Effects of Bromide Ion and Natural Organic Matter Fractions on the Formation and Speciation of Chlorination By-Products

The impacts of bromide concentration and natural organic matter (NOM) characteristics on the formation and speciation of disinfection by-products (DBPs) in chlorinated NOM fractions were investigated. A total of 20 bulk water NOM fractions with a wide range of specific ultraviolet (UV) absorbance (SUVA254) values were obtained from a source water employing XAD-8 or XAD-4 resin adsorption in completely mixed batch reactors. SUVA was not a good predictor of DBP [trihalomethanes (THMs), haloacetic acids (HAAs), and adsorbable organic halogens (AOX)] formation and speciation. The destruction in the UV254 absorbance from chlorination did not correlate with DBP formation at any bromide level. NOM moieties which do not absorb UV light at 254?nm significantly contributed to DBP formation. Mass balance calculations on halogens using THMs, HAAs, and AOX data indicated that significant amounts of DBPs (>54% of AOX) other than THMs and HAAs were formed in NOM fractions with 60–110?μg/L bromide concentration. The relative occurrence of such other halogenated by-products decreased with increasing bromide concentrations up to 500?μg/L level. NOM in the studied water was more susceptible to the formation of brominated THM species as opposed to brominated HAAs. At constant dissolved organic carbon concentration, chlorine dose and pH, increasing bromide concentrations in NOM fractions increased the total concentrations of DBPs and resulted in a shift toward the formation of brominated species. Further, increasing bromide concentrations increased the spectrum of detected species (i.e., occurrence of all nine HAAs) and provided a competitive advantage to THM and HAA precursors in NOM over precursors of other DBPs.     

Predicting Chlorine Residuals and Formation of TTHMs in Drinking Water

Chlorination is the most widely practiced form of disinfection in the United States. It is highly effective against most microbiological contaminants. However, there is concern that the disinfection by-products (DBPs) formed by the use of chlorine might be carcinogenic. One class of DBPs that are formed and the only class of DBPs that currently are regulated are total trihalomethanes (TTHMs). Therefore, much effort is being expended in developing models that can be used to predict both TTHMs and chlorine residual levels in treated drinking water. This paper presents a model that predicts both TTHMs and chlorine residuals based on the consumption of chlorine and can be used to assist in evaluating the complex balance between microbial and DBP risks associated with disinfecting drinking water with chlorine. The parameters of the model have been found to be functions of total organic carbon, pH, temperature, and initial chlorine residual level. Bromide and the subsequent formation of brominated by-products were not considered in this paper.     

化工含氯废弃物焚烧技术

介绍了一种行之有效的处理含氯废弃物的成熟技术,通过合理控制焚烧温度(氯废弃物焚烧后产生大量的HCl气体和少量的Cl2),最大限度地回收了烟气中的HCl和去除了极毒气体Cl2。该焚烧技术经过了10年实际检验非常成功,实现了无公害的要求。     

Metallic Characterization of Foundry By-Products per Waste Streams and Leaching Protocols

In the United States, foundry facilities produce huge quantities of by-products to be disposed of annually. These by-products are broadly divided into three waste streams: sand, dust, and slag. To characterize foundry by-products in terms of waste streams helps beneficially manage and reuse foundry by-products based on individual environmental characteristics. One thousand one hundred eighty two data sets addressing bulk and leaching characterization of up to 24 metallic elements in sand, dust, and slag are collected and assessed using statistical methodologies. Findings indicate that sand is not hazardous with high confidence per metallic elements, and a leaching program is not mandatory in assessing whether sand is hazardous or not regarding metallic elements. No evidence indicates that dust and slag are nonhazardous materials. Only a fraction of metallic elements are extracted from as-received waste streams. Through comparisons of statistical parameters including estimated means, 95th percentiles and data distributions, sand is found less contaminated by most metallic elements than dust and slag, but metallic elements in sand leachate are in the similar levels as those in dust and slag leachates. Fe, Zn, and Al are highly concentrated in dust and slag on average, which suggests their potential reclamations.     

