افشین تکدستان

The quality of water available to humans has been seriously threatened due to population growth and the resulting increase in urban and industrial wastewater. To evaluate changes in the water quality of the Karun River in the urban area of Ahvaz, a simulation model was developed and used to assess the river's water quality based on existing standards. Results show that the quality variables of the river are highly dependent on the season of the year, with the largest changes in dissolved oxygen occurring during the driest and wettest seasons. Comparison of the river's current situation with national and international standards indicates that the water quality does not meet most standards, except during the autumn season when the flow rate is highest. Even if all effluents entering the river comply with existing discharge standards, the quality of the river does not meet desired standards. This highlights the importance of considering specific hydraulic conditions and the effect of time on river quality when updating existing standards.

The presence of emerging-resistant contaminants in wastewater poses challenges to the efficacy of the biological treatment process. Advanced oxidation processes show great potential for enhancing the quality of wastewater. The aim of this study was to enhance the efficacy of the effluent from the Parand City treatment plant through the optimization of the sonoelectrochemical process.

Pilot used 500 cc sonoelectrochemical reactor with direct current generator, ultrasonic, and graphene electrodes. To determine pH (4–8), direct electric current (50–100 mA), reaction time (60–120 min), and frequency (30–50 kHz), the central composite design was used. We looked at the process pace, energy utilization, waste physical and chemical qualities, and overall impact. The purification parameters were obtained using water and wastewater testing methods.

The P-value and F-value indicate the selected model was significant. The best process conditions to use are a pH of 6.5, an electric current intensity of 82.8 mA, a reaction time of 113 min, and a frequency of 35 kHz. Under these conditions, the removal of COD, TOC, BOD5, nitrogen, and phosphorus was 81%, 69%, 93.2%, 96%, and 94.7%, respectively. The kinetics of the process follow first-order kinetics, and the synergistic effect coefficient was 1.62. The energy efficiency was determined to be 98.07 mg/kWh.

The utilization of the sonoelectrochemical process can be employed as a sophisticated method for treatment. However, it is imperative to conduct a comprehensive analysis of the process's efficacy by utilizing raw wastewater samples.

Nowadays, the contamination of water resources with antibiotics are known as one of the major pollutants in the environment due to their widespread use, toxicity, causing drug resistance, and lasting effects. This study was designed to evaluate the efficiency of the advanced oxidation process of sodium persulfate activated with steel industry slag in the presence of ultraviolet rays, solution temperature, and pH aimed at eliminating the Azithromycin antibiotic from aqueous and effluent media. In the present study, the effect of the variables, including pH, solution temperature, reaction time, initial concentration of antibiotics, sodium persulfate concentration, and UV ray intensity was examined on the process efficiency. A High-Performance Liquid Chromatography (HPLC) machine was also used to measure the concentration of the Azithromycin antibiotic. According to the study results, under optimal and certain conditions in which sodium persulfate: 2 mM, pH: 2, iron ions level in the steel industry slag: 0.4 g/l, UV intensity: 8 watts, and during 60 minutes, the elimination efficiency rates of Azithromycin antibiotic, COD, and TOC were obtained as 91%, 57/4%, and 43/8%, respectively with a mineralization level higher than 55%. The rate of Azithromycin antibiotic removal was directly related to the concentrations of iron ions, sodium persulfate, UV intensity, and the temperature. However, increase in the pH from 2 to 10 led to decrease in the process efficiency from 81% to 43%, and enhance in the initial concentration of Azithromycin antibiotic from 5 to 50 mg/l also reduced the removal rate of the antibiotic from 73% to 43%. The research revealed that the advanced oxidation process of sodium persulfate activated by steel industry slag in the presence of ultraviolet rays can be used as a proper method with high efficiency to eliminate the high concentration of antibiotics found in a real sewage sample.

Removal of ammonia from wastewater in the treatment plants due to its dangerous and toxic effects on human health and biotic resources is essential. This study was aimed to investigate the effective operational parameters on the efficiency of the air stripping process, determine their priority and degree of effect on ammonia removal and compare the ammonia removal efficiency during the air stripping process in the municipal wastetewater treatment plants using synthetic and real wastewater.

