Iranian Journal of

Background and Objective: Antibiotics are hardly decomposable and resistant contaminants in the environment that according to their anti-biological properties, it is necessary to eliminate or reduce the amount of them before entering the environment. Therefore, the main goal of this research is to investigate the Fenton and Fenton-like process efficiency for the treatment of wastewater containing Spiramycin antibiotic.
Materials and Methods: The effect of independent variables including pH, contact time, oxidant concentration (H₂O₂), and catalyst concentration (Fe²⁺ and Fe³⁺) on the COD removal efficiency were measured using COD meter. The ranges and number of experiments were assigned by RSM (Response surface method) using design expert software.
Results: The optimum conditions of Fenton process with treatment efficiency of 63.31% were obtained at pH 4, hydrogen peroxide concentration of 50 mg/L, Fe²⁺ concentration of 75 mg/L and contact time of 5 min. The optimum conditions of Fenton-like process with treatment efficiency of 51.21% were obtained at pH 3, hydrogen peroxide concentration of 60 mg/L, Fe³⁺ concentration of 137.5 mg/L and contact time of 32.5 min. Based on the ANOVA analysis results, the f value in Fenton method indicates that the model is significant.
Conclusion: According to the results, Fenton oxidation process was selected as the optimum method to remove COD from synthetic wastewater containing Spiramycin antibiotic which may be applied as an efficient method for the treatment of wastewaters containing antibiotic.

Background and Objective: Wastewater treatment and stabilization always imposes costs and consequently a lot of energy on wastewater treatment plants. To achieve the purification and stabilization of as much sludge as possible, breaking complex components into simpler components is considered a critical step. Therefore, this study aimed to evaluate the feasibility of treating the produced sludge in the municipal wastewater treatment plant using ozonation method.
Materials and Methods: In this study, sludge was obtained from the return line of activated sludge from the wastewater treatment plant in the south of Tehran. An ozonation generator with a discharge rate of 3 L/min and an ozone concentration of 40-35 mg/L was discharged to the reactor and the residual ozone concentration was measured by iodometric method. Finally, the total suspended solids and volatile, soluble chemical oxygen demand, total organic carbon, and biochemical oxygen demand during ozonation processes were measured using the Standard Method.
Results: The results of this study showed that the amount of TSS and VSS in the activated return sludge decreased from 4060 to 2100 mg/L and from 3300 to 1850 mg/L during the ozonation process, respectively. However, SCOD, TOC, and SBOD had an upward trend of about 18, 11.7, and 14 times in the same reaction time, respectively.
Conclusion: According to the results of this study, it can be concluded that the ozonation system can be proposed as a suitable process for the decomposition of sludge produced in wastewater treatment plants and increasing the biodegradability of these sludges.

Background and Objective: The aim of this study was to evaluate the chemical and microbial quality of bottled water in Iran and to calculate the water quality index (WQI).
Materials and Methods: Different brands of bottled water (4 samples from 71 brands) were randomly collected from the market. Chemical and microbial characteristics of the samples were examined and determined. Finally, the calculations related to the WQI index were performed and the water samples were classified as excellent, good, poor, very poor and unsuitable.
Results: None of the samples exhibited concentration of heavy metals beyond Iranian water standards, and the concentration of sulfate (SO₄), chloride (Cl) and fluoride (F) did not exceed international standards. However, in some samples, nitrite (NO₂) and nitrate (NO₃) concentrations were higher than recommended standards. With Regard to other water quality parameters, 8% to 89% of the samples exhibited concentration higher than the values provided on the water bottle label. 5 species of different bacteria were found in 15 water samples. According to the WQI index, about 63% of the samples were of excellent quality. Also, the water quality of 34% and 3% of the samples fell in good and poor quality categories, respectively. None of the bottled water samples was of very poor quality.
Conclusion: The quality of bottled water investigated in this study was generally suitable, but due to the wide range of bottled water in Iran based on brand and seasons, continuous evaluation of water treatment methods in companies and careful monitoring of chemical and microbial quality of bottled water in all seasons is recommended.

