Showing 38 results for Water Treatment
B Ghoreishi, M Shaker Khatibi, H Aslani, A Dolatkhah, A Abdoli Seilabi, M Mosaferi,
Volume 9, Issue 1 (6-2016)
Abstract
Background and Objectives: Qualitative evaluation of sewage sludge before any kind of application is essential. The present study was aimed to investigate Total coliform, Fecal coliform and Salmonella in sewage sludge produced at wastewater treatment plants in Azerbaijan Province, Iran.
Materials and Methods: Nine wastewater treatment plants were chosen in East Azerbaijan Province, and their sludge from drying bed was studied. Total coliforms, thermo-tolerant coliforms, and Salmonella spp., were surveyed during winter time, 2015. Total and thermos-tolerant coliforms were enumerated by EPA method 1680 and salmonella was counted using EPA method 1682.
Results: In the case of total coliform, sludge sample from Jolfa with 1.82×106 MPN/g showed the highest contamination, while Sarab showed lowest fecal coliform count with 2.02×103 MPN/g. As in the case for fecal coliform, the bacteria count for thermo-tolerant coliforms was higher in Jolfa than other cities; on the other hand, Ahar with no fecal coliform count or less than 2.2 showed the minimum contamination rate to fecal coliforms. In case of Salmonella spp., sludge samples from Ahar and Bostan Abad did not show any salmonella. While sludge sample from Tabriz wastewater treatment plant was determined as the most contaminant sludge with bacteria count equal to 84 per g. Moreover, sludge sample from Sarab wastewater treatment plant showed the least contamination rate, and bacteria count was 6 per g.
Conclusion: From the stand point of microbial quality, all sludge samples met class B standards set by USEPA, while none of them could provide class A standards. Thus, special precautions must be taken in case of soil amendments by the sludge produced from wastewater treatment plants.
M Aqanaghad, G Moussavi,
Volume 9, Issue 3 (12-2016)
Abstract
Background and Objective: Being low cost of building and operation, anaerobic baffled reactor is considered superior to aerobic methods of wastewater treatment, especially for small communities. However, it needs to be studded for upgrade and overcome of its limitations. The purpose of this study was to evaluate the performance of FABR and RABR reactors for the municipal wastewater treatment at laboratory scale and in field conditions to determine their optimum conditions in reaching effluent discharge standards.
Materials and Methods: This study was conducted in Khoy wastewater treatment plant. FABR was operated for 267 days with hydraulic retention time of 18-48 h and RABR was operated for 90 days with media bad rotation of 10-50 rpm. The reactors were fed in line from the wastewater canal. Using composite sampling, 224 samples were taken from the inflow and outflow of the reactors and each sample was analyzed for parameters of COD, BOD, TSS, VSS, TKN, and TP.
Results: The reactor startup took about 107 days. FABR removal efficiency was 93-80, 21-10, and 30-21% for COD, TKN, and PO4 respectively at HRT of 48-18 h. FABR reached effluent disposal standard of TSS, COD, and BOD in all conditions and optimum HRT of 36 h. RABR reached to these standards at HRT 24 h and 50 rpm. However, none of them could meet the nutrient effluent standards.
Conclusion: FABR is an appropriate system for municipal wastewater treatment but for reaching N and P effluent standard, it should be combined with aerobic post-treatment. Moreover, in order to reuse the reactor's nutrient-rich effluent for irrigation; it can be reused as subsurface irrigation.
R Shokohi, A Shabanloo, F Zamani,
Volume 10, Issue 2 (9-2017)
Abstract
Background and Objective: Nitrophenols are among the most common and toxic compounds in industrial effluents that 2, 4 dinitrophenol (2, 4-DNP) is the most toxic compound in this group. The object of this study was to optimize the removal of 2, 4-DNP by thermally activated persulfate using a central composite design.
Materials and Methods: This study was performed on a batch thermal reactor with a volume of 4 L. In this study, a central composite design (CCD) with RSM method was used for designing and optimizing the operation parameters such as initial pH of solution, potassium persulfate concentration and temperature. The effect of 2, 4-DNP concentration and reaction time at optimum conditions were also investigated.
Results: The results indicated that the degradation rate of 2, 4-DNP was enhanced by increasing the concentration of persulfate and reducing temperature and pH. The optimum conditions for the highest degradation efficiency (99%) were as initial concentration 10 mg/L, reaction time 30 min, temperature 60 °C, Potassium persulfate concentration 10 mmol/L, and pH 5. At the optimum conditions, when 2, 4-DNP concentration was increased to 50 mg /L, the 2, 4-DNP degradation rate decreased to 73%.
