nasser mehrdadi

The objective of this study was to establish a facility-level modeling tool to assess the performance of internal operational strategies and external emissions.

The biological process model in Benchmark Simulation Model No. 2 (BSM2) was upgraded to include two-stage and four-stage nitrification, as well as denitrification processes, to effectively simulate nitrous oxide (N2O) production. Emissions of carbon dioxide (CO2), methane (CH4), and N2O were also incorporated, taking into account digestion, cogeneration, and sludge storage processes. The refined model was utilized in a case study at the Isfahan Wastewater Treatment Plant (WWTP) in Iran to assess various operational strategies and explore potential challenges related to emission management.

The simulation results, based on the model’s structural assumptions, indicate a negative impact on greenhouse gas (GHG) emissions associated with regional energy upgrades in the ventilation system and activated sludge sector. For example, variations in the biogenic and non-biogenic CO2​ proportions were observed when the total suspended solids (TSS) removal efficiency was altered, decreasing or increasing to 30/70 and 20/80, respectively. While off-site CO2​ emissions can be mitigated, this reduction is offset by a significant rise in N2​O emissions. This is particularly concerning given that N2​O exhibits a greenhouse effect nearly 300 times greater than that of CO2​.

It should be pointed out that numerous studies are needed to evaluate plant-wide control strategies in WWTPs for informed and effective decision-making regarding performance optimization.

Wastewater treatment is a critical environmental challenge, and moving bed biofilm reactor (MBBR) technology is an effective solution. The selection of appropriate biofilm media significantly impacts treatment efficiency, particularly in terms of organic matter and nutrient removal. This study aims to optimize media selection for MBBR systems to improve wastewater treatment.
Three biofilm media types-K3, MB3, and K5-were evaluated based on key properties such as specific surface area (SSA), porosity, buoyancy, and economic feasibility. The analytical hierarchy process (AHP) was employed to assess and prioritize these criteria. Expert Choice software facilitated the analysis, followed by a laboratory-scale investigation to assess pollutant removal efficiency.
K5 media outperformed K3 and MB3 in terms of nitrogen removal (90%), chemical oxygen demand (COD) reduction (90%), biochemical oxygen demand (BOD) elimination (95%), and TSS removal (89%). K5 also demonstrated superior efficiency in pollutant removal while maintaining consistent pH regulation. K3 and MB3 displayed relatively lower performance, especially in nitrogen and COD removal.
The study confirms that K5 media, selected using the AHP method, provides the highest treatment efficiency in MBBR systems. The AHP-based media selection process enhances the decision-making process, ensuring that economic and performance factors are adequately considered. Future studies should focus on scaling up the MBBR system with K5 media to further evaluate its long-term performance in real-world conditions.

Natural disasters, such as earthquakes, can disrupt water distribution systems, leading to prolonged water shortages and associated crises. Tehran, with its high seismic risk, necessitates robust emergency water management solutions to ensure adequate potable and non-potable water supply during critical conditions.

Using GIS and WaterGEMS software, we evaluated the design and placement of emergency water reservoirs in ASP Town, Shahriar. Hydraulic modeling was conducted to optimize the piping, pressure, and flow dynamics for potable water supply under emergency conditions. Additionally, non-potable water reservoirs utilizing treated wastewater were designed for irrigation and fire suppression, incorporating solar-powered pumping systems to ensure energy efficiency.

A 50 m3 cylindrical steel emergency tank, connected to the urban water network, was proposed to provide 3 L of potable water per person for three days in a crisis. The system includes solar panels, a 250-W pump, and a hydraulic shut-off valve to maintain water quality and availability. For non-potable uses, a wastewater reservoir with a variable-speed pumping station supports irrigation and supplies 12 fire hydrants, meeting pressure and flow requirements during emergencies.

This study highlights the importance of integrated water management strategies, including solar-powered systems and treated wastewater reuse, to improve resilience against natural disasters. The proposed designs ensure sustainable water supply and effective crisis management for drinking and non-potable applications in high-risk urban areas.

