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Abstract Since spring discharge, especially in arid and semiarid regions, varies considerably in different months of the year, a time series of spring discharge observations is needed to determine the firm yield of the spring and the amount of water allocated to different needs. Because most springs are in mountainous and inaccessible areas, long-term observational data are often unavailable. This study proposes a probabilistic method based on bivariate analysis to estimate the discharge of the Absefid spring in Iran. This method constructed the bivariate distribution of the outflows of Absefid (AS) and Gerdebisheh (GS) springs using Copula functions. For this purpose, the fit of 11 different univariate distributions to the discharge data of each spring was tested. The results revealed that the GEV and log-normal distributions best fit the discharge data of GS and AS springs, respectively. In addition, among eight different copula functions, the Joe copula function was selected to construct the bivariate distribution of the discharge data of AS and GS springs. With the help of the created bivariate distribution and assuming a certain probability level, it is possible to estimate the discharge of Absefid spring based on the discharge of Gerdebisheh spring in a particular month. The estimated values of the discharge of the Absefid spring in the period from March 1993 to August 2022 show that with a probability of 90%, the lowest discharge of this spring is 600 L per second and occurred in June 2001. Therefore, to allocate the water from this spring for drinking purposes, this discharge value can be considered as the firm yield of this source. However, the amount of allocated water from this source should be determined by considering the ecological needs of the river downstream of this spring.

In recent years, the development of submerged membrane systems has led to the significant development of ultrafiltration/water purification markets. The study aimed to investigate the efficiency of Poly-Aluminum Chloride coagulant in removing turbidity using a submerged membrane reactor for simultaneous coagulation and flocculation of filtration and determine the optimal values of its performance parameters. In this study, the Poly-Aluminum Chloride coagulant along with lime and polyelectrolyte for water coagulation and flocculation was firstly evaluated by the Jar test in different turbidities. Also, pH (5-10), Poly-Aluminum Chloride (1-50 mg/L), and coagulant aids of lime (0.5-15 mg/L) and polyelectrolyte (0.1 to 2 mg/L) were examined. Then, a pilot-scale submerged membrane reactor was designed for coagulation, flocculation, and membrane filtration processes. Pilot experiments were used as closed systems, and then different parameters of flux, aluminum concentration in the treated water, and membrane fouling were investigated. Jar test results showed that Poly-Aluminum Chloride had a great performance in removing turbidity. In addition, the use of lime and polyelectrolyte coagulant aids improved the turbidity removal process by 3%. Furthermore, pH=8 was selected as the optimal range, and the best flux performance was obtained at turbidity less than 100NTU in a submerged membrane pilot. The flux reduction in eight hours of operation time was only 5% while this increased to 50% in turbidity above 200NTU. The turbidity removal percentages were reported to be constant and higher than 99.5%. The removal rate of total aluminum by the membrane process has been over 99%, and the type of membrane fouling is surface sediment and is reversible. Results indicated that the submerged membrane reactor along with coagulation and flocculation could be applied as an efficient method in water treatment with different turbidity.

Determining the spatio-temporal variations of precipitation patterns plays a key role in water resource management, control of natural hazards, and the design of infrastructures. In this study, the spatial and temporal alterations of daily precipitation concentration index (CI) in Iran territory for the period of 1987 to 2016 was determined, considering 80 metrological stations, Which are well distributed throughout the country. In addition, the trend of annual CI variations was examined using non-parametric Mann-Kendal test. The results indicated that CI varies between 0.57 and 0.71 in Iran, considering the last three decades. The highest CI values were obtained for the Caspian Sea and Persian Gulf coastlines, indicating the concentration of rainfall in limited days in these regions. Moreover, 64 out of 80 stations have experienced an increasing trend in CI values. According to spearman tests, the significant reverse correlation was revealed between CI value and elevation from sea level, and latitude.

