铁盐和铝盐混凝对印染废水生化出水中溶解性有机污染物的去除特性

以三氯化铁和硫酸铝为混凝剂,印染废水二级生化出水为研究对象,并利用XAD-8/XAD-4吸附树脂联用技术将印染废水生化出水中溶解性有机物分为疏水酸、非酸疏水物质、弱疏水物质及亲水物质4类有机物,通过小试实验探讨了2种混凝剂对生化出水中各类溶解性有机物的去除效果及特点。实验结果表明,对于该印染废水的生化出水,溶解性有机物的主要成分是疏水性物质,以DOC表征时占总DOC的75%,其中疏水酸约占41%,疏水性物质也是引起色度的主要物质,所占比例以ADMI7.6表征时为89%,其中以非酸疏水物质的贡献最大,达到52%,并且非酸疏水物质中不饱和双键或芳香环有机物的含量较高。在三氯化铁和硫酸铝各自最佳的混凝条件下,均能够有效去除由疏水性物质（疏水酸和非酸疏水物质）引起的色度,但三氯化铁对弱疏水性物质以及亲水物质的去除率高于硫酸铝,这使得三氯化铁对印染废水生化出水中的溶解性有机物的去除效果优于硫酸铝。并且三氯化铁和硫酸铝混凝工艺均能明显降低生化出水的毒性。     

丙烯腈废水及几种处理工艺出水的毒性

分别利用小麦、发光菌毒性测试技术研究了模拟丙烯腈废水以及几种处理工艺出水对小麦芽伸长、根伸长、发芽率和发光菌发光度的毒性效应差异。结果表明,丙烯腈对小麦芽伸长的毒性影响最大;各类物质对小麦根伸长和发芽率并未造成毒性影响;其他物质对发光菌发光度的毒性最大。模拟废水对小麦芽伸长、根伸长、发芽率和发光菌发光度的毒性效应分别为:部分相加、部分相加、协同和拮抗作用。几种处理工艺出水对上述指标的毒性影响顺序依次是:模拟废水加成出水活性炭吸附出水Fenton法出水;Fenton法出水模拟废水加成出水活性炭吸附出水;Fenton法出水活性炭吸附出水模拟废水加成出水;活性炭吸附出水加成出水Fenton法出水模拟废水。比较几种处理工艺出水的毒性发现,几乎每种废水的毒性都有所降低,这说明几种处理工艺能有效降低模拟废水的毒性,具有深刻的实际指导意义。     

Treatment of dye-containing effluents with different bentonites

Six different bentonites were studied for colour removal from dye-containing effluents. Two dyes of each of the basic, acid and direct categories were studied. Because of good results we have received with relatively small amounts of bentonite we propose this material as an effective and cheap adsorbent for this purpose.     

Estimation of the volatilization of organic compounds from soil surfaces

Several simple models for the estimation of the half-life (t(1/2)) for the depletion of an organic chemical from a soil surface to air were examined. For moist surfaces, two models are proposed: the first requires knowledge of the soil/organic carbon partition coefficient (K(oc)) and the Henry's law constant (H) and the second the vapor pressure (P(s)) of the chemical involved. Due to uncertainties in the experimental K(oc) values those ones predicted by the group-contribution model of Meylan et al. [Environ. Sci. Technol. 26 (1992) 1560]-and proposed by the U.S. Environmental Protection Agency (EPA)-should be used. If reliable experimental P(s) values are not available, the first model is proposed, where in cases when H values are not available, predicted ones by the Bond-Contribution method of Meylan and Howard [Environ. Toxicol. Chem. 10 (1991) 1283]-and also proposed by EPA-can be used. In general, the agreement of the predicted t(1/2) values with the measured ones is within a factor of 3-5. Similar expressions, but with somewhat poorer results, are presented for dry field soils. In all cases, the obtained results represent a substantial improvement over those obtained with the currently used Dow method: t(1/2) = 1.58 x 10(-8)((K(oc) x S)/P(S)), where S is the solubility of the compound in water.     

Bioavailability of dissolved organic nitrogen in treated effluents.

The research objective was to assess dissolved organic nitrogen (DON) bioavailability in wastewater effluents from a pilot-scale nitrification plant and a laboratory-scale total nitrogen (TN) removal plant. The DON bioavailability was assessed using a 14-day bioassay protocol containing bacterial and algal inocula. Nitrogen species, dissolved organic carbon, chlorophyll a, and biomass (as total suspended solids and culturable cell counts) concentrations were measured to assess DON bioavailability. The results showed an increase in algal chlorophyll a concentration, with a concurrent increase in algal biomass over time; increased bacterial counts and a decrease in DON concentration over time; and increased carbon-to-nitrogen ratio at the end of the 14-day bioassay, indicating effluent DON bioavailability to algae and bacteria. Approximately 18 to 61% of the initial DON in low-total-nitrogen wastewater effluent (TN = 4 to 5 mg/L) sample was bioavailable. The results show that bacteria and algae uptake and release DON during their growth.     