The main goal of the current research is to study the feasibility of using renewable hybrid systems and introducing the optimal configuration from a technical-economic and environmental point of view in supplying electrical energy for desalination plants (South of Iran). HOMER analyzer software is used to simulate the load and introduce renewable systems to provide part of the energy of this complex. The electrical energy required for this complex to produce approximately 300 cubic meters of fresh water per hour is estimated at approximately 5.5 kilowatt-hours per cubic meter. Currently, this energy is supplied only through the power grid, which has a cost equivalent to 0.088 dollars per kilowatt-hour. In the following, the possible scenarios are introduced and compared in two modes, grid-off and grid-connected. The optimal off-grid configuration with an initial cost of $65.8 million will have an electricity cost of 12 cents/kWh, with 37% of the energy needed coming from wind and solar energy. In the state connected to the grid, the optimal configuration provides 44% of the required electrical energy through renewable energy, which reduces the carbon dioxide emissions by 4527 tons per year, and by selling excess electricity to the grid, the cost of energy is decreased to $0.078/kWh, which means that the cost of electricity needed to supply each cubic meter of freshwater falls down about 11.4%. Also, 47% reduction in carbon dioxide emissions.

A high concentration of Hydrogen Sulfide in biogas is a major problem associated with anaerobic digestion of waste rich in sulfate. It disrupts the functional process and reduces the lifespan of biogas facilities. The micro-aerobic (MA) process is an alternative method for direct sulfurization.

The effect of sulfate loading (200, 500 and 700 mg/L) on H2S in biogas were investigated. Subsequently, the effect of MA process (0.88, 1.04, 1.34 NL/day) on H2S reduction in biogas production was evaluated. Additionally, oxidation-reduction potential (ORP) and pH were measured. Finally, under optimal conditions, the biogas volume and the content of CH4 and CO2 in biogas were determined.

The results indicated that there were no significant differences in biogas volume production between the reactor fed with 200 mg/L sulfate and the control. However, the biogas production in reactors with 500 and 700 mg/L sulfate decreased to 4103 and 3929 mL, respectively. The H2S levels in control and reactors with 200, 500, 700 mg/L sulfate were 0.35, 0.46, 2.4, and 1.8%, respectively. In reactors with MA at rates of 0, 0.88, 1.04, 1.34 NL/day, the H2S levels were 1.95%, 0.9%, 0.4% and 0.1% (V/V) in biogas, respectively. The pH in reactor varied between 2.7 and 4.7, and the ORP was measured between -281 and -291 mV. Statistical analysis shows that no significant difference was observed between the average daily production of biogas with MA process of 0.88 and 1.04 NL/day. However, MA with 1.34 NL/day resulted in a decrease in biogas production.

The results indicated MA at a rate of 1.04 NL/day is a favorable option for the treatment of sulfate-rich urban wastewater sludge due to its efficiency in H2S removal.

The chemical precipitation using lime, caustic soda and soda ash was investigated for the simultaneous removal of Cu and Zn from copper mine industrial wastewater by conducting jar tests in the present study. Jar experiments were performed with a set of polyethylene beakers (500 ml) in order to investigate the effect of two reaction parameters (precipitant doses and initial pH) on the removal of heavy metals. X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) equipped with X-Ray Energy Diffraction Spectroscopy (EDX) were used to identify the important chemical compounds and to study the surface morphology, chemical composition and particle size of the sludge samples. An increase in the removal of Cu and Zn was observed by increasing the precipitant dose (10-400 mg/L) for each reagent used. Removal efficiency of 90% were obtained for both heavy metal ions. The chemical precipitation efficiency was affected by pH. At high final pH levels (8<pH<10), Cu had higher removal efficiency than Zn by all precipitating agents. In the sludge produced, Zn and Cu were precipitated as amorphous hydroxides including Zn(OH)2 and Cu(OH)2. SEM images showed that the produced sludges have small size and compact structure. EDX analysis determined that in all sludge samples, the content of Cu was higher than Zn. Effluent treatment with soda ash resulted in the sludge production with lower volume and larger particle size. As a result, the use of this precipitating agent can be less expensive for sludge drying steps.

