堆肥 + 零价铁可渗透反应墙修复黄土高原地下水中铬铅复合污染简

为了研究堆肥+零价铁混合可渗透反应墙（PRB）修复黄土高原地下水中铬铅复合污染的可行性,分别用堆肥、零价铁、堆肥+ 零价铁、堆肥+ 零价铁+活性炭为反应介质,通过模拟柱实验考察PRB修复铬铅复合污染黄土高原地下水的效果。结果表明,在实验进行30 d后当反应柱1和2对六价铬的去除率接近于零,而且对二价铅的去除率迅速下降时,反应柱3对2种污染物仍保持较高的去除率;反应介质质量比为10：2：1的反应柱4和质量比为10：1：2的反应柱5对污染物的去除效果均优于质量比为10：1：1的反应柱3;反应50 d后,添加活性炭的反应柱6对2种污染物的去除率仍在90%。这说明使用堆肥+零价铁混合可渗透反应墙修复黄土高原地下水中铬铅复合污染是可行的;且以堆肥+零价铁作为介质的反应柱去除效果优于单独以堆肥或铁粉为介质的反应柱;增加铁粉或堆肥的用量有利于铬铅复合污染的去除;且同时添加活性炭更有助于污染物的去除。     

Removal of organic contaminants in bioretention medium amended with activated carbon from sewage sludge

Bioretention, also known as rain garden, allows stormwater to soak into the ground through a soil-based medium, leading to removal of particulate and dissolved pollutants and reduced peak flows. Although soil organic matter (SOM) is efficient at sorbing many pollutants, amending the bioretention medium with highly effective adsorbents has been proposed to optimize pollutant removal and extend bioretention lifetime. The aim of this research was to investigate whether soil amended with activated carbon produced from sewage sludge increases the efficiency to remove hydrophobic organic compounds frequently detected in stormwater, compared to non-amended soil. Three lab-scale columns (520 cm³) were packed with soil (bulk density 1.22 g/cm³); activated carbon (0.5% w/w) was added to two of the columns. During 28 days, synthetic stormwater—ultrapure water spiked with seven hydrophobic organic pollutants and dissolved organic matter in the form of humic acids—was passed through the column beds using upward flow (45 mm/h). Pollutant concentrations in effluent water (collected every 12 h) and polluted soils, as well as desorbed amounts of pollutants from soils were determined using GC-MS. Compared to SOM, the activated carbon exhibited a significantly higher adsorption capacity for tested pollutants. The amended soil was most efficient for removing moderately hydrophobic compounds (log K _ow 4.0–4.4): as little as 0.5% (w/w), carbon addition may extend bioretention medium lifetime by approximately 10–20 years before saturation of these pollutants occurs. The column tests also indicated that released SOM sorb onto activated carbon, which may lead to early saturation of sorption sites on the carbon surface. The desorption test revealed that the pollutants are generally strongly sorbed to the soil particles, indicating low bioavailability and limited biodegradation.

     

Comparison of AC/O3-BAC and O3-BAC processes for removing organic pollutants in secondary effluent

AC (activated carbon)/O3-BAC (biological activated carbon) process was employed to treat secondary effluent and compared to O3-BAC process. The effects of ozone dosages and empty bed contact time (EBCT) in BAC on dissolved organic carbon (DOC) removal were investigated. The results showed that the presence of AC improved ozone utilization and biodegradability of the effluent. DOC removal increased with ozone dosage and EBCT in BAC, however, 3 mg l(-1) ozone dosage with 15 min oxidation time and 15 min EBCT in BAC were more economical and efficient. For DOC removal, AC/O3-BAC was more efficient than O3-BAC and its synergetic effect was more than that in O3-BAC process. The biomass of the subsequent BAC unit in AC/O3-BAC process was more than that in O3-BAC process and much more than that in BAC alone. Except for organic pollutants with molecular weight (MW) >10 kDa, those of other MW range were decomposed much more by AC/O3 process than by O3 process. GC/MS analysis showed that dibutyl phthalate, bis(2-ethylhexyl) phthalate, 4-bromo-3-chloroaniline, 2-propanone-ethylhydrazone and phenol derivatives were prevalent organic compounds in the secondary effluent. Some aromatic compounds, such as 4-bromo-3-chloroaniline and 2,4-dichloro-benzenamine disappeared after AC/O3 treatment. However, some small molecules were generated, after further biological treatment by BAC, the kinds and concentration of organic compounds were greatly reduced.     

Comparative effectiveness of mixed organic substrates to mushroom compost for treatment of mine drainage in passive bioreactors

Bioreactors are one possible best sustainable technology to address the mine-impacted water problems. Several prospective substrates (mushroom compost, cow manure, sawdust, wood chips, and cut rice straw) were characterized for their ability to serve as a source of food and energy for sulfate-reducing bacteria. Twenty bench-scale batch bioreactors were then designed and set up to investigate relative effectiveness of various mixtures of substrates to that of mushroom compost, the most commonly used substrate in field bioreactors, for treating mine drainage with acidic (pH 3) and moderate pH (pH 6). Overall, reactive mixtures showed satisfactory performances in generating alkalinity, reducing sulfate and removing metals (Al>Fe>Mn) (up to 100%) at both pH conditions, for all substrates. The mixture of sawdust and cow manure was found as the most effective whereas the mixture containing 40% cut rice straw gave limited efficiency, suggesting organic carbon released from this substrate is not readily available for biodegradation under anaerobic conditions. The mushroom compost-based bioreactors released significant amount of sulfate, which may raise a more concern upon the start-up of field-scale bioreactors. The correlation between the extent of sulfate reduction and dissolved organic carbon/SO(4)(2-) ratio was weak and this indicates that the type of dissolved organic carbon plays a more important role in sulfate reduction than the absolute concentration and that the ratio is not sensitive enough to properly describe the relative effectiveness of substrate mixtures.     

Characterization and reactivity assessment of organic substrates for sulphate-reducing bacteria in acid mine drainage treatment

Acid mine drainage (AMD), which contains high concentrations of sulphate and dissolved metals, is a serious environmental problem. It can be treated in situ by sulphate reducing bacteria (SRB), but effectiveness of the treatment process depends on the organic substrate chosen to supply the bacteria's carbon source. Six natural organic materials were characterized in order to investigate how well these promote sulphate reduction and metal precipitation by SRB. Maple wood chips, sphagnum peat moss, leaf compost, conifer compost, poultry manure and conifer sawdust were investigated in terms of their carbon (TOC, TIC, DOC) and nitrogen (TKN) content, as well as their easily available substances content (EAS). Single substrates, ethanol, a mixture of leaf compost (30% w/w), poultry manure (18% w/w), and maple wood chips (2% w/w), and the same mixture spiked with formaldehyde were then tested in a 70-day batch experiment to evaluate their performance in sulphate reduction and metal removal from synthetic AMD. Metal removal efficiency in batch reactors was as high as 100% for Fe, 99% for Mn, 99% for Cd, 99% for Ni, and 94% for Zn depending on reactive mixtures. Early metal removal (0-12d) was attributed to the precipitation of (oxy)hydroxides and carbonate minerals. The lowest metal and sulphate removal efficiency was found in the reactor containing poultry manure as the single carbon source despite its high DOC and EAS content. The mixture of organic materials was most effective in promoting sulphate reduction, followed by ethanol and maple wood chips, and single natural organic substrates generally showed low reactivity. Formaldehyde (0.015% (w/v)) provided only temporary bacterial inhibition. Although characterization of substrates on an individual basis provided insight on their chemical make-up, it did not give a clear indication of their ability to promote sulphate reduction and metal removal.     

