Wastewater Sources and Uses
The increasing demand for water for industrial supply, food production and human support has contributed to the competition of the scarce resource. The use of wastewater has been seen as the only appropriate option to meet the growing demand. According to Pedrero, Allende, Gil and Alarcón (2012), the recent changes in attitude, as well as technology developments toward the reuse of wastewater have necessitated the potential for wastewater reuse in the continuous developing world. With the increasing population, improvement in sanitation services as well as rapid urbanization, the amount of wastewater collected and treated is projected to improve (Hanjra, Blackwell, Carr, Zhang, & Jackson, 2012).
Most of the wastewater is produced from commercial, industrial and domestic sources. The wastewater generated from domestic sources accounts for more than 50 to 80 per cent of the total water use (Scott et al., 2010). On the other hand, the agricultural department is the biggest wastewater user accounting for 70 per cent of water use in the world. The use of wastewater for irrigation can eradicate water resources stresses by being a dependable source for the supply of water with adequate nutrients for crop development throughout the year. There exist potential health implications that are linked with the use of wastewater.
In most cases, wastewater is released into water bodies with little treatment or no treatment because of inadequate wastewater treatment facilities. Untreated wastewater is commonly utilized for urban or rural agriculture. The untreated wastewater from the industrial, domestic as well as municipal sources contains a substantial excreta-related pathogen, toxic chemicals and skin irritants which causes health risks to the families, workers, farmers and communities living near the wastewater irrigation (Scott et al., 2010).
The exposures of wastewater have been associated with protozoan, bacterial as well as viral diseases such as diarrhoea, amoeba and cholera. This paper seeks to elaborate on the public health concerns that emanate from wastewater use and the exposure pathways through which pathogens enter human bodies from the use of wastewater in garden plants irrigation and toilet flushing. The paper further seeks to provide solutions to eliminate or mitigate the risks associated with wastewater.
The health effects that are related to wastewater reuse in irrigation can be both positive and negative. The positive effect of wastewater is linked to food security in poor areas. Wastewater use increases food production which consequently increases income, nutrition as well as improves the quality of life in poor areas. On the other hand, the negative effects associated with wastewater use are caused by pathogens and hazardous chemical compounds (Calderón-Preciado et al., 2013). Irrigating the land with untreated as well as less treated wastewater causes a significant number of risks to the human health through the direct or indirect consumption of pathogenic micro-organisms and other toxic organic chemicals.
Potential Health Implications
Wastewater comprises numerous excreted organisms and the concentrations of the pathogens vary depending on the background levels of the disease in the population. The pathogens present in wastewater can live for a long period until transmitted to animals and humans (Farahat and Linderholm, 2013). The pathogenic microorganisms generally pose a threat to human health. The domestic wastewater has a high percentage of pathogenic microorganism as well as organic materials such as viruses, bacteria and protozoan. The diseases that are caused by pathogenic microorganism include diarrhoea, typhoid, mal-absorption and vomiting. Any human exposure to both the untreated and less treated wastewater might lead to infections. For instance, helminth infections are commonly associated with frequent contact with wastewater. The helminth infection is associated with anaemia which leads to impaired and cognitive development (Grangier, Qadir and Singh, 2012).
Because of the constant exposure to wastewater, the workers on farms are prone to skin diseases such as rashes and dermatitis. The major concern that may arise with regard to chemical compounds is metals. The small amounts of metals are biologically important for the body but become toxic at an increased level. Cadmium causes extensive risks to the body. The uptake of cadmium increases over time depending on the concentration of soil. Cadmium is highly harmful to humans in lower doses as compared to those that affect the plants (Silverman, Akrong, Amoah, Drechsel and Nelson, 2013). The cadmium accumulation damages the kidney and causes osteoporosis. Additionally, personal care products, as well as endocrine-disrupting chemicals, cause potential health risks but there is constrained information on their uptake of food (Tai et al., 2013).
With the increasing health risks, numerous organizations such as WHO have established standards to guarantee that wastewater contaminant levels are below the limits that are toxic to human health (Zhang et al., 2013). As much as both the untreated wastewater cause acute public health risks to consumers as well as farmers exposed to contaminants, wastewater utilization has been imperative to the smallholders’ livelihoods, especially in economically disadvantaged areas. The utilization of wastewater has emerged as a form of climate change adaptation because it provides water both at variable or dry conditions.
