Field efficacy of expanded polystyrene and shredded waste polystyrene beads for mosquito control in artificial pools and field trials, Islamic Republic of Iran

Concerns about traditional chemical pesticides has led to increasing research into novel mosquito control methods. This study compared the effectiveness of 2 different types of polystyrene beads for control of mosquito larvae in south-east Islamic Republic of Iran. Simulated field trials were done in artificial pools and field trials were carried out in 2 villages in an indigenous malaria area using WHO-recommended methods. Application of expanded polystyrene beads or shredded, waste polystyrene chips to pool surfaces produced a significant difference between pre-treatment and post-treatment density of mosquitoes [86% and 78% reduction respectively 2 weeks after treatment]. There was no significant difference between the efficacy of the 2 types of material. The use of polystyrene beads as a component of integrated vector management with other supportive measures could assist in the control of mosquito-borne diseases in the Islamic Republic of Iran and neighbouring countries

Optimization of operational parameters for decolorization and degradation of c l reactive blue 29 by ozone

Because conventional wastewater treatment of effluent containing anthraquinone dye causes notable environmental problems, it is important to find effective alternative methods for dye removal. This study evaluated the efficacy of ozonation for dye removal and Chemical Oxygen Demand reduction and identified optimal operational conditions for parameters such as pH, contact time and concentration of C.I. Reactive Blue 29 dye in a semi-batch reactor. Values of pH between 3 and 11 and contact times between 15 and 120 minutes were investigated. Dye concentrations were based on the American Dye Manufacture Institute standards and ranged from 1000 to 5000. Although results showed that Chemical Oxygen Demand removal by ozone alone was not very efficient [58%], ozonation proved to be an efficient method for decolorizing Reactive Blue 29 [96%]. pH was found to significantly influence the effectiveness of Chemical Oxygen Demand removal, and optimal pH conditions [95% confidence interval] were between 9 and 11. For decolorization, pH adjustment was not necessary. Degradation and decolorization of dye were found to be strongly influenced by the contact time, optimal conditions [95% confidence interval] for degradation and decolorization were 60 and 30 minutes, respectively. The optimal dye concentration was 1000 American Dye Manufacture Institute

Methyl tert-butyl ether adsorption on surfactant modified natural zeolites

Surfactant-modified clinoptilolite-rich tuff was used for the removal of methyl tert-butyl ether [MTBE] from aqueous solutions. Clinoptilolite zeolite from Miyaneh region of Iran was treated with sodium chloride and then modified with hexadecyltrimethylammonium chloride [HDTMA-Cl] and n-Cetylpyridinium bromide [CPB] to be used in different experimental conditions. The ability of raw or Non-Modified Zeolite [NMZ] and Surfactant-Modified Zeolites [SMZ] to remove MTBE from aqueous solutions was investigated as a function of contact time, pH and concentrations of adsorbent and adsorbate, by using a batch technique in aqueous system. The removal of MTBE from aqueous solutions by modified zeolites seemed to be more effective than non-modified samples. Also, HDTMA-modified zeolite had more effective performance than CPB-modified zeolite. The adsorption efficiency of MTBE onto SMZ[S] was found to increase by contact time and adsorbent concentrations, and by decreasing of pH and adsorbate concentrations. Empirical adsorption models of Langmuir and Freundlich were applied for the experimental data. Results showed that Langmuir isotherm was more suitable for this process. The experimental data fitted very well with the pseudo-second-order kinetic model. It was overally found that Surfactant-Modified Zeolites is an effective adsorbent for removal of methyl tert-butyl ether from contaminated solutions

Survey on degradation rates of trichloroethylene in aqueous solutions by ultrasound

