ENVIRONMENT and ENERGY
15 further endangering human health and ecosystems , contributing to water scarcity , and constraining sustainable economic development .
Global trends On average , high-income countries treat about 70 % of the municipal and industrial wastewater they generate . That ratio drops to 38 % in upper middle-income countries and to 28 % in lower middle-income countries .
In low-income countries , only 8 % undergoes treatment of any kind . These estimates support the often-cited approximation that , globally , over 80 % of all wastewater is discharged without treatment .
In high-income countries , the motivation for advanced wastewater treatment is either to maintain environmental quality , or to provide an alternative water source when coping with water scarcity . However , the release of untreated wastewater remains common practice , especially in developing countries , due to lacking infrastructure , technical and institutional capacity , and financing .
Wastewater , sanitation , and the sustainable development agenda Access to improved sanitation services can contribute significantly to the reduction of health risks . Further health gains may be realized through improved wastewater treatment . While 2.1 billion people gained access to improved sanitation facilities since 1990 , 2.4 billion still do not have access to improved sanitation and nearly one billion people worldwide still practice open defecation .
However , improved sanitation coverage does not necessarily equate with improved wastewater management or public safety . Only 26 % of urban and 34 % of rural sanitation and wastewater services effectively prevent human contact with excreta along the entire sanitation chain and can therefore be considered safely managed .
The extremely low level of wastewater treatment reveals an urgent need for technological upgrades and safe water reuse options to support the achievement of targets . The efforts required to achieve Target 6.3 of the Sustainable Development Goals will place a higher financial burden on low-income and lower middle-income countries , putting them at an economic disadvantage compared to high income and upper middle-income countries .
Municipal and urban wastewater The composition of municipal wastewater can vary considerably , reflecting the range of contaminants released by various domestic , industrial , commercial , and institutional sources . Wastewater from domestic sources is usually relatively free of hazardous substances , but there are growing concerns about emerging pollutants , including commonly used medications , that , even at low concentrations , may have long-term impacts .
Accelerated urban growth poses several challenges , including dramatic increases in the generation of municipal wastewater . However , this growth also offers opportunities to break away from the past ( inadequate ) water management practices and adopt innovative approaches , which include the use of treated wastewater and by-products .
Wastewater generation is one of the biggest challenges associated to the growth of informal settlements ( slums ) in the developing world . There were more slum dwellers in 2012 than in 2000 , a trend that will likely continue in the future . Slum dwellers frequently have to rely on unsewered communal toilets , use open spaces , or dispose of faeces in polythene bags ( that is , flying toilets ).
Communal toilets are not widely used , due to a lack of water , poor maintenance , and the cost to the user . Finding a suitable place to go to the toilet is especially problematic for women , causing risks related to personal security , embarrassment , and hygiene .
Industry The toxicity , mobility , and loading of industrial pollutants have potentially more significant impacts on water resources , human health , and the environment than actual volumes of wastewater . The first step is to keep the volumes and toxicity of pollution to a minimum at the point of origin , from concept to design and in operations and maintenance . This includes substitution with more environmentally friendly raw materials and biodegradable process chemicals , as well as staff education and training to address pollution-related issues .
The second step is to recycle as much water as possible within a plant , thus minimizing discharge . Small- and medium-sized enterprises ( SMEs ) and informal industries often discharge their wastewater into municipal systems or directly into the environment . Industries discharging into municipal systems or surface water have to meet discharge regulations to avoid fines , so in many cases end-of-pipe treatment is required at the plant before release .
In some situations , however , industries may find it more economical to pay fines than to invest in treatment to meet regulations . One notable opportunity for industrial wastewater use and recycling is the cooperation between plants through industrial symbiosis .
Agriculture Over the past half century , the area equipped for irrigation has more than doubled , total livestock has more than tripled , and inland aquaculture has grown more than twentyfold . Water pollution from agriculture occurs when fertilizers ( nutrients ) and other agrochemicals are applied more heavily than crops can absorb them or when they are washed away . Continued on page 17 >>
www . plumbingafrica . co . za September 2017 Volume 23 I Number 7