Selected Projects

The water treatment plant at Saman Darou-ye Hashtom Company was constructed as an important water supply infrastructure project for this industrial complex. The facility was designed to produce high-quality water for both potable and industrial applications and to provide a reliable supply of safe water that meets health standards.

Raw water entering the plant passes through several treatment stages to remove impurities, suspended solids, organic compounds, and microbial contaminants. The use of combined physical and chemical processes improves treatment efficiency and ensures the required quality of treated water.

A key stage of the system is clarification, where suspended particles and colloidal matter are removed to prepare water for subsequent treatment. The water then enters filtration units to remove remaining fine particles, reduce turbidity, and improve clarity.

At the final stage, disinfection is carried out through methods such as chlorination or ultraviolet radiation to eliminate microorganisms and pathogens. The project supports safe water supply, improved water-use efficiency, and enhanced health and safety standards within the industrial environment.

The wastewater transmission lines, collection network, and treatment plant project for the Kermanshah Petrochemical Complex was designed and implemented to manage wastewater generated by this major industrial facility. Due to the production of both industrial and sanitary wastewater, an integrated collection and treatment system was required to prevent environmental pollution.

A wastewater collection network was designed and constructed to convey wastewater from different units of the complex to transmission lines and ultimately to the treatment plant. This network plays an important role in safe wastewater transport and in preventing leakage or uncontrolled release of pollutants into the environment.

Transmission lines were designed according to operational conditions and wastewater flow rates to safely convey sewage from different points of the complex to pumping stations and the treatment plant. Pumping stations were installed where elevation differences and hydraulic conditions required mechanical conveyance.

The collected wastewater enters the treatment plant, where the activated sludge process is used to remove organic pollutants and suspended solids. Designed and implemented by Zist Ab Pajouhesh Company, this integrated project contributes to industrial wastewater management, environmental protection, and the preservation of water and soil resources.

The Al-Mahdi Aluminum Company wastewater treatment plant was constructed as a key environmental facility within the company’s industrial complex in Bandar Abbas. As a major aluminum ingot producer located in the Persian Gulf Mining and Metal Industries Special Economic Zone, the project supports the complex’s environmental commitments.

With a design capacity of 1,500 cubic meters per day, the plant treats industrial and sanitary wastewater generated by cooling operations, washing activities, and auxiliary units. The facility uses a combination of physical, chemical, and biological processes to remove contaminants and ensure compliance with Department of Environment standards.

One of the main objectives is to reduce fresh-water consumption and increase wastewater recycling. Through water treatment and recovery initiatives, the company reduced water consumption from approximately 68,000 cubic meters per month to around 36,000 cubic meters per month.

Part of the treated effluent is reused for industrial applications, including cooling systems and irrigation of green spaces. The project helps reduce pressure on freshwater resources, prevents pollutants from entering the Persian Gulf, and supports sustainable development in Hormozgan Province.

The central wastewater treatment plant at the University of Zanjan was designed and constructed to manage wastewater generated by this major educational and research complex. With more than 10,000 students and over 425 faculty members, the university required an efficient treatment system to protect the environment and manage water resources responsibly.

The plant has a design capacity of 660 cubic meters per day and includes screening, a pumping station, four anoxic tanks, eight aeration tanks, four sedimentation tanks, a chlorination tank, sludge and effluent storage tanks, and internal and sludge-return pumps.

Wastewater first passes through screening to remove coarse solids and debris, then enters the pumping unit. It subsequently flows into anoxic tanks for nitrogen removal and biological treatment under oxygen-free conditions, followed by aeration tanks where microorganisms degrade organic matter.

After biological treatment, wastewater enters sedimentation tanks for separation of activated sludge and suspended solids. Final disinfection is completed in the chlorination unit. The project supports sanitary wastewater management, pollution reduction, and environmental infrastructure development at the university.

The wastewater treatment plant for the University of Zanjan men’s dormitory was designed and constructed to ensure sanitary management of wastewater generated by the dormitory complex. Given the large student population, the project was important for pollution prevention and water-resource reuse.

