The Growing Importance of Effluent-Water Recycling
There can be few people in South Africa who are unaware that we are facing an impending water crisis and that drastic action is required if we are to avert its consequences. In 1804, before piped distribution systems were introduced, the world’s first municipal treatment plant began filtering the influent from a Scottish river and distributing it to homes by horse and cart. Three years later, the introduction of piped distribution that was to spread globally led, ultimately, to the wholesale consumption that has since made effluent-water recycling essential. In practice, what this means is that, rather than relying solely on the content of rivers and lakes, it has become necessary to begin processing the wastewater that would otherwise have been disposed of by returning it to the environment. While the latter option is still practised by many industries, treatment of their effluent water is necessary, whether for recycling or to comply with the legal standards of purity required for safe disposal.
For residential users, the disposal of domestic wastewater is managed by municipalities with the provision of city-wide sewer systems. These are generally designed to separate rainwater and domestic greywater from that produced by toilets. The rain and greywater are purified for redistribution to consumers. Liquid from the latter source is treated sufficiently for safe disposal while its solids may be used as fertiliser or, in some cases, turned into biomass fuel. Without such forms of effluent-water recycling, it would be nearly impossible to continue meeting the steadily growing combined demands of domestic, commercial, and industrial consumers.
Fortunately, the technology that first made this type of processing possible has since become more scalable. As a result, the means to perform this crucially important task is no longer restricted to the large-scale plants operated by the world’s municipalities and utility companies. The development of compact processing plants is now enabling not just farmers and other industries to take on the task of effluent-water recycling but domestic users also. Given that South Africa’s demand for this life-giving liquid is frequently exceeding the supply (as demonstrated by 2018’s near-disaster in the Mother City), this form of conservation is no longer an option but a dire necessity. On the farm, for example, wastewater can be recovered and suitably treated to supply an irrigation system or to clean farm equipment, vehicles, and soiled surfaces. In many other industries, following similar small-scale treatment, that which has been used in some production process and which has become contaminated can be re-used for the same or a similar purpose. Not only does it conserve this vital natural resource but effluent-water recycling can also result in a substantial reduction of a factory’s operating costs.
Such is the severity of the crisis we share globally that it may soon become necessary to process the black wastewater from our toilets to supplement potable supplies. Referred to by some as toilet-to-tap schemes, they are already in operation in some parts of the world. Despite the end-product being perfectly safe to drink and as palatable as any other accepted source, psychological resistance has seen some plants first using this product to replenish aquifers to make it more acceptable. Either way, authorities in the Australian city of Perth believe that this type of effluent-water recycling will eventually be responsible for providing as much as 20% of its population’s total requirement.
In the meantime, every extra drop counts. While agriculture is by far the biggest consumer, surprisingly, domestic use accounts for around double that of other industries, including mining. What this means is that conservation needs to be as much the responsibility of South Africa’s homeowners as it is of its industrialists. A summer storm is an opportunity to harvest rainwater as a hedge against periods of drought and the possibility that usage restrictions could be imposed by municipalities. Even without the effluent-water recycling that might be needed when including domestic greywater, the stored rainwater can be safely used for a variety of cleaning tasks or watering the lawn. However, with the addition of a compact domestic treatment plant, rainwater on its own or in combination with that from sinks, showers, and washing machines can be rendered fit for drinking and actually piped back into the household supply.
For more about types of effluent-water recycling contact WaterIcon today.