Tracing volatile organic compounds in sewers

A combined method of passive and active sampling of volatile organic compounds (VOCs) in a sewer system is presented. Passive sampling devices are used to locate and identify volatile organic compounds in the sewer atmosphere. Passive sampling is a time-integrating method and its results are only qualitative. To get quantitative information active sampling of wastewater is necessary. Concentrations of VOCs obtained from active sampling are used as input values for a simplified form of the two-film-model. This model allows to compute concentrations of VOCs at different points in a sewer stretch. We employed this method to describe the behaviour of volatile chlorinated hydrocarbons within a sewer stretch in Bayreuth, Germany.     

Removal of endocrine-disrupting chemicals by ozonation in sewage treatment.

Treatment experiments by two laboratory scale semi-batch reactors and a demonstration scale process were both carried out to evaluate endocrine disrupting chemical removal characteristics by ozonation in sewage treatment. In the semi-batch mode experiments, secondary effluent and primary effluen of sewage treatment plants were ozonated respectively. Behaviour of brominated by-products was also evaluated. The results based on these studies indicated that estrogenicity in wastewater can be removed by ozonation effectively. The condition of ozonation until dissolved ozone concentration increased to 0.1 mg/L, which corresponded to 1 mgO3/mgC and 0.4 mgO3/mgC of ozone consumption per initial DOC for secondary effluent and primary effluent, respectively, is proposed as an appropriate operational condition for efficient removal of EDCs as well as UV254 and SUVA without production of brominated by-products.     

硅酸锌催化臭氧氧化净水效能连续流实验研究

以实验室制备的硅酸锌为催化剂,考察了在连续流实验中催化臭氧氧化对滤后水水质的影响。结果表明,与单独臭氧氧化相比,在相同实验条件下,硅酸锌的存在能够提高水体中的臭氧浓度。硅酸锌催化臭氧氧化对滤后水的总有机碳(TOC)和天然有机物的去除效果均好于单独臭氧氧化。连续运行10 h,硅酸锌催化臭氧氧化系统中TOC的去除效果稳定,并且Zn2+的溶出非常少。生物可同化性有机碳(assimilable organic carbon,AOC)的测定结果表明,经过硅酸锌催化臭氧化处理后,滤后水中的大分子有机物所占比例明显降低,小分子有机物含量增高。GC-MS分析结果表明,单独臭氧氧化可使滤后水中有机物的种类从41种减少到27种;而硅酸锌催化臭氧化效果明显优于单独臭氧氧化可以使水中有机物种类减少到21种。     

Liquid-gas partitioning of selected volatile organic sulfur compounds in anaerobically digested sludges

The gas phase partitioning of volatile organic sulfur compounds (VOSCs) in anaerobic sludge digesters contributes to odors and can impact upon the suitability of biogases for use in alternative energy recovery technologies. In the present study, effective Henry's law coefficients (H') were estimated for methyl mercaptan (MM), dimethyl sulfide (DMS), and dimethyl disulfide (DMDS) in both deionized water and deactivated digested sludge. It was found that the complex matrix of digested sludge did not significantly affect the partitioning of VOSCs. Therefore, partitioning of VOSCs in digesters could be represented by their partitioning in clean water. A regression model was developed for the linear relationship between ln H' and 1/T in the gas-water system. The H' values of MM, DMS, and DMDS were able to be calculated over a temperature range of 12-58 °C.     

生物负载微孔渗水型混凝土对土壤中残留毒死蜱的去除试验

为了解决农村农药面源污染问题,利用小流量渗透法将毒死蜱降解菌负载在微孔渗水型混凝土上,研究不同降雨强度下不同孔隙率混凝土对毒死蜱的降解截留效果.结果表明:对于3种不同透水系数的微孔混凝土,微孔渗水型混凝土负载生物量和生物活性随孔隙率增大呈先升高后降低趋势;对于两种不同的降雨强度,毒死蜱降解率最优的都是孔隙率为48.1％...     