Background and Objective: Corrosion and precipitation are important indicators of water quality assessment. The aim of this study was to analyze water stability water in Semnan distribution networks.
Materials and Methods: To achieve the purpose, samples were taken from 5 points (3 points of storage tanks and 2 distribution network points) and analyzed for physical-chemical analysis. The concentration of common anions and cations was determined by ion chromatography (IC). The sediment formed in the water distribution network was also investigated for studying its structure and main elements by using X-ray fluorescence spectroscopy (XRF) and induced coupling plasma spectroscopy (ICP). The corrosion and scaling indices, including the Ryznar stability index (RSI), Langelier index (LI), and calcium carbonate precipitation potential (CCPP) were also studied.
Results: According to the obtained results, the quality (physically-chemically) of most of the taken samples lies within the permissible limits of Iran's national standard (1053). However, in terms of total harness all sampling point showed values beyond WHO guidelines for drinking water. Magnesium and sulfate concentrations were also exceeded in one of the reservoirs. The results also showed the main sediment structures were calcium carbonate (calcite) and silica oxide. Moreover, According to the results, the average values of LSI and CCPP represented the scaling due to carbonate calcium nature of water. Water stability analysis indicated major roles of calcium and magnesium bicarbonate formation as temporary hardness and minor roles of magnesium sulfate and chloride as permanent hardness.
Conclusion: According to the results, to prevent water scaling in pipes it is recommended to use lime softening at pH=10 which not only removes temporary hardness but enhances silicate ions removal by co-precipitation with Mg(OH)₂ formed followed by filtration.

Background and Objective: Microbial fuel cell (MFC) is a new green technology that uses the catabolic ability of microorganisms to produce bioenergy while simultaneously removing organic matter and other wastewater contaminants. Electrode material is one of the factors affecting the performance of microbial fuel cells. The aim of this study was to investigate the performance of microbial fuel cells in COD removal and bioenergy production from synthetic and real beverage wastewater.
Materials and Methods: In this research, a two-chamber microbial fuel cell with Nafion membrane and aerated  cathode was set up using two electrodes made of carbon felt and flat graphite after being contacted by synthetic wastewater with a concentration of COD 5000  mg/L and real beverage wastewater. Organic matter removal efficiency and voltage, power density and maximum current were determine.
Results: Experimental results showed that maximum COD removal efficiency of 92 % was achieved in synthetic wastewater and with a carbon felts electrode. In this condition, maximum voltage, power density and output current density of 469 mV, 175.28 mW/m², and 855 mA/m², were obtained, respectively. However, by using real industrial wastewater (beverage), maximum removal efficiency of COD, voltage, power density and output current density, related to carbon felt electrodes ‎were obtaines as 84 %, ‎460 mV, 91/65 mW/m², and 635 mA/m², respectively.
Conclusion: The findings showed that synthetic wastewater outperforms microbial fuel cells in terms of bioelectric production and organic matter removal as compared to real wastewater (beverage). The reason for the decrease in the cell performance might be the presence of solids and other confounding pollutants in real wastewater.

