Al Awir


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INTRODUCTION

The Al Awir Sewage Treatment Plant is currently the only wastewater treatment plant serving Dubai City. Both domestic wastewater and septage, is colleted by sewers and pumped to the treatment plant site, about 25 kilometres from the city centre. The plant provides both tertiary wastewater treatment for irrigation reuse, and sludge treatment for reuse as a soil fertilizer. Since both wastewater and sludge are reused, continued successful operation of the Al Awir STP is of critical importance to Dubai.

Wastewater flows have been increasing rapidly in Dubai. The Dubai Municipality therefore planned an extension of the Al Awir STP to increase its design capacity from 130,000 m³/d to achieve an average capacity of 260,000 m³/d (PE 650,000)

SCOPE OF WORKS

Process additions, rehabilitation, facility modifications, testing, cleaning, calibration, maintenance, commissioning, and operation for 9 months of the extension to the existing Al Awir STP.

PRELIMINARY TREATMENT

  • Dual compartment inlet chamber.
  • Minor modifications to existing inlet chamber.
  • Yard piping modifications for bypassing the existing inlet chamber.
  • Screening building with 3 travelling screens.
  • Replacement of screens in the existing screening building.
  • Four vortex type grit chambers, covered for odour control and mounted outside. Only three of the grit chambers include a vortex mechanism.
  • Modifications to existing aerated grit chambers.
  • Three covered pre-aeration tanks designed to strip un-ionized hydrogen sulfide.
  • Blower building housing aeration equipment, for the pre-aeration process.
  • Minor modifications to the existing pre-aeration tanks.
  • One 2-stage, packed tower scrubbers to neutralize H2S in the foul gas stream. A second scrubbing stage was also added to each of the two existing scrubbers.
  • Caustic and sodium hypochlorite storage and feed facilities for the odour scrubbers.

PRIMARY TREATMENT

  • Yard piping modifications for bypassing DC 1.
  • Covering and ventilating DC 1 to the odour control system.
  • Six new primary settling tanks similar to the existing units.
  • New flow splitting chamber to uniformly distribute flow to each new settling tank.

SECONDARY BIOLOGICAL TREATMENT

  • New flow splitting chamber to uniformly distribute primary effluents to each new aeration tank.
  • Yard piping modifications.
  • Three new aeration tanks similar to the existing.
  • Additional of anoxic treatment facilities to existing aeration tanks to improve sludge settling characteristics.
  • Two new secondary settling tanks similar to the existing.
  • New flow splitting chamber to uniformly distribute secondary effluent to each new settling tank.

TERTIARY BIOLOGICAL TREATMENT

  • One new flow splitting chamber to uniformly distribute secondary effluent to each new biological filter.
  • Yard piping modifications.
  • Three new biological filters similar to the existing units.
  • Modifications to existing biological filters, including the media, underdrains, and rotary distributors. Reuse (re-process) the existing media to produce high density media.
  • New big-filter recirculation pumping station.
  • Two new tertiary settling tanks and yard piping modifications.

SAND FILTRATION

  • Four new sand filters similar to the existing units.
  • Piping and valves to bypass the filters and direct flow to the existing effluent storage basins.

DISINFECTION

  • Replacement of existing pre and post chlorinators with larger units and convert the system to Vacuum operation.
  • Modification of chlorine storage facilities to provide a safer operation.
  • Installation of a new chlorine scrubber to neutralize leaks, should they occur.

SLUDGE CONSOLIDATION

  • Four new gravity sludge thickeners (three with sludge collection mechanisms installed) with pumps and piping similar to the existing.
  • Modification of the existing consolidation system to provide additional digester feed and centrifuge feed pumping capacity.
  • Addition of a new polymer make-up and feed system.
  • Installation of separate odour exhaust fans for each consolidation and holding tank.

ANAEROBIC DIGESTION

  • Two new “egg shaped” digesters with pumps, piping and appurtenances.
  • Modifications to existing digesters piping to resolve operating problems.
  • New gas flaring system.

SLUDGE DEWATERING AND DRYING

  • Modifications of the existing dewatered sludge handling system.
  • Provision of one additional “high solids” centrifuges in a new dewatering building.
  • New air drying facility to dry dewatered sludge to approximatly 65 percent dry solids.
  • New sludge drying beds to dewater either thickened or anaerobically digested sludge.

MISCELLANEOUS

  • Electrical, distribution systems.
  • Instrumentation and monitoring.
  • Yard piping.
  • Site work.
  • Testing, cleaning, calibration and commissioning of Works.
  • Maintenance of Works for a period of 12 months in accordance with the Conditions of Contract.

Project Details

Client: Al Awir

Industry: Wastewater Treatment

Application: