Impact of Effluent Recirculation on Stabilization Pond Performance

This paper presents a test case for the effects of recirculation on stabilization pond performance. The BOD₅, COD, SS and Total Coliform removal at the intermediate treatment stages and the outlet of a stabilization pond treatment line, over a 2-year operational period (January 2000-December 2001), is described in detail and the effluent at different stages of treatment is compared to that of a conventional stabilization pond treatment line operating under similar conditions. The system consisted of four ponds in line—an anaerobic pond, followed by three individual ponds (Pond 1, Pond 2 and Pond 3). The effluent of the last pond (Pond 3) was recirculated back to the inlet of the first pond (Pond 1) at a discharge ratio 2:1 (recirculation:inflow). The overall BOD₅, COD, SS and Total Coliforms total reduction was 89%, 81%, 85% and 99.7%, respectively. The anaerobic pond proved to be the most efficient in removing COD and SS (57% and 68%, respectively) whereas Pond 1 achieved the most significant reduction in BOD₅ and Total Coliforms (69% and 86%, respectively). Although BOD₅ and COD were adequately reduced by the recirculating pond line, the SS concentration was high due to algae presence in the final effluent. Moreover, the Total Coliforms were insufficiently removed due to the reduced hydraulic retention time involved in this type of recirculation.     

Screening of wood rotting fungi potentially useful for the degradation of organic pollutants

Many papers have shown that white rot fungi can degrade aromatic pollutants under laboratory conditions, but few report field scale trials. Here we report the first steps in the development of a remediation system for Greek conditions. A review of the available organochlorine compound pollution information in Greece is presented. White rot fungi isolated from sites in Greece have been screened for growth rate and ligninolytic activity, using decolourisation of the dye Poly R-478 as an indicator of enzyme activity. Use of white rot fungi under field conditions in Greece will require bioaugmentation to be effective at high temperatures and low water activity for much of the year. The most potent strains have been selected under a range of conditions and have been challenged with priority pollutants to determine their degradative ability under laboratory conditions and subsequently ex situ in soil.     

Occurrence of organic pollutants in recovered soil fines from construction and demolition waste

The objective of this study was to characterize recovered soil fines from construction and demolition (C&D) waste recycling facilities for trace organic pollutants. Over a period of 18 months, five sampling trips were made to 14 C&D waste recycling facilities in Florida. Screened soil fines were collected from older stockpiles and newly generated piles at the sites. The samples were analyzed for the total concentration (mg/kg) of a series of volatile organic compound (VOCs) and semi-volatile organic compounds (semi-VOCs). The synthetic precipitation leaching procedure (SPLP) test was also performed to evaluate the leachability of the trace organic chemicals. During the total analysis only a few volatile organic compounds were commonly found in the samples (trichlorofluoromethane, toluene, 4-isopropyltoluene, trimethylbenzene, xylenes, and methylene chloride). A total of nine VOCs were detected in the leaching test. Toluene showed the highest leachability among the compounds (61.3-92.0%), while trichlorofluoromethane, the most commonly detected compound from both the total and leaching tests, resulted in the lowest leachability (1.4-39.9%). For the semi-VOC analysis, three base-neutral semi-VOC compounds (bis(2-ethylhexyl)phthalate, butyl benzyl phthalate, and di-n-butyl phthalate) and several PAHs (acenaphthene, pyrene, fluoranthene, and phenanthrene) were commonly detected in C&D fines samples. These compounds also leached during the SPLP leaching test (0.1-25%). No acid extractable compounds, pesticides, or PCBs were detected. The results of this study were further investigated to assess risk from land applied recovered soil fines by comparing total and leaching concentrations of recovered soil fines samples to risk-based standards. The results of this indicate that the organic chemicals in recovered soil fines from C&D debris recycling facilities were not of a major concern in terms of human risk and leaching risk to groundwater under reuse and contact scenarios.     

Biodegradability of Urea-Aldehyde Condensation Products

Condensation products of urea and different aldehydes (formaldehyde, isobutyraldehyde, crotonaldehyde) are used in large amounts (more than 300,000 tons per year) as resins, binders, and insulating materials for industrial applications, as well as in controlled-release nitrogen fertilizer for greens, lawns, or bioremediation processes. The biodegradability of these condensates and the enzymic mechanism of their degradation was studied in mircoorganisms isolated from soil, which were able to use these compounds as the sole source of nitrogen for growth. Different pure cultures of both gram-positive and gram-negative bacteria completely degraded methylenediurea, dimethylenetriurea, isobutylidenediurea, and crotonylidenediurea to urea, ammonia, and the corresponding aldehydes and carbon dioxide. Enzymes initiating this degradation were purified and characterized and turned out to be different with regard to their regulation of expression, their physicobiochemical properties, and their reaction mechanism.     

