焦化废水生化处理过程中溶解性有机物及毒性变化规律

焦化废水中的溶解性有机物(DOM)作为废水污染物和毒性的主要来源受到广泛关注。厌氧-缺氧-好氧(A-A-O)生物法联合混凝沉淀工艺在焦化废水处理中被广泛应用。于2018年4,7和11月分别采集4座焦化废水处理厂废水,采用光谱学分析手段和水生生物急性毒性试验对A-A-O联合混凝沉淀处理过程中焦化废水的DOM和毒性变化进行分析。结果表明,焦化废水中含有大量不饱和芳香性物质,其中类色氨酸、络氨酸物质占主导,其次为类溶解性微生物代谢产物、类富里酸物质和类腐殖酸类物质;未经处理的焦化废水对藻类和大型溞的急性毒性等级为中毒至高毒。A-A-O联合混凝沉淀处理可去除90%以上的类色氨酸、络氨酸和类富里酸物质,但对类腐殖酸类物质去除率相对较低,仅为约80%,关键去除段为缺氧段和好氧段;该工艺对焦化废水急性毒性削减率为80.51%~94.30%,关键削减段为厌氧段。Pearson相关性分析结果显示,焦化废水溶解性总有机碳(TOC)、类腐殖酸类物质荧光组分C1和类富里酸类物质荧光组分C4与废水急性毒性存在显著正相关关系,可利用其作为水样急性毒性初筛的指示性指标。可为焦化废水生化处理的效能优化和废水毒性控制及安全评估提供科学支撑。     

Biological treatment of textile wastewater using sequencing batch reactor technology

This study was conducted to biologically treat wastewater discharged from the textile industry (textiles made of cotton and/or synthetic fiber) using sequencing batch reactor (SBR) technology (activated sludge process operating on batch mode). To achieve the objectives of the study, the characteristics of textile wastewater and the biodegradation of its organic constituents under unsteady state conditions were studied. Then, a bench-scale pilot plant was used to study the performance of SBR by monitoring the settleability and change in the constituents (chemical oxygen demand and solids) over time. Results of the study showed that textile wastewater has different types of pollutants: heat, basicity, suspended solids, organic and inorganic matter, and heavy metals. The factors affecting the biodegradation of organic matter were determined as the reaction time and the ratio of initial substrate to sludge concentrations. Also, removal of solids was monitored, and the settling velocity as affected by sludge concentration was graphically presented to enable the determination of settling time. Finally, the outcome of this study was used to suggest a procedure for the design of a full-scale SBR unit for treatment of textile wastewater.     

Pharmaceuticals and personal care products in effluent matrices: A survey of transformation and removal during wastewater treatment and implications for wastewater management

Pharmaceuticals and personal care products (PPCPs) represent pollutants of emerging concern, originating in surface and drinking waters largely from their persistence in wastewater effluent. Accordingly, a wealth of recent investigations has examined PPCP fate during wastewater treatment, focusing on their removal during conventional (e.g., activated sludge) and advanced (e.g., ozonation and membrane filtration) treatment processes. Here, we compile nearly 1500 data points from over 40 published sources pertaining to influent and effluent PPCP concentrations measured at pilot- and full-scale wastewater treatment facilities to identify the most effective series of technologies for minimizing effluent PPCP levels. Available data suggest that at best a 1-log(10) concentration unit (90%) of PPCP removal can be achieved at plants employing only primary and secondary treatment, a performance trend that is maintained over the range of reported PPCP influent concentrations (ca. 0.1-10(5) ng L(-1)). Relatively few compounds (15 of 140 PPCPs considered) are consistently removed beyond this threshold at facilities using solids removal and conventional activated sludge (CAS), and most PPCPs are removed to a far lesser extent. Further, increases in CAS hydraulic retention time or sludge retention time do not appreciably increase removal beyond this limit. In contrast, plants employing advanced treatment methodologies, particularly ozonation and/or membranes, remove the vast majority of PPCPs beyond 1-log(10) concentration unit and oftentimes to levels below analytical detection limits in effluent. Data also indicate that passive approaches for tertiary treatment (e.g., wetlands and lagoons) represent promising options for PPCP removal. We conclude by addressing future challenges and frontiers in wastewater management posed by PPCPs including analytical needs for their real-time measurement, energy demands associated with advanced treatment technologies, and byproducts arising from transformation of PPCPs during treatment.     

