UASB-SBR处理生物柴油制环氧脂肪酸甲酯废水

采用上流式厌氧污泥床(UASB)-序批式活性污泥法反应器(SBR)组合工艺处理生物柴油制环氧脂肪酸甲酯废水,考察了反应器各个阶段废水的处理效果。试验结果表明:当调整废水的氧化还原电位(ORP)降至-50~+50mV,UASB稳定运行阶段进水COD约为6 000mg/L时,出水COD在1 300mg/L以下,COD去除率约为80%,VFA浓度为180mg/L(以乙酸计)左右,最佳容积负荷为6.0kg/(m3·d);采用SBR处理UASB出水,当容积负荷为1.27kg/(m3·d)时,出水COD在250mg/L以下,COD去除率在80%以上,氨氮浓度在25mg/L以下,TP浓度在4mg/L以下,且处理后废水的COD、氨氮浓度、TP浓度均达到《污水排入城市下水道水质标准》(CJ343—2010)的A级要求。     

皂素生产废水处理方法比较研究

皂素生产废水为难处理高浓度酸性含硫有机废水,目前常用处理工艺为UASB+SBR,但该工艺运行效果较差。文章对UASB+SBR改进工艺进行了比较研究,结果表明:在UASB中加入适量铁屑和颗粒活性炭解除了SO42-的二次抑制,COD去除率比对照组UASB高2%～3%,出水水质COD一直稳定在1300mg/L左右,去除率在95%以上,出水无异味。UASB中污泥增长速率约为0.0686d-1,是仅加活性炭污泥增长速率(0.0197d-1)的3.48倍,可见加入铁屑后污泥增长速率改变明显。该改进UASB+SBR工艺的COD去除率高于对照组,出水COD维持在200mg/L以下,略带浅黄色(20倍左右),低于GB8978-1996《污水综合排放标准》原料药料二级排放标准值(300mg/L),SBR污泥增长速率为0.3083d-1,略高于对照组。     

常温条件下UASB+SBR工艺处理甲胺、甲醇废水试验研究

甲胺、甲醇及其产品均具有较强的毒性和危险性,因此含甲胺的废水须经一定处理达标后才能排放.以山东肥城某化工厂含甲胺、甲醇混合(体积比1∶1)废水.在常温条件下,采用厌氧 好氧(UASB SBR)2级串联组合工艺进行处理.该甲胺,甲醇混合废水呈酸性,COD浓度较高.其BOD与COD比值为0.64.可生化性良好.试验中调整、控制UASB和SBR反应器的各运行参数,通过检测处理效果比较得出该工艺在常温条件下处理该化工废水的最佳运行参数值.试验结果表明UASB在常温下运行81d,启动基本完成.UASB最佳水力停留时间为24h整个工艺对COD有机物有一定的去除效果,COD平均去除率为68.14%;系统的TN去除效率较为稳定.平均去除率可达72.3%.出水TN浓度在16.56mg/L以下;系统有一定的抗冲击负荷能力,但不是很强;系统有一定的耐低温性,低温环境下(9.0～14.2'C.平均为12.3℃)系统COD平均去除率为55.80%,UASB反应器未发生酸化现象.     

果蔬汁饮料废水的混凝强化试验研究

某饮料厂采用"UASB+BAF"工艺处理该厂的果蔬汁饮料废水,但UASB出水中COD、SS浓度较高,不能直接作为BAF的进水。研究表明,用931型复合混凝剂对UASB出水进行强化处理后可满足后续处理要求。在931投加量为40 mg/L、PAM-投加量为1 mg/L、pH=6的条件下,混凝效果最好,出水中COD和SS分别在800mg/L以下和80 mg/L以下,去除率分别在40%和85%以上。现场运行数据表明,混凝强化处理后的出水水质稳定,完全可满足BAF进水的要求。混凝沉淀的总运行成本约0.25元/m3,运行成本合理,具有较高的应用价值。     

UASB工艺对饮料废水去除效果

采用UASB工艺在饮料废水去除COD的效果,废水水质为CODCr≤3000mg/L,处理出水CODCr≤600mg/L。工程实践表明该处理系统具有处理效果稳定,运行管理简便,运行费用低等优点。     

处理DMF废水连续流和SBR两系统污泥毒性对比研究

以处理难降解有机污染物N,N-二甲基甲酰胺(DMF)模拟废水的好氧活性污泥系统为研究对象,考察污泥毒性的形成规律及空间分布。污泥经120 mg/L的DMF冲击驯化后,继续提高DMF浓度至200 mg/L进行驯化。在相同DMF浓度下,对比连续流和间歇式(SBR)两系统的出水COD浓度、水泥相DMF含量及污泥毒性变化趋势和空间分布。结果表明,连续流和SBR两系统均能很好的降解DMF。但在稳定运行周期末,不管DMF浓度是120 mg/L还是200 mg/L,连续流系统污泥毒性均高于SBR系统,连续流系统污泥毒性平均为57%,55%;间歇式污泥毒性平均为47%,42%。故从污泥土地利用和污泥毒性消减的角度考虑,SBR系统是处理DMF废水的理想选择。     