Background and Objective: As pharmaceutically active compounds (particularly antibiotics) are known emerging contaminants (EC), their occurrence in the environment has high health risks for the living organisms and the public. The effluent of wastewater treatment plants (WWTPs) is the most important source of residues of these compounds in the environment. The urban wastewater of Bandar Abbas is discharged into the marine environment of the Persian Gulf at the rate of 500 to 700 L/s, which could be a potential source of pharmaceutical contamination for the marine ecosystem.
Materials and Methods: In this research, two main wastewater discharge stations at Gursuzan and Suru were sampled during three phases between December 2020 to February 2021. The concentration of Erythromycin residues, as the first antibiotic clinically used to treat human infections, was assessed by high performance liquid chromatography (HPLC) method.
Results: Data analysis showed that mean (± 95% CI) concentration of Erythromycin in Suru and Gorsuzan stations were 16 ± 1.53 and 19 ± 5.86 μg/L, respectively; which their differences did not differ significantly (p>0.05). Pooled data also indicated that the wastewater discharge contained 13.2 to 23.50 μg/L of Erythromycin (α=0.05). Considering the discharge of high volume of Bandar Abbas wastewater effluent into the Persian Gulf (500-700 L/s) as well as the data obtained from this study, the results of the simulation model showed that 5184×10⁴ L Bandar Abbas municipal wastewater is discharged into the Persian Gulf marine ecosystem daily. This volume contains 0.877×10³-1.02×10³ g active residues of Erythromycin antibiotic (α=0.05).
Conclusion: The present study is the first report of contamination of residues of medicinal compounds into the Marine Environment of the Persian Gulf by urban wastewater. Regarding the high volume of wastewater discharged, which calls for immediate actions to be taken.

Background and Objective: Pharmaceutical wastewater has a high level of pollution load that should be treated before discharging to the environment. Integrated processes using different mechanisms are one of the most fruitful methods in wastewater treatment. In this study, combined Integrated Fixed Film Activated Sludge (IFAS) and photocatalytic processes are utilized using of Fe₃O₄/TiO₂ nanocatalysts to decrease the COD value of pharmaceutical wastewater.
Materials and Methods: In this study, the variables of each process are optimized using Response Surface Methodology (RSM). In the IFAS process, the variables were dissolved oxygen (DO), media filling percentage and hydraulic retention time (HRT); while in the photocatalytic process, the effects of pH of wastewater, catalyst dose and reaction time were investigated.
Results: In optimal conditions (DO 3 mg/L, HRT 24 h and media filling percentage 65%), COD removal rate was obtained 59.15%. With the initial concentration of 1725 mg/L COD and the mentioned efficiency, the concentration of COD in the effluent diminished to 704 mg/L. However, in the photocatalytic process, during optimal conditions (pH 6.8, reaction time 105 min and catalyst dose 60 mg/L), The efficiency of the process was determined 81%, which by considering the input COD (704 mg/L), the output concentration was reduced to 134 mg/L.
Conclusion: According to the standards provided by the Environmental Protection Agency (EPA), the effluent from the combined process can be discharged into the environment.
 

Background and Objective: Groundwater is the primary water source for drinking and agricultural activities in arid and semi-arid regions. Rainfall, land use, geological structure, aquifer mineralogy, and duration of water contact with the environment in the basement are the main factors affecting the chemical quality of groundwater. This study aimed to determine the physicochemical properties of groundwater by considering the water quality index (WQI) and its quality assessment for drinking water.
Materials and Methods: In this study, 71 wells of Kashan were sampled in summer 2020 with three samplings from each well, and physical and chemical parameters were studied, water quality index was determined using mathematical methods, and Pearson correlation coefficient was determined. Correlation analysis was used. Finally, the collected data were analyzed using SPSS-16 software, Excel 2013, and statistical tests. 
Results: The calculated WQI of 71 wells in Kashan shows that 67% of the wells were of excellent quality, and 33% were of good quality in terms of water quality parameters. In total, out of 71 samples, the numerical index of water quality was 44.94, and the water was of excellent quality.
Conclusion: The results show that ions such as sodium, sulfate, and chlorine are directly related to the counting in an area and increase the concentrations of EC and TDS, and can impair the balance of anionic and cationic aqueous solution. It was also found that more than half of the wells have excellent quality due to using water wells for drinking.

