Wastewater Treatment Plant

General Information:

  • Project Name: Hamedan Waste Water Treatment Plant
  • Client: Hamedan Water and Waste Water Company
  • Location: City of Hamedan, Iran
  • Consultant: Mahab Ghodss Consulting Engineering Company
  • Commencement Date: 2005
  • Project Status: Completed    
  • Recognition: Governor of Hamedan

Technical Information:

Hamedan Wastewater Treatment Plant was awarded in 2005 as an EPC contract to ABIRAN-BAMRAH Joint Venture. Scope of the project included the design, construction, installation, testing and commissioning of two complete modules, each with average capacity of 640 liters per second. The plant was designed to serve the population of 500,000 by treating 1280 liters of sewage per second and a total of 110,000 cubic meters in 24 hours through the activated sludge method by using the combination process of Step-Feed including anaerobic digestion for stabilization of sewage sludge.

The main items of the project are as follows:

    • Basic and detailed design of wastewater treatment plant
    • Domestic and foreign procurement of required machineries and equipments
    • Plant construction:
      • Two sludge treatment modules including two anaerobic digesters with a capacity of 8,500 cubic meters each. The plant designed in two identical and independent lines capable of operating independently which includes the following equipments:
        • Automatic coarse screens to protect the inlet pumps, the screenings are conveyed to movable dewatering containers by means of conveyor belt
        • Inlet pump station with screw pumps
        • Automatic fine screens, the discharged screenings fed to screw presses where they will be washed, dewatered and compacted
        • Aerated grit chamber and grease removal of twin type with traveling bridge
        • Parshall flume flow meters
        • Primary settling tanks with half diameter rotating bridge
        • Activated sludge reactors dimensioned in such a way that not only organic carbon, but also nitrogen and phosphorous can be eliminated by biological means
        • Final sedimentation tanks equipped with sludge scrapers
        • Return activated sludge pumping station through propeller pumps
        • Disinfection of treated sewage by chlorination gas system
        • Sludge treatment starts with sludge thickening tanks for primary sludge and excess sludge are thickened separated
        • Sludge digestion through two huge anaerobic digesters with draft tube mixers
        • Digester bio gas collection system with gas storage tank & gas purification accessories
        • Gas flares
        • Gas boiler system to supply hot water for heating of digester
        • Instrumentation and PLC control system
        • Electrical supply system
      • Design and implementation of electrical, mechanical, control and instrumentation utilities
      • Design and construction of structures and site drainage system
      • Landscaping
    • Major Civil Quantities:
      • Excavation: 260,000 cubic meters
      • Concrete: 40,000 cubic meters
      • Form Work: 100,000 cubic meters
      • Rebar: 4,300 tons
    • Manpower per day: 210.000 (person . day) involved in the project


Technology used in the construction and operation of Hamedan Wastewater Treatment Plant is one of the most advanced methods of sewage treatment in the world and a unique process in the country. The employed technology applies the Step-Feed Process in three stages for sewage feeding to the biological reactors, nitrification and de-nitrification including the removal of phosphorous through anaerobic tanks.

In the case of the step-feed process, the return activated sludge is completely fed into the 1st de-nitrification stage while the wastewater normally is distributed to all three de-nitrification stages. A fine-bubble aeration system is employed for aeration of sewage and for mixing in the non-aerated zones; agitators of submersible type are used.


      • Average flow rate: 1.28 cubic meters per second
      • Maximum flow rate:   3 cubic meters per second
      • BOD5      25000   kilograms per day
      • SS            3000   kilograms per day
      • TN            5000   kilograms per day
      • TP            1500   kilograms per day


      • BODs            5    milligrams per liter (equivalent of BOD5 of rivers with unpolluted and quality water)
      • SS               10   milligrams per liter
      • TN               12   milligrams per liter
      • TP                6    milligrams per liter



The ancientand cultural city of Hamedan has been struggling with the problem sanitary sewage collection and disposal for many years. Currently, the city’s wastewater is channeled toward the nearest rivers via the existing 650 kilometers of sewage network system.

Consequently, city’s shortcomings mentioned above has led to serious environmental and sanitary issues, such as pollution of surface and underground water resources located in the wastewater transfer and accumulation route, negative city image and unpleasant odor of transferring rivers as well as outbreak of epidemics. Moreover, the wastewater can spread over farmlands, contaminate the underground water resources and be used for irrigation purposes mistakenly. Hence, Hamedan Water and Wastewater Company put the sewage collection, transfer and treatment as high priority on the city’s agenda within the framework of Hamedan Sewage Project. Needless to say, Hamedan Wastewater Treatment Project is among some of the most significant national development plans in the province. The objectives of construction of Hamedam Wastewater Treatment Plant are as follow:      

    • Collection, transfer and treatment of wastewater
    • Decontamination of rivers and wells from sewage and restoration of their natural state
    • Prevention of the direct and indirect social and economic costs resulted as improper collection and disposal of urban wastewater such as pollution of surface and underground water resources, epidemic diseases and mortality caused by pollution 
    • Prevention of the depletion of available water resources by supplying adequate water through sewage treatment for industrial and agricultural purposes such as water supply for Shahid Mofatteh Power Plant in Hamedan
    • Prevention of the use of raw sewage for irrigation purposes
    • Sludge stabilization and manufacturing of clean fertilizers in the process of sewage treatment given all the social and economical benefits