Conclusion: This study indicated that the heat-activated PS oxidation could be an efficient approach for decomposition of 2, 4-DNP. Temperature was the most influential variable in this regard (p<0.0001).
F Akhlaghian, H Azadi,
Volume 10, Issue 2 (9-2017)
Abstract
Background and Objective: All around the worlds, wastewater containing dye pollutants are considered serious problem. Rhodamine B dye which is used in textile, leather, drug, and cosmetic industries exert carcinogenic and strong toxic effects. The aim of this research was to remove of Rhodamine B dye by nanowires of zinc oxide doped with lanthanum.
Materials and Methods: In this work, nanowire of zinc oxide doped with lanthanum was synthesized by hydrothermal method. The obtained photocatalyst was characterized by XRF, XRD, and SEM method. Effects of batch process variables such as pH, initial concentration of Rhodamine B, and photocatalyst dose were investigated. The kinetics of the reaction was also studied.
Results: The SEM images showed a hexagonal structure of ZnO, and La/ZnO nanowires. XRD results also confirmed the formation of ZnO with wurtzite hexagonal structure in both samples (ZnO and La/ZnO). The kinetics studies showed that the reaction was a pseudo first order. The apparent constants of ZnO and 2%La/ZnO nanowires were 0.0045 min-1 and 0.0074 min-1; respectively. In a batch experiment, the degradation yield of 99.8% was obtained at operating conditions of 1.25 g/L of 2% La/ZnO photocatalyst, initial concentration of Rhodamine B solution 4.78 mg/L, and pH=9 under ultra violet irradiation for 4 h.
Conclusion: The nanowire of La/ZnO with an optimum load of lanthanum has a better photocatalytic activity than nanowire of ZnO for degradation of Rhodamine B in aqueous solution.
R Mirzaei, M Yunesian, Ar Mesdaghinia, S Nasseri, M Gholami, E Jalilzadeh, Sh Shoeibi,
Volume 11, Issue 3 (12-2018)
Abstract
Background and Objective: Antibiotics are a group of emerging contaminants in the aquatic environment. Antibiotic residues threaten the human health and ecosystem in the low concentrations found in the environment. Hence, the present work has been conducted to investigate the occurrence and removal efficiency of most prescribed antibiotics including amoxicillin, penicillin, cefixime, cephalexin, ciprofloxacin, erythromycin and azithromycin detected in two urban wastewater treatment plants (WWTPs) in Tehran.
Materials and Methods: The present work is an applied research based on USEPA method no. 1694, to investigate pharmaceuticals residues in water by HPLC/MS/MS in year 2016. The differences between target antibiotics residues were investigated statistically. After the calculation of the removal efficiencies, the normality of the data was assessed. Then, parametric and non-parametric tests were used to compare the removal efficiencies in both WWTPs.
Results: There was not a significant difference between the influent and effluent concentrations of cefixime and azithromycin (in Ekbatan WWTP) and cefixime (in southern Tehran WWTP). There is a significant difference between the removal efficiencies of cephalexin (p=0.005) and erythromycin (p=0.002) in two WWTPs. The Highest median removal efficiencies were observed for cephalexin 94.41 and 99.47 in Ekbatan WWTP and southern Tehran WWTP, respectively.
Conclusion: In addition to the type of treatment processes, it is physicochemical properties of the selected compound has a significant influence on removal efficiencies.
Se Mahdavian, F Ostovar, H Mirbolooki,
Volume 11, Issue 3 (12-2018)
Abstract
Background and Objective: Coagulation, which is carried out by mixing coagulants such as alum, ferric chloride and poly aluminum chloride PAC with raw water, is one of the main processes in conventional water treatment plants. Sludge from this process contains high amounts of coagulants with high economic value. Therefore, if these coagulants are recovered, in addition to reducing the risks relate to sludge disposal, the expenses related to the supply of fresh coagulant in water or wastewater treatment plant may decrease.
Materials and Methods: To access related documentation, ScienceDirect, Google scholar and other databases were searched using keywords such as “coagulant recovery”, “water residuals management”, etc. More than one hundred fifty documents were investigated based on the content validity and thematic relation. Gathered contents were classified and summarized under the titles of “recovery methods”, “repeated recoveries”, “recovery regarding economic aspect” and “advantages and disadvantages of methods”.