Background and Objective: With the industrialization of communities, population increase and use of surface water, river pollution has been increased by agricultural, industrial pollutants and urban wastewater. Therefore, investigation of river pollution for regional and environmental planning is of great importance. To evaluate surface water pollution, a number of surface water quality indices have been investigated.
Materials and Methods: Iran water quality index for surface water resources (IRWQI_SC) approach was used to evaluate the water quality of the Mahabadchai river, Iran. Sampling was carried out along the Mahabadchai river based on some criteria such as approximately to drainage areas for landfills/domestic and agricultural effluents.
Results: Pearson correlation coefficient between physical, chemical and microbial parameters of water showed that fecal coliform, BOD, COD, nitrate, ammonium, phosphate, turbidity and total hardness had a significant positive relationship with each other at 99% confidence. According to this index, upstream samples of the river are classified as good, mid-stations relatively good to moderate category, and downstream samples of the river are classified as relatively bad.
Conclusion: Based on the relationship between each variable, fecal coliform, BOD, COD, ammonium, and turbidity were more effective in determining the IRWQI_SC. Most of the examined variables showed low concentrations in upstream areas of the river while their concentration gradually increased along the river to downstream areas, especially close to urban and industrial districts.
 

Background and Objective: Water distribution networks are prone to terrorist attacks by injecting toxic substances, due to their vastness and availability. The main objective of this paper was detecting the extent of intentional pollution in the urban water distribution network by self-organizing map (SOM).
Materials and Methods: The existing hydraulic condition of the water distribution network covered by reservoir No. 4 in Tehran was modeled as a pilot. Possible injection scenarios of contamination in different parts of the water distribution network were performed using qualitative analysis of the water distribution network, using the EPANET analyzer engine and coding in R software environment. Artificial neural network of SOM was used to find the contamination range for the injection of arsenic at different times and places in the distribution network.
Results: The concentration of contamination at a certain point decreased over time and a high correlation was observed between time and concentration. The extent of contamination depended on the consumption of subscribers and consequently, the time of contaminat injection. The results of the artificial neural network model showed that the method developed in this research was 91% accurate and was able to determine the extent of contamination in the water distribution network at high speed.
Conclusion: SOM can be used as a complement to the water quality monitoring and pollution detection system in the urban water distribution network to determine the extent of pollution when detecting potential pollution in the shortest possible time, and as an alternative to quantitative-qualitative modeling of the water network.
 

Background and Objective: With increasing population growth and water pollution, fresh water supply sources are declining and can not meet today's human needs. Thus, energy conversion systems with high efficiency and low pollution such as desalination microbial cell have been considered. Therefore the aim of this research was to investigation the efficiency of microbial desalination cell (MDC) for desalination and treatment of salt wastewater.
Materials and Methods: To address this issue, the decision was taken to use saline synthetic wastewater with different initial salt concentrations (2, 5, 7 and 10 g/L NaCl) and, different hydraulic retention times (1, 2, 3 and 72 h) in open circuit voltage (OCV) and closed circuit voltage (CCV) continuous mode.
Results: The results showed that highest EC removal was 11.2% and 14.3% with 10 g/L NaCl in open and closed circuit mode, respectively. Maximum COD removal of 68.7% was achieved in CCV mode that was obtained at 10 g/L NaCl. Additionally, Escherichia coli, Bacillus, Enterobacter, Staphylococcus aureus, Pseudomonas and Citrobacter were diagnose as effective bacteria in decomposing wastewater.
Conclusion: The obtained results proved that MDC desalination microbial cell technology is Emerging technology that has many unknown aspects; however, it is expected to be an appropriate technique for wastewater treatment and desalination.
 

Background and Objective: Microplastics can have harmful effects on living things, including humans. These particles have been identified in all water, soil, and food sources. Among these, freshwater resources are more important, because they are considered a water source for humans through drinking water treatment plants (DWTPs). Therefore, this study investigates the performance of Tehran DWTPs in removing these particles.
Materials and Methods: In this study, the performance of three DWTPs in Tehran in removing these particles was investigated. In most studies worldwide, particles larger than 1 µm were examined, but in this study, nanoplastic particles smaller than 1 µm, as well as the effect of the warm and cold seasons of the year on the concentration of these particles were also examined.
Results: According to the results of the study, the amount of micro and nanoplastic particles at the inlet of treatment plants in the warm season of the year was 2569 ± 309 to 3918 ± 425 MP/L, and the output was 1492 ± 32 to 2279 ± 146 MP/L, which indicates an increase in these particles in the warm season. As a result, the studied treatment plants were only able to remove 32.1 to 59.9% of these particles. In addition, using electron microscopy, MPs were classified into three categories in terms of appearance: fiber, fragment, and film. This study completes the knowledge of MPs in this area.
Conclusion: Based on the results of this study, Tehran DWTPs have poor performance in removing these particles.
 