The combination of oxidation and flocculation has been used to alleviate the membrane fouling in MBR systems. As common and cheap additives, NaOCl and FeCl3 were employed to prolong the operation life of the membranes. To achieve the highest performance in terms of the SMPs and COD removal, the optimum dosages of FeCl3 and NaOCl additives were first evaluated. To do so, using the jar test, optimum dosages of 2 mg/L and 2 mg/L were respectively determined for the FeCl3 and NaOCl, leading to the highest possible SMPs and turbidity removals of 20.1% and 91%. Using such optimal dosages, different scenarios were examined and the MBR experiments were then conducted in three stages designed to have no chemical addition (stage 1), FeCl3 (stage 2), and a combination of FeCl3 and NaOCl (stage 3) to assess the effect of the additives on membrane performance under continuous flow condition. The results revealed that, although at such dosages, the additives were not able to affect the nitrifying and heterotrophic bacteria, when simultaneously employed (stage 3), they were able to significantly lower the cake layer resistance and the operating time by 4.3 and 2.6 times when compared to the conventional MBR systems (stage 1) and the ones flocculated by FeCl3 (stage 2).

The effluent from copper industries is important in terms of production volume, environmental pollution and cost of treatment and disposal. In addition to its economic reasons, the effluent recovery also reduces the pollutant load. Such cases therefore prove the necessity of investigating different methods for reducing water consumption and effluent generation. This study investigated the minimization of water consumption and effluent production in Khatoon Abad copper refinery plant. For this purpose, the conventional method of reducing water consumption and a new technology called water pinch were explained. The water pinch technology was examined for three pollutant indices (TSS, TDS and turbidity) in three high consumption units of Khatoon Abad copper refinery plant. For TSS, TDS and turbidity as pollutant indices, total 614, 525 and 451 cubic meters of raw water consumption per day equivalent to 40.96, 35 and 30 percent could be saved, respectively. According to the results, the pinch technology could help researchers to make decisions for reducing water consumption and according to the observations, suspended solids are regarded as the basis for reducing water consumption. Minimization of water consumption, Water pinch, Mass transfer networks, Water reuse, Total suspended solids, Turbidity.

Referring the World health Organization definition, a safe drinking water should not threat the consumer health over the lifetime of consumption. The objective of the present study is to investigate the present guidelines in order to improve the Iran drinking water guidelines. To obtain this, the present drinking water guidelines in Iran (named 1053 and 1011 standards) and some well-known guideline (WHO,US EPA and the European Communities) were studied. The Iran guidelines were compared to the other ones and the different points and values were presented as Tables. It was understood that the present drinking water guidelines of Iran do not cover areas such as the water quality indicators based on their resources and lack some suggestions about in-network monitoring plans. It is recommended that Iran guidelines should be revised in two categories: 1. The primary standard including the pollutants threatening the consumers health and the Secondary standards which should be prepared by the local water authorities. Keywords: Drinking water, drinking water standards, water quality indicators, World Health Organization, Iran drinking water standards

The aim of this study was to investigate the application of micro-filtration and ultra-filtration membrane systems in order to improve the physical and microbial quality and the reuse of backwash water from the sand filter units in water treatment plants. The backwash water from filters makes up for 3 to 5 percent of the total water treated, which is disposed in most WTPs. However, the treatment and reuse of the backwash water is more admissible from technical and economic viewpoints, especially in view of the present water scarcity. For the purposes of this study, use was made of membrane modules of micro- and ultra-filters on a pilot scale. The micro-filter employed consisted of a polypropylene membrane module with a porosity of 1 micron in size and a fiberglass module with a porosity of 5 microns. The ultra-filter was made of PVC hollow fiber with a molecular weight of 100,000 Dalton. In order to feed the two pilots, backwash water from a sand filter was collected from one of the WTPs in Tehran. After samples were taken from the backwash water, the physical and microbial removal efficiency was periodically evaluated based on the standard method and the micro-filtration, ultra-filtration, and combined MF/UF processes were compared with respect to their performance. The results indicate that the combined MF/UF process is able to decrease turbidity, MPN, COD, TSS, and Fe with efficiency values of 99.9, 100, 61.5, 99.9 and 98.8 percent, respectively. Overall, the findings confirmed the technical capabilities of this method for the recovery and reuse of the effluent produced in the backwashing mechanism of sand filters in WTPs.

Existence of antibiotic in wastewater causes wastewater treatment more difficult. The amount of antibiotic consumption, especially Cephalexin, is considerable so that it concentration in pharmaceutical wastewater is usually high. This study attempts to determine the efficiency removal of Cephalexin by iron nanoparticles from synthetic wastewater. Moreover, the effect of operating parameters such as initial concentrations of Cephalexin, pH, amount of iron nanoparticles and detention time on removal efficiency are investigated and the optimum operating range for each of these operating variables is experimentally determined. The preparation of iron nanoparticles were carried out daily. Samples were prepared with different concentration from a stock solution with 100 mg/L Cephalexin concentration. Cephalexin concentration in each experiment was determined by HPLC method. The results showed that the removal efficiency of Cephalexin in the optimal condition (initial Cephalexin concentration, of 100ppm; detention time, of 10min; iron nanoparticles amount, of 0.8gr; pH, of 5) about 52%.