Catalytic ozonation for odour removal of high temperature alumina refinery condensate

Odour emissions from aluminium processing can cause an impact on local communities surrounding such facilities. Of particular concern is fugitive odours emitted from the handling and use of refinery condensate streams, particularly the digestion condensate. This study evaluated the application of using catalytic ozonation to treat alumina refinery condensate in order to remove the potential emission of odourous compounds from the industrial wastewater. The technical challenges in treating the alumina refinery condensate are the high pH and temperatures of the wastewater effluent (over 80 °C and pH above 10) due the industrial process. The odour removal efficiencies for different catalysts (FeCl(3), MnO, and MnSO(4)) under experimental conditions in terms of controlled pH, temperature and ozone dosage were determined before and after ozone treatment using dynamic olfactometry. The result demonstrated that the addition of both FeCl(3) and MnO catalysts improved odour removal efficiencies during the ozonation of alumina condensates at similar pH and temperature conditions. FeCl(3) and MnO had similar enhancement for odour removal, however MnO was determined to be more appropriate than MnSO(4) for odour removal due to the colouration of the treated condensate.     

Comparison of different TiO2 photocatalysts for the gas phase oxidation of volatile organic compounds.

Gas-solid photocatalyzed oxidation of air contaminants is being explored more and more for possible application to decontamination, purification and deodorization of enclosed atmospheres. Indoor air is characterized by a huge number of pollutants at low concentrations. Volatile organic compounds (VOC) represent the main indoor air pollutants category, and are of great concern since some of them can act negatively on human health. Several treatments exist to reduce VOC concentrations in gaseous effluents, but photocatalytic oxidation appears to be the most appropriate regarding indoor air specific constraints. It is then necessary to develop photocatalysts, which can possibly be used in an application such as indoor air-quality improvement. In the present work, three different TiO2-based materials were studied and compared for the photocatalytic oxidation of a typical pollutant of indoor air: methyl ethyl ketone. Kinetic studies were performed for each material in dry and humid air conditions, and the Langmuir-Hinshelwood model was satisfactorily applied in almost every case. A second approach consisted of determining methyl ethyl ketone degradation by-products. Acetaldehyde was found to be the main gaseous intermediate, and could be taken into account in the general Langmuir-Hinshelwood modeling.     

A kinetic study of enhancing effect by phenolic compounds on the hydroxyl radical generation during ozonation.

Ozone decomposition in aqueous solution proceeds through a radical type chain mechanism. These reactions involve the very reactive and catalytic intermediates O2- radical, OH radical, HO2 radical, OH-, H2O2, etc. OH radical is proposed as an important factor in the ozonation of water among them. In the present study, the enhancing effects of several phenolic compounds; phenol, 2-, 3-, 4-monochloro, 2,4-dichloro, 2,4,6-trichlorophenol on OH radical generation were mathematically evaluated using the electron spin resonance (ESR)/spin-trapping technique. OH radical was trapped with a 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a stable adduct, DMPO-OH. The initial velocities of DMPO-OH generation in ozonated water containing phenolic compounds were quantitatively measured using a combined system of ESR spectroscopy with stopped-flow apparatus, which was controlled by homemade software. The initial velocities of DMPO-OH generation increased as a function of the ozone concentration. The relation among ozone concentration, amount of phenolic compounds and the initial velocity (v0) of DMPO-OH generation was mathematically analyzed and the following equation was obtained, v0 (10(-6) M/s) = (A' x [PhOHs (10(-9) M)] + 0.0005) exp (60 x [ozone (10(-9) M)]). The equation fitted very well with the experimental results, and the correlation coefficient was larger than 0.98.     