In this study, the effect of each operating parameter on the ammonia removal efficiency including initial ammonia concentration, pH and temperature during the air stripping process for synthetic and real wastewater, respectively, based on standard methods (the Nesslerization method, preparation of standard solutions) using a spectrophotometer, pH meter and temperature module were evaluated.

The results of this study showed that the maximum of ARE for synthetic wastewater with Air to water ratio 80 and an initial ammonia concentration of 59. 6 mg /l, pH 12.05 and temperature 46.3°C was %91. Also, the results of the study on the ARE during the air stripping process showed that the maximum of ARE (%91) for real wastewater (primary sedimentation tank effluent (PST)) with Air to water ratio 80 and an initial ammonia concentration of 61.04 mg/l, pH 12.53 and temperature 45.9 ° C was obtained.

Based on the results of univariate regression model, initial ammonia concentration˃ temperature˃ pH have the greatest effect on the ammonia removal efficiency in synthetic wastewater and real wastewater, respectively. In the multivariate regression model, the effect of temperature and pH on the ammonia removal efficiency in synthetic and real wastewater is increasing and decreasing, respectively. Based on the findings of this study, the air stripping process can be successfully used to remove ammonia from wastewater in the municipal treatment plants, especially in the tropics.

Recently, significant efforts have been performed for the removal of various emerging pollutants (EPs) from water sources. Among these EPs, benzotriazole has been widely identified in aquatic environments, which has harmful health and environmental effects, so it is necessary to apply various methods to remove it. Up to date, the use of advanced oxidation processes (AOPs) as an efficient method for the degradation and mineralization of EPs pollutants from aqueous solutions has attracted so much attention. Therefore, in this research, the performance of the persulfate activation process using magnetic nanocatalyst iron oxide-activated carbon prepared from coconut shell for the removal of benzotriazole from aqueous solution, and also the effect of different parameters have been investigated.

This research is an experimental-laboratory study. The effect of various variables such as solution pH (2-10), catalyst dose (0.1-0.5 g/L), persulfate concentration (1-5 mM), and initial concentration of benzotriazole (10-50 mg/L) was investigated. The final concentration of benzotriazole was measured using a spectrometer. Also, the characteristics of the synthesized catalyst were investigated using numerous analyzes such as BET, FESEM, XRD, EDX and VSM, and

The results showed that the highest efficiency of the process for the removal of benzotriazole was attained at pH: 6, initial concentration: 10 mg/L, catalyst dosage: 0.5 g/L, persulfate concentration: 3 mM, and more than 80% of benzotriazole was removed. On the other hand, the results of catalyst characterization showed that the catalyst was perfectly synthesized and could be reused in five consecutive cycles.

Based on the results of this research, this catalyst had a high performance for the removal of organic pollutants from aqueous solution.

Atrazine is one of the most widely used herbicides in the country, including Khuzestan province. The presence of this herbicide in aquatic environments poses a serious threat to human health and the aquatic ecosystem. Atrazine is an endocrine disruptor and is considered a carcinogen. The half-life of this herbicide in water and soil is between 20 and 50 days, that depends on the temperature and pH. Therefore, the present study aimed to determine the pesticide atrazine in agricultural drains and water of Karun and Dez Rivers. In order to measure the concentration of atrazine in agricultural effluent and Karun and Dez River, 15 stations upstream and downstream of the river were used. Determination of atrazine herbicide concentration was used by high performance liquid chromatography equipped with ultraviolet detector at maximum absorption wavelength. Construction of stock solutions was done by adding standard atrazine solution at concentrations of 1.5 and 0.5 ppm, 0.1, 0.05, and 0.05. Data analysis was performed using Excel software. The results showed concentration mean of atrazine in the downstream station (9, 11, 12 and 15) decreases compared to the upstream statin (1, 3, 5 and 6). Maximum concentrations of atrazine in summer, winter, autumn and spring were measured with 55.16, 53.02, 111.51, 49.86 µg/L, respectively, which is beyond the standard of the environment organization (MCL=3 µg/L). Liters and different seasons of sampling are about 94.56%, 94.34%, 94.13% and 93.98% higher than the WHO standards. The results showed that the amount of atrazine herbicide in most water samples of Karun River is beyond the standard and WHO and EPA regulations. The Karun River was observed. Maximum concentrations were observed in maxing point of Karoon and Dez Rivers (station 1) followed by Dehkoda agro – industry (station 6) upstream.

