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مهندسی محیط زیست - مقاله

شيرابة زبالة شهري داراي بارآلودگي بسيار بالايي است. شيرابة زبالة شهري كه در اثر فعل و انفعالات شيميايي ناشي از فعاليت    ميكروارگانيسم ها در توده هاي زباله از هنگام جمع آوري تا دفن بوجود توليد مي شود،   به علت آلودگي آلي بسيار زياد، مي تواند   در    

اثر نفوذ از محل دفن به آبهاي زير زميني، منابع آب را آلوده نمايد

                                                                                                                                                                           

 

 


ادامه مطلب
+ نوشته شده در  یکشنبه 20 دی1388ساعت 17:1  توسط azra setoudeh,bahram aghai | 

Anaerobic treatment of a highly alkaline fruit-cannery lye-peeling wastewater was investigated, using an upflow anaerobic sludge blanket (UASB) reactor. Only a short initialisation period was required before COD reduction and OLR had stabilised at 85 to 90% and 2.40 kgCOD·m-3·d-1, respectively.


ادامه مطلب
+ نوشته شده در  یکشنبه 20 دی1388ساعت 16:55  توسط azra setoudeh,bahram aghai | 
Abstract

Chlorination has been the major strategy for the disinfection of drinkingwater in Taiwan. The use of chlorinatedwater has been hypothesized to lead to several adverse birth outcomes, including low birth weight and preterm delivery.

. We have performed a study to examine the relationship between the use of chlorinated water and adverse birth outcomes in Taiwan. The study areas included 113 “chlorinating municipalities” (CHMs) (which were defined as municipalities in which more than 95% of the municipality population was served by chlorinated water) and 15 “nonchlorinating municipalities” (NCHMs) (defined as municipalities in which less than 5% of the municipality population was served by chlorinated water)

 

 The study population comprised 182,796 women residing in the 128 municipalities who had a first parity singleton birth between 1 January 1994 and31 December 1996, and for which complete information on maternal age, education, gestational age, birth weight, and sex of the baby were available The results of this study suggest that there was an association between the consumption of chlorinated drinking water and the risk of preterm delivery.

 

Chun-Yuh Yang

Institute of Public Health, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung City, Taiwan 80707, China

+ نوشته شده در  شنبه 28 آذر1388ساعت 15:17  توسط azra setoudeh,bahram aghai | 
[Article in Chinese]

Dai DJ, Li GH, Zhang X, Zhong Y, Jia JL.

Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, China. daidj03@mails.tsinghua.edu.cn

Biodegradation efficiency of hydrocarbons and melioration of micro-ecosystem conditions in acid soils should be seriously concerned due to either occurrence of acid polluted soils or acidification during bioremediation process. The influence of acid situation on degrading microbes and the biodegradation rate were figured out by monitoring variations of biomass, microbial activities and petroleum contents with time in acid and alkaline polluted soils in laboratory. Injecting degrading microbes and meliorating micro-ecosystem conditions of acid soils were conducted. The results showed that acid soils (pH = 5.4-5.7) had extreme restraint on local microbe numbers and activities, and biodegradation rate almost reached zero. Injection of degrading microbes could not remarkably reduce the restriction of acid conditions. The microbe numbers quickly went down from 10(6) cells/g dried soil to zero in 14 days and the Fluorescein Diacetate (FDA) activities were only about 0.10 Abs/g dried soil. However, addition of bio-carriers could effectively improve micro-ecosystem conditions in acid soils, thus notably diminish the restraint to some extent. In 19 days, the amount of microorganisms decreased from 2 x 10(6) to 2.2 x 10(2) cells/g dried soil. And up to 49 days, about 13% hydrocarbons were removed from the polluted soils by microbes.

+ نوشته شده در  شنبه 28 آذر1388ساعت 15:17  توسط azra setoudeh,bahram aghai | 
Damian E. Helbling_, Jeanne M. VanBriesen1

Department of Civil and Environmental Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, USA

a r t i c

 

a b s t r a c t

The utility of chlorine residual and chlorine demand as a surrogate for microbial

contamination in the water distribution system was evaluated. The chlorine demanded

by and cell survival of pure culture suspensions of Escherichia coli, Staphylococcus epidermidis, and Mycobacterium aurum were quantified in solutions with initial free chlorine concentrations of 0.20, 0.40, and 0.80 mg/L. The chlorine demand increased with initial concentration of cells and free chlorine for all species. At equivalent initial cell concentrations, chlorine demand was greatest for M. aurum, followed by S. epidermidis and E. coli.

 

The chlorine contact time required for a 3-log inactivation of E. coli, S. epidermidis, and M. aurum was calculated as 0.03270.009, 0.22170.080, and 42.972.71mgmin/L, respectively. The ultimate chlorine demand and cell survival were directly proportional. No chlorine demand was observed at cell concentrations less than 105 CFU/mL for E. coli or 104CFU/mL for S. epidermidis. M. aurum demanded chlorine at all initial cell concentrations including103 CFU/mL, which was the detection limit of the cell quantification assay. Chlorine demand was determined to be a suitable surrogate indicator of the organisms studied and its utility may be enhanced in locations of the water distribution system that maintain a higher free chlorine residual.

 

 

+ نوشته شده در  شنبه 28 آذر1388ساعت 15:14  توسط azra setoudeh,bahram aghai | 
 

 

Effects of nutrient and temperature on degradation of petroleum hydrocarbons in contaminated sub-Antarctic soil




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Frédéric Coulona, Emilien Pelletierb, Lénaick Gourhantb and Daniel Delillea,

aObservatoire Océanologique de Banyuls, Université P. et M. Curie UMR-CNRS 7621, Laboratoire Arago, 66650 Banyuls sur mer, France

bInstitut des Sciences de la Mer de Rimouski (ISMER), Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Canada G5L3A1

 

Abstract

Mesocosm studies using sub-Antarctic soil artificially contaminated with diesel or crude oil were conducted in Kerguelen Archipelago (49°21′ S, 70°13′ E) in an attempt to evaluate the potential of a bioremediation approach in high latitude environments. All mesocosms were sampled on a regular basis over six months period. Soils responded positively to temperature increase from 4 °C to 20 °C, and to the addition of a commercial oleophilic fertilizer containing N and P. Both factors increased the hydrocarbon-degrading microbial abundance and total petroleum hydrocarbons (TPH) degradation. In general, alkanes were faster degraded than polyaromatic hydrocarbons (PAHs). After 180 days, total alkane losses of both oils reached 77–95% whereas total PAHs never exceeded 80% with optimal conditions at 10 °C and fertilizer added. Detailed analysis of naphthalenes, dibenzothiophenes, phenanthrenes, and pyrenes showed a clear decrease of their degradation rate as a function of the size of the PAH molecules. During the experiment there was only a slight decrease in the toxicity, whereas the concentration of TPH decreased significantly during the same time. The most significant reduction in toxicity occurred at 4 °C. Therefore, bioremediation of hydrocarbon-contaminated sub-Antarctic soil appears to be feasible, and various engineering strategies, such as heating or amending the soil can accelerate hydrocarbon degradation. However, the residual toxicity of contaminated soil remained drastically high before the desired cleanup is complete and it can represent a limiting factor in the bioremediation of sub-Antarctic soil.

Keywords: Sub-Antarctic soil; Fertilizer; Crude oil; Diesel; Biostimulation; Mesocosms

 



+ نوشته شده در  شنبه 28 آذر1388ساعت 15:11  توسط azra setoudeh,bahram aghai |