Fungal Degradation of the Bioplastic PHB (Poly-3-hydroxy- butyric acid)

PHB (poly-3-hydroxybutyric acid) is a thermoplastic polyester synthesized by Ralstonia eutropha and other bacteria as a form of intracellular carbon and energy storage and accumulated as inclusions in the cytoplasm of these bacteria. The degradation of PHB by fungi from samples collected from various environments was studied. PHB depolymerization was tested in vials containing a PHB-containing medium which were inoculated with isolates from the samples. The degradation activity was detected by the formation of a clear zone below and around the fungal colony. In total, 105 fungi were isolated from 15 natural habitats and 8 lichens, among which 41 strains showed PHB degradation. Most of these were deuteromycetes (fungi imperfecti) resembling species of Penicillium and Aspergillus and were isolated mostly from soils, compost, hay, and lichens. Soil-containing environments were the habitats from which the largest number of fungal PHB degraders were found. Other organisms involved in PHB degradation were observed. A total number of 31 bacterial strains out of 67 isolates showed clear zones on assay medium. Protozoa, possible PHB degraders, were also found in several samples such as pond, soil, hay, horse dung, and lichen. Lichen, a fungi and algae symbiosis, was an unexpected sample from which fungal and bacterial PHB degraders were isolated.     

Ability of Fungal Strains to Degrade PVA Based Materials

The aim of this work was to select a fungal strain with degradative potential upon PVA based materials. The polymeric materials tested were PVA films which contain different percentages of PVA, starch and glycerol. These materials are of interest for food packaging applications, which presume to solve the problems concerning accumulation, disposal and degradation. Eleven strains were tested in solid culture for the ability to use PVA based composites as carbon and energy sources. The fungal strain selected was cultivated in liquid medium with different compositions. The scanning electron microscopy (SEM) investigations revealed the effects of microorganism growth upon polymeric films. Significant changes in polymer surface aspects were observed depending on the medium culture composition, the presence of supplementary carbon source facilitating microbial growth and degradation process.     

Bacterial degradation of a new polyester,polyethylene glycol-phthalate polyester

Microorganisms which can assimilate a new polyester synthesized from polyethylene glycol (PEG) as a dihydroxyl compound and phthalic acid as a dicarboxyl compound were isolated from soils by enrichment culture techniques. Two cultures, K and N, were obtained: Culture K grew on PEG 4000 polyester and culture N assimilated PEG 6000 polyester. Each culture included two bacteria indispensable for the degradation of polyesters: bacteria K1 and K2 for PEG 4000 polyester-utilizing culture K and bacteria N1 and N2 for PEG 6000 polyester-utilizing culture N. Bacteria K2 and N2 were responsible for the hydrolysis of ester bonds in a polyester and both were identified as the same species,Comamonas acidovorans. Bacteria K1 and N6 could assimilate PEG as a sole carbon and energy source. Both are Gram-negative, non-spore-forming rods and resembled each other on their colony characteristics, although strain K1 could not grow on PEG 6000.C. acidovorans N2 (K2) grew on dialkyl phthalates (C₂–C₄) and phthalate and tributyrin, but not on PEG, diphthalic PEG, and PEG phthalate polyesters. Their culture supernatant and washed cells hydrolyzed PEG (400–20,000) phthalate and sebacate polyesters.C. acidovorans had higher esterase activity toward PEG phthalate, isophthalate, and terephthalate polyesters than known esterase and lipases. The esterase seemed to be an extracellular one and attached to the cell surface.     