Background and Objective: Chlorpyrifos (CPF), an organophosphate pesticide, has been widely used in the agricultural industry and may cause environmental damage. The present study aimed to evaluate the potential application of Fe(VI) and Fe(VI)/PMS processes for oxidation of CPF in water after pretreatment with ferric chloride coagulant.
Materials and Methods: This study was performed in two phases including coagulation and flocculation process and advanced oxidation process (AOP). In the first phase, the coagulation process was performed for turbidity removal by ferric chloride (FeCl₃). In this phase, using a central composite design (CCD) with R software, the combined effect of four variables including initial turbidity, initial pH, coagulant dose and contact time was investigated. The supernatant from this process was transferred to the next phase for further analysis. In the AOP phase, the effect of Fe(VI) and Fe(VI)/PMS oxidants were investigated separately.
Results: In the first phase (coagulation and flocculation), FeCl₃ showed the highest efficiency (95.79%) at alkaline pH (pH=8). In the next phase (AOP), the results showed that the degradation efficiency of Fe(VI)/PMS process was higher compared to sole Fe(VI) process at all pHs. Also, by examining the reaction kinetics, it was found that after the coagulation process by FeCl₃, the removal rate in the Fe(VI)/PMS process is 1.5 times higher than the Fe(VI) process.
Conclusion: Due to the high removal efficiency and higher degradation rate of Fe(VI)/PMS process, this technique can be used as a relatively effective method in removing chlorpyrifos from aqueous solution.
 

Background and Objective: With increasing water pollution, serious water shortages and increased pressure to save water, recycling and reuse of water has attracted more attention in various industries. Removal of silica from cooling water is essential for recycling and reuse of water. The aim of this study was to remove silica from water using magnesium oxide nanoparticles (MgO) synthesized by chemical deposition method.
Materials and Methods: Synthetic nanoparticles were successfully determined using field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR) and X-ray diffraction (XRD). To determine the optimal adsorption conditions the batch system, the effect of important parameters such as pH (2-8), contact time (0-150 min), initial concentration of silica solution (50-1000 mg/L), adsorbent amount (0.01-0.14 g) and temperature (25-60 ˚C) were studied.
Results: Under optimal conditions, an almost removal of 200 mg/L silica solution was achieved in 60 min reaction time. Equilibrium data were analyzed using the Langmuir and Freundlich isotherms. The adsorption process can be well described by the Langmuir model, and the maximum adsorption capacity was calculated as 75.76 mg/g. Synthetic data were analyzed using pseudo-first-order and pseudo-second-order equations. The pseudo-second-order model showed good agreement with the obtained data (R² = 0.9949).
Conclusion: Due to the high potential of magnesium oxide nanoparticles in silica removal, it can be a good candidate for the removal of silica and industrial wastewater treatment.
 

Background and Objective: With the expansion of urbanization and the development of industry, environmental pollution, including sources of drinking water to heavy metals, has become a global problem. Therefore, the present study was conducted to measure the concentration of lead and cadmium in the water of Gorgan distribution network.
Materials and Methods: This is a descriptive cross-sectional study in which the concentrations of heavy metals lead and cadmium were measured in 25 different stations of the Gorgan drinking water distribution network from April to September 2018 by atomic absorption device. Statistical analysis was used from SPSS ver 22 software. Also, zoning maps based on the concentration of these two metals were prepared by Geographic Information System (GIS) software.
Results: The results of measuring the lead and cadmium concentration showed that all measured values are less than national and international standards. In general, the average concentrations of lead and cadmium were 4.38 and 0.1 μg/L, respectively. The results of Kruskal-Wallis test showed that there was a significant difference (p <0.01) between the concentrations obtained from lead metal in different months. Additionally, the distribution map of this lead and cadmium exhibited that in the central areas and some border areas, the concentration of these two metals is higher.
Conclusion: According to the obtained results, it can be seen that the concentration of heavy metals lead and cadmium in the water of Gorgan distribution network is within the permitted standards.
 