Sonochemical degradation of different compounds such as chlorinated aliphatic hydrocarbons is one of the recent advanced oxidation processes and it may be effective for removing low concentration organic pollutants from aqueous streams. Trichloroethylene [TCE] is one of these compounds that is mainly used as a degreaser. Important studies about TCE sonolysis have been focused at millimolar levels and natural pH, but in this study the ultrasonic degradation of TCE at different micromolar initial concentrations [30, 300 and 3000 micro g/L] and 4 different initial pH with a 35 kHz frequency was investigated. Furthermore, the degradation of TCE by ultrasound with different concentrations of hydrogen peroxide at pH= 7 was also performed. Gas chromatography with FID detector was used for analyses of TCE. Results showed that the degradation of TCE increased with decrease in the initial concentration of TCE from 3000 to 30 micro g/L at all initial pH. Initial pH of solution and different concentrations of H[2]O[2] did not affect significantly the TCE destruction

Optimization of reactive blue 19 decolorization by ganoderma SP. using response surface methodology

Synthetic dyes are extensively used in different industries. Dyes have adverse impacts such as visual effects, chemical oxygen demand, toxicity, mutagenicity and carcinogenicity characteristics. White rot fungi, due to extracellular enzyme system, are capable to degrade dyes and various xenobiotics. The aim of this study was to optimize decolorization of reactive blue 19 [RB19] dye using Ganoderma sp. fungus. Response Surface Methodology [RSM] was used to study the effect of independent variables, namely glycerol concentration [15, 20 and 25 g/L], temperature [27, 30 and 33 °C] and pH [5.5, 6.0 and 6.5] on color removal efficiency in aqueous solution. From RSM-generated model, the optimum conditions for RB19 decolorization were identified to be at temperature of 27°C, glycerol concentration of 19.14 mg/L and pH=6.3. At the optimum conditions, predicted decolorization was 95.3 percent. The confirmatory experiments were conducted and confirmed the results by 94.89% color removal. Thus, this statistical approach enabled to improve reactive blue 19 decolorization process by Ganoderma sp. up to 1.27 times higher than non-optimized conditions

Up-flow sludge blanket filtration [USBF]: an innovative technology in activated sludge process

A new biological domestic wastewater treatment process, which has been presented these days in activated sludge modification, is Upflow Sludge Blanket Filtration [USBF]. This process is aerobic and acts by using a sludge blanket in the separator of sedimentation tank. All biological flocs and suspended solids, which are presented in the aeration basin, pass through this blanket. The performance of a single stage USBF process for treatment of domestic wastewater was studied in laboratory scale. The pilot of USBF has been made from fiberglass and the main electromechanical equipments consisted of an air compressor, a mixing device and two pumps for sludge return and wastewater injection. The wastewater samples used for the experiments were prepared synthetically to have qualitative characteristics similar to a typical domestic wastewater [COD=277 mg/l, BOD5=250 mg/l and TSS=1 mg/l]. On the average, the treatment system was capable to remove 82.2% of the BOD5 and 85.7% of COD in 6 h hydraulic retention time [HRT]. At 2 h HRT BOD and COD removal efficiencies dramatically reduced to 50% and 46.5%, respectively. Even by increasing the concentrations of pollutants to as high as 50%, the removal rates of all pollutants were remained similar to the HRT of 6 h

Improving efficiency of disinfection of water for non-contact UV system

The goal was to upgrade and/or uprate the traditional non-contact array by producing few modifications in the configuration of this model in order to maximize light receiving of water from the UV lamp and a better disinfection. An innovative non-contact model was made with a design based on irradiation of water, which was flowing as two thin waterfalls around a UV lamp in order to have direct germicidal rays from all positions of the lamp. By this water circulating and traditional water flow in an ordinary canal below the lamp, UV light would reach every drop of water effectively. Another model which had been studied was a simple stair type design in which a bare lamp was fixed over the shiny steel steps. Results of water disinfection in two flow rates of 12 and 24 L/min were compared with traditional design at exactly similar conditions. Disinfection in this new model produced more reduction in fecal coliforms concentration than the traditional array and the inactivation efficiency was specified to be 3.65 log reduction compared to 2.93 log, in the turbidity of 0.5 NTU. Besides, this new model was quite capable in disinfection of water with high turbidities up to 20 NTU. The reduction in disinfection efficiency at higher flow rates for new model was much less than traditional array. Results of water disinfection in the simple stair type were not wonderful and even it was less satisfactory compared to traditional model. The reason is that the flow of water was not set parallel to the length of the lamp