催化臭氧氧化降解PCB有机废液及其机理

为了高效、快速治理高浓度难降解PCB(printed circuit board)有机废液,研究了氧化钙非均相催化臭氧氧化降解PCB废液的催化机理和催化性能。采用叔丁醇淬灭自由基实验和水杨酸羟基化实验探究催化机理;通过GC/MS研究了PCB废液中有机物可能降解途径;通过单纯形优化法对实验因素进行优化,并通过XRD和BET探究催化剂的循环稳定性。结果表明：氧化钙非均相催化臭氧氧化过程遵循羟基自由基机理;在pH为12.97、CaO质量为1.0 g、废液深度为11 cm、降解时间为150 min、臭氧用量为120 mg·min⁻¹时,COD去除率可达到90.045%;氧化钙经过5次循环后,废液的COD去除率没有显著降低,从92.78%降低至84.04%。CaO应用于催化臭氧氧化过程处理高浓度且难降解的PCB废液,能维持良好的催化性能和循环稳定性,具有良好的应用前景。     

Use of hydrophilic and hydrophobic microfiltration membranes to remove microorganisms and organic pollutants from primary effluents.

Primary-effluent wastewater from the Allegheny County Sanitary Authority (Pennsylvania) was used as a surrogate for combined-sewer-overflow waters contained in the sewershed. Pathogens contained in combined-primary-effluent wastewaters or combined-sewer overflows (CSOs) may pose a human-health threat to those coming in contact with such receiving waters. Polymeric ultra- and nano-membranes can be used to capture these microorganisms from CSOs. This research investigates the ability of polymeric hydrophobic and hydrophilic membranes, ranging in pore size from 0.2 to 0.8 microm, to remove pathogen-indicator organisms (Escherichia coli, enterococcus, and fecal coliforms). Membranes, with pore size 0.45 microm and smaller, were able to reduce the bacteria levels to nondetectable levels, with the sole exception of one membrane with pore size 0.3 microm.     

复合电化学法处理含盐有机废水

研究了复合电化学法处理含盐，酚废水的可行性及处理效果，实验结果表明，在110－160℃，PH3-3.5，处理电压5V，电流密度6-9mA/cm^2,H2O2/苯酚（质量比）＞0．06时，200mg/L的苯酚溶液经处理后，酚去除率大于98％，CODCr去除率大于70％，该法电能消耗低，是一种适合于含盐有机废水处理的新方法。     

Emissions of unintentional persistent organic pollutants from open burning of municipal solid waste from developing countries

Open burning of waste is the most significant source of polychlorinated dibenzo-para-dioxins and dibenzofurans (PCDD/PCDF) in many national inventories prepared pursuant to the Stockholm Convention on Persistent Organic Pollutants. This is particularly true for developing countries. Emission factors for POPs such as PCDD/PCDF, dioxin-like polychlorinated biphenyls (dl-PCB) and penta- and hexachlorobenzenes (PeCBz/HCB) from open burning of municipal solid waste in China and Mexico are reported herein. Six different waste sources were studied varying from urban-industrial to semi-urban to rural. For PCDD/PCDF, the emission factors to air ranged from 3.0 to 650 ng TEQ kg⁻¹ waste and for dl-PCB from 0.092 to 54 ng TEQ kg⁻¹ waste. Emission factors for PeCBz (17-1200 ng kg⁻¹ waste) and HCB (24-1300 ng kg⁻¹ waste) spanned a wide but similar range. Within the datasets there is no indication of significant waste composition effect on emission factor with the exception of significantly higher Mexico rural samples.     

Influence of pH on adsorption of dye-containing effluents with different bentonites

The influence of pH on adsorption of dye-containing effluents with three different bentonites was studied. One dye of each of the basic, acid and direct categories were studied. A considerable increase of dye adsorption degree was observed in different pH.     