Removal of trace organic chemical contaminants by a membrane bioreactor

Emerging wastewater treatment processes such as membrane bioreactors (MBRs) have attracted a significant amount of interest internationally due to their ability to produce high quality effluent suitable for water recycling. It is therefore important that their efficiency in removing hazardous trace organic contaminants be assessed. Accordingly, this study investigated the removal of trace organic chemical contaminants through a full-scale, package MBR in New South Wales, Australia. This study was unique in the context of MBR research because it characterised the removal of 48 trace organic chemical contaminants, which included steroidal hormones, xenoestrogens, pesticides, caffeine, pharmaceuticals and personal care products (PPCPs). Results showed that the removal of most trace organic chemical contaminants through the MBR was high (above 90%). However, amitriptyline, carbamazepine, diazepam, diclofenac, fluoxetine, gemfibrozil, omeprazole, sulphamethoxazole and trimethoprim were only partially removed through the MBR with the removal efficiencies of 24-68%. These are potential indicators for assessing MBR performance as these chemicals are usually sensitive to changes in the treatment systems. The trace organic chemical contaminants detected in the MBR permeate were 1 to 6 orders of magnitude lower than guideline values reported in the Australian Guidelines for Water Recycling. The outcomes of this study enhanced our understanding of the levels and removal of trace organic contaminants by MBRs.     

臭氧氧化对地表水溶解性有机物去除效果的影响研究

针对臭氧氧化作用对受污染地表水中溶解性有机物去除效果的影响进行研究。结果表明:臭氧投加比低于1mgO3/mgDOC时,臭氧对UVA、CODCr和UV410等有机物去除效率较高;臭氧投加比例为0.7mgO3/mgDOC时,BOD/COD由7.4%提高至18.4%,比紫外消光度(SUVA)逐渐降低并趋于平缓;不同臭氧投加比例下水中溶解性有机物的三维荧光指纹光谱变化规律表明,受污染地表水DOM中主要荧光物质为芳香族蛋白质(荧光峰A、B和C)及类腐殖酸(荧光峰D),其中,A峰、B峰和C峰的中心位置分别位于225/300nm、225/338nm和275/342nm;臭氧投加比例为0.7mgO3/mgDOC时峰强削减率为64%～81%,同时部分芳香族蛋白质的结构也发生了变化。     

Rejection of trace organic compounds by high-pressure membranes.

High-pressure membranes, encompassing reverse osmosis (RO), nanofiltration (NF), and low-pressure RO, may provide an effective treatment barrier for trace organic compounds including disinfection by-products (DBPs), pesticides, solvents, endocrine disrupting compounds (EDCs) and pharmaceutically active compounds (PhACs). The objective is to develop a mechanistic understanding of the rejection of trace organic compounds by high-pressure membranes, based on an integrated framework of compound properties, membrane properties, and operational conditions. Eight trace organic compounds, four DBPs and four chlorinated (halogenated) solvents, are being emphasized during an initial study, based on considerations of compound properties, occurrence, and health effects (regulations). Four polyamide FilmTec membranes; three reverse osmosis/RO (BW-400, LE-440, XLE-440) and one nanofiltration/NF (NF-90); are being characterized according to pure water permeability (PWP), molecular weight cutoff (MWCO), hydrophobicity (contact angle), and surface charge (zeta potential). It is noteworthy that rejections of compounds of intermediate hydrophobicity by the candidate membranes were observed to be less than salt rejections reported for these membranes, suggesting that transport of these solutes through these membranes is facilitated by solute-membrane interactions. We are continuing with diffusion cell measurements to describe solute-membrane interactions by estimation of diffusion coefficients through membranes pores, either hindered or facilitated.     

纳滤膜对饮用水中可同化有机碳的去除效果

考察了纳滤膜对饮用水中有机物和可同化有机碳(AOC)的去除效果。对纳滤膜进水和出水进行了AOC的相对分子质量分布测定,分析AOC和有机物相对分子质量分布间的关系,探讨纳滤膜去除AOC的机理。结果表明,纳滤膜能有效地去除TOC和UV254,去除率均高达95%以上;在不同季节,自来水中AOC浓度有显著的变化,其中AOCP17约占AOC总量的60%~70%;纳滤膜对饮用水中AOC的去除率约为60%,其去除效果受到筛分效应和电荷效应的双重影响。AOC多与相对分子质量小于1000的有机物有关。     