Carbon deposition in soil rhizosphere following amendments with compost and its soluble fractions, as evaluated by combined soil-plant rhizobox and reporter gene systems

We determined the organic carbon released by roots of maize plants (Zea mays L.) when grown in soils amended with compost and its soluble fractions. In rhizobox systems, soil and roots are separated from the soil of a lower compartment by a nylon membrane. Treatments are applied to the upper compartment, while in the lower compartment luminescent biosensors measure the bioavailable organic carbon released by roots (rhizodeposition). The rhizobox-plants systems were amended with a compost (COM), its water extract (TEA), the hydrophobic (HoDOM) and hydrophilic (HiDOM) fractions of the dissolved organic matter (DOM) extracted from the compost. After root development, the lower untreated compartments were sampled and sliced into thin layers. The bioavailable organic carbon in each layer was assessed with the lux-marked biosensor Pseudomonas fluorescens 10586 pUCD607, and compared with total organic carbon (TOC) analyses. The TOC values ranged between 8.4 and 9.6 g kg(-1) and did not show any significant differences between bulk and rhizosphere soil samples in any treatment. Conversely, the biosensor detected significant differences in available C compounds for rhizosphere soils amended with various organic materials. Concentrations of available organic compounds in the first 2 mm of soil rhizosphere were 1.69 (control), 1.09 (COM), 2.87 (HiDOM), 4.73 (HoDOM) and 2.14 (TEA)micromol Cg(-1) soil g(-1) roots. The applied rhizobox-biosensor integrated method was successful in detecting and quantifying effects of organic amendments on organic carbon released by maize plant roots. This approach may become important in assessing the carbon cycle in agricultural soils and soil-atmosphere compartments.     

Waste green sands as reactive media for the removal of zinc from water

Waste green sands are industrial byproducts of the gray iron foundry industry. These green sands are composed of fine silica sand, clay binder, organic carbon, and residual iron particles. Because of their potential sorptive and reactive properties, tests were performed to determine the feasibility of using green sands as a low cost reactive medium in permeable reactive barriers (PRBs). Serial batch kinetic tests and conventional batch sorption tests were conducted to determine the removal characteristics for zinc in aqueous solutions. Removal characteristics for zinc in the presence of green sands are comparable to those of Peerless iron, a common reactive medium used in PRBs. High removal capacities for zinc of green sands are attributed to clay, organic carbon, and residual iron particles, which are known sorptive media for heavy metals. Furthermore, high pH values in the presence of clay and residual iron particles enhanced sorption and precipitation of zinc.     

Removal of added nitrate in cotton burr compost, mulch compost, and peat: mechanisms and potential use for groundwater nitrate remediation

We conducted batch tests on the nature of removal of added nitrate in cotton burr compost, mulch compost, and sphagnum peat that may be potentially used in a permeable reactive barrier (PRB) for groundwater nitrate remediation. A rigorous steam autoclaving protocol (121 degrees C for 2h each day for three consecutive days) for the cotton burr compost and autoclaving of all labware and the nitrate working solutions resulted in drastically different results compared to the non-autoclaved treatment. In the non-autoclaved cotton burr compost, added nitrate at 20 mg N l(-1) decreased rapidly and was not detected after 3d; whereas, the autoclaved cotton burr compost showed persistent nitrate above 15.5 mg N l(-1) even after 10d, which is comparable with nitrate concentrations above 17.6 mg N l(-1) in a treatment using NaN(3) at 1000 mg l(-1). Dewaxed cotton burr compost showed decreased nitrate reduction compared to the pristine cotton burr compost. No nitrate reduction was detected in the dewaxed sphagnum peat. It is concluded that nitrate removal in the organic media is controlled by microbiologically mediated processes. The use of readily available cotton burr and mulch composts may offer a cost-effective method of nitrate removal from contaminated groundwater.     

Taking advantage of aerated-anoxic operation in a full-scale University of Cape Town process.

To evaluate the potential benefits or limitations of aeratedanoxic operation in high-rate biological nutrient removal processes, we conducted a full-scale experiment in a University of Cape Town (UCT)-type wastewater treatment plant by reducing oxygen supply and increasing flowrates within one treatment train so that aerated-anoxic conditions (i.e., zones that receive oxygen but maintain dissolved oxygen concentrations below 0.5 mg/L) could be implemented in a section of the aerated zone. With this retrofitted configuration, total nitrogen removal increased from 54 to 65%, but was limited by the organic carbon available for denitrification. Furthermore, the significant reduction in dissolved oxygen concentrations in the aerated zone did not negatively affect enhanced biological phosphorus removal, demonstrating that the implementation of an aerated-anoxic zone within a UCT-type reactor can contribute to a reduction in operational costs and a slight improvement in total nitrogen removal, without compromising the extent of phosphorus removal.     