Graywater and rainwater reuse is one of the primary alternatives for diminishing water consumption in households, commercial and industrial buildings. However, investigating the performance of membrane technology coupled with UV system for the treatment of gray water and rainwater needs more applicable information. The purpose of this study is to evaluate the performance of an experimental system based on membrane technology combined with UV for the treatment of gray water and rainwater in Iran. In this regard, at different pressures (9.5, 4.5, and 1.5 bar), different arrangements of membranes, including microfiltration (MF), ultrafiltration (UF), and reverse osmosis membranes were investigated along with UV lamps. Laboratory scale experiments were conducted to investigate the potential of these technologies and present an optimal membrane arrangement. The efficiency of the process has been discussed in terms of turbidity, TDS, pH, COD, Escherichia coli, and total coliforms. The results indicated that for both gray water and rainwater treatment, the arrangement consisting of a screen, MF, UF, RO, and UV with a pressure of 9.5 bar is the best scenario for reducing COD, TDS, turbidity, and coliform. According to the obtained results, the output flow in the optimal state was 6 liters per minute, and the mentioned scenario was able to remove 95% COD, 98% TDS, 96% turbidity, and 100% coliform from graywater, as well as 82% COD, 94% TDS, 91% turbidity, and 100% coliform from rainwater. Therefore, the study acknowledges that membrane technology with UV is an attractive process and will play an important role in future sustainable life.

In this work, it was attempted to evaluate and demonstrate disinfection effectiveness of an electrochemical process to entirely remove coliform from wastewater effluent following secondary treatment. For the tests, an experimental bench-scale batch electrochemical cell was constructed, and aluminum electrodes were employed in the electro-disinfection reactor. In the electric disinfection phase, wastewater samples were put in the reactor/disinfector and a direct current (DC) was applied to it. According to findings, a significant decrease occurred in the total number of coliforms in the treated wastewater, and a high improvement occurred in the effluent properties. At a contact time of 15 min and a current density of 5.5 mA/cm2, led to a bacterial killing effectiveness of 97.7% or above. As the current density and contact time increased, a general increase occurred in the bacterial killing efficiency, and the effect of the two above-mentioned factors was much greater than the effect of salinity. Moreover, according to the experimental data, the removal efficiency of chemical oxygen demand (COD) and total suspended solids (TSS) by the aluminum electrodes were 78.50% and 99.93%, respectively. The findings indicate the applicability of the proposed electrochemical treatment to wastewater effluent. Nevertheless, to be able to apply this system at an industrial scale in the future, it is necessary to conduct more research into the optimum operation conditions and make an in-depth comparison of energy consumptions between the electrochemical treatment and the conventional approaches.

Sludge is a by-product of urban wastewater treatment plants using a biological method, which needs to be properly processed and managed in order to avoid environmental pollution and maintain the health of society. The main goal of the current research is to analyze the amounts of sludge disposal and energy recovery in the wastewater treatment plant in south of Tehran, emphasizing the nexus between carbon and energy footprints. Biogas and electricity produced in the wastewater treatment plant were carefully examined. Their impact on reducing direct and indirect emissions and carbon footprint was calculated using relevant international coefficients based on the amount of methane gas and electricity produced. Also, the amount of waste sludge was analyzed during the period of eight years (2014 to 2021). During the investigated period, at least 2414 tons, maximum 22850 tons and an average of 7265.4 tons of sewage sludge were produced per month. The amount of waste sludge produced per million cubic meters of treated wastewater is 24.4, 99.8 and 57.1 tons, respectively. On average, 9.5 million m3 of methane are produced every year, which is equivalent to 146347.54 tons of CO2/ year. On average, 1.1 MW/hr is produced in the power plant of the treatment plant, which is equivalent to preventing the emission of 3612 to 6472 tons of CO2/ year. The total direct and indirect emissions prevented are equal to 149,960 to 152,820 tons of CO2 equivalent. The production of biogas and its consumption to produce electricity in the investigated wastewater treatment plant has a significant effect on reducing greenhouse gas emissions.

