The Northern Wastewater Treatment Works is the largest of six wastewater treatment works situated in the city of Johannesburg, South Africa. Designed to treat 400 million litres of wastewater every day for approximately 1.6 million people, Knight Piésold has made regular upgrades and improvements to this plant since 1992, having been responsible for the development of Units 4 and 5.
Unit 3 required the design and construction monitoring of two 35 m diameter primary sedimentation tanks (PSTs) on Unit 3, to replace existing, rectangular PSTs. Unit 4 involved the design and construction of the fourth unit with a capacity of 200 MP/d using biological nutrient removal activated sludge process and a sludge handling and composting plant capable of treating sludge arising from Units 3 and 4 (350MP/d). Unit 5 required design and construction with a capacity of 150 Mℓ/d using biological nutrient removal activated sludge process in three stages of 50M ℓ/d each. Another aspect was the sludge-drying bed and ancillary works to solar dry sewage sludge, in accordance with sludge guidelines, before being transported for use on agricultural land.
2012 CESA AON Engineering Excellence Awards – The Sludge-drying Bed Project received a commendation in the category “Projects with a value ranging from R50m to R250m”