焦化副产品蒸馏试验的气压校正

采用蒸馏试验作为质量评价方法的焦化副产品，占有相当高的比例。任何一定组成的液体其沸点或沸程都与环境气压有关。目前有关的技术标准，其校正公式存在某些局限性，不能完全满足焦化副产品蒸馏的需要。就苯、酚类产品，通过实验室试验，得出更准确的气压校正公式，用以指导生产。     

煤及其副产物中锗的提取利用研究进展

锗作为高科技新兴产业的高价值稀散元素,已被众多国家列为战略性关键矿产资源,而煤及其副产物中锗资源的提取利用也已成为了行业研究的热点。总结了煤中锗的富集模式与赋存状态,系统分析了煤及其副产物中锗资源的提取利用技术的现状,对比了现有技术的优势与不足,并初步分析了目前研究的难点和未来的发展方向,以期为煤及其副产物中锗的高效提取利用和综合利用奠定基础。     

Trihalomethane and Haloacetic Acid Disinfection By-Products in Full-Scale Drinking Water Systems

Trihalomethane (THM), haloacetic acid (HAA5), and total organic carbon (TOC) data provided by the Missouri Dept. of Natural Resources for drinking water treatment systems in the State of Missouri was analyzed for the years 1997–2001. These data indicated that a significant portion of systems exceeded the current regulatory limits of 80 and 60?μg/L for THM and HAA5 in these years. The vast majority of the treatment plants exceeding the regulatory limits were small plants with service populations less than 10,000 people. No significant temporal trend in either THM or HAA5 was noted for the years 1997–2001. This work suggests that the proposed use of a locational running annual average may have a significant effect on compliance. The use of chloramines (combined chlorine) versus free chlorine (HOCl/OCl?) as a residual disinfectant was shown to significantly reduce both THM and HAA5 in systems that treat their own water (primary systems), but did not have a significant effect in systems which purchase their water from primary systems (secondary systems). Comparison of finished water at the treatment plant versus in the distribution system suggested that a majority of THM and HAA5 may be produced within the plant as opposed to the distribution system. Hence, reducing these chlorinated disinfection byproducts within the treatment plant itself should be a key focus for achieving compliance, and supports Environmental Protection Agency disinfection byproducts compliance guidelines using enhanced coagulation.     

Physical Properties of Vegetable Oil and Chlorinated Ethene Mixtures

Laboratory experiments were conducted to investigate the abiotic interactions of soybean oil (SoyOil) and chlorinated ethene (CE) nonaqueous phase liquids (NAPLs). The mixed NAPL density and interfacial tension behaved ideally, as predicted by the volume ratio. The mixed NAPL viscosity increased exponentially from that of the pure CE to that of pure SoyOil as the volume fraction increased. The measured contact angle was highly variable and was unpredictable as a function of the volume composition of the mixed NAPL. The physical property effects indicate that the mobilization of residual CE NAPLs because of SoyOil injection is unlikely. Equilibrium dissolution of CEs from the NAPL mixtures behaved linearly as a function of the mole fraction. Dissolved SoyOil in simulated groundwater enhanced the dissolution of trichloroethene (TCE) during flow tests, increasing the effluent TCE concentration from 141?to?202?mg/L. The ready intermingling of the CE dense nonaqueous phase liquids (DNAPLs) and SoyOil indicate that such interactions may be significant at sites where vegetable oil is injected into DNAPL source areas to enhance in situ anaerobic bioremediation.     