Today, the use of freshwater production methods from saltwater can be a solution for the drastic reduction of freshwater resources. This study aimed to investigate the direct usability of Spirulina maxima as a new conceptual method to remove total dissolved solids (TDS) of artificial industrial wastewater (AIW). The effects of TDS levels, pH, light intensity, and light-dark duration were examined on the microalgal growth and TDS removal, and optimal conditions were obtained with the response surface method and Box-Behnken Design (RSM-BBD). According to the obtained model, effluent TDS and pH respectively have the greatest effect in reducing TDS. The calculated values of coefficient of determination (R2), adjusted R 2, and predicted R2 were 0.9508, and 0.8636, which were close to R 2 values and confirmed the proposed statistical model. Based on this, the maximum TDS removal efficiency in this study was obtained with TDS variables (2000 mg/l), (pH 9.36), lighting intensity 4010 lux and light-dark duration of 15 hours at the rate of 76%, which shows the efficiency of this It had a method in removing artificial effluents.

Today, antibiotics are known as one of the major environmental pollutants, particularly of water, due to their widespread use, toxicity, causing drug resistance and their lasting effects. This study was designed to evaluate the efficiency of the advanced oxidation process of sodium monopersulfate activated with steel industry slag in the presence of ultraviolet rays aimed at eliminating the tetracycline antibiotic from aqueous and effluent media. We examined the effect of the variables of pH, solution temperature, reaction time, initial concentration of antibiotics, sodium monopersulfate concentration, and the UV ray intensity on the process efficiency. A high-performance liquid chromatography machine was used to measure the concentration of the tetracycline antibiotic. According to the study results, under optimal and certain conditions (sodium monopersulfate: 2 mM, pH: 2, iron ions level in the steel industry slag: 0.4 g/L, UV intensity: 8 watts) and during 60 minutes, the elimination efficiency rates of tetracycline antibiotic, COD, and TOC were obtained as 98%, 61.8%, and 48.9%, respectively, with a mineralization level higher than 55%. The rate of tetracycline antibiotic removal was directly related to the concentrations of iron ions, sodium monopersulfate, UV intensity, and the temperature, while increasing the pH from 2 to 10 decreased the process efficiency from 98% to 46%; and enhancing the initial concentration of tetracycline antibiotic from 5 to 50 mg/L also reduced the removal rate of the antibiotic from 86% to 47%. The research revealed that the advanced oxidation process of sodium monopersulfate activated by steel industry slag in the presence of ultraviolet rays can be used as a proper method with effective efficiency to eliminate the high concentration of antibiotics found in a real sewage sample.

Conventional water treatment processes include screening, coagulation, flocculation, sedimentation, filtration and disinfection. Many coagulants are widely used in conventional water treatment processes. These materials can be classified into inorganic and organic coagulants. Many researches on natural coagulants were carried out in recent years. This study evaluates Tragacanth as natural coagulants aids with poly aluminum chloride (PAC) for the removal of turbidity and coliform bacteria from water Karoon River. Tragacanth is a gum that extracted from astragalus. According to results of this study, adding tragacanth as a coagulant aid improved performance of the process and experimental observations showed that by applying tragacanth as coagulant aid in optimal conditions, larger flocks are formed compared to PAC applications and the sedimentation rate was higher. In total, this study showed that dose of 0.06 mg/l of tragacanth as a coagulants aid with 15 mg/l of PAC coagulant in high turbidity (480-500 NTU) has the best performance in reducing turbidity and total coliform.

Ammonia in form of ammonium ions is toxic and could decrease the dissolved oxygen in water and endanger the aquatic life. The aim of this study is the removal of ammonium using oxidation and adsorption by catalytic ozonation and clinoptilolite zeolite, respectively.

The research method is Experimental. First, optimal pH of ammonium adsorption on carbon catalyst (5 g/L), Garmsar and Firoozkooh zeolites and oxidation were determine. Then, in catalytic ozonation process, the effect of other variables on ammonium removal efficiency such as the concentration of carbonic catalyst (0.5- 50 g/L) and the reaction time were investigated. Then the effect of retention time and adsorbent concentration on adsorption of the remaining ammonium and nitrate produced by the oxidation process using zeolites and their modifications were determined.