Arsenic which is present in the underground and surface water is one of the most toxic elements threating human health and animals. Arsenic has been removed in different type of ways. In this study Arsenic removal from drinking water and its decreasing rates were investigated by NZVI (nanoparticle zerovalent iron) to standard limit (I.e. 0.01 mg/lit) . The tests were conducted on reactor containing 100 ml water containing 1mg/L. Arsenic by virtue of Batch method. The mixture was executed in mixing was done an Oultrasnic device in order to have better mixture and complete distribution of nanoparticles in water. Then the arsenic was removed from the water by VATMAN paper of 0.45 Hm. The remained arsenic in the water was measured by ICP device. In this article the influence of the parameters including mixture time , PH ,NZVI and arcenic doses were examined . Having perfomed many tests the results showed that 1 mg arsenic can be removed 100 percent by 0.05 g NZVI in 8 min. It is possible to remove by 98 percent arsenic in 5-10 PH range. Iron nanopaticle way is an effective and rapid way to remove arsenic from water and various conditions have not considerable effect on it.

In this study, the performance of an anaerobic baffled reactor (ABR Pilot 100 l and six compartments) for sulfate removal from the wastewater from Amirkabir Industrial Estate was investigated. The reactor was started with a hydraulic retention time (HRT) of 25 h at 35°C to be gradually reduced to 3.33 h. The best reactor performance was observed at a HRT of 4 h and a sulfate loading rate of 3.318 Kg SO4/m3.d at which the sulfate removal efficiency was 89.15%. In this condition, the highest sulfate removal was observed in the first compartment (69.08%) which had the lowest pH as acidogenesis and acetogenesis had taken place in earlier compartments. This result demonstrated that the sulfidogenesis occurred in the acidogenic phase. Maximum sulfate removal (66.11%) was obtained when temperature was reduced to 20°C (HRT of 4 h). Under the same conditions, the fourth compartment which had lowest pH level exhibited maximum sulfate removal percent (28.98%). This indicates that decreasing temperature leads to the acidogenic phase to shift toward the following reactor compartments. Also, these findings are a further indication of the ability of the acidogenic phase for sulfate removal.

Most organic compounds are resistant to conven­tional chemical and biological treatments. For this reason, other methods are being studied as alter­natives to the biological and classical physico-chemical pro­cesses. In this study, advanced photochemical oxidation (APO) processes (UV, UV/H2O2, UV/H2O2/Fe(II), andUV/H2O2/Fe(III)) were investigated in lab-scale experiments for the degradation of phenol in an aqueous solution. A medium-pressure 300 watt (UV-C) mercury ultraviolet lamp was used as the radiation source and H2O2 30% as the oxidant. Phenol (initial concentration= 0.5 mmol/L) was selected as the model due to its high use and application. Some important parameters such as pH, H2O2 input concentration, iron catalyst concentration, the type of iron salt, and duration of UV radiation were studied based on the standard methods. The results showed that the Photo-Fenton process was the most effective treatment under acidic conditions producing a higher rate of phenol degradation over a very short radiation time. The process accelerated the oxidation rate by 4-5 times the rate of the UV/H2O2 process. The optimum conditions were obtained at a pH value of 3, with a molar ratio of 11.61 for H2O2/Phenol and molar ratios of 0.083 and 0.067for Iron/H2O2 in the UV/H2O2/Fe (II) and the UV/H2O2/Fe (III) systems, respectively.

