Northern Wastewater Treatment Works
Northern Wastewater Treatment Works collects and treats mainly domestic sewage from Alexandra, Sandton, Randburg, the northern areas of Johannesburg, Bedfordview and portions of Edenvale and Germiston
The works consists of 4 units:
Unit 1: is a biofilter plant was commissioned in 1962. It consists of lime addition, primary sedimentation, primary biological filtration, primary humus removal and secondary biological filtration.
The Unit treats stormwater and sewage overflows and the effluent produced provides irrigation water for the Northern Farm. Although the unit is rated at 45 MI/d, it is licensed to 'only treat 20 MI/d of sewage due to the process being unable to meet the effluent standards. The availability of adequate areas of land for irrigation on the Northern Farm was a prerequisite for the operation of this unit.
Unit 2: was commissioned in 1963, but later decommissioned except for 6 of the digesters, 4 of which have been completely refurbished. The biofilters were demolished in 2007 to allow for construction of a
Unit 3: was commissioned in 1979 and initially designed as a five stage Phoredox process but converted to a four-stage Johannesburg process in 1993.
It consists of screening, degritting, primary sedimentation, acid
Unit 4: was commissioned in 1993 as a four stage Johannesburg process for biological nutrient removal. It consists of screening, degritting, primary sedimentation, acid fermentation of raw sludge, flow balancing, final clarification, chlorination, sludge thickening, dewatering, solar drying and composting.
Unit 5: Construction of a new 50MI/d extension was completed in October 2009. It consists of primary sedimentation, acid fermentation of raw sludge, flow balancing, a four stage Johannesburg process bioreactor, chlorination and waste sludge thickening.
Northern Wastewater Treatment Works collects and treats mainly domestic sewage from Alexandra, Sandton, Randburg, the northern areas of Johannesburg, Bedfordview and portions of Edenvale and Germiston
The works consists of 4 units:
Unit 1: is a biofilter plant was commissioned in 1962. It consists of lime addition, primary sedimentation, primary biological filtration, primary humus removal and secondary biological filtration.
The Unit treats stormwater and sewage overflows and the effluent produced provides irrigation water for the Northern Farm. Although the unit is rated at 45 MI/d, it is licensed to 'only treat 20 MI/d of sewage due to the process being unable to meet the effluent standards. The availability of adequate areas of land for irrigation on the Northern Farm was a prerequisite for the operation of this unit.
Unit 2: was commissioned in 1963, but later decommissioned except for 6 of the digesters, 4 of which have been completely refurbished. The biofilters were demolished in 2007 to allow for construction of a
new 50 MI/d activated sludge treatment plant.
Unit 3: was commissioned in 1979 and initially designed as a five stage Phoredox process but converted to a four-stage Johannesburg process in 1993.
It consists of screening, degritting, primary sedimentation, acid
fermentation of raw sludge, flow balancing, bioreactors, final
clarification and chlorination.
Unit 4: was commissioned in 1993 as a four stage Johannesburg process for biological nutrient removal. It consists of screening, degritting, primary sedimentation, acid fermentation of raw sludge, flow balancing, final clarification, chlorination, sludge thickening, dewatering, solar drying and composting.
Unit 5: Construction of a new 50MI/d extension was completed in October 2009. It consists of primary sedimentation, acid fermentation of raw sludge, flow balancing, a four stage Johannesburg process bioreactor, chlorination and waste sludge thickening.
Many of the operations on the works are automated via PLC and
SCADA systems. Waste activated sludge is
gravity thickened, anaerobic digested, dewatered on filter belt presses and the
dewatered sludge produced is solar dried and composted. The design treatment
capacity of the plant is 435 MI/d and incorporates a 100 dry ton per day
drying/composting area. The final effluent produced by the works is discharged
to the Jukskei River.
Northern
Works supplies
about 30 MI/d of final effluent as cooling water to the Kelvin power station.
The pump station and pipeline are owned by the City of Johannesburg.
A biogas to electrical energy installation was
commissioned in 2012. The installation provides 760 kW of electrical energy to Unit
5 of the Works.