The facility has a treatment capacity of approximately 400 cubic meters per day. Its main objective is to treat sanitary wastewater and reuse the treated effluent for irrigation of university green spaces, thereby reducing fresh-water consumption across the campus.

Influent wastewater first passes through screening to remove coarse solids and protect downstream equipment. It is then transferred through a pumping station to an aeration reactor, where oxygen supply and microbial activity enable the decomposition and removal of organic matter.

Following biological treatment, wastewater enters a sedimentation tank for separation of activated sludge and suspended particles. Sludge is directed to a sludge aeration unit for stabilization, while final effluent is disinfected in the chlorination unit and pumped for irrigation reuse.

The Ghalian Water Treatment Plant in Sanandaj is a key water supply and quality-improvement project designed and implemented by Zist Ab Pajouhesh Company. The facility was constructed to increase the capacity for supplying safe water and improve drinking-water quality for residents of the Ghalian area.

The plant is designed with two treatment modules and a final planned capacity of 60 liters per second. Its modular structure enables phased development and operation, with the first phase commissioned in spring 2020 to meet part of the region’s water demand.

The process begins with the uniform mixing of coagulation chemicals into raw water through a static mixer. Water then enters the flocculation unit, where fine suspended particles combine to form larger flocs that can settle more effectively.

Following flocculation, water enters the sedimentation basin for separation of flocs and suspended particles. In the final stage, filtration removes remaining particles and improves clarity, ensuring that treated water meets required drinking-water standards.

The water treatment plant of the West Seraju Water Supply Complex in Maragheh was designed and constructed to improve drinking-water quality and provide safe water for residents of the complex. Excess iron in groundwater sources was a major water-quality concern, causing possible discoloration, unpleasant taste, and sediment formation in the distribution network.

The treatment process begins with oxygen-based oxidation, converting dissolved ferrous iron into insoluble compounds that can be removed in later stages. This process transforms Fe²⁺ into settleable particles.

After oxidation, water enters the clarification unit, where oxidized iron particles and other suspended matter are separated. The water then passes through multilayer filters containing silica and activated carbon.

Silica filters remove remaining suspended particles and improve clarity, while activated carbon assists in removing organic compounds and improving taste and odor. The project enhances the reliability of safe water supply and reduces issues caused by iron in the distribution network.

The emergency wastewater treatment plant in Pishva was designed and implemented as a rapid and efficient solution for municipal wastewater management under emergency or temporary conditions. The facility has an average capacity of 700 cubic meters per day and helps prevent the discharge of raw sewage into the environment.

The plant uses the activated sludge process, one of the most common and effective municipal wastewater treatment methods. Physical, chemical, and biological treatment stages remove suspended solids, organic compounds, and pollutants, bringing effluent quality to an acceptable level.

A key characteristic of the project is the use of ST-37 steel process structures with epoxy coating. This protective layer increases resistance against corrosion, moisture, and environmental conditions and extends the service life of equipment.

The treatment system is designed as a modular package, enabling easier transportation, installation, and relocation. This design reduces setup time and makes the project highly suitable for emergency, temporary, and rapidly deployable treatment applications.

The Farahzad Valley, also known as Zhinayi, wastewater treatment plant is an environmental project in Tehran implemented to control and treat wastewater and polluted runoff generated by urban activities in the Farahzad area. The plant has a design capacity of approximately 1,000 cubic meters per day.

The project was developed to prevent direct discharge of pollutants into the river valley and protect the natural environment. In the preliminary stage, screening and grit-removal units remove coarse solids and heavy particles, protecting equipment and improving downstream treatment performance.

After pre-treatment, wastewater enters an Anaerobic Baffled Reactor (ABR), where anaerobic biological processes remove a considerable portion of organic matter. Wastewater is then pumped to a trickling filter, where biofilm microorganisms further degrade organic pollutants.