吹扫捕集/气相色谱-质谱法监测黄河干流水源地挥发性有机物

为了全面了解黄河干流重点城市水源地挥发性有机物的污染情况,采用吹扫捕集/气相色谱-质谱法对水源地38种挥发性有机物进行定性定量分析.该方法的加标回收率为94.4%～105.6%,精密度为1.7%～24.0%,检测限为0.02～0.04 μg/L,满足痕量有机物的分析要求.对3个城市水源地丰、平、枯水期进行监测分析.结果...     

Effects of synthetic organic chemicals on bacterial death and lysis

A technique derived from the tritiated thymidine method was used to characterize the effects of synthetic organic compounds (SOCs) on the specific rate of bacterial death as functions of chemical concentration, the physiological state of the cells, and exposure time to the toxicant. The rate of bacterial death was estimated by following over time the release of radioactive tracer from the DNA of thymidine-requiring (thy) mutant E. coli cells (ATCC 23820). Results indicate that the lysis rate of unexposed microbial cultures was the same whether or not the cells were growing or had reached the stationary phase. Lysis rates were calculated from exposures to single SOCs: acrylonitrile, ethylene glycol, isophorone, phenol, 2-chloro- and 4-chlorophenol. The concentrations tested were 250, 1000 and 5000 mg COD/1. The major effect observed with stationaryphase cultures was a stimulation of the rate of lysis, whereas a reduction in the rate of lysis was the primary effect observed with growing cells. A physiological interpretation for these opposite effects is provided. The physiological state of the microorganisms influenced the magnitude, intensity and type of effects caused by the presence of synthetic organic compounds.     

三卤甲烷在臭氧工艺中的形成与控制

研究了臭氧氧化对三卤甲烷生成潜能的去除规律,发现臭氧对氯仿生成潜能有较好的去除效果,但对溴仿生成潜能的去除能力很差.在高臭氧投加量下,臭氧会明显促进溴仿的生成.臭氧对总三卤甲烷生成潜能的去除效果是其对"氯代三卤甲烷生成潜能的去除"和对"溴代三卤甲烷生成潜能的促进"两方面综合作用的结果.     

Characteristics of estrogen decomposition by ozonation.

Since the natural estrogens 17 beta-estradiol (E2) and estron (E1), and the synthetic estrogen 17 alpha-ethynyl estradiol (EE2) have strong endocrine disrupting effects and the tendency to persist in effluent from wastewater treatment plants, effective measures are needed to remove them from wastewater. In this research, to gain an understanding of the characteristics of estrogen decomposition by ozonation, experiments were conducted using effluent from an actual wastewater treatment plant. In this experiment, estrogen was added to effluent at a concentration of 200 ng/l and 20 ng/l before the ozonation experiments. The results showed 90% or more of estrogen concentration and estrogenic activity of E2, El and EE2 to be removed at an ozone dose of 1 mg/l. At an ozone dose of 3 mg/l, the estrogen concentration and estrogenic activity of E2, El and EE2 in the treated water fell below the detection limit. The removal rate was not influenced by the kind of estrogen. No generation of byproducts with estrogenic activity was observed. The authors conclude that estrogen in secondary treated wastewater can be almost entirely removed at the practical ozone dose rate applied for the purpose of disinfection, which is up to about 5 mg/l.     

Removal of inhibitory phenolic compounds by biological activated carbon coupled membrane bioreactor.

