The wastewater in the catchment area of the WWTP Quesna is characterized by three wastewater partial flows, which are conveyed to the WWTP Quesna via pumping stations.
- Partial flow 1: Partial flow from the leather industry with a daily wastewater quantity of QD = 5,000 m³/d.
- Partial flow 2: Partial flow from industrial settlements of different origin with a daily wastewater quantity of QD = 37,000 m³/d.
- Partial flow 3: Partial flow from the urban area of Mubarak City including the population growth of QD = 20,000 m³/d.
The wastewater in the inlet of the WWTP is conveyed to the WWTP Mubarak City by pumping stations in three partial flows. One of the three partial flows contains wastewater from the leather industry with chromium rates Cr6 ≥ 7 mg/l and Cr3 ≥ 17 mg/l; this water currently gets to the WWTP without any preliminary treatment. The wastewater containing chromium is diluted by mixing with industrial and municipal wastewater, but it still remains above the permitted limit value. Therefore a separate preliminary treatment of the partial flow and further biological treatment in the WWTP are absolutely necessary to respect the discharge values and to be able to react quickly to the changing conditions in the catchment area of the WWTP, e. g. different industries etc.
The concept for the wastewater treatment is explained as follows in consideration of the existing plant components:
- Partial flow treatment of the wastewater containing chromium in a precipitation plant with sedimentation of the sludge containing chromium. A fine screening plant is installed to retain solids from the leather industry.
- Combination of all partial flows and mechanical treatment in the existing screens and in the grit chamber.
- Modification of the biological wastewater treatment from a one-stage wastewater treatment plant without preliminary treatment to a two-step treatment plant with A-B technology which meets the industrial requirements. This process has been successfully applied for several decades in the whole world. The A-B process is especially applied, when wastewater with different substances is treated together with municipal and industrial wastewater. The first high-loaded biological stage causes a preliminary decomposition and a buffering of the wastewater so that the second biological stage is low-loaded and also protected against loadings, concentrations and toxins.
- The final treatment of the wastewater is effected in the second biological stage, where the existing volume is sufficient for the elimination of carbon.
Scope of Work:
Design & Build, All Mechanical, Electrical, Monitoring & Control Works:
- Chromium removal Plant:
- 1 Fine filter mechanical screen
- Emergency Screen
- Spiral conveyor
- pH rising dosing pumps
- 2 pH rising mixers
- Dosing Pumps for precipitation
- 2 GRP Storage tanks 25m³ each
- 4 Precipitation mixers
- 3 Submersible Pumps for outlet 150m³/h @ 8.5m
- 3 Submersible Pumps for excess sludge 33m³/h @ 15m
- Penstocks
- Inlet chamber:
- 4 Mechanical raked screens SS316L with belt conveyor
- Emergency Screen
- 8 Penstocks
- Dosing pumps for pH rising
- Storage Tank for NaOH
- Continuous pH & flow measurement devices
- Grit and grease removal (4 channels 13.1x2m & 5.4m depth each):
- 2 Grit scraper bridges
- 4 SS Grit Pumps 30m³/h @ 8m
- 2 Sand Silo
- 2 Grit Rotary piston blowers 335 Nm³/h @ ∆p 0.8mbar
- 1 Grit Rotary piston blowers 670 Nm³/h @ ∆p 0.8mbar
- 4 Grit chamber aeration lines
- 4 Grease blades
- 2 Channel Penstocks
- 2 High load aeration rectangular concrete tanks 19,711m³, A-Stage:
- 12 Vertical surface aerator with oxygen capacity 163 kgO2/h
- 4 Adjustable outlet / overfall weir
- 4 Penstocks
- Intermediate settling tank (6 rectangular concrete tanks):
- 6 nonmetallic sludge collector
- 3 SS scum pumps 15m³/h @ 12.5m
- 6 Penstocks
- Return and excess sludge pumping station, A-Stage:
- 4 Return sludge pumps 960m³/h @ 4.51m
- 3 Submersible Excess sludge Pumps 170m³/h @ 16m
- 6 Penstocks
- Fine bubbles diffusers aeration tanks (4 rectangular concrete tanks, 22,600m³ each):
- 24 Floating Stirrer for 4 Denitrification zones
- 4 Diffused air aeration systems (membrane-aerators)
- 8 Submersible recirculation pumps 1500m³/h @ 0.5m
- Inlet & outlet penstocks
- Blowers station:
- 8 Centrifugal Multistage 3000 RPM direct-driven 700Kw, 11Kv motor, 27200 Nm³/h @ ∆p 0.562mbar
- Final settling tanks (4 concrete tanks, 30m dia. Each):
- 4 Scraper bridges 16.5m length with driving equipment
- V-notch weirs
- Penstocks
- Return & excess sludge pumping station:
- 8 Return sludge pumps 940m³/h @ 18m
- 3 Progressive cavity excess sludge pumps 275m³/h @ 30m
- Penstocks
- Effluent pumping station:
- 8 Effluent pumps 940m³/h @ 20m
- 2 Washing pumps 108m³/h @ 40m
- Raw sludge thickeners for excess sludge:
- 4 fixed steel bridges 12m length with driving equipment
- 12 Picket fence stirrer to suit the 4 sludge thickeners
- V-notch weirs
- Thickened sludge feeding pumps:
- 3 Submersible sludge pumps 55m³/h @ 20m
- Pre-thickener A-Stage (3 concrete tanks, 20m dia. Each):
- 3 bridges 20m length with driving equipment
- 9 Picket fence stirrer to suit the 3 sludge thickeners
- V-notch weirs
- Sludge aerobic digester (2 rectangular concrete tanks 1,865m³ each):
- 4 Vertical surface aerator with oxygen capacity 245 kgO2/h
- Adjustable outlet weir
- 3 Excess sludge outlet progressive cavity pumps 58m³/h @ 15m
- Sludge dewatering:
- 6 Belt filter press 43 m³/h each complete with feeding & washing pumps.
- 2 Belt conveyors
- 2 Polymer make-up units complete with preparation, storage tanks & feeding pumps.
- Drainage pumping station:
- 3 Drainage pumps 250m³/h @ 17.5m
- 2 Sanitary pumps 36m³/h @ 17.5m
- Diesel Electric generators building:
- 2 DG sets 3000 KVA complete with the fuel system.
See The Plant Video