Background and Objective: In some villages of Mazandaran, drinking water may be polluted with various pollutants, especially heavy metals (HMs), due to the shallow depth of drinking water sources and the proximity of these sources to farmlands. Therefore, this study aimed to measure the HM pollution level of drinking water in some villages of Mazandaran province and to assess the attributed health risks.
Materials and Methods: HMs content of drinking water in 30 villages with separate water sources in Mazandaran province was measured. Concerning the HMs concentration and toxicity, and exposure route through water drinking, carcinogenic and non-carcinogenic risks were assessed using a Monte-Carlo simulation-based method.
Results: The concentration values of arsenic, cadmium, chromium, nickel and lead in water were <1/0-4.26, < 0.05, <0.15-3.74, <0.3-10.89, and <0.8-4.68 µg/L, respectively. The hazard index (HI) values for non-carcinogenic risk due to the exposure to HMs through drinking of water in various age groups ranged from 3.04E-04 to 9.94E-04. Values of cumulative excess lifetime cancer risk (ELCR_T) for As and Cr were 9.72E-08 and 6.13E-08, respectively.
Conclusion: The results of this study showed that, fortunately, the concentration of metals in drinking water in the studied area was much lower than the national standards and the attributed health risk. Therefore, the drinking water sources in the studied villages had acceptable quality. However, due to the existence of rice paddies in some villages of Mazandaran province, continuous monitoring of pollution levels in the drinking water sources of these areas is essential.
 

Background and Objective: Based on its unique characteristics, oil industry wastewater must be treated before discharging into the environment. The study aimed to optimize the catalytic sonopraxone process in the treatment of petroleum wastewater using a statistical method.
Materials and Methods: The synthesis of Iron Oxide-Zinc Oxide was carried out by air oxidation and layer-by-layer self-assembly method. XRD, SEM, EDAX, FT-IR, BET, DRS, VSM and TGA techniques were used to investigate the structure. In this study, applied CCD method optimization of pH parameters, reaction time, ozone gas concentration, hydrogen peroxide concentration and catalyst amount in the process. In optimal conditions, BOD₅ and TPH removal values, reaction kinetics and synergistic effect of mechanisms were studied. COD, TPH and BOD₅ were measured by spectrophotometer (DR6000), GC-FID and incubator, respectively.
Results: The results indicated that the Fe₃O₄@ZnO structure is well formed. A quadratic model was proposed to model the process based on the correlation coefficient. Based on ANOVA analysis and p and f indices, the proposed model was reported to be significant. Optimum conditions include pH 6.4, ozone concentration 1.3 mg/L.min, hydrogen peroxide concentration 2.5 mL/L, reaction time 51 min and catalyst amount equal to 0.64 g/L. In these conditions, the amount of COD reduction was 82.3 and 70% theoretically and experimentally, respectively. Also, in optimal conditions, BOD₅ and TPH removal rates were 90.5% and 85.8%, respectively. The kinetics of the process follows the kinetics of the first order (R²=0.98) and the presence of different mechanisms together causes a synergistic effect and increases the efficiency of the process.
Conclusion: This process can improve the quality of oil effluent based on COD, BOD₅, and TPH removal.
 

