Bandar Abbas wastewater treatment design

Design Landscape

Bandar Abbas is the capital of Hormozgan province which is located in an area of 5120 hectares south of the country besides Persian Gulf. High groundwater level and lack of soil permeability in the region have led wastewater to flow at the surface of the city public ways. On the other hand, water sources shortage and its high cost price in the region require using and recycling treated effluent for irrigation of public grass space, agriculture and industry consumptions.

The mentioned design was revised in 1986 and was approved by design master.

In 1990, technical revision studies of the first and second stages were delegated to Mahab Qods consulting engineers. The city wastewater collection network (Golshahr region) has been implemented since 1994.

Design main components

Bandar Abbas city population was 201650 persons in 1986. It has been predicted that in the startup year of operation and at the end of the plan the population will be 336000 and 570000 persons respectively. The city wastewater collection system works by way of gravity and it is considered as a distinct network. Considering the position of the treatment plant which is located at the farthest end of the northern part of the city, the collection pattern was chosen in a step feed manner to avoid rotation of wastewater flow into the network as much as possible. The existence of fishery and Goorsoozan estuaries inside the city is the natural thalweg in the city which influences the entire network. By using east-west axes inside the city, the surrounding area wastewater is transferred toward Goorsoozan estuary and then, through the main collecting line which is located along eastern side of Goorsoozan estuary is conveyed to the wastewater treatment plant place.

Total length of the wastewater treatment plant (initial agreement) is about 510 km, and it is considered to be 880 km in the development plan. The minimum and the maximum value of the pipe diameter are 200 mm and 2000 mm respectively. It is worth mentioning that all pipes of the network in minor lines are made of poly ethylene and concrete, and it has been recommended to use concrete for major and semi major lines. 

The chosen treatment process in Bandar Abbas wastewater treatment plan is complete - mix activated sludge method using anaerobic digesters, and surface aeration process is done through vertical surface aerators. Moreover, in order to stabilize sludge, two-stage anaerobic digesters will be used; and the sludge will be stabilized and dewatered through drying sludge beds. The maximum capacity of the treatment plant is considered to serve 320000 persons. In the new contract, engineering services (coded by 3691020 for a two years period) including 80 km minor network and 5.4 km major and semi major collecting lines and establishing a pumping station east north of the region adjacent to the medical university have been predicted.

In treatment plant part it has been predicted to promote the first module from 320000 persons to 340000 persons and to establish the second module with a capacity to serve 340000 persons.

Design objectives

Providing domestic wastewater collection network in the city and transferring wastewater to treatment plant for promoting the health level and preserving the environment, removing the available contaminations at the city level, treating wastewater in terms of using agricultural effluent, using obtained compost (fertilizer) through wastewater treatment;

Providing the appropriate biological conditions for the target year

Technical specifications of the plan

  • Covered area: 5120 hectares
  • Network covered population: 570000 persons
  • Length of major and semi major pipelines: 50 km
  • Length of minor network: 480 km
  • Number of lift stations: 4 stations
  • Diameter of waste water transfer line: 1000 mm (pair pipes)
  • Length of transfer line: 5.2 km
  • Total capacity of treatment plant: 5.1 m3/s
  • Modules number: 2 modules
  • Population covered by total design: 6800000 persons
  • The number of implemented modules at this stage: 1 module
  • Covered population; 340000 persons
  • Wastewater treatment method: activated sludge- common aeration
  • Treatment feature: Nitrogen removal
  • Main units: Screening, grit-chamber, primary sedimentation, aeration, secondary sedimentation, disinfection, sludge thickener, sludge anaerobic digestion, mechanical dewatering
  • Sludge treatment method: thickener, anaerobic digestion
  • Byproducts: Biogas