The dynamic drivers that are linked with wastewater use indicate that prudent steps ought to be taken into consideration to minimize the health risks to a level that can be balanced with the expanded interest of food security, nutrition and livelihoods. It is also clear that wastewater can add contaminants to groundwater which can cause a tremendous impact on the environment which eventually contribute to the health risks. The use of wastewater for irrigation is expected to increase in many nations as a result of the scarcity of freshwater, particularly in light of the increased amounts of wastewater discharged from urban areas. According to Wu, Ernst, Conkle and Gan (2013), there is a need to examine the increasing chemical contaminants generated by the emerging industries as well as the increased wastewater that is related to the large population.
Positive and Negative Effects of Wastewater Use
There are a number of exposure pathways that are linked with wastewater irrigation. One of the exposure pathways is the consumption of crops irrigated by wastewater such as cereals and vegetables. However, there are other additional atmospheric depositions of toxic metals that contaminate vegetables. In the case of crop contamination, the crops absorb the contamination which is then consumed by humans. The contaminant moves into the food chain which is one of the principal concerns related to wastewater irrigation and the broadest exposure route. The little number of metals in soils has been a challenge in regions with long-term water irrigation. The take-up of metals and metalloids is dictated by the soil conditions and the vegetable type. The microbiological risks can be minimized or completely eliminated when food is thoroughly washed and prepared before consumption.
Additionally, individuals who work in agricultural farms face immediate health risks because of the direct exposure to the contaminated soil (World Health Organization, 2015). The measure of occupational health risks is complex due to varying exposure time and the changing contaminant concentration as a result of the seasonal differences in the treatment level and availability of water of the effluent utilized for irrigation. In addition, the different irrigation techniques, as well as farming practices, contribute to wastewater exposure on humans and this vary based on gender roles. The food contamination can also occur in the processing chain as well as food supply from sources such as household food hygiene, market selling and transportation (Wang et al., 2012).
Researchers need to identify extra contamination routes to enhance the target risk minimization measures that aim at the major hazards. Education and awareness campaign to address food hygiene on markets and households should be conducted to guard the public health without limiting the livelihood of the farmer. The benefits that are linked with wastewater such as nutrient input, water and food security and livelihood improvement should be considered together with the risks (Assouline, 2013). For instance, the children in the wastewater irrigated areas in Vietnam had better nutritional status as compared to that using river water for irrigation. This suggests that recommendations to minimize risks must be based on local situations.
The population living close to irrigated land may likewise encounter indirect exposure. For instance, cricket games near contaminated soil were reported by (Jang Lee, Sung, Lee & Park, 2010) as a conceivable unplanned ingestion source. There are still health risks in high-income communities particularly individuals who are close wastewater water irrigation zones where there exist lower treatment levels that are utilized to develop non-food crops. In Northern Ireland and Sweden, the groundwater contamination and drinking water supplies are related to wastewater. It has been noted that children are the most vulnerable group to some wastewater contaminants. The children might come into contact with wastewater through direct playing in contaminated zones. They are also less likely to practices sanitary behaviour, for example, hand washing and this makes them prone to sicknesses.
Exposure Pathways of Wastewater Irrigation
Assessing the health risks of wastewater use has become a challenge because the individuals who live in wastewater-irrigated areas are exposed to contamination from a range of sources which make the examination of risks to be complicated. The practices of animal husbandry, as well as utilize excreta in agriculture, are further pathways of introduction to excreta-related pathogens. According to Gupta, Khan and Santra (2012), wastewater use did not increase helminth risk in Hanoi, Vietnam while the absence of adequate sanitation facilities and utilization of excreta compost did. Ferrer (2012) recognizes recreational facilities such as washing, swimming and canal fishing polluted with wastewater from industries and residents to be among the exposures to contaminants in Bangkok.
The constructions of wastewater treatment plants and ponds have been considered as the absolute solution for minimizing risks of wastewater. However, the questions about the effectiveness of the conventional treatment systems in eliminating pathogens from emerging chemical compounds remain unanswered. The most conventional treatment systems comprise two treatment systems; the primary system and the secondary system. The primary treatment systems eliminate organic matter as well as suspended solids (Jang, Lee, Sung, Lee & Park, 2010). The secondary systems remove biodegradable organic and the main work of the tertiary system is to remove nutrients and toxic compounds. In this regard, the conventional treatment plants are mainly developed to address concerns of the environment but not human health risks. Therefore, innovative changes ought to be developed on the conventional wastewater treatment to be viewed as a realistic health-risk mitigation option.
The multiple-barrier approach use is one of the mitigation approaches that can be used to mitigate the health risks associated with wastewater. The approach combines both the conventional and non-conventional treatment methods while putting into consideration the health security measures to meet the health targets. The non-customary wastewater treatment techniques incorporate the utilization of low-cost systems, for example, sedimentation traps and sand-filter combined with health protection measures, for example, enhanced water system (drip irrigation) and stopping of irrigation prior to harvesting and thorough washing of produce after harvesting (Wang et al., 2012). The farmers should not only depend on the treatment methods but should also adopt safer practices without involving direct business and personal benefits. The governments of various nations should educate the public as well as raise awareness on food-safety issues. Better checking as well as testing techniques is needed to guarantee the full scope health risk considered by decision-makers, especially with expanding worldwide trade of food. In a worldwide evaluation, Sato, Qadir, Yamamoto, Endo and Zahoor (2013) reported constrained data accessibility on the wastewater utilization in numerous nations but the human health risks are a crucial reason to spur information gathering.
Occupational Health Risks
Further studies should be conducted to characterize the attitude, knowledge and behaviours that is associated with wastewater health risks for consumers as well as farmers in different regions. By doing this, a better comprehension of the extent of the health risks will be observed. In many cases the economic benefits that come from wastewater use are some of the motivators that make farmers to use wastewater for irrigation while minimizing fertilizer use. The comprehension of vast perspective of wastewater use will assist people to identify the best awareness building techniques as suitable education activities to reduce the health risks.
The use of protective equipment as well as hygienic practices should be implemented to minimize risks but seem expensive. For migrant workers, they should be monitored closely as well as ensuring that measures are enforced. Additionally, the practices of consumer such as hygienic cooking which comprise of vegetable washing with clean water should be understood. These kinds of studies will advance collaboration in physical as well as social sciences to include various evidence forms. The economic evaluations should be done through analyzing of the acute healthcare costs by comparing the wastewater benefits use in food security as well as nutrition. This can further provide useful evidence for decision making.
Conclusion
Wastewater use has increased in the farming sectors because of freshwater shortage. As much as people utilize it, they ought to be educated on the wastewater use related health risks. The developing nations are required to investigate the expanding chemical contaminants number generateed by the developing industries and in addition, expanded wastewater related to the vast urban population. Nations are required to create wastewater rules to accomplish a harmony between health advancement and protecting different advantages, for example, secure food supply and the livelihood of farmers. In order to properly interpret and apply the rules in a way appropriate to the local conditions, a wide-based strategy approach is required that will incorporate legislation and additionally positive and negative motivating forces to help in the selection of good non-treatment or post-treatment hones.
The efforts to increase wastewater treatment are essential and there is a need to speed up the process. Presently, the WHO standards were designed to support worldwide guidelines by setting bodies in their effort to come up with their own system as well as their protocols on the most proficient method to accomplish the suggested targets of health. The methodology varies between areas based on variations in financial, institutional as well as technological conditions. While the targets based on health will remain in a given particular setting, local measures and actual usage ought to continuously be developed as the nation moves the sanitation ladder.
Risk Minimization Measures and Benefits of Wastewater
Finally, various aggregate environmental exposures influencing the population in wastewater use places, for example, the access of sanitation and water ought to be extensively analyzed to set up risk minimization steps as well as aim defenceless gatherings. The examination gaps distinguished in this study give knowledge on opportunities for future work that will contribute to wastewater advantages in changing social and environmental settings while moderating risks to public health.
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