探讨UASB反应器处理浓缩果汁废水的控制条件

文章用厌氧颗粒污泥接种启动UASB反应器,通过调节碱度和出水回流来实现浓缩果汁废水在低碱度下的稳定运行。研究结果表明:经35天UASB反应器可完全启动,负荷为9.5gCOD(/L·d),COD去除率在80%以上;回流比为0.3,进水碱度和pH值分别为1500mg/L和6.75、1000mg/L和6.52时,反应器能够稳定运行;采用出水回流的方法可以使酸性的浓缩果汁废水厌氧处理大幅度降低用碱量甚至完全不加碱的条件下实现稳定运行,本试验在回流比为8~10时,反应器也有很好的处理效果。通过对其控制条件实验室研究,显著的降低了浓缩果汁废水的处理成本,在工程上具有广泛的应用性。     

UASB反应器处理CMC废水的启动特性研究

采用上流式厌氧污泥床(UASB)反应器,以高浓度羧甲基纤维素(CMC)废水为处理对象,研究了中温条件下UASB反应器的启动、颗粒污泥特性和废水处理效果.结果表明,采用接种颗粒污泥与消化污泥的混合泥进行培养,并逐步提高进水CMC废水浓度,运行80 d后,可实现UASB反应器的启动;当进水COD值达到4 000 mg/L,容积负荷6.86 kg/(m3.d),COD去除率在80%以上;反应器内污泥实现颗粒化,且颗粒污泥的比产甲烷活性良好.     

厌氧处理乙酸丁酯废水的实验研究

乙酸丁酯废水是一种重要的化工原料,每生产一顿乙酸丁酯可产生140kg废水,本实验利用3L上流式厌氧污泥床UASB反应器在中温条件下处理高浓度乙酸丁酯废水。当UASB反应器稳定运行时,进水CODcr=10000mg／L时,容积负荷可达到13kgCOD／（m^3d）,水力停留时间24h,COD去除率可以达到80％以上,出水COD小于2000mg／L。通过本试验取得的良好试验效果,为处理乙酸丁酯废水找出了可行的途径。     

电解-SBR法处理制药废水试验研究

采用电解 SBR串联工艺处理化学合成制药废水 ,试验分别考察了电解电压、pH以及电解时间对电解效果的影响 ,不同电解时间对后续SBR反应器处理效果的影响。结果表明 ,原水BOD5/COD仅为 0 .1 7,是难生物降解废水 ,经过电解法预处理后 ,出水BOD5/COD可达到 0 .51 ,可生化性大大提高 ,但电解时间过长反而有可能使废水可生化性下降。在进水COD在 2 0 0 0mg/L以下时 ,出水水质可达GB8978- 1 996的二级排放标准     

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).     

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.     

Effects of arsenic on seed germination and physiological activities in wheat seedlings

The effects of arsenic(As)were investigated on seed germination,root and shoot length and their biomass and some other factors to elucidate the toxicity of As.The results showed low concentrations of As(O-1 mg/kg)stimulated seed germination and the growth of root and shoot,however,these factors all decreased gradually at high concentrations of As(5-20 mg/kg).The contents Of O2-,MDA,soluble protein and peroxidase(POD)activity all increased with increasing As concentrations.Soluble sugar content,ascorbate peroxidase(APX),and superoxide dismutase(SOD)activities decreased at low concentrations of As,and increased at high concentrations of As.While acetylsalicylic acid(ASA)and chlorophyll contents,catalase(CAT)activity displayed increasing trend when the concentrations of As was lower than 1 mg/kg,and then decreasing trend.By polyacrylamide gel electrophoresis(PAGE).As induced the expression of POD isozymes of wheat seedlings.As induced the expression of CAT isozymes but inhibited the expression of SOD isozymes of wheat seedlings at concentrations lower than 1 mg/kg.However,As inhibited the expression of CAT isozymes but induced the expression of SOD isozymes at concentrations higher than 5 mg/kg.The results indicated As could exert harmfulness in the early development stage of wheat at inappropriate concentrations.     