Effectiveness of three configurations of membrane bioreactors on the removal of priority and emergent organic compounds from wastewater: comparison with conventional wastewater treatments

In this work the effectiveness of membrane bioreactors as advanced treatment on the removal of emergent and priority organic compounds in wastewater treatment plants has been evaluated during a one-year monitoring study. The studied wastewater treatment plant operates with flat sheet and hollow fibre membranes in two parallel lines. Moreover, a reverse osmosis module connected in series after the hollow fibre membrane was evaluated for one month. Comparison of membrane bioreactor and conventional activated sludge treatment was also investigated, as well as the influence of the physicochemical properties of the compounds on the removal rates achieved. Sixteen pharmaceutical compounds belonging to seven therapeutic groups and eight priority organic pollutants, including linear alkylbenzene sulfonates, nonylphenol and its ethoxylates and phthalate, were monitored. The highest mean concentrations corresponded to priority organic pollutants (309 μg L(-1) of linear alkylbenzene sulfonate C(12)) followed by pharmaceutical compounds (24.5 μg L(-1) of ibuprofen). No significant difference of effectiveness was found among flat sheet and hollow fibre membranes. However, an improvement was obtained with the addition of a reverse osmosis module for most of the compounds. Biodegradation has been shown as the main route involved in the removal of organic compounds during both technologies.     

Determination of synthetic musk compounds in sewage biosolids by gas chromatography/mass spectrometry

A review of sewage sludge regulations and land application practices by the United States National Research Council (2002) recommended development of improved analytical techniques to adequately identify and quantify new chemical contaminants, such as synthetic musk compounds in Class A sewage sludge (i.e., biosolids). This prompted the development of a rugged analytical method using gas chromatography coupled to mass spectrometry to detect this group of organic pollutants in biosolids. In this paper, the term "biosolids" is used interchangeably with "sewage sludge", which is defined in the regulations and used in the statue (Clean Water Act). Samples of Class A biosolids obtained from sewage treatment plants in Los Angeles, California, the City of Las Vegas, Nevada, and also in the form of a commercial fertilizer, were extracted using pressurized liquid extraction technique, subjected to gel permeation chromatography clean-up, and analyzed by GC/MS using the selected ion monitoring mode. The method developed has the potential to detect synthetic musk compounds in complex matrices, may provide accurate data useful in human health and environmental risk assessment, and may be useful in determining the efficacy of municipal sewage treatment plants for removing synthetic musk compounds.     

Removal of phenols and other pollutants from different landfill leachates using powdered activated carbon supplemented SBR technology

In this research, two types of sequencing batch reactors (SBRs) with 8 h of cycle times, namely non-powdered activated carbon (NPAC-SBR) and powdered activated carbon (PAC-SBR), were used for the treatment of raw leachates at Kulim and Pulau Burung landfill sites. To test the performance of SBRs, phenols, total iron, zinc, ammonia, nitrite, nitrate, color, suspended solids, chemical oxygen demand, biochemical oxygen demand, and total dissolved salts removal efficiencies and sludge volume index (SVI) were studied at both sites. The rates of phenols removal, for instance in NPAC-SBRs and PAC-SBRs at Kulim, were 25% and 55%, respectively, whereas those at Pulau Buring were 94.81% and 97.75%, respectively. PAC as adsorbent in PAC-SBRs enhanced the removal efficiencies of the aforementioned pollutants from leachates at both sites. In addition, PAC as adsorbent decreased the SVI values at Kulim (59.7 mL/g) and Pulau Burung (91.4 mL/g) leachates and improved the nitrification and denitrification processes.     