Results: Use of new methods such as combination of membrane and chemical processes or ion exchange membrane processes leads to the recovery of coagulants with a similar quality to the commercial ones. In case of using conventional and less costly methods such as acid digestion, quality of recovered coagulants is not comparable with those of commercial ones, which are used in water treatment.
Conclusion: Different coagulants recovery methods were investigated to determine the reuse strategies. It is likely that using of recovered coagulants through conventional methods is in accordance with the related regulations of the wastewater treatment plants. Industrial use of novel processes for recovery of coagulants with higher quality needs precise technical and economical investigations.
S Abolli, M Alimohammadi, M Zamanzadeh, K Yaghmaeian, M Yunesian, M Hadi, Z Soliemani,
Volume 12, Issue 3 (12-2019)
Abstract
Background and Objective: Surface water and underground water quality in countries that facing dehydration have increased the interest of the community to use Household Water Treatment devices. The aim of this study was the evaluation of the quality of drinking water of Household Water Treatment devices and general distribution network in Garmsar, which is under the control of the water safety plan.
Materials and Methods: A descriptive cross-sectional study administered in 6 regions and 41 cities of Garmsar city in spring and summer seasons in 2018. Chemical tests performed according to the standard methods for the examination of water and wastewater, general measurements were performed using the multi-tube fermentation method and counting of heterotrophic bacteria by pour plate method. The results analyzed by using Excel and SPSS software.
Results: The average values during two seasons were reported as: EC= 1507 (μS/cm), TDS= 786.8 (mg/L), F= 0.048 (mg/L), residual free chlorine= 0.67 (mg/L), pH=7.9, total coliform= 0.16 (MPN/100 mL), fecal coliform= 0.14 (MPN/100 mL) and HPC= 112 (CFU/mL). No significant difference found between the chemical and microbial parameters in the general distribution network and the output of the Household Water Treatment devices during the two seasons.
Conclusion: Household water treatment devices did not affect the microbial burden but caused a change in the amounts of some chemical parameters. Drinking water from the distribution network, with the proper application of the water safety plan, is of good quality.
E Khanpour-Alikelayeh, A Partovinia, A Talebi, H Kermanian,
Volume 12, Issue 4 (2-2020)
Abstract
Background and Objective: Petroleum compounds are major contributors to aquatic environmental pollution. In recent years, biological treatments as environmental-friendly and cost-effective techniques have been used alongside the various physico-chemical methods. Microbial cell immobilization in hydrogel carriers has been the focus of researchers due to various advantages such as ease of microbial species control, non-direct exposure of pollutants to the cells, increasing cell resistance during different types of stresses and reusability. The main goals of this study were introduction to electrospraying technique in order to size reduction of alginate beads and comparison of heavy crude oil biodegradation using an isolated strain of Bacillus licheniformis in free and immobilized cells.
Materials and Methods: The oil-degrading strain was isolated from oil-polluted site on Kharg Island. Microbial cells were examined in both free and immobilized systems under different conditions (pH=5,7) and initial crude oil concentration (1500,3500 ppm). Electrospraying technique was used for alginate beads production. Residual crude oil content was analyzed by gas chromatograph and gravimetrically method.
Results: The maximum oil removal (61%) was obtained for the immobilized cells at a concentration of 3500 ppm in neutral medium. Overall, according to the results, after the 14th day, the biodegradation through the immobilized cells was significantly (p<0.05) higher than the free cells. Moreover, the cell immobilization caused the microorganisms to be more resistant to the harsh environments.
Conclusion: This study showed that the immobilized microbial cell system has a great potential for oil wastewater treatment. The electrospraying technique can be used to overcome to the mass transfer limitations.
Azadeh Modiri, Shadab Shahsavari, Ali Vaziri Yazdi, Ali Akbar Seifkordi,
Volume 13, Issue 1 (4-2020)
Abstract
Background and Objective: Arsenic has long been considered as a heavy metal and toxic pollutant due to its potential to harm the human health and the environment. Adsorption is one of the mechanisms for arsenic removal from wastewater. Therefore, the purpose of this research was to investigate the feasibility of synthesized chitosan-zirconium magnetic nano fiber on arsenic adsorption from wastewater and to evaluate its kinetic and isotherm models.
Materials and Methods: Synthesis of nanofibers was performed by electrospinning method and the optimal formulation was determined following the experimental design. Then, kinetics and isotherms of arsenic adsorption on the as synthesized nanofibers were investigated. The prepared nanofiber was characterized using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopes (FESEM), Infrared Fourier Transform (FT-IR) and Vibrational Sampler Magnetic Meter (VSM).