Removal of added nitrate in the single, binary, and ternary systems of cotton burr compost, zerovalent iron, and sediment: Implications for groundwater nitrate remediation using permeable reactive barriers

Recent research has shown that carbonaceous solid materials and zerovalent iron (Fe(0)) may potentially be used as media in permeable reactive barriers (PRBs) to degrade groundwater nitrate via heterotrophic denitrification in the solid carbon system, and via abiotic reduction and autotrophic denitrification in the Fe(0) system. Questions arise as whether the more expensive Fe(0) is more effective than the less expensive carbonaceous solid materials for groundwater nitrate remediation, and whether there is any synergistic effect of mixing the two different types of materials. We carried out batch tests to study the nature and rates of removal of added nitrate in the suspensions of single, binary, and ternary systems of cotton burr compost, Peerless Fe(0), and a sediment low in organic carbon. Cotton burr compost acted as both organic carbon source and supporting material for the growth of indigenous denitrifiers. Batch tests showed that cotton burr compost alone removed added nitrate at a greater rate than did Peerless Fe(0) alone on an equal mass basis with a pseudo-first-order rate constant k=0.0830+/-0.0031 h(-1) for cotton burr compost and a k=0.00223+/-0.00022 h(-1) for Peerless Fe(0); cotton burr compost also removed added nitrate at a faster rate than did cotton burr compost mixed with Peerless Fe(0) and/or the sediment. Furthermore, there was no substantial accumulation of ammonium ions in the cotton burr compost system, in contrast to the systems containing Peerless Fe(0) in which ammonium ions persisted as major products of nitrate reduction. It is concluded that cotton burr compost alone may be used as an excellent denitrification medium in a PRB for groundwater nitrate removal. Further study is needed to evaluate performance of its field applications.     

Persistent organic pollutants (POPs) in the conventional activated sludge treatment process: model predictions against experimental values

The FATE and treatibility estimator (FATE) model, developed by the United States Environmental Protection Agency was used for the prediction of the FATE of 26 persistent organic pollutants (POPs), i.e. 7 PCBs and 19 organochlorine compounds (OCs), during the conventional activated sludge treatment process applied in the waste water treatment plant (WWTP) of Thessaloniki, Greece. The removal rates predicted by the model for the primary and the secondary treatment stages were found to differ substantially from those experimentally measured. When the overall treatment was considered, the differences between measured and model predicted removals were within acceptable limits of confidence. Possible reasons that might cause deviations from experimental values were suggested to be the wastewater content in dissolved organic carbon (DOC), and/or the low concentrations of POPs in untreated wastewater.     

Influence of organic matter on arsenic removal by continuous flow electrocoagulation treatment of weakly mineralized waters

The aim of this study is to evaluate and understand the electrocoagulation/flocculation (ECF) process to remove arsenic from both model and natural waters with low mineral content and to compare its performances to the coagulation/flocculation (CF) process already optimized. Experiments were thus conducted with iron electrodes in the same specific treatment conditions (4≤current density (mAcm(-2))≤33) to study the influence of organic matter on arsenic removal in conditions avoiding the oxidation step usually required to improve As(III) removal. The process performance was evaluated by combining quantification of arsenic residual concentrations and speciation and dissolved organic carbon residual concentrations with zeta potential and turbidity measurements. When compared to CF, ECF presented several disadvantages: (i) lower As(V) removal yield because of the ferrous iron dissolved from the anode and the subsequent negative zeta potential of the colloidal suspension, (ii) higher residual DOC concentrations because of the fractionation of high molecular weight compounds during the treatment leading to compounds less prone to coagulate and (iii) higher residual turbidities because of the charge neutralization mechanisms involved. However, during this process, As(III) was oxidized to As(V) improving considerably its removal whatever the matrix conditions. ECF thus allowed to improve As(III) removal without applying an oxidation step that could potentially lead to the formation of toxic oxidation by-products.     

