Evaluating of the disinfection and water quality effects on UV application in the primary stage of water treatment

Background: Irradiation of water by UV has been considered as an attractive alternative for disinfection because its low-impact, pathogen killing capacity shows tremendous promise for meeting today's drinking water regulatory requirements. This study has been performed with the objective of utilizing medium pressure lamp in the preliminary stage of municipal water treatment, namely prior to water clarification and filtration. Methods: Raw water samples were irradiated for 30 s in a lab-scale closed reactor. Disinfection results showed nearly 2 log reduction in HPC for all the samples without formation of nitrite in excess of its MCL. As in a few previous works the formation of nitrite as an objectionable DBP had been reported, this study was extended by preparing synthetic water samples having different amounts of nitrate and turbidities. Results: As far as the initial nitrate concentration dose not exceed 10 mg/L N-NO3, there would be no risk of nitrite increasing in excess of the MCL. Conclusion: Meeting the goal of at least 90 % disinfection for water samples with turbidity levels of as high as 750 NTU is possible by utilizing medium- pressure UV lamp

Determination of hydrophobic and hydrophilic fractions of natural organic matter in raw water of Jalalieh and Tehranspars water treatment plants (Tehran)

The aim of this research was to determine hydrophobic and hydrophilic fractions of Natural Organic Matter (NOMs) in drinking water Sources of Tehran. Water sampling was conducted monthly from Aug 2006 to Jan 2007 in two drinking water treatment plants (Jalalieh and Tehranpars) in Tehran. Quantitative parameters of pH, EC, UV254 and DOC were studied based on standard methods. The XAD-7 resin method was used for fractionation of NOM. Results showed that NOM concentrations in Jalalieh and Tehranpars water treatment plants were 2.47 and 1.63 mg L-1, respectively. The mean of total percent of HPO (hydrophobic) and HPI (hydrophilic) fractions were about 41 and 59, respectively. Since the hydrophobic NOM fraction exhibits higher trihalomethane formation potential (THMFP) than hydrophilic NOM, Tehran water chlorination exhibits higher THMFP than halo acetic acid formation potential (HAAFP). The information obtained from this study may be further employed in the design of the control technique and management strategies for the water treatment plant, especially for DBP, reduction. © 2007 Asian Network for Scientific Information

UPGRADING AN EXISTING WASTEWATER TREATMENT PLANT BASEDON AN UPFLOW ANAEROBIC PACKED-BED REACTOR

The performance of an upflow anaerobic packed-bed reactor in the upgrading of Parkandabad (Mashhad, north east of Iran) wastewater treatment plant was studied in a pilot plant. The experiments were performed at hydraulic retention times of 6, 12, 18 and 24h based on empty reactor volume and the performance of the reactor was evaluated based on the removal of organic matter (BOD5 and COD) and SS. The average BOD5 and COD removal efficiencies were in the ranges of 79.0-89.3% and 75.7-87.2%, respectively, depending on HRT. The relationship between the organic loading rate and organic removal rate was linear in the loading range of 0.52-2.10kg BOD5/m3.d. The average SS removal efficiencies at hydraulic retention times of 6, 12, 18 and 24h were obtained to be 82.9, 83.6, 81.2 and 87.4%, respectively. The results indicated that the reactor in combination with existing biological treatment process (completely mixed aerated lagoon) can produce a high quality effluent

Survey of microbial quality of drinking water in rural areas of kashan-Iran in second half of 2008

