The municipality relies on the Umgeni river system for water. But demand on the system, which supplies drinking water to about five million people and fuels industry in the economic hubs of Durban and Pietermaritzburg, a town 66kms from the coast, has outstripped supply for the past seven years. To boost supply in future, the South African government has proposed building a dam with a capacity of 250 million cubic metres on the uMkhomazi river, the third-largest river in KwaZulu-Natal, and transferring water to the Umgeni system. But, according to Speedy Moodliar, the Municipality’s Senior Manager of Planning for Water and Sanitation, this scheme will only be operational by 2024 at the earliest till then re-use will be the mitigation measure.
In 2011 the Beaufort West municipality, which serves close to 50,000 people, began treating its sewage for use as drinking water after a vicious drought, making it the first in South Africa to do so. According to a 2012 World Bank report , few cities in Africa have functioning wastewater treatment plants and ‘only a small proportion of wastewater is collected, and an even smaller fraction is treated’.
Ethekwini municipality plans to upgrade two of its existing, and underperforming, wastewater treatment plants – the KwaMashu and Northern treatment works, Moodliar explained. To remove contaminants and clean the water to drinking quality standard, a three-stage system that treats effluent through ultra-filtration and reverse osmosis, as well as disinfection by ultraviolet light and chlorine would be used. The treated water would also be stored and tested before being released.
The purified water will be mixed with conventional drinking water at a ratio of 30% re-used water to 70% conventional, said Moodliar. It will feed the municipality’s northern regions, including Umhlanga, Durban North, Reservoir Hills, and KwaMashu. Re-using wastewater in this way will add 116 megalitres of tap water to the municipality’s supply daily. This is enough to fill just more than 46 Olympic-size swimming pools. It is roughly 13% of the municipality’s current daily consumption, and will provide an estimated seven years of water security.
While it will cost more to produce drinking water through wastewater recycling – about 75 cents per kl compared to 50 cents per kl for conventional treatment – the municipality sees it as “the best fit,” said Moodliar.
The municipality has touted the effectiveness and safety of the proposed system, but there has been opposition to the plan, including the submission of a 5,000-signature petition during the public participation process last year.
Citizens have raised concerns about the safety of drinking the re-used water. ‘Recycling of toilet water to drinking water is a death sentence to the general public because of the health implications,’ wrote Jennifer Bohus in an email to Golder Associates, the firm that produced the basic assessment report for the wastewater recycling proposal. But the municipality has maintained that treated water will be of drinking quality standards.
Courtesy: Brendon Bosworth, IPS News