Impact of composting strategies on the treatment of soils contaminated with organic pollutants

Chemical pollution of the environment has become a major source of concern. Studies on degradation of organic compounds have shown that some microorganisms are extremely versatile at catabolizing recalcitrant molecules. By harnessing this catabolic potential, it is possible to bioremediate some chemically contaminated environmental systems. Composting matrices and composts are rich sources of xenobiotic-degrading microorganisms including bacteria, actinomycetes and lignolytic fungi, which can degrade pollutants to innocuous compounds such as carbon dioxide and water. These microorganisms can also biotransform pollutants into less toxic substances and/or lock up pollutants within the organic matrix, thereby reducing pollutant bioavailability. The success or failure of a composting/compost remediation strategy depends however on a number of factors, the most important of which are pollutant bioavailability and biodegradability. This review discusses the interactions of pollutants with soils; look critically at the clean up of soils contaminated with a variety of pollutants using various composting strategies and assess the feasibility of using composting technologies to bioremediate contaminated soil.     

Applicability of MIEX®DOC process for organics removal from NOM laden water

The aim of this study was to evaluate applicability of ion exchange process for organics removal from Douro River surface water at the intake of Lever water treatment plant using magnetized ion exchange resin MIEX®. Qualitative analysis of the natural organic matter present in the surface water and prediction of its amenability to removal in conventional coagulation process were assessed. Results obtained in MIEX®DOC process kinetic batch experiments allowed determination of ion exchange efficiency in dissolved organic carbon (DOC), UV absorbing organics, and true color removal. The data were compared with the efficiencies of the conventional unit processes for organics removal at Lever WTP. MIEX®DOC process revealed to be more efficient in DOC removal than conventional treatment achieving the efficiencies in the range of 61–91 %, lowering disinfection by-products formation potential of the water. DOC removal efficiency at Lever WTP depends largely on the raw water quality and ranges from 28 % for water of moderated quality to 89 % of significantly deteriorated quality. In this work, MIEX®DOC process was also used as a reference method for the determination of contribution of anionic fraction to dissolved organic matter and selectivity of the unit processes at Lever WTP for its removal.     

Limitations on the role of incorporated organic matter in reducing pesticide leaching.

The use of organic amendments has been suggested as a method of controlling pesticide leaching through soils. The enarenados soils of the intensive horticulture of the Almeria province of southern Spain contain buried organic matter horizons above a soil layer amended with clay. This region is ideal for understanding the potential for and limitations of organic amendments in preventing pesticide pollution. This study measured the sorption and degradation potential of carbofuran in this soil system and the hydrological behaviour of the soil horizons. The sorption of carbofuran was controlled by the organic carbon content, the degradation was strongly pH-dependent and the acidic organic layer protected the sorbed carbofuran against degradation. Hydrologically, the soil system is dominated by ponding above an amended clay layer and by the presence of macropores that can transport water through this clay. A simple model is proposed on this basis and shows that although high levels of dissolved organic carbon can be released by buried organic horizons, the major control on re-release of sorbed pesticide is the potential for sorption hysteresis in this organic layer. A comparison of sorption and degradation data for carbamate insecticides used in the region with groundwater observations for these compounds shows that no amount of incorporated organic would protect against pollution from highly water-soluble compounds.     

The size distribution of organic carbon in headwater streams in the Amazon basin

Despite the strong representativeness of streams in the Amazon basin, their role in the accumulation of coarse particulate organic carbon (CPOC), fine particulate organic carbon (FPOC), and dissolved organic carbon (DOC) in transport, an important energy source in these environments, is poorly known. It is known that the arboreal vegetation in the Amazon basin is influenced by soil fertility and rainfall gradients, but would these gradients promote local differences in organic matter in headwater streams? To answer this question, 14 low-order streams were selected within these gradients along the Amazon basin, with extensions that varied between 4 and 8 km. The efficiency of the transformation of particulate into dissolved carbon fractions was assessed for each stream. The mean monthly benthic organic matter storage ranged between 1.58 and 9.40 t ha^?1 month^?1. In all locations, CPOC was the most abundant fraction in biomass, followed by FPOC and DOC. Rainfall and soil fertility influenced the distribution of the C fraction (p?=?0.01), showing differentiated particulate organic carbon (POC) storage and DOC transportation along the basin. Furthermore, the results revealed that carbon quantification at the basin level could be underestimated, ultimately influencing the global carbon calculations for the region. This is especially due to the fact that the majority of studies consider only fine particulate organic matter and dissolved organic matter, which represent less than 50 % of the stored and transported carbon in streambeds.     