Results: The optimal formulation was obtained: 2.84% chitosan, 0.97% nano-zirconium and 0.94% nano-iron. The adsorption of arsenic on synthetic fibers was found to follow quasi-first-order kinetics and the Freundlich isotherm. Furthermore, the effect of initial concentrations of arsenic, contact time, temperature and pH on arsenic adsorption were surveyed. The optimal condition for nitrate arsenic adsorption was obtained at initial concentration of 70 mg/L, 45 min contact time and at pH 3.
Conclusion: According to the results, the synthesized nanofiber displayed a regular network structure with the distribution of the Zr-nanoparticles in its shape. Also, according to the form of magnetometric analysis, it was found that chitosan-nanosirconium magnetic nanofibers are well magnetized and are free magnetic. Finally, it can be concluded that the synthesized nanosorbent has a high potential for arsenic removal from industrial effluents.
Mohsen Ansari, Mahdi Farzadkia,
Volume 13, Issue 1 (4-2020)
Abstract
Background and Objective: Considering 829000 annual diarrhoeal deaths due to water pollution worldwide, the World Health Organization has emphasized that countries should reduce this rate by upgrading their wastewater treatment systems. The purpose of this study was to evaluate the performance of a modified up flow septic tanks reactor for treatment of synthetic wastewater.
Materials and Methods: In this experimental study, a modified septic tank system based on the upstream hydraulic regime, and also a conventional septic tank system was designed, manufactured, and operated. The municipal wastewater was used to operate, and synthetic wastewater was used to maintain. The major performance indicators of septic tanks include: volatile solids (VS), volatile suspended solids (VSS), total suspended solids (TSS) and chemical oxygen demand (COD) were sampled and measured in triplicates. The experiments were done in three hydraulic retention times of 24, 48, and 72 hr. Finally, the results of the study were analyzed by statistical tests in the SPSS software.
Results: The average removal of TSS, VS, VSS, and COD in HRT 24 h for the conventional reactor were 55.07, 27.36, 30.82, and 55.52%, respectively, and for the upstream-modified reactor at HRT 24 h were 66.57%, 34.05%, 38.47%, and 65.57%, respectively.
Conclusion: Changing septic tanks to up flow regimes and creating a cylindrical shape in conventional septic tanks, the removal efficiency of conventional septic tanks was improved, and the effluent contamination load was reduced.
Abdolmotaleb Seid Mohammadi, Ghorban Asgari, Reza Shokoohi, Parastoo Shahbazi,
Volume 13, Issue 3 (11-2020)
Abstract
Background and Objective: Considering the importance of alkalinity in pH regulation and its buffering role, in this study, the effect of inlet wastewater alkalinity on the efficiency of the anaerobic unit of the wastewater treatment plant. Moreover, a superior chemical compound in providing alkalinity to wastewater was investigated.
Materials and Methods: This study was performed in the treatment plant to determine the relationship between input alkalinity and removal efficiencies of COD, BOD5 and TSS. In order to determine the optimal alkali material for superb anaerobic wastewater performance, four common chemical substances including, NaOH, Na2CO3, Ca(OH)2 and MgO were selected and examined using One Factor At Time (OFAT) test method.
Results: According to the results maximum removal efficiencies were obtained 62, 66.6 and 71.2% for COD, BOD5 and TSS, respectively under alkaline condition of 1260 mg/L CaCO3. Furthemore, the optimal dose to supply one unit of alkalinity by Na2CO3, Ca(OH)2 and MgO were 0.53, 0.54 and 0.3 mg/L, respectively. These values were obtained 5 min contact time and mixing rate of 150 rpm. However, for NaOH the optimal dose supply was obtained 0.35 mg/L for 3 min contact time and mixing rate of 100 rpm.
Conclusion: In conclusion, the performance of anaerobic baffled reactor is highly related to the supply of influent alkalinity to the reactor. In addition, the use of MgO can be considered as a suitable alkaline substance to neutralize acidic wastewater and provide alkalinity for ABR system.
Mohsen Ansari, Mahdi Farzadkia,
Volume 14, Issue 2 (9-2021)
Abstract
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.
Farah Rashadi, Nahid Navidjouy, Ali Ahmad Aghapour, Mostafa Rahimnejad,
Volume 14, Issue 3 (12-2021)
Abstract
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.