Background and Objective: Increasing the productivity of surface water, the unsustainable development of agriculture in the boundaries of rivers, and human sewage have reduced the quality of these water resources. Therefore, investigating the amount of pollution and its sources is very necessary for regional planning. This study aimed to evaluate the water quality of the Golin River using WQI and Liou indexes.
Materials and Methods: Sampling of Golin river water was performed to check water quality based on (WQI) and (Liou) indices in Najjar village station for one year from April 2019 to March 2020.
Results: Water quality, according to the Liou index, during the research period in the sampling station in September and March, was in a good category and other months were slightly polluted. According to the results of the WQI index, water quality in September and March were in the excellent descriptive category, with values of 47.82 and 49.74, respectively, but in other months it was in a good category. In September and March, water quality improved compared to other months because of lower BOD5 due to reduced agricultural activities, and both indicators showed these quality changes well.
Conclusion: Due to the lack of stable conditions in water quality affected by seasonal changes and its departure from the category of high-quality water according to the results of the WQI index and also a little water pollution according to the Liou index, the direct use of Golin River water for drinking purposes is recommended and for this purpose, regular purification should be done and accurate and continuous evaluations of water quality in Golin River are necessary.
 

Background and Objective: The consequence of using coagulant materials such as aluminum sulfate and ferric chloride in the coagulation unit of conventional water treatment plants can generate plenty of sludge that contains large amounts of coagulant, which in addition to environmental risks, will also possess disposal costs. Today, intending to preserve the environment and reduce treatment costs, researchers emphasize the recovery and reuse of coagulants from sludge. In this regard, the present study was proposed and implemented to recover and reuse water treatment plant sludge as a low-cost coagulant in wastewater treatment.
Materials and Methods: This research is an experimental-laboratory study. In order to recover the coagulant from the collected sludge, acid hydrolysis method was used. The physicochemical characteristics of the recovered sludge were also determined using FTIR, FE-SEM, and BET analysis. Moreover, the efficiency of recovered sludge in different doses (50 to 300 mg/L) on wastewater treatability in terms of COD, TSS, VSS, turbidity, phosphorus, and coliform indices was compared with aluminum sulfate, ferric chloride coagulants, also the results of the study were analyzed and presented using Excel software (version, 2016).
Results: According to the results, the prepared sludge had no crystalline structure with amorphous morphology. In addition, recovered coagulant from water treatment sludge has demonstrated high efficiency for wastewater treatment, so 66.6%, 82.49%, 79.66%, 80%, 65 %, 99.18% of COD, turbidity, TSS, VSS, phosphorus, total coliform were removed at the highest dosage of recovered coagulant (300 mg/L), respectively. Furthermore, the recovered coagulant dosage had a significant effect on the performance of the coagulation and flocculation process in wastewater treatment.
Conclusion: The results showed that recovered coagulant from the sludge of the water treatment plant can be considered an acceptable option with appropriate effectiveness in the wastewater treatment processes.
 

Background and Objective: Due to the presence of heavy metals (HMs), sludge produced in industrial wastewater treatment plants (WWPT) is classified as special waste and can cause adverse health effects. The present study aimed to identify special wastes and assess the risk associated with the presence of HMs in the sludge of WWTP from an Industrial City.
Materials and Methods: Identifying the special wastes was conducted using a checklist, and classification was performed in accordance with the Basel Convention. Ecological risk assessment was done by determining the geo-accumulation and ecological indexes. The estimation of health risk was done by determining HQ and ELCR indexes.
Results: The highest amount of special waste was allocated to sludge with a value of 3900.0 kg/month. Chromium was detected in the highest concentration (95.89 ± 52.15 mg/kg). The level of chromium and nickel pollution was evaluated in the low range, and cadmium was very severe. The ecological risk of lead was estimated in a significant range and was very high for cadmium. The HQ was less than 1, and the ELCR for inhalation and dermal exposure was estimated to be lower than the acceptable risk level of WHO.
Conclusion: The present study showed that the largest amount of special waste is dedicated to sludge. Although the concentration of  HMs was lower than the acceptable limits, the sludge had a high ecological risk level. Therefore, the accumulation and transfer of sludge must be carried out under the provisions of the Basel Convention and environmental considerations.