One of the most challenging and critical processes in wastewater treatment is sludge treatment. This study aimed to investigate the effects of low frequency ultrasound and high level of energy on inactivation rate of total coliform of sludge and ascertain the optimal operating parameters of the ultrasound waves.

In this research, the density of ultrasound (W/mL) and time (minutes) were investigated. The effect of these parameters on the inactivation of total coliform in sludge was also investigated.

The results revealed that the optimum operating time and ultrasound density were 30 minutes and 2.5 W/mL, respectively. Also, the frequency of 20 kHz of total coliform removal rate in these conditions was 99.44% .

Ultrasound waves as well as micro and nano bubbles could remove total coliform and decontaminate the sludge, thereby incrementing the rate of treatment.

In this study, an optimized composite of expanded graphite /g-C3N4 /phenylenediamine was synthesized and characterized by SEM, FESEM, EDS, XRD, and BET methods.The composite was prepared with an optimized combination using response surface methodology (RSM) as a proper adsorbent for eliminating heavy metals from water samples. The evaluation of the final adsorbent was accomplished by removing metal ions like Pb2+ and Cd2+. Under the optimum adsorption conditions for Pb2+ and Cd2+ (pH:5, adsorbent dosage:2 g/L, and Time:60 min), elimination efficiencies were 78.4% for Cd2+ and 71.35% for Pb2+. pH was the most important factor that influenced the adsorption rate. A short contact time for maximum removal efficiency was reported because of the porous structure of the constructed composite. As a result of the absorptive construction, the equilibrium showed a satisfactory agreement with the Freundlich model. The kinetic evaluations showed that the adsorption process of both heavy metals fitted the pseudo-second-order model. Furthermore, the results of thermodynamic studies indicated that the adsorption was an endothermic and spontaneous process. A series of regeneration experiments (5 cycles) was directed to evaluate the adsorbent reusability. The results presented that it was a suitable adsorbent for heavy metal uptake from aquatic solutions.

In recent decades, the management and treatment of sewage and sludge dewatering process have become crucial due to their high nutrient content. However, choosing the right technology in this area is a big challenge due to the complexities and the existence of many uncertainties. In this article, an analytical hierarchy process is used as a decision-making tool to choose the appropriate dewatering method in the southern Tehran treatment plant, in which the criteria structure and the evaluation process are defined by describing several possible options for sludge dewatering to be compared and weighted. The results were analyzed and evaluated using Expert choice software. According to the results, the belt filter press is the best and most appropriate technology for sewage sludge dewatering among pressure and belt filter press, lagoon, centrifuge, and sludge drying beds. Finally, validation had been done based on the sensitivity analysis method, which shows the effect of changes in input parameters on the results and was carried out for technical, economic, environmental, and management criteria, and the sensitivity of the options to the change in the weight of the main criteria was determined and the results showed that the most sensitivity in the economic criteria refers to the lagoon process, in the technical criteria refers to the centrifuge process, in the environmental criteria refer to the centrifuge process, and in the management criteria refers to the belt filter press process. The results show that this method, due to its simplicity and adaptability to different situations and regions, can be considered at the national level for different decision-makers in the field of selecting processes in water and wastewater treatment.