Resuts:

 The results showed that optimum pH for the ammonium adsorption process by carbon catalyst, catalytic ozonation and zeolite was 8, 9 and 8, respectively. However, the optimum pH 4 was determined for nitrate removal. The highest ammonium absorption capacity was related to natural Firoozookh zeolite and 18.5 mg/g, and the effect of ligand and acid modification decreased 12 and 14% of absorbed capacity, respectively. It is also, the highest nitrate removal efficiency was related to Garmsar ligand modified zeolite (98%) and an absorption capacity of 11.2 mg/g. In the COP/absorption process the concentration of ammonium was decreased to 0.6 m /L.

This method effectively eliminates ammonium, and the modification of zeolite with cationic surfactant increases the efficiency of nitrate removal and the concentrates of all pollutants are brought below standards.

The purpose of this study was survey on 2,4-D concentration in Ahvaz drinking water in 2018-2019. A descriptive cross-sectional study was based on 10- month sampling program (from December 2018 to September 2019) in six points of distribution networks were conducted. All measured concentrations were less than the maximum allowable concentrations recommended by the National Standards Organization of Iran (1053) and WHO guidelines. In this study, the total THMs determined in autumn, winter and spring ranged from <0.004-2.98μg/L, 0.02-2.41μg/L and 0.01-0.04μg/L, and in summer less than the LOD, respectively. Different studies have shown that pesticides residue concentration in water samples have a relationship with the amount of pesticides used in an area, physical and chemical refractory properties of pesticides and environmental conditions. Thus, using resistant pollutants such as pesticides will be a serious threat to health of water consumers if they are not properly controlled.

The aim of this study is to reduce p-nitrophenol from wastewater using an SBR reactor for biological treatment of sewage and to study the effect of concentration of p-nitrophenol in wastewater on reduction of biomass production and sludge volume index. For this study, two SBR reactors with a volume of 20 liters with on-line control system were used. Once the stable conditions in the reactors are met, sampling and testing of parameters such as COD, MLSS, MLVSS, PH, DO, SV1, SOUR, and p-nitotrophenol (PNP), as well as the rate of reduction in production of biological solids were performed during the 12 months of research. The results showed that for the inserted amount of more than 100 mg/l of PNP, the COD decreased from 772 to 193 mg/l while the COD removal efficiency decreased to 75% and the PNP concentration decreased to 36.7 mg/l. The biodegradable solids decreased by about 49.5% relative to the control reactor. On the other hand, in this dose of PNP, the amount of SOUR was 31 mg O2/h, and VSS and the SVI value was less than 48 ml/g.  For the PNP dose of 150 mg/l, no biosolids was produced in the reactor but COD and PNP levels increased in the effluent. The presence of toxic organic compounds such as p-nitrophenol in high concentrations in the wastewater while reducing the removal efficiency of the organic matter decreases the biological solids and thus reduces the amount of excess sludge.

In this study, the production of biogas from vinasse by using three SGBR reactors with the same volume of 5.6 liters for three hydraulic retention times (2, 3 and 4 days) and organic loading rates of 86002, 28667 and 21500 mgCOD/L.d was investigated. The water bath method was used to provide the temperature of mesophyll reactors at 35, and NaOH solution was used for buffer. The biogas volume was measured using the water displacement method. The results showed that the methane production was almost constant with HRT of 4, 3, and 2 days after 11, 13, and 16 days, respectively. Methane gas production with HRT of 2, 3, and 4 days was 6.66, 16.66 and 27.38 LCH4(STP)/L.day per liter of vinasse, respectively. For three reactors, methanogen and acidogenic bacteria were in the equilibrium state at pH 5.57 after 2 days. The amount of methane gas production per volatile solids with the HRT of 2, 3, and 4 days was 244, 345 and 434 m3CH4/gvs, respectively.

