无排泥条件下的膜-生物反应器系统处理焦化废水可行性研究

小试规模浸没式厌氧/缺氧/好氧-膜-生物反应器(A1/A2/O-MBR)系统用于处理实际焦化废水,在无排泥条件下连续运行160 d.考察了长期运行条件下系统对不同污染物的去除性能,并通过亲疏水组分分离和三维荧光光谱法,对进出水焦化废水中溶解性有机物(DOMs)特征进行分析.结果表明,A1/A2/O-MBR系统能稳定去除88.0%±1.6%的COD,99.9%的挥发酚,99.4%±0.2%的浊度和98.3%±1.9%的NH4+-N,相应的平均出水浓度分别为249 mg/L±44 mg/L、0.18 mg/L±0.05 mg/L、1.0NTU±0.2 NTU和4.1 mg/L±4.3 mg/L;最大TN去除率可达到74.9%.在系统160 d运行过程中,MLVSS/MLSS维持在90.2%±1.0%,没有出现无机物的积累;污泥的表观产率(MLVSS/COD)逐渐降低并最终稳定在0.035 kg/kg.在焦化废水DOMs的疏水酸性、疏水中性、疏水碱性和亲水物4种组分中,疏水酸性物是进出水中最主要的溶解性有机碳(DOC)和色度组分,分别占进出水总DOC的70%和67%,总色度的75%和76%.三维荧光光谱分析表明腐殖质类物质是系统出水中残留的主要难降解有机物和致色物质.     

腐殖酸对铜的吸附与解吸特征

采用铜离子选择电极研究了铜在腐殖酸两组分(富里酸FA、胡敏酸HA)中的吸附-解吸特征,以及介质pH对这种吸附-解吸的影响。结果表明,腐殖酸对铜的吸附量为FA>HA,吸附强度为HA>FA,解吸量FA-Cu>HA-Cu。腐殖酸两组分对铜的吸附,当介质pH为4.00～7.00时,很好地符合Langmuir等温吸附方程;当pH<4.0时,符合Freundlich方程。FA、HA与铜作用的条件稳定常数与介质pH有关,pH提高则条件稳定常数增大;但在低pH段和高pH段,其增长规律不一致,当4.00相似文献   

不同方法对南方几种土壤阳离子交换性质的测定比较

分別采用1mol L~(-1) NH_4OAC淋洗法,0.1mol L~(-1)BaCl_2捕掳交换法,6.667×10~(-3)mol L~(-1)Co(NH_3)_6Cl_3提取法以及电荷测定法测定了南方几种不同性质的土壤的阳离子交换性质。结果表明,酸性土壤的阳离子交换量具有不定性,NH_4OAC法的结果很高,而其它方法的结果显著偏低,但方法间仍存在显著差异。不过,各法对微酸性、中性土壤的测定结果无显著差异。与NH_4OAC法相比,BaCl_2法得到较多的Ca,而Co法则交换出较少的K。各法的浸提液pH间虽存在差异,但彼此间有良好的统计相关性。Co法测定的CEC值与交换性阳离子总和较为吻合,其浸提液pH与pH_(KCl)、pH_(CaCl_2)有良好的线性关系。看来,不同方法对酸性土壤阳离子交换量的测定差异主要来自測定过程中介质pH条件及离子强度不同所浸出的交换性酸的多寡。本文认为,Co(NH_2)_6Cl_3法可以作为这些土壤阳离子交换性质测定的例行方法。     

