用改性硅藻土、活性污泥处理城市垃圾渗滤液的研究

改性硅藻土对城市垃圾渗滤液处理仅限于去除渗滤液中的悬浮物.悬浮物和色度的去除率分别大于98%和96%,CODcr的去除率仅为18.1%～26.4%,而对NH3-N的去除没有任何作用.用特殊驯化过的活性污泥进一步处理改性硅藻土处理后的渗滤液,CODcr又可去除80%,NH3-N去除85%,处理废水达到垃圾渗滤液排放二级标准.     

改性废岩棉预处理垃圾渗滤液的实验研究

对废弃的玄武岩棉进行改性,改性后用于预处理垃圾渗滤液。结果表明:用7%PFS溶液浸泡,采用超声波以60%的频率振荡20 min,改性后废岩棉性能最佳;当岩棉用量为15 g,垃圾渗滤液pH为7时,用改性废岩棉处理垃圾渗滤液效果最佳,COD和浊度除率可达75.20%和98.75%,并对废岩棉可循环使用进行了研究。     

改性膨润土预处理垃圾渗滤液试验研究

以溴化十六烷基三甲基胺为改性剂制备了有机改性膨润土,并对其进行了性能表征。将其应用于COD高达20000～37000mg/L的垃圾渗滤液的预处理,以垃圾渗滤液的COD去除率为考察指标,对原土和有机改性土的处理效果进行了对比,确定了改性膨润土最佳用量以及最佳反应条件。研究结果表明,有机改性膨润土处理效果明显优于原土。在改性土用量为30g/L,pH值为5左右,搅拌时间为40min,静置时间为30min时,能够使垃圾渗滤液的COD去除率达到67%以上,减轻了下一步生物处理的负荷。     

硅藻土预处理垃圾渗滤液的试验研究

垃圾渗滤液成份复杂,较难处理。硅藻土具有较强的吸附性能和化学稳定性,因为硅藻土具有较好的絮凝沉淀性能,所以常应用于污水处理中。通过在渗滤液中进行硅藻土不同投加量的试验发现:硅藻土用量越大,絮凝效果越好;串联样中去除污染物的效果明显好于同等投加量的非串联样;在投加硅藻土的同时,适量复合其他絮凝剂像聚合氯化铝(PAC)等,处理效果会更好。后续处理如果再利用膜生物反应器(MBR),处理后的垃圾渗滤液排放标准将大大提高。     

海泡石、炉渣、改性钢渣吸附处理垃圾渗滤液中Cr(Ⅵ)的对比研究

为了选择低成本、高效果的处理垃圾渗滤液的吸附剂,本文通过静态吸附试验对比研究了海泡石、炉渣、改性钢渣对垃圾渗滤液中Cr6+的吸附规律,结果表明:吸附平衡时,炉渣对垃圾渗滤液中Cr6+的吸附量最大,为0.001 8mg/g,海泡石次之,为0.001 5mg/g,改性钢渣为0.000 9mg/g;酸性环境及低浓度有利于炉渣、改性钢渣吸附垃圾渗滤液中的Cr6+,且pH值及初始浓度对海泡石吸附垃圾渗滤液中Cr6+的效果影响较小;经综合比较,炉渣吸附性能最为优异。该研究成果可为开发新型吸附剂提供依据。     

硅藻土在城市污水和工业废水处理中的应用

硅藻土是由硅藻及其他微生物的硅质遗骸组成的生物硅质岩,具有巨大的比表面积和强大的表面吸附性能。硅藻土特殊的架构特征、分子筛功能使其在废水处理领域表现出越来越广泛的应用前景。本文介绍了硅藻土的物理化学性质,重点对硅藻土和改性硅藻土在城市污水、工业废水尤其是含重金属废水以及垃圾渗滤液中污染物的去除中的应用进行了研究,认为硅藻土作为一种新型的天然微孔材料,具有来源广泛、污水处理效果好等特点,并对硅藻土的改性方法和应用前景进行了展望。     

一种复配絮凝剂处理垃圾膜滤浓缩液的研究

以二甲胺(33%)、甲醛(37%)、杨梅单宁为原料制备出阳离子型改性单宁絮凝剂,并将其与三氯化铁无机絮凝剂进行复配用于处理垃圾渗滤液膜滤浓缩液,考察其对垃圾渗滤液膜滤浓缩液进行处理时的最优条件。试验表明,当阳离子型改性单宁絮凝剂为0.1 g/L,三氯化铁无机絮凝剂为4 g/L时,可以使垃圾渗滤液膜滤浓缩液的COD去除率达到60.43%,色度去除率达到91.67%。改性天然高分子絮凝剂无毒环保,与无机絮凝剂的复配处理垃圾渗滤液膜滤浓缩液具有较好的应用前景。     

活性焦对垃圾渗滤液中难降解有机物的吸附及影响因素研究

垃圾渗滤液经预处理后与城市污水混合进行生物处理是较为有效的方法,但垃圾渗滤液中含大量难降解有机物,严重影响了城镇污水处理厂出水COD.因此,需强化垃圾渗滤液预处理过程,使其适用于生物处理.本研究采用活性焦吸附某垃圾焚烧发电厂垃圾渗滤液,发现活性焦对垃圾渗滤液中COD、色度、恶臭、TOC、TN等均具有良好的处理效果.通过对吸附性能的影响因素研究发现,活性焦种类、投加量、p H和吸附时间均会影响吸附效果,最佳活性焦投加量为20 g·L~(-1),酸性条件更有利于吸附,渗滤液中COD的去除主要发生在吸附过程的前1 h.活性焦吸附可提高垃圾渗滤液的可生化性,主要吸附垃圾渗滤液中难降解芳香族大分子有机物,其中,对溶解性有机物中疏水性有机酸组分的吸附效果最佳,使其出水适用于生物处理,从而保证污水处理厂COD可以稳定达标排放.     