The objective of the study is surveying microbial quality of drinking water in Kashan rural areas and determining the rural population that using safe water in terms of microbial quality in second-half of 2008. In this cross-sectional study, microbial quality of water in all rural areas was determined in 3 stages based on 3 parameters as Total Coliforms, Fecal Coliforms and Heterotrophic Plate Count (HPC). The results of this study illustrates that 100.0, 47.71 and 92.99 population in under coverage and non under coverage areas of Kashan Rural Water and Wastewater Company (KRWWC) and all Kashan rural areas, respectively using safe water in terms of Fecal Coliforms and 98.4, 21.2 and 88.00 population in under coverage and non under coverage areas of KRWWC rural areas and all Kashan rural areas, respectively using safe water in terms of Total Coliforms. There is also a meaningful difference in microbial quality between under coverage and non-under coverage rural areas. The results of this study express that the fecal contamination in under coverage rural areas is excellent, but there is a bad condition in non-under coverage areas. Generally, the microbial quality in all Kashan rural areas is approximately equal to national microbial criteria. Its been also illustrated that the role of KRWWC in supplying safe drinking water in terms of microbial quality for rural population is very important. © 2011 Asian Network for Scientific Information

Effect of electrochemical process on phosphorous removal from activated sludge effluent

Background : The nutrition role of phosporous to macroscopic and microscopic plants is well known. Discharge a source of phosphorous to surface water sources ultimately results in eutrophication. The present study was conducted to determine the effect of electrochemical process on phosphorous removal from activated sludge effluent. Samples were collected from wastewater treatment plant effluent of Kashan University of Medical Science Campus. Materials and methods : The study was carried out as a bench scale experimental type using batch system and the effects of electrical current, type of electrodes, reaction time and initial characteristics of samples (temperature, pH, and electro conductivity) were investigated. Ineach run, 1500ml secondary effluent was placed in an electrolytic cell equipped with magnetic stirrer. The anode and cathode was each made of 4 pieces of still (or aluminium) 1.5cm apart, which both were submerged in the sample. The total effective area of used electrodes was 336cm2 and the input power was controlled by an ammeter and voltmeter. Reduction of total phosphorous to less than 1mg/L-P (as standard) was considered as the desired removal. Results : The results showed that by increment in direct current and reaction time the phosphorous removal efficiency will increased and the still electrodes are slightly more efficient than aluminum ones. Adjustment of temperature, pH and electroconductivity of samples, each in a special range, improve s the efficacy. To obtain best results the required electrical current density and reaction time are recommended to be in the range of 1.78-3.57 mamp/cm2 and 10-30 minutes, respectively. Conclusion: Electrochemical process by using steel electrode can successfully remove total phosphorous that is remained in activated sludge effluent, of course, there is no need to adjust temperature, pH, and electro conductivity

Efficiency study for integrated stabilization pond (ISP) in municipal wastewater treatment

History and Objectives: Considering the high cost of mechanical treatment of wastewater and the necessity to investigate more economical methods, specially the ones involving natural treatment processes, a study on efficiency of integrated stabilization pond (ISP) was conducted in Shoosh Sewage Treatment Plant during 1999. Materials and Methods: This ISP experimental study was conducted during three seasons with two types of raw sewage feeding. The system consists of an anaerobic pond in combination with facultative pond in series with a high rate and a maturation samples from inflow and effluent were taken on weekly basis and COD, BOD5, TSS, total nitrogen and total phosphorous were checked, the resulting reduction in mentioned parameters formed the basis of a statistical evaluation. Results: Pollutants reduction was higher in spring compared with summer and fall. BOD5 with 89 reduction showed the highest and total phosphorous with 60 showed the lowest reduction levels during the said period. The level of sewage pollutant reduction during three stages of the study shows that the anaerobic pond in combination with facultative pond registed the highest percentage of pollutant removal. Conclusion: ISP systems are effective in treatment of sewage. Up flow of sewage in fermentation pit has a positive effect on the system efficiency and shows the fermentation pits considerable role in facultative ponds. Since there is little available experience about ISP in Iran, more investigation on the subject is recommended

Evaluation of Streptococcal (Type B) rectal colonization incidence in pregnant women at an gestational age greater than 35 weeks and its relationship with infantile premature infection