The flow subsequently enters a clarifier for separation of suspended particles and sludge. Final chlorine disinfection removes pathogens before compliant effluent is discharged, contributing to lower pollution levels and improved environmental conditions in the Farahzad Valley.

The Jajrud municipal wastewater treatment plant is an infrastructure project designed and implemented to reduce environmental pollution and improve public health in the Jajrud region. With an average daily capacity of 700 cubic meters, the facility collects and treats municipal wastewater.

The plant uses the activated sludge process to remove suspended solids, organic compounds, and other contaminants through physical, chemical, and biological treatment stages. The resulting effluent achieves a quality suitable for discharge or reuse, depending on applicable requirements.

The project utilizes metal process structures manufactured from ST-37 steel and protected by epoxy coating. This coating improves resistance to corrosion, moisture, and environmental conditions while increasing equipment service life.

Its modular wastewater treatment package design allows convenient transportation, rapid installation, and relocation where required. This operational flexibility reduces project implementation time and makes the system practical for locations requiring adaptable wastewater infrastructure.

The wastewater treatment plant in Ben City is a major environmental and infrastructure project in Chaharmahal and Bakhtiari Province. It was implemented to manage municipal wastewater properly and prevent contamination of water and soil resources.

The facility has a design capacity of approximately 3,500 cubic meters per day and serves a population of around 20,000 people. In addition to treating municipal wastewater, the project enables reuse of treated effluent in different non-potable sectors.

The treatment process is based on an activated sludge system with nutrient-removal capability for nitrogen and phosphorus. The system significantly reduces organic pollution and lowers wastewater BOD from approximately 250 mg/L to less than 10 mg/L.

The high-quality effluent complies with Department of Environment standards and can be used for agricultural irrigation, urban landscaping, and some industrial purposes. The project helps protect groundwater, qanats, and local ecosystems while supporting public health and sustainable urban development.

The Borujen municipal wastewater treatment plant was constructed as a key project for water-resource management and environmental protection in the Borujen region. The facility was designed to reduce pollution, prevent untreated wastewater discharge into natural resources, and optimize the use of treated effluent.

The plant was designed to serve a population of approximately 100,000 people and currently treats wastewater from about 79,000 residents. It handles an average daily flow of 9,000 to 12,000 cubic meters.

The treatment process is based on activated sludge technology and includes physical, chemical, and biological stages. Effluent quality is continuously monitored through important parameters including BOD, COD, TSS, and pH to ensure compliance with Department of Environment requirements and international FAO standards.

Treated effluent is used for non-potable applications, including irrigation of potatoes, alfalfa, and wheat. A portion also supports artificial recharge of the Borujen-Faradombeh Plain aquifer, while additional effluent is available for local industries such as steel production.

The Al-Teymour Wastewater Treatment Plant, also known as Mashhad Municipal Wastewater Treatment Plant No. 4, is one of the major treatment facilities serving eastern Mashhad. The plant was developed to provide reliable municipal wastewater treatment and protect groundwater and surface-water resources in the region.

Available project information indicates a treatment capacity of approximately 80,000 cubic meters per day, serving a population of around 500,000 people. The plant uses an advanced Modified Ludzack–Ettinger (MLE) biological process for carbon removal and biological nitrogen removal.

Zist Ab Pajouhesh Company provided engineering services for the project, including review of wastewater characteristics and design criteria, process development and optimization, mass-balance calculations, hydraulic calculations, hydraulic profile development, aeration design, clarification design, sludge circulation, pumping systems, piping, valves, PFDs, P&IDs, datasheets, technical specifications, and technical support during implementation.

The MLE process integrates anoxic and aerobic zones. Nitrate-rich mixed liquor is recycled from the aerobic zone to the anoxic zone to enable denitrification, while aerobic treatment provides biological oxidation and nitrification. The project demonstrates ZAPCO’s ability to coordinate process, hydraulic, mechanical, electrical, instrumentation, and operational requirements for large-scale wastewater treatment facilities.