结果表明,在最佳反应条件即活性炭投加量6g·L-1,温度30, pH=9,反应时间20min的情况下处理废水有机物去除率大于70%,原水中检测出的56种有机物中的45种被去除,如长链烷烃、多环芳香族及氮杂环化合物等的浓度降至检测限以下,剩余的11种有机物中苯胺、苯酚、吲哚、乙酸-2-甲基苯酯的去除率分别达到63.5%、42.6%、88.1%、28.1%,甲苯酚(邻、间)和二甲苯酚(5种)去除率在70%和85%以上.结果分析表明,多组分有机污染物共存体系的焦化废水活性炭吸附过程中,多环芳香族和氮杂环等弱极性且-ΔG°较大的大分子有机物优先被吸附且吸附容量大,构成了快速吸附过程;而苯胺、苯酚等强极性且-ΔG0较小的小分子单苯环有机物则表现为弱吸附过程.     

疏水性分子筛对焦化废水生物处理尾水的吸附过程解析

采用表面活性剂为模板剂常温一步合成疏水性介孔分子筛(MCM-41-dry)和通过煅烧去除模板剂得到亲水性介孔材料(MCM-41-cal).分别以制备的两种分子筛作为吸附剂吸附焦化废水生物出水中COD和TOC组分,考察吸附剂浓度、pH值等对吸附过程的影响,并对吸附过程进行动力学拟合.结果表明,MCM-41-dry的吸附效果远远强于MCM-41-cal,归因于含有模板剂的材料表面具有较强的疏水性及含有高吸附容量的季铵基团.在25℃、吸附剂浓度为2g·L-1时,MCM-41-dry对焦化废水中COD和TOC的去除率分别达53%和66%,吸附量分别为64mg·g-1和17mg·g-1.拟二级动力学模型能够真实反映整个吸附过程.水样吸附前后的GC/MS数据表明,焦化废水生物出水中残留了长链烷烃、卤代物、多环芳烃等难降解有机物,经MCM-41-dry吸附后,各种物质浓度均得到降低,MCM-41-dry尤其对疏水性烷烃类有较好的吸附效果,表明该吸附剂能够优先吸附疏水性物质.此外,吸附剂对水具有一定的润湿性能,能与废水充分接触,从而利于其吸附水中的污染物,这使其用于实际废水的处理成为可能.     

有机改性凹凸棒石对养猪废水中有机物的吸附研究

研究表征了十二烷基二甲基甜菜碱和十六烷基三甲基溴化铵改性凹凸棒石的结构,探讨了改性凹凸棒石对猪粪废水中的有机污染物的吸附性能及机理,并考察了改性剂修饰比例、废水p H、吸附剂的投加量对吸附过程的影响.结果表明,两种改性剂成功结合到了凹凸棒石表面,有机改性凹凸棒石的晶体结构未发生改变,但对有机污染物的吸附能力显著高于原土.两性和阳离子改性凹凸棒石吸附有机污染物的最佳参数为:修饰比例为100%,吸附剂浓度为16 g·L~(-1),p H=4(阳离子改性为6),对猪粪废水中COD的去除率分别达到88%和92%,吸附量分别达到79 mg·g~(-1)和82 mg·g~(-1).吸附过程均符合二级动力学模型(R20.998),两性和阳离子改性凹凸棒石对有机物的吸附分别符合Freundlich和Langmuir等温式.有机改性凹凸棒石的疏水性增强,提高了对有机污染物的吸附能力,其沉降性能良好,这使其作为一种吸附剂用于实际养猪废水的处理成为可能.     

活性炭对焦化废水的吸附特性研究

采用活性炭对焦化废水进行吸附处理,考察了吸附时间、活性炭用量、pH值、吸附温度等工艺条件对处理效果的影响。结果表明,50 mL废水pH值为6,活性炭用量0.5 g,室温下吸附120 min后,焦化废水COD去除率达60%以上。该过程的吸附等温线可用Fre-undlich吸附等温式表示为：q=10-6.0 065c3.3 303;吸附热为26.35 kJ/mol;动力学方程可用班厄姆方程表示为：q=17.5-17.5exp（100.9053t-0.7839）。     

碳纳米管修饰电极对焦化废水的降解性能研究

文章制备了多壁碳纳米管修饰电极(MWCNT-ME)并考察了其对焦化废水中难降解有机物的电催化性能.对MWCNTME的表面形貌、有机污染物吸附性能及苯胺和苯酚单项污染物电化学特性进行初步表征分析,在此基础上结合气质联用(GC/MS)检测和COD检测分析对比了MWCNT-ME与IrSnSb金属电极对焦化废水中难降解有机污染...     