Fatemeh Tabatabaei, Roya Mafigholami, Hamid Moghimi, Sanaz Khoramipour,
Volume 15, Issue 1 (4-2022)
Abstract
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.
Samira Sheikhi, Hassan Aslani, Reza Dehghanzadeh, Ammar Maryamabadi,
Volume 15, Issue 1 (4-2022)
Abstract
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.
Nahied Shahbodaghi, Daryoush Afzali, Maryam Fayazi,
Volume 15, Issue 1 (4-2022)
Abstract
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.
Arezoo Mahmoudi, Seyyed Alireza Mousavi, Danial Nayeri, Parastoo Darvishi,
Volume 15, Issue 3 (12-2022)
Abstract
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.
Hamid Kariab, Mohammad Mehdi Emamjomeh, Sheida Zakariaie,
Volume 15, Issue 4 (3-2023)
Abstract
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.
Ehsan Rafeemanesh, Habibollah Esmaily, Farzaneh Rahimpour, Mohammad Javad Fahoul, Habib Herati, Hasan Jahed Taherani,
Volume 16, Issue 2 (9-2023)
Abstract
Background and Objective: Employees of wastewater treatment plants are exposed to various harmful factors in the work environment that can threaten their health. In this research, the health status of the employees of Mashhad sewage treatment plants has been evaluated to help by implementing intervention programs to improve the health of employees.
Materials and Methods: In this descriptive-analytical study, (bioaerosols, UV rays, heat stress, and hydrogen disulfide gas) were measured in 5 treatment plants in Mashhad. All study variables, including health status, clinical tests, and job stress, were analyzed analytically in two operational and administrative employee groups. The standard HSE occupational stress questionnaire was used to investigate the state of occupational stress. All data were transferred to the computer and data analysis was done with the help of software SPSS20.
Results: The amount of pollutants except H2S gas was lower than the national occupational exposure limit. The number of smokers, diabetics, knee pain, and hearing loss was higher among operational than administrative employees, and hypertension, increased cholesterol, back pain, and skin disease were also more common in office workers than operational workers, but there were no statistically significant differences. Obesity and overweight (p<0.009) and increased triglycerides (p<0.05) were more common in administrative than operational workers, which had statistically significant differences. The state of job stress in operational employees was statistically significant compared to administrative employees regarding role (p<0.018) and communication (p<0.002).
Conclusion: Appropriate occupational health interventions to reduce pollutants, implement ergonomic programs and improve nutrition and increase physical activity and stress management can play an effective role in improving the health of employees of these units.
Abbas Khazaee, Mehrnoosh Abtahi, Mahsa Jahangiri-Rad, Fatemeh Shokri-Daryan, Mohammad Rafiee,
Volume 17, Issue 1 (6-2024)
Abstract
Background and Objective: Identifying the quality of non-conventional waters and exploring their optimal utilization are fundamental measures for maintaining public health. This study aims to investigate the effluent quality of the irrigation canals in Pakdasht farms.
Materials and Methods: In this cross-sectional descriptive study, 120 samples were collected from 6 irrigation canals in Pakdasht fields over a period of 5 months. The physicochemical and microbial characteristics of the canal effluents were determined based on the standard methods of water and wastewater tests. The concentration of heavy metals was measured using an ICP device. To determine the possibility of using the effluent of Pakdasht canals for agricultural purposes, the Environmental Protection Organization of Iran and FAO standards were used.
Results: The average concentrations of COD, BOD5, TSS, TDS, NO3-, SO4-2, PO4-3 parameters were 259, 125, 105, 697, 4.5, 94.4, 13.5 mg/L. Additionally, the average number of total and fecal coliforms in the effluent of the canals exceeded the standard values set by IRNDOE and FAO. The mean pH was 6.97, the electrical conductivity (EC) was 1014 μm/cm, and the turbidity was 76.2 NTU. The detected concentrations of heavy metals were awithin the following ranges: Cr (0.025-0.045 mg/L), Cd (0.0006-0.001 mg/L), Pb (0.0006-0.001 mg/L), Co (0.038-0.059 mg/L), and Ni (0.05-0.06 mg/L), which were roughly lower than the suggested standards. However, both HEI and WWQI indices confirmed that the water was unsuitable for agricultural irrigation.
Conclusion: Based on the comparison of the results of the parameters measured in this study with the environmental and FAO standards, the effluent from the irrigation canals of Pakdasht city is deemed unsuitable for the irrigation of warm-season crops but suitable for fodder and industrial crops.