Assessing the feasibility of wastewater recycling and treatment efficiency of wastewater treatment units

Wastewater reuse can significantly reduce environmental pollution and save the water sources. The study selected Cheng-Ching Lake water treatment plant in southern Taiwan to discuss the feasibility of wastewater recycling and treatment efficiency of wastewater treatment units. The treatment units of this plant include wastewater basin, sedimentation basin, sludge thickener and sludge dewatering facility. In this study, the treatment efficiency of SS and turbidity were 48.35–99.68% and 24.15–99.36%, respectively, showing the significant removal efficiency of the wastewater process. However, the removal efficiencies of NH₃–N, total organic carbon (TOC) and chemical oxygen demand (COD) are limited by wastewater treatment processes. Because NH₃–N, TOC and COD of the mixing supernatant and raw water are regulated raw water quality standards, supernatant reuse is feasible and workable during wastewater processes at this plant. Overall, analytical results indicated that supernatant reuse is feasible.     

Effects of multi-metal toxicity on the performance of sewage treatment system during the festival of colors (Holi) in India

The present study investigated the effects of heavy metals (Ni, Zn, Cd, Cu, and Pb) toxicity on the performance of 18 MLD activated sludge process-based sewage treatment plant (STP) during celebration of Holi (festival of colors in India). The composite sampling (n?=?32) was carried out during the entire study period. The findings show a significant decrease in chemical oxygen demand removal efficiency (20%) of activated sludge system, after receiving the heavy metals laden wastewater. A significant reduction of 40% and 60% were observed in MLVSS/MLSS ratio and specific oxygen uptake rate, which eventually led to a substantial decrease in biomass growth yield (from 0.54 to 0.17). The toxic effect of metals ions was also observed on protozoan population. Out of the 12 mixed liquor species recorded, only two ciliates species of Vorticella and Epistylis exhibited the greater tolerance against heavy metals toxicity. Furthermore, activated sludge shows the highest metal adsorption affinity for Cu, followed by Zn, Pb, Ni, and Cd (Cu?>?Zn?>?Pb?>?Ni?>?Cd). Finally, this study proves the robustness of activated sludge system against the sudden increase in heavy metal toxicity since it recovered the earlier good quality performance within 5?days.     

COD adsorption capacity of the activated sludge — Its determination and application in the activated sludge process

Proper control of the activated sludge process is essential in ensuring production of good effluent. COD adsorption capacity (CAC) of the activated sludge could be used as a control parameter. CAC is determined by mixing the activated sludge with the settled sewage and measuring the instantaneous COD reduction per unit mass of activated sludge. CAC measures substrate removal by physical adsorption and reflects the quality of the activated sludge. CAC of a healthy activated sludge increases with the flow along the aeration units. CAC could be used for process decision on variation in air supply and feed pattern to the aeration units. In a modified process to cope with sludge bulking problem, CAC could be used to estimate the air supply to the aeration unit which is merely used for reaerating the returned sludge.     

Optimized Coagulation of High Alkalinity, Low Temperature and Particle Water: pH Adjustment and Polyelectrolytes as Coagulant Aids

The Yellow River in winter as source water is characterized as high alkalinity, low temperature and low particle concentrations, which have brought many difficulties to water treatment plants. This study fully examines the optimized coagulation process of the Yellow River by conventional and pre-polymerized metal coagulants, pH adjustment and polyelectrolytes as the primary coagulants or coagulant aids. For all the metal coagulants, polyaluminum chlorides are superior to traditional metal coagulants due to their stable polymeric species and low consumption of alkalinity. The removal of natural organic matter by monomeric metal coagulants can be improved through pH adjustment, which is in accordance with the higher concentration of polymeric species formed at corresponding pH value. With the addition of polyelectrolytes as coagulant aids, the coagulation performance is significantly improved. The effective removal of dissolved organic matter is consistent with high charge density, while molecular weight is relatively important for removing particles, which is consistent with polyelectrolytes as primary coagulants. These results suggest that the coagulation mechanisms in the removal of dissolved organic matter and particles are different, which may be exploited for optimized coagulation for the typical source water in practice.     