Removal of propylene and butylene as individual compounds with compost and wood chip biofilters

Propylene and butylene are highly reactive volatile organic compounds (HRVOCs) in terms of ground-level ozone formation. This study examined the effectiveness of biofiltration in removing propylene and butylene as separate compounds. Specific objectives were (1) to measure maximum removal efficiencies for propylene and butylene and the corresponding microbial acclimation times, which will be useful in the design of future biofilters for removal of these compounds; (2) to compare removal efficiencies of propylene and butylene for different ratios of compost/hard wood-chip media; and (3) to identify the microorganisms responsible for propylene and butylene degradation. Two laboratory-scale polyvinyl chloride biofilter columns were filled with 28 in. of biofilter media (compost/wood-chip mixtures of 80:20 and 50:50 ratios). Close to 100% removal efficiency was obtained for propylene for inlet concentrations ranging from 2.9 x 10(4) to 6.3 x 10(4) parts per million (ppm) (232-602 g/m3-hr) and for butylene for inlet concentrations ranging from 91 to 643 ppm (1.7-13.6 g/m3-hr). The microbial acclimation period to attain 100% removal efficiency was 12-13 weeks for both compounds. The lack of similar microbial species in the fresh and used media likely accounts for the long acclimation time required. Both ratios of compost/wood chips (80:20 and 50:50) gave similar results. During the testing, media pH increased slightly from 7.1 to 7.5-7.7. None of the species in the used media that treated butylene were the same as those in the used media that treated propylene, indicating that different microbes are adept at degrading the two compounds.     

Intrinsic degradation of volatile fatty acids in laboratory-compacted clayey soil

Volatile fatty acids (VFAs) represent the major organic constituent of landfill leachate and provide the greatest potential for leachate induced organic contamination of groundwater (e.g. as represented by an increase in the concentration of dissolved organic carbon and chemical oxygen demand). Long-term diffusion tests were performed for laboratory-compacted clayey soil plugs exposed to continuous supply of synthetic leachate containing VFAs. Significant microbial activity developed upon exposure of the soil's indigenous microorganisms to these degradable contaminants. The growth of heterotrophic aerobic bacteria (HAB, which include facultative anaerobes), sulfate reducing bacteria (SRB) and methanogenic bacteria carrying out fermentation and mineralization of the VFAs became evident after 30-50 days of testing. The maximum microbial counts of (2-8) x 10(8) and (0.1-1) x 10(8) cfu/g for HAB and SRB were localized in the soil layer at the interface with the source of organic and inorganic nutrients. Regardless of this rapid growth in microbial population, the VFA consumption was small and measurable only after a lag of 140-180 days. It is considered that this lag of otherwise readily degradable organic compounds (such as VFAs) persisted due to a combination of the effects of a high initial concentration of these acids (2.4 g/l as dissolved organic carbon, DOC) applied to carbon starved soil microorganisms and the small pore size of the compacted clay. Once the significant amounts of gas were generated from fermentation, conditions developed for improved mass transport and exchange of the nutrients and bacteria and the outcome of the intrinsic degradation was more apparent. The breakdown of VFAs that followed after the lag was localized near the top of the soil and was characterized by a short half-life of 0.75-5 days for DOC (total VFAs as dissolved organic carbon).     

The fate of dissolved organic carbon (DOC) in the wastewater treatment process and its importance in the removal of wastewater contaminants