铝碳微电解法降解水中邻苯二甲酸酯

采用铝碳微电解法降解水中邻苯二甲酸酯（PAEs）。首先考察了初始废水pH、铝碳质量比和反应时间对邻苯二甲酸二甲酯（DMP）降解率的影响,然后分别考察了超声波频率、其他金属的添加和H₂O₂加入量对铝碳微电解法降解模拟混合PAEs废水中DMP、邻苯二甲酸二乙酯（DEP）和邻苯二甲酸二丁酯（DBP）的影响。实验结果表明：在初始DMP质量浓度为20 mg/L、初始废水pH为12.0、铝碳质量比为1∶1、反应时间为30 min的条件下,DMP降解率达49.94%;在上述最佳反应条件下处理DMP,DEP,DBP的质量浓度分别为20,10,8 mg/L的模拟混合PAEs废水,当超声波频率为80 kHz时,模拟混合PAEs废水中DMP,DEP,DBP的降解率分别为63.38%,32.75%,32.23%,当铝铁质量比为100∶1时,DMP,DEP,DBP的降解率分别为59.61%,37.39%,31.50%;添加铜和H₂O₂对PAEs的降解有抑制作用。     

Occurence and Distribution of Polycyclic Aromatic Hydrocarbons in Ankara Precipitation

Urban atmospheric environment contains many trace organic pollutants that are related to the incomplete fuel combustion in domestic heating, industrial plants and automobile traffic. Removal of these pollutants from the atmosphere takes place through wet and dry deposition as well as chemical transformations. In this study, concentrations of polycyclic aromatic hydrocarbons (PAHs) in wet deposition samples were determined at an urban site of Turkey. Wet and dry deposition samples were collected using Andersen Rain Sampler. The sampler was modified accordingly for the collection of organic pollutants. Collected samples were preconcentrated by using solid phase extraction (SPE) disks and consecutively analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). Among the 13 compounds quantified in this study, anthracene, fluoranthene, and pyrene were found more frequently and at elevated concentrations (202, 271 and 260 ng L^-1 mean concentrations, respectively).Concentrations of PAHs were found to be high in winter period.     

Chemical and microbiological hazards associated with recycling of anaerobic digested residue intended for agricultural use

In the present study, three full-scale biogas plants (BGP) were investigated for the concentration of heavy metals, organic pollutants, pesticides and the pathogenic bacteria Bacillus cereus and Escherichia coli in the anaerobically digested residues (ADR). The BGPs mainly utilize source-separated organic wastes and industrial food waste as energy sources and separate the ADR into an ADR-liquid and an ADR-solid fraction by centrifugation at the BGP. According to the Norwegian standard for organic fertilizers, the ADR were classified as quality 1 mainly because of high zinc (132-422 mg kg(-1) DM) and copper (23-93 mg kg(-1) DM) concentrations, but also because of high cadmium (0.21-0.60 mg kg(-1) DM) concentrations in the liquid-ADR. In the screening of organic pollutants, only DEHP (9.7-62.1 mg kg(-1)) and ∑ PAH 16 (0.2-1.98 mg kg(-1) DM) were detected in high concentrations according to international regulations. Of the 250 pesticides analyzed, 11 were detected, but only imazalil (<0.30-5.77 mg kg(-1) DM) and thiabendazol (<0.14-0.73 mg kg(-1) DM) were frequently detected in the ADR-fiber. Concentrations of imazalil and thiabendazol were highest during the winter months, due to a high consumption of citrus fruits in Norway in this period. Ten percent of the ADR-liquid samples contained cereulide-producing B. cereus, whereas no verotoxigenic E. coli was detected. The authors conclude that the risk of chemical and bacterial contamination of the food chain or the environment from agricultural use of ADR seems low.     

Anaerobic microbial degradation of poly (3-hydroxyalkanoates) with various terminal electron acceptors

The microbial degradation of poly (3-hydroxyalkanoates) (PHAs) under anaerobic conditions with various terminal electron acceptors was examined. Nitrate-reducing consortia were established using activated sludge, and PHAs were shown to be biodegradable under these conditions. A positive correlation between carbon dioxide production and nitrate reduction was demonstrated. Nitrous oxide accumulated as the main N-containing product of nitrate reduction. The amount of PHAs in activated sludge cultures decreased approximately 20% within 40 days of incubation. Attempts were made to establish iron- and sulfate-reducing consortia from spring water, yet it could not be demonstrated that the mixed cultures were capable of degrading PHAs. Pure cultures of iron- and sulfate-reducing bacteria could not utilize PHAs as sole carbon sources. Methanogenic environments sampled included pond sediment and rumen fluid. PHAs were fermented to methane and carbon dioxide after 10 weeks by a sediment consortium, with 43 to 57% of the substrate carbon transformed to methane. Although it could not be demonstrated that PHAs were biodegraded by a rumen fluid consortium, a facultative anaerobic bacterium, identified as aStaphylococcus sp., that could grow on PHAs was isolated from rumen fluid.     

