催化还原法净化处理氮氧化物的工程实例

针对不锈钢产品酸洗处理过程中产生的氮氧化物浓度高、对大气污染的影响大、且难于净化治理等特性,在上海某不锈钢项目中设计了一套酸雾净化系统。该设计解决了酸洗中产生的氮氧化物难以净化的问题,提升了氮氧化物处理技术,它将成为不锈钢酸洗行业中氮氧化物净化处理技术的发展方向。     

不锈钢酸洗钝化含氟废水处理

引言不锈钢经过酸洗,钝化处理可以在表面生成一层均匀的氧化膜,提高不锈钢设备的耐蚀性,延长使用寿命。在不锈钢酸洗、钝化工艺中我们使用的酸洗液为HF5％(v/v％),HNO_310％(v/v％)水溶液。我厂含氟废水来自不锈钢酸洗废水。规定的氟的最高允许排放浓度为10mg/升,水中含有过量的氟对人体健康有很大影响,特别是对发育期儿童可造成斑齿和骨胳变质等     

化学法处理不锈钢酸洗废水技术

采用化学法处理不锈钢酸洗废水.去除其中的重金属离子,中和后使PH值呈中性,达到国家排放标准.     

钢铁酸洗废水资源化工艺研究

介绍了酸洗废水资源化的几种工艺:蒸发、喷雾焙烧、膜分离、结晶、离子交换。分析了这些技术的原理及优缺点,并与欧盟最佳可行技术的要求进行了比较,对酸洗废水的资源化处理进行了展望。     

中和沉淀—混凝气浮法在废水处理中的应用

本文介绍营口铁尔曼。辽河不锈钢制品有限公司用“中和－隔油－混凝沉淀－混凝气浮－过滤”工艺处理不锈钢原料板脱脂，酸洗钝化废水的运行状况，并指出运行中存在的问题及改进的方法。     

扩散渗析—电渗析法回收盐酸酸洗废水中的酸和铁

为了达到盐酸酸洗废水＂零排放＂的要求,采用扩散渗析—电渗析联合工艺技术,进行回收酸洗废水中的盐酸和铁的试验研究。考察了扩散渗析装置料液进水流量、蒸馏水与酸洗废水流量比、电渗析装置阴极室进水pH值、阴极室和阳极室进水流量和槽电压对酸洗废水中盐酸和铁回收效果的影响。结果表明,用不锈钢作阴极,自制改性Ti/SnO2-Sb2O3/PbO2电极作阳极,采用DF120型均相阴离子交换膜,当扩散渗析装置料液进水流量为0.35L/h,维持蒸馏水与酸洗废水流量比为1,电渗析装置阴极室进水pH值为2.50,阴极室和阳极室进水流量为0.06L/h,槽电压为10V时,回收盐酸浓度平均为0.2mol/L,盐酸回收率平均为66.7%;出水中Fe2＋浓度平均为99.5mg/L,铁回收率均可达到88%。     

渗析法处理回收硝酸、氢氟酸的试验研究

<正> 1 前言不锈钢及高温合金材料,在加工过程中其表面产生一层氧化物通常是用酸洗法去除。酸洗经常采用的是盐酸、硫酸,对于不锈钢和特殊钢则用混酸酸洗。采用硝酸-氢氟酸混酸酸洗,具有酸洗速度快,钢材表面质量好,且不易过酸洗的优点。目前国内外生产不锈钢的厂家大多采用硝酸-氢氟酸混合酸酸洗去除不锈钢表面的氧化层。经多次酸洗,酸洗液中的金属离子增加到一定浓度,含酸量降低,失去酸洗能力即成为废液。该废液中除含有硝酸、氢氟酸外还含有     

不锈钢酸洗废水的化学还原沉淀法处理

无锡县自动焊丝厂在用混合酸(HF+HNO_3)处理不锈钢材料表面氧化膜的过程中,产生一定量的倒槽废酸和酸洗后的冲洗水。其主要污染物为:F~-、NO_3~-、Cr~(6+)、Cr~(3+)、Ni~(2+)、Fe~(2+)等,且酸性很强。本文介绍采用铁屑还原-石灰乳沉淀法处理此种酸洗废水,获得了满意的效果。该法最大的优点在于应用了铁屑还原技术,同时解决了Cr~(6+)还原、酸度降低这两个问题,能减少中和剂的用量。     

某金属制品厂酸洗废水综合治理的工程实践

摘要：通过分析金属酸洗废水的特．最，采用混凝十沉淀法对某金属制品厂废水进行处理达标排放后经中水回用到生产车问的工程实践。其运行证明，该处理工艺具有工程费用低，运行稳定，维护方便，效果显著的优点，为酸洗清洗废水的处理提供了一种简单而行之有效的方法。     

含铬废水的回收利用与处理

含铬废水的来源铬与铬的化合物具有一系列重要用途,广泛用于多种工业部门。含铬废水中铬的存在形式有六价和三价两种。六价铬产生于机械、航空、仪表、电气和医疗器械制造工业的电镀厂(或车间),电解研磨企业,以及制造铬酸盐和三氧化二铬的工厂。三价铬产生干皮革厂的铬鞣车间,染料厂的还原咔叽2G车间,制药厂的对硝基甲酸车间,以及某些化工厂、香料厂。此外在石油炼厂等企业,把铬的化合物加入冷却水中以抑制腐蚀,在对不锈钢制品进行酸洗处理,以及由于不锈钢和其它铬合金材料遭受腐蚀而     

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.