Background and One of the solutions for sludge production is to reduce that via decreasing the yield coefficient by oxic-settling anoxic process with different oxidation reduction potential (ORP) in sequencing batch reactor (SBR) activated sludge.
We used 2 SBR reactors (20 L volume) that were controlled online. At a steady state in reactors, some parameters such as COD, DO, SVI, ORO, dry solids and moisture of sludge were tested during 12 months. Finally, yield coefficient and reduction rate of biological excess sludge were studied.
At 10-day sludge age, the best removal efficiency of COD (95%) was seen without any sludge bulking problems and the kinetic coefficient Y and Kd were 0.58 and 0.058, respectively. The anoxic and anaerobic phase of the sludge holding tank showed that sludge storage after 7 hours in the reactor with ORP=-238 decreased the yield coefficient from 0.58 in the control reactor to 0.25g of biomass in g of COD. Consequently, the excess sludge decreased by almost 60%. On the other hand, compared to the control reactor (92 ml/g), the SVI reduced to less than 40 ml/g.
Using holding tanks in aerobic conditions with ORP greater than 230mv could cause appropriate settling and lead to a high efficiency of COD removal from wastewater.

Recently the low-cost adsorbent for heavy metals removal such as Lead in recent years has been noticed by researchers. In this study, lead removal by clinoptilolite has been investigated. Non-continuous lead absorption from aqueous solution was carried out by using clinoptilolite. The zeolite characteristics were analyzed with SEM and XRD. The effect of pH variables (1, 3, 5, 7, 10), contact time (15, 30, 45, 60, 90 min), clinoptilolite adsorbent dosage (1, 3, 5, 7, 10 g) and lead concentrations (10, 20, 40, 50, 60, 70, 80 & 100 mg/L) were studied on lead removal efficiency and adsorption isotherms and kinetics in constant temperature and stirrer speed of 250 rpm. According to the results, optimum conditions of lead removal by natural zeolite were pH of 8, adsorbent dosage of 5 g/L and contact time of 45 min., the highest removal efficiency of 89.6 achieved. By increasing metal concentration, the amount of removed lead was decreased while absorption capacity increased. Of the two studied models, the Langmuir isotherm had better conformity for lead adsorption (R2=0.99) than other isotherms. Also the pseudo second order kinetics model had better conformity with achieved data than other models. Results of this study indicated that natural clinoptilolite zeolite can be considered as an efficient and cost effective adsorbent for lead removal from aqueous solutions.

Nitrate is a non-concentrated source of environmental pollution caused by fertilizer overdose in agricultural wastewater. These poisonous compounds are accumulated in aquatics tissues specially fishes and affect their reproduction and procreation ability. Generally, to eliminate nitrate from urban, agricultural, and industrial wastewater using of physical, chemical and biological methods is very complicated and expensive at industrial scales. Surface absorption method is one of the useful methods for removing nitrate compounds. Due to the high cost of activated carbon, researchers have always been searching for a more economic method alternatively to remove nitrate. Bagasse is one of the wastages of sugarcane industry which contains some amounts of cellulose, pentosane and lignin. In this research, efficiency of sugarcane bagasse absorbent for nitrate removal from agricultural drainage have been studied.

PolyDADMAC is used in water and waste water treatment as a primary organic coagulant which can neutralize colloidal material with negative charge and reduces sludge volume compared with Mineral coagulants. The aim of this study was to evaluate and compare of PolyDADMAC with ferric chloride as a coagulant on the removal of turbidity, Coliform and Organic matter from Ahvaz drinking water.
This study was carried out in a lab scale and using a jartest device in Ahwaz water treatment. In this research, the coagulation of raw water was studied using PolyDADMAC alone, and mixed coagulant of PolyDADMAC and ferric chloride at various dose and ferric chloride alone were compared. The study range was selected for turbidity (NTU3850, 80), pH (9-5) and different concentrations of coagulant material .Data analysis was performed using Excel, SPSS software and one way ANOVA (p The optimal efficiency conditions of PolyDADMAC in turbidity 3850 NTU, pH=8, Flash Mix =120rpm and resulted in an optimum dose of 0.5 mg/L which the highest turbidity removal percentage was to be 99.84% in optimal dose of 0.5ppm of coagulant. The optimum doses of ferric chloride with PolyDADMAC were obtained at 15mg/L and 0/4mg/L, respectively. Under higher doses of PolyDADMAC, flocs showed stabilized in solution .In addition, PolyDADMAC also produced larger floc with higher settling velocity that need less time to settle.
The results from the comparison of the effect of coagulants mentioned in the high turbidity removal (NTU 3850) indicate the good performance of PolyDADMAC as coagulant to ferric chloride Also, the results showed that the removal efficiency was affected by the initial turbidity so that the higher the initial turbidity, would be the more efficient the turbidity removal.