Urban governments face a number of challenges today related to water governance. As a result, a variety of water governance models have emerged involving governments, public-private partnerships, and private firms. Using a descriptive model, this paper describes how water and wastewater companies in integrated urban management are modeled, and then it suggests how the optimal type of water governance is established in Iran. This study analyzed all parameters and effective variables in continuous management of Iran's water resources, along with the set of laws and regulations that govern upstream activities and the authorities of the governing bodies. Based on institutional mapping, four scenarios were created for dividing responsibilities between government, municipality and private sector in water governance, including governmental planning, semi-centralized governance with the central government, semi-centralized governance with municipalities and decentralized governance based on local government mapping (municipalities). On the basis of the considerations, advantages, and disadvantages of every scenario, scenario 2 has been proposed as the most desirable scenario for application under the country's circumstances.

As the veins of the Earth, Rivers have a determinative role in regulating the functional behaviors of their linked ecosystems and supporting human life. This research was conducted to address the major issue to assess the river's health and survival condition alongside its vulnerability potential, using a benthic-based sustainability index. For this purpose, river-bed sediment oxygen demand (SOD) rate and its associated factors, including Texture, fine-PSD, Nutrients (TOM), besides some basic field parameters of river-water were measured. All required samples were collected from 9 sampling points located on the target zones of Karkheh River in due course. SOD data with regard to related factors were calculated and analyzed. The rates of SOD ranged from 0.71 to 1.74 g O2/m2/day. Further, this index was classified in varied quality domains. Afterward, a predictive equation was determined among SOD rate and its associated parameters using MATLAB software. Finally, the results revealed that the river health suitability in the research area is in categories moderately clean and slightly degraded during the study period. Additionally, the increase in TOM concentrations, together with a decrease in sediment particle size, led to an increase in SOD-rate accordingly. The source pollution load reduction rate under the optimal suites of BMPs in the range of 15 to 66 percent was also one of the outputs of this research.  In conclusion, the consequences of this study can be used as a rapid diagnostic tool to support regional water authorities and other stakeholders to promote the best practices for protecting the health condition of the riverine system, focusing on selecting the appropriate discharge points along the receiving watercourse and on effectively managing the drain-waters/effluents.

In copper industries, mining has a great importance from the environmental point of view, as during this process many by-products are generated. Most of the mining tailings are sulfide minerals, which are oxidized just after they are extracted and exposed to the oxygen and water which consequently leads to produce acid mine drainage (AMD). Water management strategies are conducted to control Acid mine drainage (AMD). Generally, one of the most important methods to refine AMD and release it into the environment is treatment technology. By and large, (AMD) treatment methods are classified as active and passive systems. In the present study, the need for the treatment methods is investigated and then the optimum system is specified.

Sungun copper mine is located in Northwest of Iran, 130 km north of Tabriz and 30 km north of Varzeqan. Production rate of tailings in this mine is roughly 11.2 million tons per year which has over 3 square kilometers area in Pakhir valley. Samples of acidic drainage from Pakhir chay river were collected 7 times and transferred to the laboratory of Omran Zist Azma Company. Bbottles of polypropylene with capacity of 200 cc were used to gather samples for analyzing acidity, sulfate and TDS and bottles of HDPE with capacity of 250 cc were used to gather samples for analysing heavy metals (copper, iron and manganese) parameters. Moreover Concentrated nitric acid was used for stabilizing sample. Flow rate of the river was measured by Mouline (flow meter and flow cross section method) which was on average 32 liters per second.

Results show that pH, sulfate, copper and manganese parameters are higher than the standard threshold. Since, before release to the environment, the parameters must be lower than the standard limits, so this indicates the need for the treatment systems.

Mineral deposits pollution significantly affects the environment, especially the strong hydrological region of Songun copper mine with the production of acidic drainage, which must be in standard threshold for the accepting source. Therefore, treating AMD and then releasing into the environment is the best and definite management strategy. In order to treat acidic drainage, there are two main treatment methods containing active and passive systems. Different types of active and passive treatment systems often are used separately or in combination with each other. This combination is a suitable solution for removing heavy metals from mines acidic drainage. The choice of these systems depend on the acidic drainage chemical composition, type of ore, topographic and climatic conditions, pH, acidity, acid load, flow rate, and the mine activity. Results show that acidity is 1600 mg / l, the acid load is 4423.68 kg / day, pH = 3.94 and the flow rate is 32 liters per second in this study. The DAOS method containing dosing with alkaline, oxidation by different methods which finally will be sediment is proposed for active treatment system.