[Investigation of existing status of hazardous wastes management in central campus of Tehran university medical sciences, Iran]

Due to having features such as toxicity, corrosiveness, ignitability, reactivity or other similar characteristics, hazardous wastes refer to the wastes that jeopardize man's health and environment. A study was required to identify the hazardous wastes in Tehran University of Medical Sciences [TUMS], since it plays an important role in the development of the country's education. The objective of this research was to provide a review of hazardous wastes production and its management at Tehran University of Medical Sciences. In this study, four schools that were in the central campus of Tehran University of Medical Sciences, Iran, were selected and the necessary data were gathered using a sampling, questionnaire, interviewing those in charge of the units, and referring to the available documents. The information includes the type and amount of waste, method of temporary storage, frequency of waste discharge, and method of final disposal of wastes. The obtained results indicate that approximately 2072 Kg of hazardous wastes are produced each year, excluding the uncontrolled waste water. Moreover, schools of dental, pharmacy, medicine, and public health produced approximately 993, 606, 256, 217 Kg/year, respectively, of hazardous wastes in the central campus. Also, the results show that, of total amount of annual hazardous waste that was 2.72 tons, 954, 848, 475, 427, 245, 49 Kg were wastes that the features infectious, toxicity, ignitability, carcinogenesis, corrosiveness, and reactivity, respectively. It is to be mentioned that hazardous solid wastes were manage with household solid waste and hazardous liquid waste were discharged into sink without any kind of control. Improper practice is evident from the point of waste production to final disposal

Wastewater characteristics and appropriate method for wastewater management in the hospitals

Hospitals generate relatively large quantities of wastewater that may contain various potentially hazardous materials; therefore the proper management of hospital wastewater is essential. In this cross-sectional study, the quality and quantity of wastewater in the hospitals of Tehran University of Medical Sciences [TUMS], Tehran, Iran, were studied and the suitable method for wastewater management in the hospitals was determined. Monitoring of pH, TSS, BOD5, COD and total coliforms indicated that the quality of wastewater in the hospitals was similar to domestic wastewater. The wastewater production in the hospitals was determined to be in the range of 398 to 1090 L/d/[occupied bed]. The study on wastewater treatment and disposal methods demonstrated that discharge to municipal wastewater collection system is the best alternative for wastewater management in the hospitals, but this approach is not applicable for all of the hospitals. Baharloo, Cancer Institute, Children, Farabi, Imam Khomeini, Razi, Roozbeh, Shariati and Valiasr hospitals can be connected to municipal wastewater collection system at present. It is recommended that these hospitals' wastewater be discharged to municipal wastewater collection system. Amir Alam, Bahrami, Mirza Koochak Khan and Sina hospitals will be able to discharge their wastewater into sewerage network at second phase of Tehran sewerage project [in 2010] and Arash Hospital will be able to discharge its wastewater into sewerage network at third phase of Tehran sewerage project [in 2015]. These hospitals have to select onsite separate wastewater treatment alternative

Use of expanded polystyrene [EPS] and shredded waste polystyrene [SWAP] beads for control of mosquitoes