Effects of Seepage Velocity and Temperature on the Dechlorination of Chlorinated Aliphatic Hydrocarbons

The influence of seepage velocity and groundwater temperature on the dechlorination rates of trichloroethylene (TCE) and tetrachloroethylene (PCE) by zero-valent iron (Fe0) were investigated by running laboratory column tests at seepage velocities ranging from 31 to 1,884?m/year at temperatures of 10 and 23°C. By increasing the seepage velocity from 31 to 1,884?m/year at 10°C, there were approximately seven- and nine-fold increases in the normalized dechlorination rate constants (SA) of TCE and PCE, respectively. Similarly, a four-fold increase in the SA of TCE and PCE was also observed at 23°C when increasing the seepage velocity from 103 to 1,183?m/year. Raising the groundwater temperature from 10 to 23°C at a given seepage velocity resulted in 2.7 and 1.1 times increases in the TCE SA and PCE SA, respectively. With the application of the Arrhenius equation, activation energies of 70.3?kJ/mol for TCE and 38.6?kJ/mol for PCE dechlorination were determined, indicating domination of the electron transfer process over the mass transfer as a major rate-limiting step of the dechlorination reactions by Fe0.     

Chlorinated hydrocarbons in coastal lagoons of the pacific coast of Nicaragua

Pelizaeus-Merzbacher disease/X-linked spastic paraplegia (PMD/SPG2) comprises a spectrum of diseases that range from severe to quite mild. The reasons for the variation in severity are not obvious, but suggested explanations include the extent of disruption of the transmembrane portion of the proteolipid protein caused by certain amino acid substitutions and interference with the trafficking of the PLP molecule in oligodendrocytes. Four codons in which substitution of more than one amino acid has occurred are available for examination of clinical and potential structural manifestations: Valine165 to either glutamate or glycine, leucine 045 to either proline or arginine, aspartate 202 to asparagine or histidine, and leucine 223 to isoleucine or proline. Three of these mutations, Val165Gly, Leu045Pro, and Leu223Ile have not been described previously in humans. The altered amino acids appear in the A-B loop, C helix, and C-D loop, respectively. We describe clinically patients with the mutations T494G (Val165Gly), T134C (Leu045Pro), and C667A (Leu223Ile). We discuss also the previously reported mutations Asp202Asn and Asp202His. We have calculated the changes in hydrophobicity of short sequences surrounding some of these amino acids and compared the probable results of the changes in transmembrane structure of the proteolipid protein for the various mutations with the clinical data available on the patients. While the Val165Glu mutation, which is expected to produce disruption of a transmembrane loop of the protein, produces more severe disease than does Val165Gly, no particular correlation with hydrophobicity is found for the other mutations. As these are not in transmembrane domains, other factors such as intracellular transport or interaction between protein chains during myelin formation are probably at work.     

氯化蒸馏渣中锗提取技术的研究和利用

氯化蒸馏渣中的锗90％为硅锗酸盐,为酸不溶锗,可溶于碱。采用碱溶液,浸出渣中的硅锗酸盐,在一定条件下,使硅锗分离（除硅）,除硅后的溶液含Ge50mg·L^-1为贫锗溶液,为降低生产成本,贫锗溶液未加任何沉淀剂,直接水解沉淀锗而达到从氯化蒸馏渣中提取锗的目的。技术指标：锗浸出率〉85％,除硅率〉95％,沉锗率〉95％,锗的回收率〉70％。此工艺技术投入生产一年余,年处理氯化蒸馏渣2000余吨,回收锗1500kg。     

