Most people gag at the thought of consuming sewerage. But environmentalists are claiming that treating our sewerage water for human consumption could be the cheapest and most efficient way to counter the water scarcity in a semi arid country like South Africa.
Sewerage water can be treated and be reused for drinking and other water related activities of daily living. That was one of the pertinent messages conveyed at the first ever Living Planet Conference.
Hosted by the World Wide Fund of South Africa (WWF SA) on Thursday July 30, the conference focused on the energy crisis, the looming water shortage disaster and food security and agricultural sustainability.
A large chunk of the conference was themed, “Water doesn’t come from a tap”, and featured environmentalists discussing the various ways that water usage can be reduced, reused and recycled.
“Waste water is filled with water!” said Dhesigen Naidoo, CEO of the Water Research Commission.
Naidoo emphasized that sewerage water is an incredible resource. One that can be used over and over for various activities by using the Water Quality Index (WQI).
The Water Quality Index (WQI) helps to determine just how clean water needs to be to be suitable for various household and industrial functions. The process of developing a WQI involves determining the intended use of water. Whether it will be used for drinking, bathing or flushing waste down the toilet.
“We don’t need super clean water for all water related activities” said Naidoo.
Drinking water would need to be purified to the point where the physical elements such as sediment, odor and temperature are treated to reach the point where it is suitable for drinking. The chemical factors like the pH levels, dissolved oxygen level, and E.coli level would need to be determined to ensure that the water is safe to drink. If the water is not suitable for drinking then it can be used for other activities like doing the laundry, or washing the dishes.
Waste water treatment process reduces pathogenic bacteria and other disease causing organisms, nutrients that can cause unwanted algae, biodegradable organisms and suspended solids. The water is purified through micro filtration and reverse osmosis. The primary phase of water treatment removes suspended and floating materials from the sewerage water.
This is followed by a secondary treatment, that eliminates any other dissolved organisms and sludge that escaped the primary treatment, using biological activity to filter and breakdown organic matter. According to the World Bank Group, about 85% of the suspended solids and bio gradable organisms can be removed by a well running plant with secondary treatment. Using specific chemicals and equipment the water is treated in the tertiary phase. The water is also disinfected with chlorine to produce drinkable water.
This method of treating sewerage water for consumption has been implemented in Orange county, California following the drought they experienced in 2014. Not without any critique from the public. According to the New York Post, many people found it hard to get over the ‘yuck’ factor.
Neil Mcleod, a panelist at the Living Planet conference and head of sanitation and water in the eThekwini Municipality, argued the point that treating sewerage water for reuse is way cheaper than desalinating ocean water. “Sewerage is a source of nutrients” said Mcleod.
According to McLeod, Namibia has more water supply than South Africa but they are using treated sewerage water to conserve their water sources. ”
“If we are sufficiently innovative, it (waste water) can become energy positive.” said Naidoo.