A tiered procedure for assessing the formation of biotransformation products of pharmaceuticals and biocides during activated sludge treatment

Upon partial degradation of polar organic micropollutants during activated sludge treatment, transformation products (TPs) may be formed that enter the aquatic environment in the treated effluent. However, TPs are rarely considered in prospective environmental risk assessments of wastewater-relevant compound classes such as pharmaceuticals and biocides. Here, we suggest and evaluate a tiered procedure, which includes a fast initial screening step based on high resolution tandem mass spectrometry (HR-MS/MS) and a subsequent confirmatory quantitative analysis, that should facilitate consideration of TPs formed during activated sludge treatment in the exposure assessment of micropollutants. At the first tier, potential biotransformation product structures of seven pharmaceuticals (atenolol, bezafibrate, ketoprofen, metoprolol, ranitidine, valsartan, and venlafaxine) and one biocide (carbendazim) were assembled using computer-based biotransformation pathway prediction and known human metabolites. These target structures were screened for in sludge-seeded batch reactors using HR-MS/MS. The 12 TPs found to form in the batch experiments were then searched for in the effluents of two full-scale, municipal wastewater treatment plants (WWTPs) to confirm the environmental representativeness of this first tier. At the second tier, experiments with the same sludge-seeded batch reactors were carried out to acquire kinetic data for major TPs that were then used as input parameters into a cascaded steady-state completely-stirred tank reactor (CSTR) model for predicting TP effluent concentrations. Predicted effluent concentrations of four parent compounds and their three major TPs were corroborated by comparison to 3-day average influent and secondary effluent mass flows from one municipal WWTP. CSTR model-predicted secondary effluent mass flows agreed within a factor of two with measured mass flows and confidence intervals of predicted and measured mass flows overlapped in all cases. The observed agreement suggests that the combination of batch-determined transformation kinetics with a simple WWTP model may be suitable for estimating aquatic exposure to TPs formed during activated sludge treatment. Overall, we recommend the tiered procedure as a realistic and cost-effective approach to include consideration of TPs of wastewater-relevant compounds into exposure assessment in the context of prospective chemical risk assessment.     

大气环境高灵敏光谱探测技术

大气环境高灵敏光谱探测技术是以光与环境相互作用为基础发展起来的学科交叉方向,使用光学的方法和手段来探知研究环境问题。大气环境高灵敏光谱探测技术能够实现从现场瞬态灵敏探测到污染时空分布等不同尺度的遥测,从而获得大气污染"点-线-面"的时空变化规律,由于光谱探测技术具有多组分、非接触、无采样、高灵敏度、大范围快速以及遥测等特点,已经成为国际上大气环境监测技术的主要方向之一。大气环境高灵敏光谱技术在污染源、工业园区、空气质量以及区域污染等监测方面都有很广泛的应用。针对化工园区复杂的环境污染问题,光谱探测技术可以高灵敏、非接触地获取多种污染物浓度特征,掌握化工园区污染时空分布状况,为化工园区的大气污染治理提供有效支撑;针对京津冀、长三角等地区大气重污染过程的核心问题,大气环境高灵敏光谱探测技术通过地基组网观测,车载/机载平台移动观测等三维立体监测手段获取重点区域污染物的生成、转化过程以及重污染过程的形成机制,为区域大气污染成因追溯、污染控制措施评估提供科学的数据和技术支撑。高灵敏光谱探测技术在大气环境领域的成功应用,为污染源、化工园区和重点区域的环境综合诊断和治理奠定了技术基础。     

Heat shock protein 47 stress responses in Chinese hamster ovary cells exposed to raw and reclaimed wastewater