The physical, chemical and microbial properties of water are crucial criteria for its drinking suitablity. Unfavorable changes in these parameters may threat consumers’ health. The aim of this study was to give a clear view of physical, chemical and microbial quality of drinking water distribution network in Ahvaz compared to the national and WHO standards. This study was a cross-sectional survey conducted based on 48-week sampling program in Ahwaz water treatment plants No. 1, 2, 3, 4 and 5 as well as in six points in water distribution networks. Water analyses were implemented according to the standard methods. Nine tube of fermentation method was used to determine fecal and total coliform bacteria. The mean values of measured parameters were as follows: electrical conductivity 2282.5 μs/cm, turbidity 2.3 NTU, pH 7.8, alkalinity 144.8, hardness 535.5 mg/L as CaCO3, calcium 137.2, magnesium 46.3, chloride 473.2, sodium 311.2, residual chlorine 1, TDS 1382.7, fluoride 0.53, nitrate 6.7, sulphate 370.2 mg/L, total coliform (0) MPN/100 ml, and fecal coliform (0) MPN/100 ml. Accordingly, the quality of drinking water in Ahvaz was not problematical from the health point of view and except the EC, hardness, sodium, and sulphate, all cited results met the national and WHO standards.

Cutting and drilling mud contains significant amounts of petroleum hydrocarbons that are detrimental to both the environment and public health. The objective of this study was to remove the hazardous components of drill cutting mud using the two biological processes of sewage sludge vermicomposting and biocomposting. In an experimental laboratory research, two pilot composting and vermicomposting processes, each over a period of two months with 2 repetitions, were conducted using the the same biological sludge mixed with drill cuttings contaminated with total petroleum hydrocarbon (TPH) along with sawdust and yard waste. The GC-FID unit was used to determine the residual total petroleum hydrocarbon concentrations. Results showed that the vermicomposting pilot had a higher TPH removal efficiency than did the composting one so that TPH concentration in the mixed waste mass declined after 60 days from its original value of 42.004 g/kg to 11.316 g/kg. In other words, TPH removal in the pilots A (vermicomposting) and B (biocomposting) were 73/06% and 55/3%, respectively. Moreover, the TPH levels in the two composting and vermicomposting pilots on the 45th and 60th days showed significant differences (p

Heavy metals are very important from environmental aspects due to their toxicity and accumulative properties. The aim of this study was to evaluate concentrations of lead, cadmium, copper and zinc in vegetables of agricultural lands in Ahvaz, capital of Khuzestan province in southwest of Iran.
This descriptive study was done on Ocimumbasilicum, Raphanussativuslongipinatu and Portulacaoleracea samples from 6 farms located in the north and south of Ahvaz city during spring, summer and autumn in 2013. In general, 60 vegetable samples were investigated. Samples were digested by using acidic digestion. Then concentrations of the elements were determined using furnace atomic absorption spectrophotometry according to standard methods. Data were analyzed by SPSS at α=0.05. The results were compared with WHO and FAO guidelines.
Mean concentrations of lead, cadmium, copper and zinc in vegetables were 10.39, 2.51, 7.20 and 31.84 mg/kg, respectively. Comparing the results with permissible levels given by FAO and WHO indicate that lead and cadmium levels in vegetables are above the recommended levels. However, average concentrations of copper and zinc in vegetables were lower than WHO/FAO recommended levels.
According to the results, vegetables cultivated in this area are polluted to heavy metals of Lead and Cadmium. Due to accumulative effects of heavy metals and their harmful effects on human societies and endangering food safety, more precautions are required to reduce such effects.