Biodegradation behavior of agricultural pesticides in anaerobic batch reactors

This study explored the biodegradation potential of two agricultural pesticides (2,4-D and isoproturon) as well as their effect on the performance of the anaerobic digestion process. Three 3.5 L batch reactors were used, having the same initial isoproturon concentration (25 mg/L) and different 2,4-D concentrations (i.e. 0, 100, or 300 mg/L, respectively). All systems were fed with equal amounts of primary sludge and digested sludge and operated at the low mesophilic range (32 ± 2°C). Following an acclimation period of approximately 30 days, complete 2,4-D removal was achieved, whereas isoproturon biodegradation was practically negligible. The presence of 2,4-D did not have a direct effect on acidogenesis since soluble organic carbon [expressed either as volatile fatty acids (VFAs) or as total organic carbon (TOC)] peaked within the first 10 days of operation in all bioreactors. Utilization of VFAs however appeared to follow two distinct patterns: one pattern was represented by acetate and butyrate (i.e. no acid accumulation) while the other was followed by propionate, isobuturate, valerate and isovalerate (i.e. acid accumulation, duration of which was related to the initial 2,4-D concentration). On the whole, all reactors exhibited a successful digestion performance demonstrated by complete VFAs utilization, considerable gas production (containing 45 to 65% methane by volume), substantial volatile suspended solids (VSS) reduction (42 to 50%), as well as pH and alkalinity recovery.     

不同填埋年龄的矿化垃圾中胡敏酸的分子荧光光谱研究

对上海市老港填埋场封场6-10年矿化垃圾中的胡敏酸(HA)进行荧光光谱分析,结果表明,不同封场时间的矿化垃圾中HA的荧光光谱均为宽带峰型,pH值对HA荧光光谱的影响较小.而且随着矿化垃圾封场时间的加长,荧光特征峰波长缓慢增加.     

顶空CO2对有机物厌氧发酵产挥发性脂肪酸的影响

研究了不同顶空CO2浓度对有机物厌氧发酵体系中底物转化速率、挥发性脂肪酸(VFA)产率及微生物相变化的影响.结果表明,顶空低浓度CO2有助于葡萄糖底物转化,在16h转化率达到93%以上,顶空高浓度CO2和对照组在20h时转化率分别为88.3%、87.6%.顶空高浓度CO2有助于乙酸积累,乙酸产率达8.2mmol/gCOD,分别是对照组和低浓度CO2组的1.52倍和1.87倍.顶空CO2浓度与同型产乙酸菌数量正相关,顶空低浓度CO2组fhs基因拷贝数为9.83×106/mL,高浓度CO2组fhs基因拷贝数为5.32×108/mL,对照组fhs基因拷贝数为6.97×107/mL.提高顶空CO2浓度有利于在混和培养环境中富集同型产乙酸菌.     

河谷型城市土壤有害金属有机酸与细菌淋溶特性

在野外调查与前期研究的基础上,根据一点多样混合采样法收集宝鸡河谷型城市污染土壤样品50个.通过等温振荡平衡法研究了人工合成的螯合剂EDTA、DTPA、低分子有机酸草酸(Oxalic acid)、丁二酸(Butanedioic acid)、柠檬酸(Citrate)和枯草芽孢杆菌对城市污染土壤有害金属As、Cr、Cu、Pb、Sb、V、Zn的淋溶解吸特性.研究结果表明,EDTA、DTPA对宝鸡城市污染土壤As、Cr、Cu、Pb、Sb、V、Zn的整体淋溶解吸效果要优于草酸、丁二酸和柠檬酸.有机酸对宝鸡城市土壤有害金属As、Cr、Cu、Pb、Sb、V、Zn淋洗速率顺序为:柠檬酸:PbSbZn≈AsCuVCr;DTPA:Pb≥Cu≈ZnSbAsVCr;EDTA:Pb≥ZnCuSbAsVCr;草酸:PbSbAsVCuCr;丁二酸:CrPbSbAsVCu(丁二酸淋洗的Cr随时间缓慢增加).枯草芽孢杆菌对土壤有害金属淋溶具有pH和温度的依赖性,特别对Pb、Sb的淋溶解吸特为敏感,较高pH(pH=6)淋溶要大于低pH(pH=2).研究表明,枯草芽孢杆菌淋溶土壤有害金属是细菌本身、有机酸和淋溶液pH共同作用的过程.重金属Pb和Sb是宝鸡市环境污染与人群健康风险最主要的因子,因此,有机酸和细菌及其淋溶pH综合作用对西部河谷型城市土壤有害金属Pb、Sb复合污染的原位修复提供了新的思路.     