改性TiO_2/浮石光催化去除二级出水中有机物

为了实现城市污水厂二级出水的回用,将La3＋、Fe3＋共掺杂TiO2/浮石光催化用于二级出水中有机物的去除。在优化工艺条件下,该方法对TOC的去除率为49.0%,对UV254的去除率为76.5%;出水BDOC/DOC值大幅度提高,由最初的0.21提高到0.56,增加了出水的可生化性;二级出水中存在着影响光催化去除有机物的因素,其中阴离子对有机物的去除有一定的抑制作用;光催化反应在通过O3强化后对有机物的去除率得到提高,TOC的去除率达到75.0%,光催化和O3氧化对有机物的去除具有协同效应;随着光催化反应次数的增加,催化剂活性有下降趋势,使用10次后TOC去除率下降到第一次使用时的16.7%,再生能够使催化活性恢复到使用前的95%,催化剂在使用15次以内稳定性较好。     

Release flux of mercury from different environmental surfaces in Chongqing, China

An investigation was conducted to estimate mercury emission to the atmosphere from different environmental surfaces and to assess its contribution to the local mercury budget in Chongqing, China. Mercury flux was measured using dynamic flux chamber (DFC) at six soil sites of three different areas (mercury polluted area, farmland and woodland) and four water surfaces from August 2003 to April 2004. The mercury emission fluxes were 3.5 ± 1.2–8.4 ± 2.5 ng m⁻² h⁻¹ for three shaded forest sites, 85.8 ± 32.4 ng m⁻² h⁻¹ for farming field, 12.3 ± 9.8–733.8 ± 255 ng m⁻² h⁻¹ for grassland sites, and 5.9 ± 12.6–618.6 ± 339 ng m⁻² h⁻¹ for water surfaces. Mercury exchange fluxes were generally higher from air/water surfaces than from air/soil surfaces. The mercury negative fluxes were found in tow soil sites at overcast days (mean = −6.4 ± 1.5 ng m⁻² h⁻¹). The diurnal and seasonal variations of mercury flux were observed in all sites. The mercury emission responded positively to the solar radiation, but negatively to the relative humidity. The mercury flux from air/soil surfaces was significantly correlated with soil temperature, which was well described by an Arrhenius-type expression with activation energy of 31.1 kcal mol⁻¹. The annual mercury emission to the atmosphere from land surface is about 1.787 t of mercury in Chongqing.     

Diagnosis of dissolved organic matter removal by GAC treatment in biologically treated papermill effluents using advanced organic characterisation techniques

Granular activated carbon (GAC) exhaustion rates on pulp and paper effluent from South East Australia were found to be a factor of three higher (3.62 cf. 1.47 kg m⁻³) on Kraft mills compared to mills using Thermomechanical pulping supplemented by Recycled Fibre (TMP/RCF). Biological waste treatment at both mills resulted in a final effluent COD of 240 mg L⁻¹. The dissolved organic carbon (DOC) was only 1.2 times higher in the Kraft effluent (70 vs. 58 mg L⁻¹), however, GAC treatment of Kraft and TMP/RCF effluent was largely different on the DOC persisted after biological treatment. The molecular mass (636 vs. 534 g mol⁻¹) and aromaticity (5.35 vs. 4.67 L mg⁻¹ m⁻¹) of humic substances (HS) were slightly higher in the Kraft effluent. The HS aromaticity was decreased by a factor of 1.0 L mg⁻¹ m⁻¹ in both Kraft and TMP/RCF effluent. The molecular mass of the Kraft effluent increased by 50 g mol⁻¹ while the molecular mass of the TMP/RCF effluent was essentially unchanged after GAC treatment; the DOC removal efficiency of the GAC on Kraft effluent was biased towards the low molecular weight humic compounds. The rapid adsorption of this fraction, coupled with the slightly higher aromaticity of the humic components resulted in early breakthrough on the Kraft effluent. Fluorescence excitation-emission matrix analysis of the each GAC treated effluent indicated that the refractory components were higher molecular weight humics on the Kraft effluent and protein-like compounds on the TMP/RCF effluent. Although the GAC exhaustion rates are too high for an effective DOC removal option for biologically treated pulp and paper mill effluents, the study indicates that advanced organic characterisation techniques can be used to diagnose GAC performance on complex effluents with comparable bulk DOC and COD loads.     

Effect of influent nitrogen speciation on organic nitrogen occurrence in activated sludge process effluents

The effect of influent nitrogen composition on organic nitrogen production in a sequencing batch reactor (SBR) activated sludge process was investigated. A laboratory-scale SBR was fed with three different type synthetic wastewaters with varying nitrogen compositions (phase I = nitriloacetic acid + ammonium [NH4-N], phase II = NH(4-)N, and phase III = amino acid mixture + NH(4-)N) was operated. The effluent contained approximately 1 to 2 mg N/L organic nitrogen, even though there was no organic nitrogen in influent. The effluent organic nitrogen increased to approximately 4 mg N/L when the influent composition was changed and then stabilized at <2 mg N/L. The maximum nitrifier growth rate constants (microN) were calculated as 0.91+/-0.10 to 1.14+/-0.08 day-1, 0.82 +/-0.13 day-1, and 0.89+/-0.08 day-1 at 20 degrees C for the three different influent compositions. The effluent colloidal organic nitrogen (CON) was negligible, suggesting that the effluent CON found in full-scale plants may be the result of influent-derived suspended matter.     