Background and Waste stabilization pond is one of the conventional wastewater treatment processes especially in warm climate regions. This study investigated the effect of baffle and attached growth on improvement of coliform removal efficiency.
This research was carried out in pilot scale adjacent to wastewater treatment plant in Ahvaz, Iran. The pilot composed of a control system and three other systems. In control system two ponds were serially connected. Dimension and configuration of other three systems were similar to those of the control system. However, the ponds in these systems were equipped with various baffles and fixed bed media. Within four months, the capability of each system in coliform removal was evaluated in various detention times and coliform die-off coefficient (Kb) of each pond was determined.
During sampling with average detention time of 8.7 day, the average of coliform removal was 69% in control system, while it in two, three and four baffles system these values were 80, 84 and 86%, respectively. Also, Kb20 average in the first pond of control system was 0.11 d-1 and in other systems with increasing of baffles and media packages number to two, three and four it increased to 0.16, 0.17 and 0.18 d-1, respectively. Furthermore, Kb20 in second pond was higher than first pond of each system.
Use of baffles and fixed bed media improved coliform removal efficiency. The efficiency of two and three baffles system was more than that of the control system and was found to be better than four baffles system technically and economically

Hospital effluents are regarded as a kind of municipal wastewater laden with additional pollutants due to the variety of wards and therapeutic activities in a hospital. This makes the determination of kinetic coefficients and parameters of utmost importance for the successful operation and maintenance of hospital wastewater treatment facilities. Extended aeration activated sludge is one of the most important processes employed in such facilities. The present study is an effort to determine these parameters for the operation of such a facility operating in hot climate conditions. For this purpose, samples of both hospital raw wastewater and plant effluent were taken during a 6-month period from January to June 2014 to determine their BOD5, COD, TSS, PH, and Turbidity. Moreover, MLSS, MLVSS, and DO in the aeration tank as well as the sludge return ratios were measured. Such operation and maintenance parameters as θc, F/M, and SVI were then calculated and the equations of the modified Monod Model were used to calculate the values of the kinetic coefficients such as Y, K, KS, Kd, and µmax for the extended aeration activated sludge process at the hospital wastewater treatment plant as follows: K= 2.19 d-1, Ks=90.74 mg/l, Y = 0.39 g Biomass/g BOD5, Kd = 0.06 d-1, and µmax =0.85 d-1. The results obtained can be usefully exploited for designing similar extended aeration activated sludge processes for the treatment of hospital effluents, especially for those operating in hot climates.

Due to the scarcity of water resources and significant population growth, water supply has become a challenge. In such circumstances,efficient and cost-effective technologies such as nanotechnology in water treatment is recommended. The latest in water purification, desalinationsystems, Nano-filtration can bepointed. Nano-filtration separation mechanism of the effect of molecular size, The difference in permeability,and solubility of the feed components and electrical interaction between the membrane and ions are present in the feed.The purpose of this study of Nano-filter system to remove contaminants is challenging.This study, using a Nano-filtration system with a nominal capacity of 300 m3/d and Recovery rate of %60,and activated carbon filtration system and sand filterconsists of three vessel was Molasani Nano-filter water treatment plants in 2013. Experiments using the standard method carried out and the results were analyzed using the Excellsoftware.The results showed that the removal efficiency of the system in EC (%98.47), TDS (%98.45), total hardness (%98.74), calcium (%98.55), magnesium (%99.15), chloride (%96.48), sodium (%96.48) and TOC (%98.57) .Due to the low renal solute dissolved in water and the nutritional value of the elements of water, particularly calcium and magnesium and absorption of these elements of water and nutrients through the body is necessary and the relationship between drinking water hardness and reduced incidence of cardiovascular disease in the community is in the long term this can be a contentious issue.

Nowadays the shrimp farming is one of the major commercial issues in some countries. The aim of this study was to evaluate the water quality of the input and output vannamei shrimp farms in Abadan Chavibdeh. In this cross-sectional study in a period of 6 months (May to October) conducted in 2012, the physical and chemical parameters of water samples were performed on a monthly basis. 3 stations were selected; 2 station on the river Bahmanshir station and 1 in the leachate was located for to evaluate the quality of the water inlet and outlet vannamei shrimp farms. In water samples taken from the inlet and outlet were measured Parameters BOD, TSS and DO. Based on result this study, all parameters during the study in the field of exhaust effluent were standard range and are not a threat to the environment. Thus, can be concluded that reverse osmosis, an ideal method to BOD, TSS and DO removal in areas with contaminated water to this Parameters.