催化氧化技术在橡胶废气处理中的应用

采用催化氧化技术处理热塑性丁苯橡胶( SBS)生产装置D线后处理单元废气,废气的非甲烷总烃去除率和环己烷去除率均达到98％以上,非甲烷总烃质量浓度达到DB11/447-2007《炼油与石油化学工业大气污染物排放标准》的要求(小于100 mg/m3).对SBS生产装置凝聚单元进行两釜流程改三釜流程后,催化氧化反应器入口非甲烷总烃质量浓度由( 3.84～5.82)×103 mg/m3降至( 2.48～2.63)×103 mg/m3,反应器出口非甲烷总烃质量浓度均小于50 mg/m3.凝聚单元改造并采用催化氧化技术处理废气后,每年节约费用约80万元.     

Characteristics variation of coal combustion residues in an Indian ash pond.

Coal-fired power plants all over the world are cited as one of the major sources that generate huge quantities of coal combustion residues (CCRs) as solid wastes. Most frequently CCRs are collected through electrostatic precipitators, mixed with bottom ash by hydraulic systems and deposited in ash ponds. The quality of the CCRs at different locations in one of the ash ponds in Central India was evaluated to understand the variation in characteristics with a view to effective utilization. Results revealed that the presence of fine particles (< 50 mocrom) increased with increasing distance from the ash slurry inlet zone in the ash pond. Wide variations in the bulk density (800-980 kg m(-3)), porosity (45-57%) and water-holding capacity (57.5-75.7%) of CCRs were recorded. With increasing distance the pH of the CCRs decreased (from 9.0 to 8.2) and electrical conductivity increased (from 0.25 to 0.65 dS m(-3)). The presence of almost all the heavy metals in CCRs exhibited an increase with distance from the ash slurry discharge zone due to the increase in surface area (from 0.1038 to 2.3076 m2 g(-1)) of CCRs particles. The present paper describes the variation of characteristics of CCRs deposited in the ash pond and their potential applications.     

生物滴滤塔处理模拟印刷有机废气

选取甲苯、乙酸乙酯为目标污染物模拟印刷有机废气,采用生物滴滤塔对其进行处理。从某污水处理厂曝气池活性污泥中筛选出3株能够高效降解甲苯、乙酸乙酯的优势菌种,经鉴定分别为枯草芽孢杆菌（Bacillus subtilis）、蜡状芽胞杆菌（Bacillus cereus）和嗜麦芽寡养单胞菌（Stenotrophomonas maltophilia）。实验结果表明：增大乙酸乙酯配比对VOCs去除率影响不大,而增大甲苯配比导致VOCs去除率下降明显;在进气VOCs质量浓度为约800 mg/m³（甲苯与乙酸乙酯的体积比1∶1）、气体空床接触时间为300 s、菌液喷淋量为800 L/h、菌液温度为25 ℃的条件下,VOCs去除率可达约99%。生物滴滤塔运行一段时间后,对菌种进行再鉴定,结果与处理前一致。     

黑麦草强化生物过滤法处理正己烷废气

采用顶部种植黑麦草的微生物填料塔,对模拟正己烷废气进行生物过滤处理。研究了反应温度、入口正己烷质量浓度、填料层高度对正己烷去除效果的影响,考察了填料塔中细菌及过氧化氢酶活性的分布。实验结果表明:黑麦草强化生物过滤的适宜反应温度为25℃;正己烷出口质量浓度随入口浓度的增加而增大,随填料层高度的增加而减小;在反应温度为25℃,入口正己烷质量浓度为100~500 mg/m3、填料层高度为600 mm的条件下,出口正己烷质量浓度为0~46 mg/m3,均低于GBZ/T 2.1—2007《工作场所化学有害因素职业接触限值》中对正己烷的限值(100 mg/m3);相同条件下,种植黑麦草的填料塔的正己烷去除率明显提高,细菌浓度及过氧化氢酶活性均高于无黑麦草的填料塔,说明黑麦草显著促进了正己烷的生物降解。     

Degradation of Poly(Ethylene Glycol)-Based Nonionic Surfactants by Different Bacterial Isolates from River Water