History and Objectives: Considering the various report on incidence of Streptococcus type-B in rectum and its role in premature infantile infection and lack of information in the region and for determination of its prevalence in pregnant women, this study was carried out in Shabihkhani hospital in Kashan in 2000. Materials and Methods: The descriptive strategy of this study was conducted on 400 pregnant women at a gestational age greater than 35 weeks. For this purpose, a questionnaire was designed for collection of data including age, occupation, academic history, nationality, inhabitation, multiparous state, number of abortion, labor type and antibiotic consumption. Sampling from rectum was done using a sterile swab. Then, it was cultured in special medium and isolated bacteria were identified using biochemical tests. All of the infants up to 48h after labor and those from mothers with signs of positive colonization up to one week were followed up. From the latter group, sampling was done and the related bacteria were identified. For statistical analysis, X² and Fischer tests were used. Results: Out of 400 samples from rectum, 30 cases (7.5) with streptococcus type-B and in 2 cases (6.7) from mothers with positive culture were identified. In addition there was a relationship between streptococcus type-B rectal colonization and premature infantile premature infection (P=0.0055). Conclusion and Recommendations: Considering a 7.5 incidence of this bacterium in rectum and its relationship with type-B streptococcal rectal colonization and premature infections and its complications, it is recommended to conduct more studies in pregnant women

REMOVAL OF CADMIUM FROM INDUSTRIAL EFFLUENTS BY ELECTROCOAGULATION PROCESS USING IRON ELECTRODES

The object of this study is the evaluation of cadmium removal from industrial wastewater by electrocoagulation process. For this study a glass tank in 1.56 L volume with four plate electrode was used to do experiments. The electrodes made of iron and connect to the positive and negative pole of DC power supply (bipolar mode). The tank was filled with synthetic wastewater that was containing cadmium ion in concentration 5, 50 and 500 mg/L and then it was started up. The percent of cadmium ion removal was measured at pH 3, 7 and 10 and in electric potential range of 20, 30 and 40 volts. At the end of each stage of experiment, volume of produced sludge was measured. The results obtained at different electrical potential showed that initial concentration of cadmium can effect on efficiency removal and for higher concentration of cadmium, higher electrical potential or more reaction time is needed. On the other hand, if the initial concentration increases, the time required of process should increase too. The final pH for iron electrodes was always higher than initial pH. As expected, the results showed that for a given time, the removal efficiency increased significantly with increase of current density. The highest electrical potential (40V) produced the quickest treatment with >99% cadmium reduction occurring after only 20 min. The result showed that, in this process, the use of different electrical potentials can provide a wide range of pH for doing this process and electrocoagulation process (using iron electrodes) is a reliable, safety, efficient and cost-effective method for removal of cadmium from industrial effluents, especially designed for pH =10 and voltage = 40V

Retention of humic acid from water by nanofiltration membrane and influence of solution chemistry on membrane performance

The objectives of this research were to investigate the rejection efficiency of salt and hydrophobic fraction of natural organic matter, to study the flux decline behavior with a spiral wound nanofiltration membrane, and also to survey the influence of water chemistry on membrane performance. Experiments were conducted using a cross flow pilot-scale membrane unit with a full circulation mode. Humic acid was used as hydrophobic organic matter and NaCl as background electrolyte. Results showed that flux reduction increased with increasing ionic strength and humic acid concentration, and with lower pH. The rejection efficiency of organic and salt decreased with the decrease in pH and increase in ionic strength, because of osmotic pressure increase, leading to permeate flux decline and decrease in salt rejection. In addition, the improved salt rejection was likely due to Donnan exclusion by humic material close to membrane surfaces. The average rejection efficiency of humic acid and salt ranged between 91.2-95.25 and 63.6-80, respectively. Dissolved organic carbon concentration was less than 0.57mg/L in permeate for all experiments. With increasing organic concentration, the charge of the membrane surface has become more negative due to the adsorption of organic foulants on the membrane surface, and thus increased the electrostatic repulsion. However, the increasing surface charge had the potential to result in a larger molecular weight cut-off of a fouled membrane due to membrane swelling which can lead to lower rejection solutes. Therefore, results of this study indicated that membrane fouling may significantly affect the rejection of organic and ion solute