Modeling Pd-Catalyzed Destruction of Chlorinated Ethenes in Groundwater

Groundwater contamination by chlorinated ethenes is a widespread environmental problem. Shortcomings in conventional remediation methods have motivated research into novel treatment technologies. A palladium/alumina catalyst in the presence of molecular hydrogen gas (referred to hereafter as the Pd/H2 system) has been demonstrated to destroy chlorinated ethenes in contaminated groundwater. This study presents a model for aqueous-phase destruction of chlorinated ethenes in contaminated groundwater using the Pd/H2 system that includes catalyst deactivation and regeneration. The model is validated using published data from laboratory column experiments from Stanford University. The model is then coupled with an analytical groundwater flow model to simulate application of in-well Pd/H2 reactors for in situ treatment of chlorinated ethene contaminated groundwater in a recirculating horizontal flow treatment Well (HFTW) system. Applying the model under realistic conditions results in approximately 130 days of HFTW system operation without significant catalyst deactivation. This suggests catalyst deactivation will not significantly affect system performance in a real remediation scenario. The model presented in this study, which simulates deactivation kinetics and regeneration of an in-well catalyst that is a component of a recirculating well system designed for in situ treatment of contaminated groundwater, represents an important step in transitioning the Pd/H2 technology to the field.     

Transformation of Chlorinated Methanes by Nanoscale Iron Particles

This paper examines the potential of using laboratory-synthesized nanoscale iron particles to transform chlorinated methanes. The iron particles have diameters on the order of 1–100 nm (0.001–0.1 μm). Palladized iron particles were prepared by depositing palladium (0.05–1% Pd by weight) on the surface of iron. Batch experiments were conducted to compare reactions of chlorinated methanes with palladized nanoscale iron, nanoscale iron, and commercial grade iron particles (～10 μm). Rapid transformations of tetrachloromethane (CT) and trichloromethane (CF) were achieved with the palladized nanoscale iron particles. Typically 0.1 mM CT or CF was reduced below detection limits within 1 h. Methane and dichloromethane (DCM) were the major end products. Yields of methane and DCM from CT were 52% and 23%, respectively. Little degradation of DCM was observed within 72 h. With the nanoscale iron and commercial-grade iron particles, much slower reactions of chlorinated methanes were observed. Kinetic analyses indicated that the surface area-normalized rate coefficients kSA of the nanoscale iron and commercial grade iron particles were one to two orders of magnitude lower than those of the palladized nanoscale iron.     

Predicting the course of disease

The ability to predict the course of disease and the effect of interventions is critical to effective medical practice and health care management. In this analysis, we sought to test whether available clinical data and analytic methodologies can be used to accurately predict the time course of the probability of death after hospital admission and the probability of readmission following discharge for patients with acute myocardial infarction or pulmonary disease. We grouped patients by selected physiologic characteristics and made time-to-event predictions using multiple regression models. These predictions were compared with observed probabilities calculated using the actuarial or life-table method. Predictions made with the Bailey-Makeham model generally replicated observed experience. They accurately accounted for substantial differences in the patterns of death and readmission and accurately delineated the effects of therapies, after adjustment for patient risk. These results were validated by analyses of resampled populations that differed in case mix from the source population. We believe that using such models to project the course of disease and the effects of treatment on that course in defined classes of patients should facilitate the development of practice guidelines for patient care and the management of health care resources.     

Predicting the near and distant future.

Four studies investigated individuals' confidence in predicting near future and distant future outcomes. Study 1 found that participants were more confident in theory-based predictions of psychological experiments when these experiments were expected to take place in the more distant future. Studies 2-4 examined participants' confidence in predicting their performance on near and distant future tests. These studies found that in predicting their more distant future performance, participants disregarded the format of the questions (e.g., multiple choice vs. open ended) and relied, instead, on their perceived general knowledge (e.g., history knowledge). Together, the present studies demonstrate that predictions of the more distant future are based on relatively abstract information. Individuals feel more confident in predicting the distant future than the near future when the predictions concern outcomes that are implied by relatively abstract information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting the long-term outcome of schizophrenia