As wastewater reclamation and reuse becomes more widespread, risks of exposure to treated wastewater increase. Moreover, an unlimited number of pollutants can be identified in wastewater. Therefore, comprehensive toxicity assessment of treated wastewater is imperative. The objective of this study was to perform a comprehensive toxicity assessment of wastewater treatment systems using stress response bioassays. This powerful tool can comprehensively assess the toxicity of contaminants. In this study, samples from conventional activated sludge treatment, membrane bioreactors (MBRs) with different pore sizes and sludge retention times (SRTs), rapid sand filtration, coagulation, nano-filtration (NF) and reverse osmosis (RO) were investigated. The results of stress response bioassays confirmed that the secondary effluent showed higher stress response than influent indicating that biological treatment generates toxic compounds. The results obtained from molecular weight fractionation of water samples demonstrated that organic matter with a higher molecular weight fraction (>0.1 μm) causes toxicity in secondary effluent. Furthermore, supernatant from MBR reactors showed toxicity regardless of SRT. On the other hand, stress response was not detected in MBR permeates except for an MBR equipped with a larger pore size membrane (0.4 μm) and with a short SRT (12 days). While rapid sand filtration could not remove the toxic compounds found in secondary effluent, coagulation tests, operated at an appropriate pH, were effective for reducing stress response in the secondary effluent. Experimental findings also showed that stress response was not detected in cases of NF and RO permeate subsequent to MBR treatment.     

印染废水处理污泥危险废物鉴别过程中有毒污染物的迁移转化及鉴别因子筛选

简述了印染废水处理污泥危险废物鉴别过程中有毒污染物的迁移转化及鉴别因子筛选。以采用活性染料的印染企业为例,从常用的原辅材料、使用的生产工艺、常用的废水处理工艺等几个方面来对印染废水处理污泥危险废物鉴别过程中有毒污染物的迁移及转化进行分析。提出危险废物鉴别工作任重而道远,危险废物鉴别的关键在于日常监管。     

Efficiency evaluation of sewage treatment plants with different technologies in Delhi (India)

Physical, chemical and microbiological efficiencies of Sewage Treatment Plants (STPs) located in Delhi's watershed in context of different treatment technologies employed in these plants have been determined. There were in all seventeen STPs treating domestic wastewater which were studied over a period of 12 months. These STPs were based on Conventional Activated sludge process (ASP), Extended aeration (Ex. Aeration), physical, chemical and biological removal treatment (BIOFORE) and oxidation pond treatment process. Results suggests that except "Mehrauli" STP which was based on Extended aeration process and "Oxidation pond", effluents from all other STPs exceeded FC standard of 10(3) MPN/100 ml for unrestricted irrigation criteria set by National river conservation directorate (NRCD). Actual integrated efficiency (IE(a)) of each STP was evaluated and compared with the standard integrated efficiency (IE(s)) based upon physical, biological and microbiological removal efficiencies depending upon influent sewage characteristics. The best results were obtained for STPs employing extended aeration, BIOFORE and oxidation pond treatment process thus can be safely used for irrigation purposes.     

Management of air quality in the vicinity of congested area in Kuwait

An assessment of air quality in the vicinity of a selected school has been carried out by monitoring the concentrations of primary pollutants. The results has shown that during the school hours, the measured pollutants emitted from the cars next to the selected school, such as CO and NO(2), are always under the allowable limits for Kuwaiti air quality standards. On the other hand, the concentrations of non methane hydrocarbon pollutant (nm-HC), some of which are considered to be cancergenic, are found to be above the Kuwaiti standard most of the times. A traffic counter is used to record the number of cars in the main road next to the school in 15 min intervals for 10 days during the monitoring period for air quality. Statistical analysis is performed to develop a relation for prediction of the necessary reduction in traffic, based on CO concentrations, during morning and afternoon periods on working days. A computer dispersion model (CALINE4) is also used to assess the CO concentrations based on recorded flow of traffic and emission inventory with the prevailing meteorological conditions existed at the specified time. After the validation of model, different scenarios have been evaluated to provide an acceptable solution to resolve the traffic congestion problem near the schools in the early morning hours with substantial reduction in pollution levels. The optimal solution for CO concentration reduction by managing smooth traffic flow is to reduce the traffic intensity by half in early morning and afternoon rush hours. The results of the predicted CO concentration in the vicinity of the school for the model and the statistical analysis has shown reduction of 30% and 42% respectively, for approximately 50% decrease in the car use. On the other hand the predicted CO concentration for the model and the statistics reached 24% and 33% respectively when 50% of students opted for buses instead of using private cars.     