Fenton法处理垃圾渗滤液的研究

本文对Fenton试剂处理垃圾渗滤液进行了研究,探讨H2O2用量、n(H2O2):n(Fe2+)、pH值、反应时间等因素对COD和氨氮去除率的影响,结果表明:Fenton法对垃圾渗滤液中COD具有良好的处理效果,最佳条件是:初始pH值为4,n(H2O2)∶n(Fe2+)为2∶1,反应时间为1 h,垃圾渗滤液的COD去除率可达70.8%。但单独采用Fenton法对垃圾渗滤液中氨氮的处理效果不明显。     

改性膨润土处理垃圾渗滤液的研究

介绍了一种采用膨润土处理垃圾渗滤液的方法。通过对钠基及膨润土进行改性,增加膨润土对污染物的吸附能力,再将其应用于垃圾渗滤液的处理中。主要用以处理经过MBR处理后的难以被生物降解的废水。当原水化学需氧量ρ(COD)为866 mg/L时,通过投加聚合氯化铝铁(PAFC)及改性膨润土,出水ρ(COD)为63 mg/L,达《生活垃圾填埋场污染控制标准》中垃圾渗滤液污染排放控制要求。     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.     

Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Sorption of 1-naphthol by plant cuticular fractions

The contribution of aliphatic-rich plant biopolymer to sorption of hydrophobic organic compounds is significantly important because of their preservation and accumulation in the soil environment,but sorption mechanism is still not fully understood.In this study, sorption of 1-naphthol by plant cuticular fractions was examined to better understand the contributions of respective fraction.Toward this end,cuticular materials were isolated from the fruits of tomato by chemical method.The tomato cuticle sheet consisted of waxes (6.5 wt%),cuticular monomer (69.5 wt%),and polysaccharide (24.0 wt%).Isotherms of l-naphthol to the cuticular fractions were nonlinear (N value (0.82-0.90)) at the whole tested concentration ranges.The KodKow ratios for bulk cuticle (TC1),dewaxed cuticle (TC2),cutin (TC4),and desugared cuticle (TC5) were larger than unity,suggested that tomato bulk cuticle and cutin are much powerful solption medium.Sorption capability of cutin (TC4) was 2.4 times higher than the nonsaponifiable fraction (TC3).The 1-naphthol interactions with tomato cuticular materials were governed by both hydrophobic-type interactions and polar (H-bonding) interactions. Removal of the wax and polysaccharide materials from the bulk tomato cuticle caused a significant increase in the sorption ability of the cuticular material.There was a linear negative trend between K_(oc) values and the amount of polysaccharides or fraction's polarities ((N O)/C);while a linear positive relationship between K_(oc) values and the content of cutin monomer (linear R~2=0.993) was observed for present in the cuticular fractions.Predominant sorbent of the hydrophobic organic compounds (HOCs) in the plant cuticular fraction was the cutin monomer,contributing to 91.7% of the total sorption of tomato bulk cuticle.     

Alterations of organ histopathology and metallolhionein mRNA expression in silver barb, Puntius gonionotus during subchronic cadmium exposure

Common silver barb,Puntius gonionotus,exposed to the nominal concentration of 0.06 mg/L Cd for 60 d,were assessed for histopathological alterations(gills,liver and kidney),metal accumulation,and metallothionein(MT)mRNA expression.Fish exhibited pathological symptoms such as hypertrophy and hyperplasia of primary and secondary gill lamellae,vacuolization in hepatocytes,and prominent tubular and glomerular damage in the kidney.In addition,kidney accumulated the highest content of cadmium,more than gills and liver.Expression of MT mRNA was increased in both liver and kidney of treated fish.Hepatic MT levels remained high after fish were removed to Cd-free water.In contrast,MT expression in kidney was peaked after 28 d of treatment and drastically dropped when fish were removed to Cd-free water.The high concentrations of Cd in hepatic tissues indicated an accumulation site or permanent damage on this tissue.     

Seed selections for crystallization of calcium phosphate for phosphorus recovery

Seed induces and promotes the crystallization of calcium phosphate, and acts as carrier of the recovered phosphorus （P）. In order to select suitable seed for P recovery from wastewater, three seeds including Apatite （AP）, Juraperle （JP） and phosphate-modified Juraperle （M-JP） were tested and compared. Batch and fixed-bed column experiments of seeded crystallization of calcium phosphate were undertaken by using synthetic wastewater with 10 mg/L P phosphate. It shows that AP has bad enduring property in the crystallization process, while JP has better performance for multiple uses, and M-JP is a hopeful seed for P recovery by crystallization of calcium phosphate.