Bed Sediment is a dynamic and complex material that plays an important role in the aquatic ecosystems and provides habitat from a highly various community of organisms. To address the major issue, this study, which its substantive subject done for the first time in Iran, aimed to assess the current status of Darreh-rood river's health and quality using SOD rate and its associated factors including Texture, fine-PSD, TOC and TP of bed sediments along with some basic field parameters of river-water. All required samples were collected from 10 sampling points in due course. SOD data with regard to related factors were calculated and analyzed. The rates of SOD ranged from 0.69 to 1.57 g O2/m2/day. Moreover, this index was classified in varied quality domains. Afterwards, a predictive equation was determined among SOD rate and its associated parameters using MATLAB software. Finally, the Results showed that the river quality and health suitability in research area are in categories slightly clean and slightly degraded, in targeted zones during the study period. Also, the increase in TOC and TP concentrations together with a decrease in sediment particle size was led to an increase in SOD-rate accordingly. In conclusion, the consequences of this study under Survivability-based Adaptive Management (SAM) perspective can be used as a rapid diagnostic tool to support water policy decision-makers and other stakeholders to promote the best practices for protecting the health conditions of riverine systems, focusing on selecting the appropriate points for discharging the wastewaters into the receiving water-bodies.

Reducing the amount of sludge produced by the biological treatment of active sludge is of great importance. The main task of dewatering unit is to separate water from excess sludge. The aim of this study is to determine the effect of ultrasonic waves on coagulants in improving the sludge dewatering process and increasing solid content of sludge cake.

This is an experimental study performed in batch laboratory scale. During the two seasons, 12 samples were taken at 15 days’ intervals. Variables include ultrasound density (0.375, 0.75, 1, 1.3 and 2.5) in watts per ml, Time (1, 5, 10, 15 and 30) in minute, and specific energy input (208, 1041, 2083, 3124 and 6249) in kilojoule on kilo total suspended solids. The effects of ultrasonic waves on coagulants were investigated by using Particle Size Analizer (PSA).

The optimum amount of solid content of sludge and capillary suction time (CST) was equal to 26.4 percent and 86 seconds in sonification time of 5 minutes and specific energy input of 1041 kj/kg TS. By applying ultrasonic waves, d10, d50, d90 and average particle size amount were equal to 6.3, 44.2, 24.4 and 28.84 micrometers respectively.

Ultrasound waves create pores in the physical structure of the polymers and the increase of cationic surface charge increases the adsorption of particles and made larger flocs and can increase the solid content of sludge and improve sludge dewatering process.

One of the useful applications of Dewatered sludge (DWS) of municipal wastewater treatment plants (WWTPs) is its use as manure in agriculture; therefore, its quality characteristics should be specified. The aim of this research was to determine biological and physicochemical characteristics of DWS of Sari WWTP and compare them with standards, and also to investigate its potential use in agriculture.
Sludge samples were taken from the sewage sludge of Sari WWTP. Sampling and analysis of samples parameters including fecal coliform, salmonella, helminth ova, carbon, nitrogen, C/N, phosphorus, organic matter, potassium, moisture, electrical conductivity, and PH, were performed during four seasons with three replications based on the standard method.
The fecal coliform, salmonella, and helminth ova of the DWS were 2.37×106 ± 1.06×106 MPN/1 g d.s weight, 47±12.92 MPN/4 g d.s weight, and 466±61.85 number/4 g d.s weight, respectively, therefore, the DWS of Sari WWTP was categorized in the class B of the EPA standard. The amounts of C/N, organic matter, carbon, nitrogen, phosphorus, potassium, moisture, electrical conductivity, and PH were obtained to be 12.7±1.15, 42.4±3.27%, 24.6±1.89%, 1.94±0.13%, 2.35±0.6%, 0.57±0.13%, 82±3.12%, 1.34±0.21 ds/m, and 7.41± 0.45, respectively.
The DWS of Sari WWTP has a good fertility value but it cannot be safely used in agriculture and should be improved for class A by the Processes to Further Reduce Pathogens (PFRP), especially by composting.