Predictors of long-term (13 year) outcome of schizophrenia are reported for a representative cohort of 'treated incidence' patients ascertained on their first contact with Nottingham psychiatric services between 1978-80. An initial (baseline) model including previously reported predictors of 2-year outcome (age, gender, ever married, acuteness of onset) and length of untreated illness was used to predict a range of outcome measures covering the domains of disability, psychopathology, hospitalization, employment, social activity, and global outcome. This model demonstrated significant prognostic ability across all non-hospitalization outcomes under both ICD-10 and ICD-9 diagnoses of schizophrenia, but was attenuated under broad (ICD-9 and CATEGO S, P or O) and restrictive (S+) diagnostic classifications. Female gender predicted more favourable outcome under all diagnostic classifications except S+. In an extended analysis, the addition of initial 2-year course type substantially increased the prognostic ability of the model under all diagnostic classifications and enabled over 30% of the variance in global ratings of disability and symptoms to be predicted. In this extended model female gender predicted more favourable outcome over and above the effect of course type, across most domains under ICD-10, and for disability and psychopathology under other diagnostic classifications. The inclusion of measures of psychopathology at the time of first assessment, pre-morbid functioning, and duration of index admission conferred only marginal additional predictive ability for respective outcomes in the domains of psychopathology, social activity, employment and hospitalization. Hospitalization during the past year was the most difficult outcome to predict under any model suggesting that resource utilization represents the 'administrative outcome' of schizophrenia and serves as a poor proxy for broader concerns in the era of community care. These data demonstrate that key demographic variables and the mode of onset influence the long-term course of schizophrenia, but that early course type is a particularly strong predictor.     

Chlorinated Ethene Reduction by Cast Iron: Sorption and Mass Transfer

Tetrachloroethylene (PCE) and trichloroethylene (TCE) exhibited significant nonlinear sorption to nonreactive sites when exposed to four cast irons. Cast iron is a reactive material that promotes reductive dechlorination and has recently been used for in-situ remediation of chlorinated solvent contaminated ground water. Comparisons between PCE sorption to cast iron, graphite, and iron-containing minerals indicate that nonreactive sorption is due to exposed graphite inclusions in the cast iron. Sorption of the homologous series of chloroethenes to a cast iron adheres to Traube's rule; thus, the extent of sorption is related primarily to compound hydrophobicity. An analytical model incorporating rate-limited sorption∕desorption to nonreactive sites was used to assess sorption nonequilibrium. Effective sorption and desorption rate coefficients determined how significant mass transfer limitations to nonreactive sorption sites exist for PCE and not for TCE. The nonreactive sorption observed indicates that flow-through cast iron treatment systems will exhibit significant delayed attainment of steady-state conditions for chlorinated ethenes, particularly PCE and TCE.     

钛设备在水相悬浮法氯化聚乙烯工业中的应用

介绍了氯化聚乙烯的性能和用途,当前水相悬浮法是应用最多的氯化聚乙烯生产方法,结合其工艺过程,水相悬浮法氯化聚乙烯工业选用钛设备的必要性和依据,钛设备在使用中应注意的问题。     

Treatment of Chlorophenols by UV-Based Processes: Correlation of Oxidation By-Products, Wastewater Parameters, and Toxicity

The aim of the study was to evaluate the toxicity and biodegradability of para-chlorophenol (p-CP) model wastewater when treated by UV and UV/H2O2 processes. We investigated the correlations between the toxicity and the concentration of p-CP and its oxidation by-products, as well as other parameters—summarizing characteristics which potentially indicate hazardous water components, e.g., AOX (adsorbable organic halides), TOC (total organic carbon), and COD and BOD5 (chemical and biochemical oxygen demand). Biodegradability is estimated by the BOD5/COD ratio. The toxic effects were investigated on luminescent bacteria Vibrio fischeri, determining the EC50 value. The correlation between each data pair was estimated using a statistical approach calculating the Spearman rank coefficients. The biodegradability of the p-CP model wastewater was improved by the UV/H2O2 process; the BOD5/COD ratio increased from 0.37 to 0.73 after a 1-h treatment (F = 1243??mJ?cm-2). According to the calculated Spearman rank coefficient, the highest correlation with toxicity data among all monitored parameters was obtained for hydroquinone and benzoquinone, as by-products of p-CP degradation, as well as for the BOD5/COD ratio.