Pollution profiles and physicochemical parameters in old uncontrolled landfills

The long-term effectiveness of the geological barrier beneath municipal-waste landfills is a critical issue for soil and groundwater protection. This study examines natural clayey soils directly in contact with the waste deposited in three landfills over 12 years old in Spain. Several physicochemical and geological parameters were measured as a function of depth. Electrical conductivity (EC), water-soluble organic carbon (WSOC), Cl⁻, NH₄⁺, Na⁺ and exchangeable NH₄⁺ and Na⁺ were used as parameters to measure the penetration of landfill leachate pollution. Mineralogy, specific surface area and cationic-exchange capacities were analyzed to characterize the materials under the landfills. A principal component analysis, combined with a Varimax rotation, was applied to the data to determine patterns of association between samples and variables not evident upon initial inspection. The main factors explaining the variation in the data are related to waste composition and local geology. Although leachates have been in contact with clays for long time periods (13-24 years), WSOC and EC fronts are attenuated at depths of 0.2-1.5 m within the clay layer. Taking into account this depth of the clayey materials, these natural substrata (>45% illite-smectite-type sheet silicates) are suitable for confining leachate pollution and for complying with European legislation. This paper outlines the relevant differences in the clayey materials of the three landfills in which a diffusive flux attenuation capacity (A_c) is defined as a function (1) of the rate of decrease of the parameters per meter of material, (2) of the age and area of the landfill and (3) of the quantity and quality of the wastes.     

畜禽粪便堆腐过程中有机碳组分与腐熟指标的变化

以牛粪、菌糠、鸡粪等为材料按照两种比例调配为混合基质,在添加或不添加发酵启动剂的条件下在发酵罐中进行为期38 d的堆肥发酵试验,研究4种处理方式下畜禽粪便腐解过程中有机碳及其组分的变化,同时通过综合发芽指数(GI)评判腐解物料的腐熟度,确定GI与有机碳组分的关系.结果表明,添加发酵启动剂可以加速有机物质的降解,使水溶性有机碳和有机酸的含量下降(比初始值含量分别下降了41.85%、85.18%),促进类富里酸向胡敏酸转化,使畜禽粪便达到快速腐熟.在两种物料配比下,较高比例的牛粪不利于堆肥物质的分解和腐熟.根据达到腐熟要求的标准(GI0.8),当TOC357.27 g·kg-1,DOC7.00 g·kg-1,FA6.45 g·kg-1,腐解后期物料的红外光谱在1020 cm-1、1427 cm-1出现较为尖锐的峰值,即碳酸盐和硝酸盐含量增加,且草酸大幅度下降时,可以认为有机物料达到完全腐熟.当牛粪、菌糠、鸡粪的混合体积比为1∶1∶1时,在添加发酵启动剂条件下有机物料在腐解29 d时达到以上腐熟指标.     

两相厌氧系统中产甲烷相有机酸转化规律

研究了两相厌氧系统产甲烷相中有机酸转化规律.以产酸相、产甲烷相COD负荷分别为41.5 kg/(m³·d)、6.05kg/(m³·d)的连续流试验装置培养种泥,运行稳定后,进行静态试验采用气相色谱仪(GC-122型)分析有机酸组成及含量结果表明,反应器相同位置的微生物降解转化有机酸速率快慢依次为:乙酸＞乙醇＞丁酸＞丙酸;利用乙醇产乙酸的微生物与产甲烷菌所需最佳pH值范围相近;乙醇型发酵是充分发挥两相厌氧系统功能的最佳发酵类型;在产甲烷反应器中,大部分挥发酸的最终降解都要经历乙酸降解途径才能完成,造成乙酸的降解转化相对缓慢,成为厌氧工艺中的限速步骤.