24 ENVIRONMENT AND ENERGY
<< Continued from page 23 processes are required to ensure that discharge consents are adhered to, but this is often not the case. Regulatory environments vary considerably. Of particular relevance, are small-scale cottage industries and businesses, which are either‘ permitted’ to operate or do so illegally. In informal settings, activities, such as lead recovery from batteries, small-scale mining and mineral processing, and the operation of motor garages and car-washing stations, can pose serious risks. There is not much published information available concerning these informal industries.
Small hospitals and clinics( and some of the larger establishments), particularly in the developing world, discharge medical waste untreated. Intensive farming methods and the profligate use of antibiotics in animal husbandry has resulted in high concentrations in municipal wastewater when such installations discharge to municipal sewers. This entails the additional risk of antimicrobial drug resistance( AMR).
Other point sources can include intensive agricultural units and large stormwater outlets that serve hazardous or industrial areas. It is important to note that wastewater from food and beverage processing establishments also generally contain relatively high BOD concentrations. This type of waste is not difficult to treat and represents a great opportunity for energy recovery.
URBAN FORM AND THE POTENTIAL FOR MUNICIPAL AND URBAN WASTEWATER USE The potential for using municipal and urban wastewater is governed by several issues: first, the level of crosscontamination of wastewater and second, the application and its location. Water scarcity and the cost and availability of new water sources are also important factors.
Obviously, it is better to restrict the discharge of hazardous substances to sewers, particularly those that render the wastewater difficult to treat. Urban run-off, for example, could be directly reused for certain purposes, but once combined with blackwater it would require additional treatment. The drivers for reuse are legislative and principally driven by economics. If used water is available at a lower or a similar price( including the cost of conveyance), it will be considered over and above conventional freshwater sources. In some water-scarce countries or regions, necessity dictates and favours high levels of reuse.
The reuse of water in agriculture is one of the areas of great potential. It is already practised formally and
February 2018 Volume 23 I Number 12 www. plumbingafrica. co. za