Mosquitoes transmit several diseases to human. There are several measures for control of larvae. As part of Integrated Vector Management [IVM] program, the utility of floating layers of polystyrene beads [EPS] is a potential alternative in habitats of mosquito larva. EPS beads prevent oviposition of mosquito as well as killing the immature stages by forming a tick layer on the water surface. They are cheap, environmentally safe and do not need frequent application and remain on the surface of water for long time. The objective of the current study was to asses the effectiveness of two types of polystyrene beads of [EPS] and [SWAP] for control of mosquito larvae under laboratory conditions. Anopheles stephensi and Culex quinquefasciatus were used for experimental purposes. In each tray 250 larvae of late 3rd and early 4th instars were introduced. The experiment was conducted on 4 replicates for An. stephensi, Cu. quinquefasciatus and combination of both. Emerging of adult mosquitoes were calculated every day until the end of experiments. Mortality rate and Inhibition of Emerge [IE] for Cu. quinquefasciatus, An. stephensi and combination of both species was 97.8%, 100% and 99.07%, respectively using EPS. In average, EPS was able to kill 98.9% of larvae. The figures with SWAP were 63%, 91.05% and 72.65%, respectively. The average mortality for mosquitoes was 75.57% EPS and SWAP beads can be very effective and practical for elimination of An. stephensi and Cx. quinquefasciatus under the laboratory conditions

[UV-lamp intensity determination without use of radiometer]

Measurement of light intensity is a recommended practice for insuring the delivery of required germicidal dose in disinfection operations by UV lamps. Use of sensitive to light chemicals which is the base of actionometeric methods could be considered as a suitable manner for estimating the intensity of UV lamp in circumstances that special radiometers are not available. lodide-iodate mixture was used as an actinometer for this study. The light intensities of a UV lamp [LP 25W] were first determined by a special UVC radiometer at certain distances from the lamp. Then the test of determining the suitable period of time for irradiation of actinometer was accomplished. Finally the color changes of iodide - iodate solutions at the predetermined distances were evaluated at the wavelength of 352 nm. The latter analysis can be done by a common [visible] spectrophotometer. Results indicated that use of this actinometer is more suitable at the distances of 35 to 60 cm from the center of the lamp bulb, since iodode-iodate solution has a detectable color change at this range of distance in one minute irradiation which may be considered as a reasonable time for actionmeteric operations. Although all kinds of actinometers should not be regarded as precise as special radiometers and there would be need to use pure chemicals for actinometeric determination of light intensity, it can be claimed that the recommended procedure in this study which is the newest actinometeric method can be used in acceptable evaluation of UV intensity with least difficulty in providing necessary instruments

[Noise pollution in Zanjan city in 2007]

Noise pollution is an important environmental problem that may cause hazardous effects, such as hearng loss, sleep disorders, hypertension and digestive problems in communities. To prevent these effects, achieving recommended standards of noise pollution measuring in cities is mandatory. This study was aimed to evaluate noise pollution in zanjan city in 2007. For measuring environmental noise levels, 64 samples were selected in 2 weeks. They were selected from 16 residential and commercial areas, 4 times daily [morning, noon, evening and night]. Noise indices were measured in A weight channel. Measurements at considered stations were gathered using a sound meter apparatus model cel-268. The maximum equivalent sound level, in A weight channel was detected at night from Sadre Jahan crossroad and at day from Sadi crossroad, being 72db and 77.7db respectively. Significant difference was seen between equivalent sound levels of night and noon [P=0.048] and night and evening [P=0.03]. It was concluded that Zanjan city noise pollution at both residential and commercial areas is higher than that of international standards in most instances. The results were also similar to the findings of other studies in Iran

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

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

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. 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. 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. 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

Upgrading an existing wastewater treatment plant based on 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 [BOD[5] and COD] and SS. The average BOD[5] 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 BOD[5]/m[3].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

Algae removal by electro-coagulation process, application for treatment of the effluent from an industrial wastewater treatment plant

