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