Determining the wastewater quality index of municipal wastewater treatment plant for reuse or disposal purposes has always been an important issue. Therefore, developing a wastewater quality index facilitates the investigation and selection of the best option for wastewater reuse or disposal. Thus, determining the important quality parameters and the level of importance of each parameter in terms of the application of the wastewater are essential. In this study, after determining the important quality parameters by Delphi method, the weight of each factor was calculated using the multi-criteria decision making tools in order to develop the wastewater quality index. Then, the matrix for wastewater quality index was presented by defining the sub-indices for each parameter using the standards for wastewater reuse and disposal and by integration methods. Results indicated that the quality parameters including BOD, COD, TSS, TDS, Fecal Coliform, pH, NH4 PO4 are the most important parameters. Also, developing the wastewater quality index through different methods for reuse and disposal and application of various weights for each parameter was found to be a more accurate and reliable method. This method allows for fast and simple evaluation of wastewater in each treatment plant and comparison of different municipal wastewater treatment plants.

Dewatered sludge of sewage treatment plants can be used in agriculture if required standards are followed. Heavy metals are among the chemical pollutants that are hazardous to health. Therefore, the aim of this study was to investigate the amount of heavy metals in dewatered sludge of municipal wastewater treatment plant and compare that with the standards and sludge of other wastewater treatment plants in Iran. In this experimental study, the sludge samples were taken from the sewage sludge in Sari wastewater treatment plant. Sampling and analysis were done during four seasons with three replicates in 2017. The samples were digested and prepared for extraction of heavy metals using standard method. Heavy metal content including Cd, Pb, Cr, Zn, Cu, and Ni was measured by atomic absorption. Data were analyzed using SPSS V24 applying t-test. The average concentrations of Cd, Pb, Cr, Zn, Cu, and Ni were 0.3 ± 0.18, 35.81 ± 9.54, 62.55 ± 14.72, 950 ± 149.93, 354 ± 107.45, and 62.4 ± 18.47 mg/kg dry weight, respectively. In current study the concentrations of heavy metals in dewatered sludge were below the maximum permissible standard of 10716 Iran for compost and other standards. So, dewatered sludge of Sari wastewater treatment plant can be used in agriculture while following all parameters and composting operations.

The main goal of controlling urban wastewater treatment plants is to adopt an algorithm in which the process works in optimal operating conditions. For this purpose, we need to use the process mathematical model. In this study, the steps of building the enchmark Simulation Model No. 1 (BSM1) were presented step by step. Appropriate numerical methods were proposed for solving the simulation model, and the most effective parameter of the process was determined to provide control strategies. Finally, behavior of the process was examined against different weather conditions. The initial values inside the reactors and the clarifier layers were calculated by solving the state equations of each reactor. Using the Euler and Range Kutta hybrid numerical approach, the BSM1 simulating model was created in MATLAB environment. By applying different weather conditions, the behavior of the treatment process was investigated. Findings: Applying more than one numerical solution to solve the simulation model reduced significantly the amount of additional calculus and time, as a very important item in predictive controlling systems. Make use of different control strategies, necessarily do not improve the quality of all process parameters. Nitrogen-containing parameters, especially ammonia nitrogen, are the most effective control parameters in activated sludge process. This process complies effluents standard limits of chemical oxygen demand (COD), 5- day biological oxygen demand (BOD5), and total suspended solids (TSS) with significant difference. Only in nitrogen parameter, we see some violations of the standard. The model that is created for the first time in the country can be used for different purposes in the fields of process recognition and operation.