土著厌氧菌修复有机氯污染土壤的方法探索

针对工业场地有机氯污染土壤探索微生物修复的方法,试验表明:添加土著厌氧菌菌液及营养液的试验组,污染物去除率比空白组明显提高。基因测定结果显示,试验土壤中至少存在具有降解有机氯污染物能力的3种菌种。     

Metal remediation from partially composted distillery sludge using composting earthworm Eisenia fetida

Distillery sludge, a sugar industry byproduct, has been recommended widely as a potential soil conditioner, but high concentrations of metals limit its continuous use for field crops. In this study we tested the feasibility of earthworm Eisenia fetida (Savigny) in removing metals (Fe, Cu, Zn, Pb) from sludge through vermitechnology. The transfer of metals during the vermicomposting process was also estimate in terms of total metal contents in vermicomposted sludge and earthworm tissues. The sludge processed by worms showed a significant reduction in concentration of metals: Zn (20.5-43.8%), Fe (23.6-34.0%), Mn (18.0-45.7%) and Cu (29.0-58.1%), at the end. The metal reduction in sludge was directly related to the bioaccumulation of metals in the tissues of composting earthworms. The inoculated earthworms showed a considerable level (dry wt basis) of Zn (103.7-143.3 mg kg(-1)), Fe (87.2-146.5 mg kg(-1)), Mn (83.7-138.6 mg kg(-1)) and Cu (16.8-25.5 mg kg(-1)) in their tissues. A higher range of bioconcentration factors (BCFs) for different metals studied further suggest the candidature of earthworm to be used effectively for removal of metals form industrial sludges. The obtained vermicomposts form different vermireactors were rich in nutrients. The feasibility of earthworms to mitigate the metal toxicity and to enhance the nutrient profile in sludge might be useful in sustainable land restoration practices at low-input basis. The ranges of metals in end product were within the standards recommended by different agencies.     

污水处理厂污水和污泥中PAHs的残留及风险研究进展

多环芳烃(PAHs)是一类极其复杂的有机污染物,衍生物种类较多,1976年美国环保局因其致癌、致畸、致突变将其中的16种列为优先控制污染物。城市污水处理厂作为一个地区污染物迁移和转化的重要媒介,在控制和截断PAHs进入天然水体的过程中扮演着重要的角色。因此,研究污水处理厂中PAHs的浓度水平对于了解和控制PAHs进入天然水体和通过污泥进入到土壤中进而通过食物链危害人类健康具有重要的意义。文章综述了污水处理厂污水和污泥中PAHs的前处理技术、分析方法、浓度水平、生态风险以及国内外污水处理厂污泥土地利用现状。     

The influence of metallurgy on the formation of welding aerosols

Recent research has indicated that insoluble ultrafine aerosols (ie., particles whose physical diameters are less than 100 nm) may cause adverse health effects due to their small size, and that toxicological response may be more appropriately represented by particle number or particle surface area. Unfortunately, current exposure criteria and the associated air-sampling techniques are primarily mass-based. Welding processes are high-temperature operations that generate substantial number concentrations of ultrafine aerosols. Welding aerosols are formed primarily through the nucleation of metal vapors followed by competing growth mechanisms such as coagulation and condensation. Experimental results and mathematical tools are presented to illustrate how welding metallurgy influences the chemical aspects and dynamic processes that initiate and evolve the resultant aerosol. This research suggests that a fundamental understanding of metallurgy and aerosol physics can be exploited to suppress the formation of undesirable chemical species as well as the amount of aerosol generated during a welding process.