焦化废水尾水O3氧化消除消毒副产物生成潜能的影响分析

焦化废水经生化处理后的尾水中含有多种溶解性有机物(DOM),可能成为消毒副产物的前体物,进而影响受纳水体下游给水厂的水质安全.因此,对焦化废水外排水(尾水)的消毒副产物生成潜能进行了分析,以实际焦化废水厂尾水为基质,采用气相色谱(GC)考察了O3氧化深度处理前后卤乙腈和三卤甲烷的生成潜能,并结合分子质量分布法和三维荧光光谱法分析了O3氧化处理尾水过程中前体物的转化规律.GC结果表明,焦化废水尾水各个分子质量范围的卤乙腈和三卤甲烷生成潜能分别达到1950.5～3965.1μg.L-1和1498.2～2571.2μg.L-1,表明工业废水排放之前需要考虑其对水体消毒副产物生成潜能的贡献.O3氧化作用可以实现尾水中消毒副产物前体物的削减,相同反应时间的条件下O3浓度越高其削减越有效.溶解性有机碳(DOC)及在254nm波长下的吸光度值(UV254)分析结果表明,O3氧化能部分矿化尾水中的有机物,并优先分解不饱和芳香性有机组分.分子质量和荧光光谱分析结果表明,O3氧化优先矿化小分子组分(<1kDa),并将尾水中大分子有机物分解为小分子(<1kDa),对活泼基团进行预氧化,从而实现氯消毒副产物生成潜能的削减.     

焦化废水后物化处理的臭氧-混凝-吸附原理选择与协同机制

以焦化废水生物出水为研究对象,对比了活性炭吸附、混凝沉淀、臭氧氧化原理及其协同的工艺技术处理效果,考察处理前后废水的分子量分布、紫外可见光谱、三维荧光光谱（EEM）和GC/MS等表征的溶液性质变化.结果表明,废水生物工艺出水的后物化深度处理的最佳组合原理序列为臭氧-混凝-吸附,响应曲面模型预测的最优反应条件为：臭氧反应时间62.56 min,聚合硫酸铁（PFS）投加量为0.87 g·L^-1,以及活性炭投加量为1.10 g·L^-1.实验过程的总有机碳（TOC）去除率达到98.29%,与模拟值98.74%相对偏差为0.45%.活性炭吸附、混凝沉淀和臭氧氧化3种技术原理对焦化废水生物出水中污染物具有选择性分离与转化的作用,组合工艺能够实现废水中残余组分有机物、UV₂₅₄吸光物质、荧光物质等的有效去除,存在废水溶液性质与工艺技术原理有效性协同增强的操作空间.     

沸石的活化及其对水中氨氮的吸附

对天然沸石进行了盐活化、盐加酸活化、盐加碱活化、热活化和热活化后加盐二次活化的处理,分别考察了活化后沸石对氨氮的吸附性能,并进行了等温吸附、解吸试验以及对经SBR-氧化处理后焦化废水的吸附试验.结果表明,沸石在100℃下经0.3 mol·L-1NaCl活化后,对氨氮的吸附效果最佳;当活化沸石投加量为10 g·L-1、接触时间为40 min时,氨氮去除率可达88.08%,比未活化条件下的47.35%提高了40.73%.沸石投加量、废水的pH和接触时间对活化沸石吸附氨氮都存在一定的影响.活化沸石对氨氯废水的吸附等温线可用Freundlich方程拟合.吸附氨氮后的沸石经1.5 mol·L-1的NaCl溶液再生4 h,解吸率可达到89.30%.活化沸石用于经SBR-氯化处理后焦化废水的吸附试验,当活化沸石投加量为120 g·L-1时,其氨氮可从219.18 mg·L-1降到4.8 mg·L-1去除率达到97.81%;活化沸石吸附焦化废水的吸附等温线可用Freundlich方程和Langmuir方程来描述.     

生物活性炭吸附石化废水有机污染物实验研究

生物活性炭吸附石化二级废水有机污染物实验主要包括生物活性炭挂膜实验和生物活性碳影响因素实验。在实验中考察了水力负荷和活性炭滤层厚度两因素对有机污染物吸附作用。结果表明:在45 d左右挂膜基本成功,最佳水力负荷为0.25~0.75m3/(m2·h),活性炭滤层最佳厚度为90cm。     

臭氧流化床深度处理焦化废水尾水过程中有机组分变化分析

焦化废水处理工程中,经过生物和混凝处理后,排放到环境中的尾水COD处于(85±20)mg·L-1范围内,这部分COD主要由一些难生物降解的物质构成,对水体环境造成污染,也给水回用带来了技术上的难度.为实现尾水中残留有机物的进一步削减,降低其在环境当中的危害,采用臭氧流化床反应器对焦化废水尾水进行深度处理并通过三维荧光光谱仪以及气相色谱/质谱(GC/MS)分析其水质组成的变化.结果表明:尾水在反应过程中,投加的臭氧量与降解的COD之间的比值(O3(kg)/COD(kg))随反应时间的延长不断增大;当pH=10时,COD、UV254和色度的去除率分别为51.5%,87.3%和85.0%,去除效果优于pH=7和pH=5条件下的反应;臭氧氧化能够有效分解尾水中类色氨酸、类溶解性微生物副产物、类腐植酸和类酪氨酸物质;经臭氧氧化后,焦化废水尾水中一些难生物降解的有机物得到了部分或完全去除,转化为一些新的有机物,如烷烃、苯甲醇、己酸等物质.研究结果证明,影响尾水的臭氧氧化效率涉及反应器结构、废水溶液性质和反应条件.     