Although stabilization ponds and lagoons are suitable treatment processes due to simplicity of operation and low per capital costs, the effluents of these systems have too high of a total suspended solids concentration to be discharged into receiving waters. This problem is mainly caused by algae. In this study, an electro-coagulation reactor was examined to remove algae from the final effluent of the wastewater treatment plant belong to Bu-Ali Industrial Estates [Hamadan City]. For the continuous flow electro-coagulation reactor used in these experiments three aluminum anodes were utilized. This type of metal was selected because it could introduce the flocculation agent into the effluent, thereby algae could be removed by both mechanisms of electro-flotation and electro-flocculation. The results of treatment were remarkably good and the efficiencies of total suspended solids [TSS] and chlorophyll a removal reached to as high as 99.5% and about 100% by applying a power input of about 550 W. In fact, this level of power input was needed for complete removal of algae in a low retention time of 15 minutes. Meanwhile, by applying less power input of about 100Wdm[-3], the required time for a relatively same treatment was reached to 30 minutes. It is expected that this method which is also known as a multiple contaminants removal process will be considered as a suitable alternative for final polishing of effluents from lagoons and similar treatment systems

Assessment of the detergent wastewater quality

Constant rise in world population is creating main problem about health and removal of pollution due to industries and due to consumption products by humans is causing the need to increase cleaning of wastewater in world which has become the reason for new pollutants to enter environment, one of them is 'detergent'. Entry of wastewater to rivers and lakes creates eutrification, resident of non-biodegradable detergent and foaming. Such as this wastewater treatment is hardly to achieve therefore, identifying wastewater characteristic is necessary to choose the specific treatment method. This paper describes a study of the characteristic of Paksan Wastewater during a five-month period. The result of wastewater characterization show that the concentration of the organic water was very high, expressed as COD ranging from 6256-13040, MBAS ranging from 245-1120, phosphorus concentration and pH were also high, however, BOD concentration was low. Therefore, before subjecting it to biological reactor the high and varied organic loads should be reduced significantly by applying proper methods of pre-treatment, like advance oxidation process, coagulation and installation of equalization pond

Performance evaluation of full scale UASB reactor in treating stillage wastewater

Upflow anaerobic sludge blanket [UASB] reactors have been widely used for treatment of industrial wastewater. In this study two full-scale UASB reactors were investigated. Volume of each reactor was 420 m[3]. Conventional parameters such as pH, temperature and efficiency of COD, BOD, TOC removal in each reactor were investigated. Also several initial parameters in designing and operating of UASB reactors, such as upflow velocity, organic loading rate [OLR] and hydraulic retention time were investigated. After modifying in operation conditions in UASB-2 reactor, average COD removal efficiency at OLR of 10-11 kg COD/m[3] day was 55 percent. In order to prevent solids from settling, upflow velocity was increased to 0.35 m/h. Also to prevent solids from settling, the hydraulic retention time of wastewater in UASB-2 reactor was increased from 200 to 20 hours. This was expected that with good operation of UASB-2 reactor and with expanding of granules in the bed of the reactor, COD removal efficiency will be increased to more than 80 percent. But, because of deficiency on granulation and operation in UASB-2 reactor, this was not achieved. COD removal efficiency in the UASB-1 reactor was little. To enhance COD efficiency of UASB-1 reactor, several parameters were needed to be changed. These changes included enhancing of OLRs and upflow velocity, decreasing hydraulic retention time and operating with new sludge

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

Biodegradation of MTBE by a microorganism consortium

Methyl Tert-Butyl Ether [MTBE] is one of the ether oxygenates which its use has been increased within the last twenty years. This compound is produced from isobutylene and methanol reaction that is used as octane index enhancer and also increases dissolved oxygen in gasoline and decreases carbon monoxide emission in four phased motors because of better combustion of gasoline. High solubility in water [52 g/L], high vapor pressure [0.54 kg/cm3], low absorption to organic carbon of soil and presence of MTBE in the list of potentially-carcinogens of U.S EPA has made its use of great concern. The culture media used in this study was Mineral Salt Medium [MSM]. The study lasted for 236 days and in three different concentrations of MTBE of 200, 5 and 0.8 mg/L. A control sample was also used to compare the results. This research studied the isolation methods of microbial consortium in the MTBE polluted soils in Tehran and Abadan petroleum refinery besides MTBE degradation. The results showed the capability of bacteria in consuming MTBE as carbon source. Final microbial isolation was performed with several microbial passages as well as keeping consortium in a certain amount of MTBE as the carbon source