Low efficiency of conventional aeration techniques and the excessive production and disposal of sludge are great concerns in biological wastewater treatment systems. The present study aimed to evaluate the active sludge method using batch reactors under continuous operation to determine the efficiency of aeration and sludge production through microbubble and nanobubble aeration. The results indicated that compared to microbubble aeration, nanobubble aeration increased the concentration of dissolved oxygen in the mixed liqueur of the reactor (from 2 to 4.5 mg/l), while reducing the production of excess sludge from 100 to 40 ml/g (SRT: 15-40 d). With the same SRT duration, these values were within the range of 160-70 ml/g using fine-bubble aeration. According to the results, nanobubble aeration could increase the efficiency of aeration, thereby increasing the capacity of the treatment plant and reducing the costs of biological wastewater treatment.

Background and Application of nanomaterials is growing in removing various contaminants, pharmaceuticals, and in deactivation of water or sewage bacteria. However, the ability to degrade or eliminate the genetic components of bacteria by nanoparticles and preventing the increasing trend of antibiotic resistance from sewage treatment plants needs to be further investigated. This study aimed at eliminating the genetic components (antibiotic resistance genes) of heterotrophic bacteria from wastewater by Zero Valent Iron Nanoparticles.
To eliminate genetic components of bacteria, the ability of nZVI was measured by cellular and molecular methods to remove the genetic components of the bacteria. Selected genes included TetW (tetracycline) Ctx-m-32 (Ceftazidime), and CmlA1 (Chloramphenicol). Polymerase chain reaction (PCR) and specific primers were used to detect resistant genes.
The average concentrations of HPC and ARBs were 1.68 × 105 and 2.58 × 104 cfu/mL in primary effluent. The mean values for ARGs were (TetW)=33.71 ±10.66, (CmlA1)=57.71 ±11.60, and (Ctx-m-32)=37.71 ±4.85 ng/μl after the experiments. The proposed software model for HPC and ARBs included nZVI= 20-23 mg/l, QN2=7-7.8l/min, and time=23-30 min and for ARGs it included nZVI=28-30 mg/l, QN2=7-7.8l/min, and time=30-38 min.
Zero Valent Iron Nanoparticles can degrade and eliminate heterotrophic bacteria, and decompose and eliminate the genetic components of bacteria and antibiotic resistance genes. Unlike the chlorination units of sewage treatment plants that increase antibiotic resistance among effluent bacteria, iron significantly reduces the populations of antibiotic resistant bacteria. Compared to TetW and CmlA1, the Ctx-m-32 genes have high stability and durability against nZVI.

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.

Nowadays, sludge dewatering is one of the most difficult treatment processes in wastewater treatment plants. This subject is an important challenge in decrease of environmental pollutants. The purpose of this study was effect of ultrasonic waves on improve sludge dewatering, increasing solid content of sludge and determine the optimum operating parameters of the ultrasonic method.
An experimental study was carried out as a batch mode. In this research effect of some variables include ultrasound density (watts per ml), Time (minutes) and amount of sonificated sludge (percentage) on the solid content of sludge and sludge dewatering was measured. The solid content of sludge samples in prior to dewatering was 20.3 ± 0.9 percent. Sstatistical analyses were performed using SPSS version 18.
Findings: The experiments determined that the optimum operating parameters are sonification time of 5 minutes, ultrasound density of 1 W/ml, amount of sonificated sludge equal to 15% and a frequency of 20 kHz, which is the amount of solid content of sludge equal to 26.4 percent that is equal to 30 percent increase in dewatering of sludge.
Based on the results of this research, ultrasound waves and micro and nano-bubbles of cavitation could increase the solid content of sludge and improve sludge dewatering process and sludge treatment efficiency.