Sustainability： A view from the wind-eroded field

This article explores the assessment of sustainability in fields subject to wind erosion. In the first part, simple sustainability audits are examined, as of soil depth and nutrients. Direct measurement of these characteristics has many problems, largely because of huge variability in space and time at all scales. Modelling still has its problems, but it may be possible to overcome many of them soon. It is true that wind erosion preferentially removes soil nutrients, but there are imponderables even here. The nutrient balance in many of these soils includes considerable input from dust. In West Africa, it has been shown that the amounts of calcium and potassium that are added in dust are sufficient to fertilize dispersed crops. In mildly acidic sandy soils, such as those found on the widespread palaeo- aeolian deposits, much of the phosphorus is fixed and unavailable to plants by the time it is removed by wind erosion, so that erosion has no added downside. Most of the nutrients carried by dust have been shown to travel close to the ground （even when they are attached to dust-sized particles）, and so are trapped in nearby fallow strips, and are thus not lost to the farming system. Second, the sustalnabillty of a whole semi-arid farming system is explored. Wind erosion in semi-arid areas （like China, the Sahel and Norflawestern Europe） generally takes place on aeolian deposits of the recent geological past. Most of these soils are deep enough to withstand centuries of wind erosion before they are totally lost to production, and some of these soils have greater fertility at greater depth （so that wind erosion may even improve the soil）. Finally some remarks are made about environmental change in relation to sustainability.     

Bioconcentration kinetics of PCBs in various parts of the lifecycle of the tadpoles Xenopus laevis

Polychlorinated biphenyls （PCBs） in Xenopus laevis have been reported only for a few congeners. Additionally, there is very little information on the ability of Xenopus laevis to bioconcentrate PCBs. To address these issues, the tadpole Xenopus laevis was exposed to Aroclor 1254 mixtures in water at room temperature for 110 d followed by an additional 110 d of nonspiked PCBs in the water for the control group. During the whole process, bioconcentration factors （BCFs） of PCBs ranged from 1180 to 15670. For most PCB congeners, the highest and lowest bioconcentrations of the kinetic curves were found to be remarkably simultaneous, respectively. All 141 PCB congeners under the same experimental conditions had no linear correlation on the lgBCF versus lgKow relationship. The relationship between lgBCFs and lgKow followed a parabolic pattern indicative of selective bioconcentration, suggesting that the kinetic curves of the PCB congeners observed in the lifecycle of the tadpoles may be concentrated due to the amphibian special species and internal metabolism. In contrast, lgBCFs for PCBs were inversely related to lgKow, suggesting that a metabolism of the higher Kow PCB congeners occurred. These results support the author＇s conclusion that the tadpole Xenopus laevis plays major roles in the bioconcentration of PCB congeners, and demonstrated that the exposure kinetic curves of PCB congeners are complex. Besides the amphibian metamorphous development, the lifecycle of the tadpole Xenopus laevis also may be of importance in determining the bioconcentration of PCB congeners.     

Amplification of plasmid DNA bound on soil colloidal particles and clay minerals by the polymerase chain reaction

Polymerase chain reaction(PCR)was used to amplify a 600-base pair(bp)sequence of plasmid pGEX-2T DNA bound on soil colloidal particles from Brown soil(Alfisol)and Red soil(Ultisol),and three different minerals(goethite,kaolinite,montmorillonite). DNA bound on soil colloids,kaolinite,and montmorillonite was not amplified when the complexes were used directly but amplification occurred when the soil colloid or kaolinite-DNA complex was diluted,10- and 20-fold.The montmorillonite-DNA complex required at least 100-fold dilution before amplification could be detected.DNA bound on goethile was amplified irrespective of whether the complex was used directly,or diluted 10- and 20-fold.The amplification of mineral-bound plasmid DNA by PCR is,therefore,markedly influenced by the type and concentration of minerals used.This information is of fundamental importance to soil molecular microbial ecology with particular reference to monitoring the fate of genetically engineered microorganisms and their recombinant DNA in soil environments.     

Arsenic uptake and transport of Pteris vittata L. as influenced by phosphate and inorganic arsenic species under sand cu｜ture

In order to understand the similarity or difference of inorganic As species uptake and transport related to phosphorus in As-hyperaccumulator, uptake and transport of arsenate (As(Ⅴ)) and arsenite (As(Ⅲ)) were studied using Pteris vittata L. under sand culture. Higher concentrations of phosphate were found to inhibit accumulation of arsenate and arsenite in the fronds of P. vittata. The reduction in As accumulation was greater in old fronds than in young fronds, and relatively weak in root and rhizome. Moderate increases, from 0.05 to 0.3 mmol/L, in phosphate reduced uptake of As(Ⅲ) more than As(Ⅴ), while the reverse was observed at high concentrations of phosphate (≥ 1.0 mmol/L). Phosphate apparently reduced As transport and the proportion of As accumulated in fronds of P. vittata when As was supplied as As(Ⅴ). It may in part be due to competition between phosphorus and As(Ⅴ) during transport. In contrast, phosphate had a much smaller effect on As transport when the As was supplied as As(Ⅲ). Therefore, the results from present experiments indicates that a higher concentration of phosphate suppressed As accumulation and transport in P. vittata, especially in the fronds, when exposure to As(Ⅴ); but the suppression of phosphate to As transport in the root or rhizome may be insignificant when P. vittata when exposure to As(Ⅲ) under sand culture conditions. The finding will help to understand the interaction of P and As during their uptake process in P. vittata.