A combination of ozonation and an aerobic biological process such as the activated sludge has been recently developed as an alternative solution for sludge reduction with the objective of minimizing the excess biological sludge production. In this study, two SBR reactors each with a capacity of 20 liters and controlled by an on-line system are used. Once the steady state conditions were set in the reactors, sampling and testing of such parameters as COD, MLSS, MLVSS, DO, SOUR, SVI, residual ozone, and Y coefficient were performed over the 8 months of research. Results showed that during the solid retention time of 10 days, the kinetic coefficients of Y and Kd were 0.58 mg biomass/mg COD and 0.058 1/day, respectively. In the next stage of the study, different concentrations of ozone in the reactor were intermittently used to reduce the excess biological sludge production. The results showed that 22 mg of ozone per 1 gram of MLSS in the reactor was able to reduce the yield coefficient Y from 0.58 to 0.23 mg Biomass/mg COD. In other words, the excess biological sludge reduced by 60% but the soluble COD increased slightly in the effluent and the removal percentage decreased from 92 in the blank reactor to 76 in the test reactor. While the amount of SVI and SOUR for this level of ozone concentration reached 6 mgO2/h.gVSS and 27 ml/g, respectively. No excess sludge was observed in the reactor for an ozone concentration of 27 mg per 1 gram of MLSS.

Coagulation and flocculation are the principal units in water treatment processes. In this study, the Jar test was used to investigate the effects of the pH and TOC on FeCl3 and PACl coagulants for further removal of turbidity, organic matter, aluminum, total organic carbon (TOC), dissolved organic carbon (DOC), organic Aadsorption at a wavelength of 254 nm (UV254 nm ), alkalinity, residual aluminum and ferric, total trihalomethans (TTHMs) in the Karaj River in the year 2007- 2008. These experiments were conducted through a bench scale study using conventional coagulation in the influent to Tehran Water Treatment Plant No. 2 (TWTP2).With normal pH levels, PACl demonstrated more efficiency than FeCl3 in removing turbidity, TOC, UV254 nm, and TTHMs. The lower coagulant consumption, high floc size, lower floc detention time, lower sludge production, lack of the need for pH adjustment in turbidity of 25 NTU and the lower alum consumption were the advantages of PACl application instead of FeCl3 as a coagulant. Also, PACl application was efficient at low turbidity (2 NTU), average turbidity (6 NTU), and high turbidity (100 NTU) in TOC, turbidity, UV254 nm , and DOC removal. Thus, PACl is an economical alternative as a coagulant in TWTP2.

Subsurface flow wetlands are one of the natural treatment methods used for municipal and industrial wastewater treatment that are economical in terms of energy consumption and cost-effectiveness. Much research has been conducted on wetland operation with continuous flow but not enough information is available on batch flow. This study investigates wetland efficiency in batch flow. For the purposes of this research, two pretreatment units of the anaerobic pond type with digestion pits and two subsurface flow wetlands with a 2-day detention time were built on the pilot scale. The cells were charged with sand of 5 mm effective size, uniformity coefficient of 1.5, and a porosity of 35%. One wetland cell and one pretreatment unit were used as control. The municipal wastewater selected to be monitored for the one-year study period had a flow rate of 26 m3/day and average BOD5 of 250mg/l, TSS of 320mg/l, TKN of 35mg/l, TP of 12mg/l and TC of 2×108 MPN/100ml from Sabzevar Wastewater Treatment Plant. The average removal efficiencies of BOD5,TSS,TKN,TP, and TC in the continuous flow for the combined control pretreatment and wetland cell were 77.2%, 92%, 91%, 89%, 96.5% while the same values for the batch flow for the combined experimental pretreatment and wetland cell were 92%, 97%, 97.5%, 97%, and 99.75%, respectively. The removal efficiency in the subsurface flow wetlands in the batch flow was higher than that of the continuous flow. Thus, for wastewaters with a high pollution level, the batch flow can be used in cell operation in cases where there is not enough land for spreading the wetland cell.

Natural organic matter (NOM) forms the group of principal precursors to organic disinfection by-products (DBPS), which have been recognized to be human carcinogens. In fact, a high TOC concentration, used as an indicator of NOM, indicates a high potential for DBP formation. The aim of the present work was to investigate the effects of nanofiltration with and without preozonation on TOC removal. Nanofiltration alone at operating pressures of 4 and 8 bars could reduce TOC levels to slightly less than 2 mgL-1, which recorded a profile of success for all the experiments. This is while preozonation at a concentration of 2 mgL-1 recorded an effluent TOC level of 3.3 mgL-1, which is not an acceptable record. Preozonation at a concentration of 4 mgL-1 increased effluent TOC to 4.2 mgL-1, which indicates that preozonation could convert NOM from higher- to lower-MW fractions, thus increasing effluent TOC. It was also shown that preozonation-nanofiltration increased effluent TOC, as compared to nanofiltration alone.