Goal, Scope and Background Dissolved organic carbon (DOC) constitutes a parameter of organic pollution for waters and wastewaters, which is not so often studied, and it is not yet regulated by directives. The term ‘DOC’ is used for the fraction of organics that pass through a 0.45 μm pores’ size membrane. The type of wastewater plays an important role in the quality of DOC and it has been shown that DOC may contain aquatic humic substances, hydrophobic bases, hydrophobic neutrals, hydrophilic acids, hydrophilic bases and hydrophilic neutrals. The quality of the DOC is expected to affect its fate in a wastewater treatment plant (WWTP), since a considerable fraction of DOC is not biodegradable, and it may be released in the aquatic environment together with the treated effluent. In the present study, the occurrence of DOC during the wastewater treatment process is investigated and its removal rates during primary, secondary and overall treatment are being estimated. Furthermore, a correlation is being attempted between DOC and the concentrations of selected Persistent Organic Pollutants (POPs) and Heavy Metals (HMs) in the dissolved phase of wastewaters, to examine whether there are common sources for these pollution parameters in WWTPs. Also, DOC is being correlated with the partition coefficients of the above-mentioned pollutants in wastewater, in order to examine the effect of ‘solubility enhancement’ in WWTPs and to evaluate the result of this phenomenon in the efficiency of a WWTP to remove organic pollutants. Methods For the purposes of this study, 24-h composite wastewater samples were collected from the influent (raw wastewater, RW), the effluent of primary sedimentation tank (primary sedimentation effluent, PSE) and the effluent of secondary sedimentation tank (secondary sedimentation effluent, SSE). Samples were analyzed for the presence of 26 POPs (7 PCBs and 19 organochlorine pesticides), 8 HMs and DOC. Results and Discussion Mean concentrations of DOC in RW and PSE were at similar levels (∼ 70 mg l⁻¹), suggesting that primary treatment has a minor effect on the DOC content of wastewater. DOC concentrations in SSE were significantly lower (∼ 19 mg l⁻¹) as a result of the degradation of organic compounds in the biological reactor. Calculated removals of DOC were 0.8% in the primary treatment, 63% in the secondary treatment, and 69% in the overall treatment, exhibiting large differences from other organic pollution parameters, such as BOD and COD. The overall DOC removal was found to be independent from the DOC concentration in raw wastewater. Poor correlation was also observed between the DOC content and the concentrations of wastewater contaminants, such as persistent organic pollutants (POPs) and heavy metals (HMs), probably suggesting that their occurrence in WWTPs is due to different sources. A good negative linear relationship was revealed between DOC concentrations and the logarithms of the distribution coefficients (K _d) of various POPs and HMs between the solid and the liquid phases of wastewater. This relationship suggests that DOC facilitates hydrophobic pollutants to remain in the dissolved phase thus causing lower removal percentages during the treatment process. Conclusion DOC was measured at three stages of a municipal WWTP that receives mainly domestic wastewater and urban runoff. DOC concentrations in untreated and primarily treated wastewater were almost equal, and only after the secondary sedimentation there was a decrease. Concentrations and removal rates of DOC were in the same levels as in other WWTPs that receive municipal wastewater. The origin of DOC was found to be different to the one of POPs and of HMs, as no correlation was observed between the concentrations of DOC and the concentrations of these pollutants. On the contrary, DOC was found to have significant negative correlation with the K _d of all pollutants examined, suggesting that it plays an important role in the partitioning of those pollutants between the dissolved and the sorbed phase of wastewaters. This effect of DOC on partitioning can affect the ability of WWTPs to remove toxic pollutants, and that way it facilitates the discharge of those chemicals in the aquatic ecosystems together with the treated effluent. Recommendation By the results of this work it is shown that the presence of DOC in wastewaters can significantly affect the partition of hazardous pollutants between the dissolved and the sorbed phase. It is therefore of importance that this parameter is controlled more in wastewaters, since it can cause a decrease in the efficiency of WWTPs to remove quantitatively persistent pollutants.     

新型水处理活性炭选型技术

活性炭依其原料不同、生产工艺不同,而有不同的吸附性能.使用简易的活性炭选型方法,可以减少应用测试时的备选炭型,从而大大降低活性炭水处理技术的运行成本.以碘值、甲基蓝值、苯酚值和丹宁酸值4种吸附容量性能指标为依据的活性炭选型技术,可以有效地预测活性炭对于水中各种大小不同污染物的去除能力.BET测试结果证明了这4项指标数据对于活性炭孔径分布预测的准确性.2,4-二氯苯酚和腐殖酸等目标化合物的吸附容量实验结果也都验证了这4项指标的预测功用,说明这种简便的活性炭选型技术有着广泛的应用价值.