The City of Harare has targeted 219 million litres of sewage treatment in its bid to achieve zero environmental pollution.
The City can presently treat 100 million litres from its major sewage works at Firle and Crowborough through the rehabilitation of 16 biofilters, desludging of 6 effluent ponds, installation of effluent pumps and the replacement of 1 km long outfall sewer under the Zimfund Phase II. Together with the replacement of raw sewage pumps (through the China Exim Bank Loan Facility), replacement of effluent pumps and the rehabilitation of Borrowdale Brooke Pump Station are now yielding results that will see minimal sewage getting into Harare’s riverine system.
“We are able to treat 100 million litres per day. The rest is being pumped to pastures. At completion the city will be able to treat 219 million litres per day (70% of wastewater generated),” said Michael Chideme, CoH Corporate Communications Spokesperson. Chideme says that under the current efforts, blockages have been reduced from an average of 50 jams per suburb per day in 2008 when there was a cholera outbreak to the current less than 10 blockages per suburb per day. Reaction time has been reduced to less than 6 hours but the target is less than 2 hours. Chideme indicated that the city is also maintaining its farms close to sewage treatments plant to encourage a sound ecosystem that will absorb some of the treated water.
Previously the CoH has been fined by the Environmental Management Agency (EMA) for polluting the environment and posing a health hazard to the city’s population.
According to CoH Environmental Regulatory Planner Clifford Muzofa, the city has a sewerage reticulation system totalling 6,000 km and 5 pump stations and 5 sewerage treatment plants namely: Firle (144 ML/day), Crowborough (54 ML/day) Hatcliffe (2.5 ML/day), Donnybrook (12 ML/day), Marlborough (7 ML/day).
The city has embarked on massive rehabilitation of its sewer system following demands from residents and environmentalists that the council should formulate new strategies to deal with the streams of raw sewage that have become a common sight in the southern suburbs. The sewer rehabilitation started in 2009 after the devastating cholera outbreak. So far a total of 200 km of sewer pipes have been replaced. “The programme must be continuous with an average of 50 km of pipe replacement every year for the system to cope with expansion and reduce collapse due to old age,” said Muzofa.
Sewage waste from the city used to travel through storm drains eventually reaching rivers like Mukuvisi and Gwebi, infecting the water with faecal coliforms that cause cholera, dysentery and typhoid. Sewage is rich in both organic matter and nutrients. Municipal or domestic sewage input is the greatest contaminant leading to cities like Harare spending millions of dollars in treating its water before it is supplied to residents.
Recently, CoH Town Clerk Tendai Mahachi told Harare News that the City will be building a new sewage plant east of the capital to treat raw sewage from the northern and eastern suburbs. The plant is said to help create a clean environment to curb outbreaks of diarrhoeal diseases. The envisaged plant will be based on a biological system, using a natural process to purify raw sewage to environmental friendly levels by removing nutrients and waste and allowing organisms to digest it. A similar system is already used at Firle and Crowborough Sewage Treatment Plants, where the process requires no chemicals. Besides treating water, the system has side-benefits, producing biogas and organic fertilizers as end-products.