Measurement of organic nitrogen and phosphorus fractions at very low concentrations in wastewater effluents

The purpose of this study was to develop simple, accurate, and inexpensive measurement protocols for dissolved organic nitrogen (DON) and dissolved non-reactive phosphorus (DNRP) at low levels in wastewater effluents. Two protocols are presented--one to measure DON exclusively, and the other to measure DON and DNRP simultaneously. Currently, DON and DNRP are calculated indirectly by subtracting the dissolved inorganic fractions from the total dissolved concentration, resulting in significant errors. To increase the accuracy of DON measurements, effluent sample pretreatment using ion exchange to remove nitrate was applied. Spectrometric methods were selected to measure the inorganic fractions-the second derivative UV spectroscopy method for nitrate, and the malachite green method for orthophosphate. These methods, combined with the optimized persulfate digestion of the samples, can be used to measure total dissolved nitrogen and phosphorus accurately. The measurement ranges attained were 0.05 to 3 mg N/L for DON and 0.01 to 0.5 mg P/L for DNRP.     

不同垃圾渗滤液组合处理工艺中DOM的变化特征

为了快速表征垃圾渗滤液处理过程中有机物的特性变化,分别采用紫外光谱和三维荧光光谱对2种垃圾渗滤液处理工艺不同单元溶解性有机物(DOM)的变化进行了系统分析。结果表明,二级RO和厌氧+好氧+MBR+NF+RO工艺对渗滤液COD和NH3-N的去除率分别为98.7%、99.0%和98.8%、98.6%。随着处理过程的进行,2个处理工艺中DOM的SUVA254、E253/E203分别由0.74、0.33和0.46、0.12下降至0.015、0.014和0.010、0.012,有机物的芳香性和不饱和性下降,脂肪链芳香烃化合物开始增加。不同处理阶段渗透液DOM三维荧光光谱表明,随着处理过程的进行,类富里酸和类蛋白物质的含量逐渐下降,芳构化程度开始降低。其中二级RO系统对渗滤液中类富里酸物质的去除效果较好,而厌氧-好氧-MBR-NF-RO工艺中,类酪氨酸物质主要通过微生物降解去除,NF和RO膜对类富里酸和类腐殖酸物质的截留效果较好。     

Equilibration time scales of organic aerosol inside thermodenuders: Evaporation kinetics versus thermodynamics

The interpretation of thermodenuder (TD) data often relies on the assumption that thermodynamic equilibrium is reached inside the instrument. We modeled the evaporation of three organic aerosol types (adipic acid, α-pinene SOA and aged OA) inside a thermodenuder with a mass transfer model, and calculated equilibration time scales for these systems at realistic conditions. The equilibrium times varied from less than a second to several hours, decreasing with increasing aerosol concentrations, decreasing particle sizes, decreasing volatilities and increasing mass accommodation coefficients. The results indicate that generally TDs measure particle evaporation rates rather than equilibria, and time-dependent modeling of the evaporation is usually needed to interpret the data. Measurements at varying residence times and temperatures, on the other hand, are desirable to investigate the equilibration of the studied aerosol and decouple the kinetic effects from the effects caused by the thermodynamic properties of the aerosol. Organic aerosol is likely to be further from equilibrium under typical field conditions compared with laboratory data. When determining the aerosol properties from TD data, assuming incorrectly equilibrium results in under-prediction of the vaporization enthalpy of the evaporating species. Similar under-estimation is predicted if multicomponent aerosols are approximated with single-component properties.     

PAH desorption from sediments with different contents of organic carbon from wastewater receiving rivers

Background and aim  

Many rivers have to receive treated or untreated wastewater as the main water sources in the world, especially in the countries facing with water shortage. For instance, the Haihe and Huaihe River Basin, which are among areas facing crises for water resources in China, receive 33,400 million tons of wastewater per year. As the sediment has large capacity for sorbing hydrophobic organic pollutants such as polycyclic aromatic hydrocarbons (PAHs), it can act as a natural repository for the contaminants. This means pollutants can release into water phase again under some conditions, such as resuspension, sediment dredging, etc. The objective of this research was to study the trends of PAH release from sediments in rivers receiving much wastewater, such as Yongding New River (YD), Northsewer (NS), and Southsewer (SS) from Haihe River Basin. These rivers received most of the wastewater from Tianjin, China and merge into Bohai Bay finally.