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.     

Oxidation of As(Ⅲ) by potassium permanganate

The oxidation of As(Ⅲ) with potassium permanganate was studied under conditions including pH, initial As(Ⅲ) concentration and dosage of Mn(Ⅶ). The results have shown that potassium permanganate was an effective agent for oxidizing of As(Ⅲ) in a wide pH range. The pH value of tested water was not a significant factor affecting the oxidation of As(Ⅲ) by Mn(Ⅶ). Although theoretical redox analyses suggest that Mn(Ⅶ) should have better performance in oxidization of As(Ⅲ) within lower pH ranges, the experimental results show that the oxidation efficiencies of As(Ⅲ) under basic and acidic conditions were similar, which may be due to the adsorption of As(Ⅲ) on the Mn(OH)2 and MnO2 resulting from the oxidation of As(Ⅲ).     

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.     

Chlorobenzenes in waterweeds from the Xijiang River （Guangdong section） of the Pearl River

The Xijiang River is the major source of water for about 4.5 millions of urban population and 28.7 millions of rural population. The water quality is very important for the health of the rural population. The concentration and distribution of chlorobenzenes (CBs) in both water and waterweeds collected from 4 stations in the Xijiang River (Gangdong section) of the Pearl River in April and November were determined. The result showed that nearly every congener of CBs was detected. The total contents of CBs (∑CBs) in the river water ranged from 111.1 to 360.0 ng/L in April and from 151.9 to 481.7 ng/L in November, respectively. The pollution level of CBs in the water in April was higher than that in November. The contents of ∑ CBs in waterweeds ranged from 13.53×102 μg/g to 38.27×102μg/g dry weight (dw). There was no significant difference between April and November in waterweeds. The distribution of CBs in roots, caulis, and leaves of Vallisneria spiralis L. showed different patterns. The leaves mainly contained low-molecular-weight CBs(DCBs), whereas the roots accumulated more PCBs and HCBs. The average lgBCFlip (bioconcentration factor) of CBs ranged from 0.64 to 3.57 in the waterweeds. The spatial distribution character of CBs in the Xijiang River was: Fengkai County ＜ Yunan County ＜Yun'an County ＜ Gaoyao County according to the ∑CBs, and the pollution deteriorated from the upstream to the downstream of the Xijiang River. Further analysis demonstrated that the discharge of waste containing CBs may be the main source of CBs pollution in the Xijiang River.     

Degradation of 2,4-dichlorophenol with a novel TiO2/Ti-Fe-graphite felt photoelectrocatalytic oxidation process

Degradation of 2,4-dichlorophenol(2,4-DCP)was studied in a novel three-electrode photoelectrocatalytic(PEC)integrative oxidation process,and the factors influencing the degradation rate,such as applied current,flow speed of O_2,pH,adscititious voltage and initial 2,4-DCP concentration were investigated and optimized.H_2O_2 was produced nearby cathode and Fe~(2 )continuously generated from Fe anode in solution when current and O_2 were applied,so,main reactions,H_2O_2-assisted TiO_2 PEC oxidation and E-Fenton reaction,occurred during degradation of 2,4-DCP in this integrative system.The degradation ratio of 2,4-DCP was 93% in this integrative oxidation process,while it was only 31% in E-Fenton process and 46% in H_2O_2-assisted TiO_2 PEC process.So,it revealed that the degradation of 2,4-DCP was improved greatly by photoelectrical cooperation effect.By the investigation of pH,it showed that this integrative process could work well in a wide pH range from pH 3 to pH 9.     

Effect of copper on the degradation of pesticides cypermethrin and cyhalothrin

The influence of coexisting copper (Cu) ion on the degradation of pesticides pyrethroid cypermethrin and cyhalothrin in soil and photodegradation in water system were studied.Serial concentrations of the pesticides with the addition of copper ion were spiked in the soil and incubated for a regular period of time,the analysis of the extracts from the soil was carried out using gas chromatography (GC).The photodegradation of pyrethroids in water system was conducted under UV irradiation.The effect of Cu~(2 ) on the pesticides degradation was measured with half life (t_(0.5)) of degradation.It was found that a negative correlation between the degradation of the pyrethroid pesticides in soil and Cu addition was observed.But Cu~(2 ) could accelerate photodegradation of the pyrethroids in water.The t_(0.5) for cyhalothrin extended from 6.7 to 6.8 d while for cypermethrin extended from 8.1 to 10.9 d with the presence of copper ion in soil.As for photodegradation,t_(0.5) for cyhalothrin reduced from 173.3 to 115.5 rain and for cypermethrin from 115.5 to 99.0 min.The results suggested that copper influenced the degradation of the pesticides in soil by affecting the activity of microorganisms.However, it had catalyst tendency for photodegradation in water system.The difference for the degradation efficiency of pyrethroid isomers in soil was also observed.Copper could obviously accelerate the degradation of some special isomers.     

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.