Different bacterial strains able to attack polyoxyethylene-type nonionic surfactants were isolated by enrichment procedure from the surface waters of the Arno River. Alkylphenol polyethoxylates and alkyl polyethoxylates, as well as polyethylene glycols, were degraded and assimilated by bacterial strains in axenic cultures. Degradative routes of polyethyleneoxide chains were investigated by matching each bacterial isolate with several types of nonionic surfactants and polyethers and by the identification of their degradation products isolated during aerobic digestion experiments. In accordance with previous reports, the first attack led to the shortening of the poly(oxyethylene) chains of the nonionic surfactants. It was found that the strains able to degrade PEG segments of nonionic surfactants possess enzymatic systems unable to degrade free PEGs, whereas those degrading the latter substrates cannot degrade PEG segments coupled to hydrophobic moieties.     

国内外煤化工行业污染物排放标准研究及启示

系统分析了煤化工行业的产排污情况,梳理了国内外相关排放标准。结果表明:国内仅焦化等部分工序有行业排放标准,其余工序目前执行水或大气的综合排放标准,其污染物项目不能全面反映煤化工行业的污染特征,急需制定煤化工行业污染物排放标准;国外相关标准情况与国内类似,无直接借鉴意义。建议:合理界定煤化工排放标准的适用范围,与其他排放标准协调配套,控制整个行业的污染物排放;针对大气污染物,明确各排放口的特征污染物,结合综合指标和高毒性物质指标进行挥发性有机物的排放控制;针对水污染物,引入综合毒性指标以有效控制废水中有毒有害污染物排放的环境风险。     

硝酸尾气SCR脱硝技术的开发及工业应用

硝酸生产尾气脱硝是大气污染治理的重要领域。中国石化开发了硝酸尾气选择性催化还原(SCR)脱硝成套技术,主要包括FN-1型蜂窝状NH_3-SCR催化剂以及SCR反应器、气体分布器等关键设备和内构件。在中国石化南化公司270 kt/a硝酸装置上的工业化应用表明,SCR脱硝装置的入口NO_x质量浓度在200～400 mg/m~3,出口NO_x质量浓度低于20 mg/m~3,NO_x去除率大于95%,逃逸氨质量浓度低于1 mg/m~3,净化效果优于国家和地方的相关排放标准。     

宁东能源化工基地核心区表层土壤酚类污染物的污染评价、空间分布及来源解析

采集了宁东能源化工基地核心区的146个表层土壤样品,检测了6种优控酚类污染物.运用单因子污染指数、内梅罗综合污染指数和致癌风险指数评价了酚类污染物的污染程度及健康风险.借助主成分分析和绝对主成分分数-多元线性回归受体模型,结合地统计学方法,对酚类污染物的空间分布及来源进行了分析.结果显示:2,4-二氯酚和2,4,6-三...     

Characterization of Aerobic Bacteria Involved in Degrading Polyethylene Glycol (PEG)-3400 Obtained by Plating and Enrichment Culture Techniques

Polyethylene glycol (PEG) 3400-degrading aerobic bacteria were isolated from tap water and wetland sediments and then characterized. Only one Sphingomonas strain was obtained in enrichment cultures from each inoculum source whereas a total of 15 bacterial strains were isolated on agar plates. Nine of the 15 isolates were confirmed as PEG 3400 degraders. Three of the 9 PEG 3400 degraders were Gram-negative bacteria belonging to the genus Pseudomonas and genus Sphingomonas. The remaining six isolates were Gram-positive bacteria belonging to genera Rhodococcus, Williamsia, Mycobacterium and Bacillus. PEG 3400 was quantified at 194 nm spectrophotometrically and, at the same time, the growth of two Gram-negative (isolates P1 and P7) and five Gram-positive (isolates P2, P3, P4, P5 and P6) PEG 3400-degrading bacteria were assayed in liquid media and on agar plates amended with PEG 3400, and also on Nutrient Agar plates and pure agar plates without PEG 3400 addition. No growth was observed on the pure agar plates for all the tested strains for a period of 31 days. All tested PEG 3400 degraders showed much lower viability in liquid culture than on the corresponding agar plates in the presence of PEG 3400. Two Gram-negative isolates P1 and P7 did not show significant growth advantage over the Gram-positive isolates both on the agar plates and in the liquid medium amended with PEG 3400. Our results suggest that diversity of PEG degrading bacteria is high in the environments and culturing techniques affect the successful isolation of the bacteria responsible for degradation.