Phenolic compounds cause problems for conventional treatments due to their toxic and inhibitory properties. This work investigated the treatability of phenolic compounds by using two membrane-bioreactor systems, namely: activated sludge coupled with MBR (AS-MBR) and biological granular activated carbon coupled with MBR (BAC-MBR). Initially, the system was fed with phenol (500 mg/L) followed by adding 2,4-dichlorophenol (2,4-DCP). Phenol, 2,4-DCP, TOC and COD removal were higher than 98.99% when the organic load ranged between 1.80 and 5.76 kg/m3.d COD. In addition to MBR system development, removal mechanisms were also investigated. Relatively low values of phenol adsorption of GAC and biomass, and high maximum substrate removal rates obtained from a biokinetic experiment, proved that the removals were mainly due to biodegradation. Analysis of sludge indicated a significant difference in the sludge characteristics of the two reactors. The high EPS content in BAC-MBR led to higher viscosity and poor sludge settling properties. The relationship between sludge properties and EPS components revealed that settleability had no direct correlation with EPS, though it was better correlated to protein/carbohydrate ratios.     

SUVA as control parameter for the effective ozonation of organic pollutants in secondary effluent.

Recent research projects have shown a good suitability of the ozonation process to transform trace concentrations of most pharmaceuticals in wastewater treatment plant (WWTP) effluents. The concentrations of carbamazepine and 17 alpha-ethinylestradiol, for instance, were reduced below their detection limits by use of ozone dosages resulting in a specific ozone consumption of 0.5 mg O3/mg DOC0. At the same time a good disinfection performance was achieved. The given hygienic requirements of the EU bathing water directive (e.g. 2,000 N/100 mL faecal coliforms) are fulfilled without the formation of bromate (<10 microg/L). As technical control parameter of the ozonation process usually the residual ozone in the liquid phase or in the off-gas are used. However, at very low specific ozone consumptions, ozone reacts instantaneously with dissolved compounds and cannot be detected. Hence, alternative parameters should be used for effective operation control. The present paper evaluates the relation between UVA decrease and the removal of different compounds (endocrine disrupting compounds, pharmaceuticals, iodinated X-ray contrast media), microbial parameters and bromate formation. The results can be used as a guideline for the control of the oxidation performance at large scale ozonation units.     

Removal of pharmaceutically active compounds in nitrifying-denitrifying plants.

The behaviour of nine pharmaceutically active compounds (PhACs) of different diagnostic groups is studied during a nitrifying-denitrifying process in an activated sludge system. The compounds selected cover a wide range of frequently used substances such as anti-epileptics (carbamazepine), tranquillisers (diazepam), anti-depressants (fluoxetine and citalopram), anti-inflammatories (ibuprofen, naproxen and diclofenac) and estrogens (estradiol and ethinylestradiol). The main objective of this research is to investigate the effect of acclimation of biomass on the removal rates of these compounds, either by maintaining a high sludge retention time or at long-term operation. The removal rates achieved for nitrogen and carbon in the experimental unit exceed 90% and were not affected by the addition of PhACs. Carbamazepine, diazepam and diclofenac were only removed to a small extent. On the other hand, higher removal rates have been observed for naproxen and ibuprofen (68% and 82%), respectively.     

饮用水源水中痕量挥发性有机物分析方法研究

目前，种类繁多的挥发性有机化合物不仅广泛用于工业，也大量应用在日常生活中，导致饮用水源水受到一定程度污染，饮用水的质量直接影响着人类的健康，日本、美国等经济发达国家对各类挥发性有机污染物都制定了严格的控制标准，我国于2005年6月开始实施的新的《城市供水水质标准》新增加了25种VOC化合物作为严格控制的目标化合物，包括5种苯系物、6种氯苯类化合物和14种卤代烃类化合物，由于水源水中VOC含量低，对分析人员和仪器需求很高，本研究目的是建立饮用水源水中痕量挥发性有机物标准分析方法，研究采用吹扫捕集／气相色谱／质谱联用技术对饮用水源水中45种痕量挥发性有机物进行分析结果表明，本方法所分析45种目标化合物的回收率范围为74％～122％，精密度RSD％范围为4．2％～22．0％，检测限范围为0．04μg／L～0．15μg／L。均满足水源水痕量分析的要求，根据研究结果可得出本方法可作为水利水质监测部门饮用水源水中痕量挥发性有机物行业标准监测方法。