Numerous advantages have been reported on PAC (poly aluminum chloride) used as a coagulant over other coagulants such as alum and ferric chloride used in conventional water treatment process with medium and high turbidity levels. These include lower amounts of PACL required specially in removing turbidity, larger floc grain formation, reduced floc sedimentation time, lower sludge production, and relaxation of the need for pH adjustment by lime, among others. The present study aims to evaluate the effects of different coagulants such as ferric chloride and PACL on direct filtration and to identify the most effective material based on both turbidity and particle removal efficiencies. A perfectly experimental pilot system, including raw water preparation, coagulation, flocculation, distribution measurement, and filtration units, was designed and used. Raw water turbidity level in the experimental pilot was below 10 NTU. The effects of various parameters such as coagulant type, filtration rate, and coagulant dosage on the performance of the filter were investigated. The results obtained from several filtration cycles under different conditions indicated that average effluent turbidity level, effluent particle numbers, effluent turbidity variation graph, and effluent particle graph were lower throughout the filtration cycle when PACL was used compared to when ferric chloride was used as the coagulant. Increasing filtration rate led to increased turbidity and particle number. Addition of 2 mg/l of PACL (poor coagulation and flocculation scenario) was compared with addition of 5 mg/l of ferric chloride (strong coagulation and flocculation scenario). The results indicated that higher average values of turbidity removal but lower turbidity and particle removal efficiencies obtained in the case of the poor coagulation and flocculation scenario.

The aim of present work was to investigate effects of the water pressure and ion compound present in water to be treated on nitrate removal efficiency of a nanofiltration membrane. Experiments were performed using sodium salts (NaNO3, Na2SO4, NaF), KNO3, Ca(NO3)2, and Mg(NO3)2 added to tap water. The effects of operating pressures were investigated for a pressure range of 4-10 bars for a nitrate concentration of 150 mg.L-1(NO3-). The effects of concentration levels were studied for the levels 50, 100, 150, 200, 250 and 300 mg.L-1(NO3-). Finally,the effects of anions were investigated for concentration levels of 50, 100, 150, 200 and 250 mg.L-1 of F- and SO42-. The results showed that nitrate removal increased with increasing pressure by up to 8 bars beyond which removal goes steady. Increased nitrate salt concentrations in monovalent salts led to reduced nitrate removal but in divalent salts led to increased nitrate removal. The effect of associated cation on nitrate removal was observed to be higher in the case of NaNO3 compared to KNO3. It was further observed that increasing sulfate ion concentrations reduced nitrate removal while increasing fluoride levels increased nitrate removal.

In drinking water treatment, preozonation is often applied in order to control the microorganisms and taste and odor causing materials, which may influence organics removal by preoxidation and adsorption. Using commercial and natural water humic substances, the positive effect of preozonation as an aid to coagulation-flocculation of these compounds was confirmed by removal of TOC removal in Tehranpars Water Treatment Plant in Tehran. These experiments were conducted as bench-scale studies through a series of jar tests using different pH coagulant dosages and total organic carbon concentration of approximately 4, 8 and 12 mg/L. In addition to TOC removal, the existence of an optimum preozonation dose (OPZD) was also confirmed. Experiments show that preozonation can improve coagulation and flocculation depending on influent TOC concentration of raw water. The results demonstrate different effects of preozonation on removal of influent TOC. Preozonation showed a positive effect on a system with low influent TOC and very low molecular weight (noncolloidal) humic substances.

During 1994 to 1999 a research program titled “A qualitative and quantitative review of industrial wastewater in Tehran province” was done . This article presents the most important results obtained from this study . The research covered 330 food , textile , chemical , and Materials (Metal and liquid materials) factories . Completing of the questionnaire , sampling from the wastewater and analyzing have been done for 5 years . The results show that completely wastewater treatment in food , textile and metal industries were done in 8% , 18% and 17% of units respectively . In chemical industries for major groups include pharmaceutical , soap and detergent , pulp and paper , and paint industries were studied . In pharmaceutical and pulp and paper industries , there were only one factory in each group which were doing a complete treatment , and in detergent and paint industries there were no complete treatment at all . Maximum discharge of wastewater in food and textile industries were into surface waters . They were 62.4% and 48.8% respectively . But mainly wastwater discharging in metal and liquid materials industries were into ground waters which were 86% and 83% respectively .