Global population is increasing and mainly in cities and towns. This is mostly characterized in developing countries where an additional 2.5 billion people are expected to be living in cities by 2050 This increase in population would also be coupled up with the increase in volumes of waste water in the cities. This is because urbanization and rapidly growing human population results in an increase in waste water discharge into fresh water ecosystems, thus impairing water quality, sometimes to unacceptable levels, thereby, limiting its beneficial use.
Wastewater can be defined as used water discharged from homes, businesses, industry, cities and agriculture. Wastewater comprises of all used water in homes and industries including storm water and runoffs from lands, which must be treated before it is released into the environment in order to prevent any harm or risk it may have on the environment and human health. The waste water can also be called sewage in waste management and a system that is connected across the city to collect the sewage is called a sewerage system. The waste water is then channeled to a waste water treatment plant or waste stabilization ponds. This is due to the fact that the wastewater organic load contains high levels of a variety of hazardous organic pollutants, and therefore additional treatment steps and control measures become very necessary. According to WHO, high-income countries treat about 70% of the municipal and industrial wastewater they generate. That ratio then 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.
Furthermore, studies have found untreated sewage to be the most critical issue with respect to water contamination because 40% of the global population do not have adequate sanitary facilities. This has been witnessed in Zimbabwe where underground water in major cities has been found to be contaminated and this has led to the outbreak of typhoid and cholera in Gweru and Harare respectively in 2018. Kanda highlighted that there is greater likelihood of increased wastewater reuse in water-stressed countries in the near future as freshwater resources are dwindling by the day. Waste stabilization ponds are large, man-made water bodies in which black water, grey water or fecal sludge are treated by natural occurring processes and the influence of solar light, wind, microorganisms and algae. The waste stabilization can be classified by considering the types of biological activity occurring in a pond and the three types of ponds namely anaerobic ponds, facultative, and maturation ponds.
Waste stabilization ponds are now the first choice treatment method for wastewater in many parts of the world. This is because they provide some advantages over conventional waste waterworks such as simple designs, low operational costs and low production of biological sludge. This can be witnessed in Europe, where developed countries like France, Spain and Portugal have already implemented such ponds in their small rural communities where conventional sewage works would be expensive to construct and to maintain. The advent of Sustainable Development Goals has also promoted the use of ponds as goal 6.3 states that by 2030, water quality is to increase by reducing pollution, eliminating dumping, minimizing release of hazardous materials, halving the proportion of untreated wastewater and substantially increasing recycling and safe reuse globally.
In Africa, the use of waste ponds system is ideal as it is cheaper to construct, simple to operate and also the favorable weather conditions ideal for the ponds as compared to Europe where sludge accumulation will be higher in cold climates due to reduced microbial activity. Also, there is large land available for such ponds as compared to some other parts of the developed world. Gokwe Town gained town status in 2007 through the Urban and Town Act. It lies at about 374km from the capital going the south easterly direction and has a population of around 24 000 according to the 2012 national census. It has 5 residential suburbs namely Mapfungautsi, Njelele, Green valley, Cheziya and Sasame. Hubs of economic activities are found in the town including retailing, milling, processing and vending.
The town constructed waste stabilization ponds as a way of managing wastewater treatment from the town. This was due to the fact that the town was still small and could not afford a conventional waste water treatment facility whilst there was the availability of vast lands for the ponds. The ponds are located about 1km away from the town and on the easterly part of the town which also houses Miti peri urban settlement nearby. The ponds are managed by the waste management supervisor who routinely goes and check to see if everything is in order. Figure 1 There is no protection at the facility, there has been no fence erected to prevent uninvited guests of all forms from accessing the facility. Livestock from the local community is sometimes witnessed grazing in between the ponds and also drinking the waste water from the various ponds available. This contrasts Lawrence county department requirements which state that a fence of 4m has to be erected around the area where stabilization ponds would be constructed. Tiley also highlights that a fence is needed to keep people and animals out of the ponds. No tests have been done to determine the quality of both the influent and effluent of the waste stabilization ponds.
This is against the notion that the quality of the final effluent should be regularly at all sites. This has put the livestock that drink water from the waste stabilization ponds at risk of drinking contaminated water which may cause diseases. The operational maintenance of the waste stabilization ponds is the responsibility of waste supervisor. The waste water facility does not have a scheduled plan for maintenance and this has led to the growth of plants like reeds inside the ponds.
The presence of these plants disrupts the normal functioning of the waste ponds and thus, the efficiency of the ponds has decreased over the years. According to Powell, a desirable waste water pond which has received good care can be characterized by the absence of plants floating on the water, tall plants on the edges of the ponds or plants that droop into the waste water. In order for stabilization ponds to be effective, they should encompass three ponds namely anaerobic, fulcatative and aerobic ponds. In Gokwe, the waste water ponds consist of anaerobic, fulcatative and maturation ponds. Having aeration ponds is beneficial as it contains higher loads of organic material than maturation ponds Tiley.
Also, aerobic ponds are responsible for the removal of pathogens in the wastewater. The waste stabilization ponds produce sludge which is then pumped and placed on the drying beds for it to dry. There is no scheduled plan for sludge removal from the ponds and the exercise is done when it is deemed necessary. This is in contrast with Gratziou who said that the sludge removal frequency from the ponds must be determined and incorporated into the pond design. After drying, the sludge is then disinfected and carried away for agricultural processes.
Waste water is known to contain substances such as pathogens and fecal coliforms. The sustainable development goals have also identified safe and clean water as one of the ways to promote good health. Gokwe Town Council constructed waste stabilization ponds as a way of treating wastewater so that the effluent released to the environment is not hazardous. However, since inception, no waste water quality monitoring mechanisms have been put in place and this contrasted Pena who stated that the quality of the final effluent should be regularly determined at all waste stabilisation sites. Population growth in the nearby community has resulted in new homes being constructed in the area as near as 130m from the wastewater ponds and there is a possibility in that in the future, more houses would be constructed even nearer to the ponds if no measures are taken.
The nearby community experiences the highest incidence rates of diarrhoea as indicated by the records of the nearby Cheziya Council Clinic which show that in the second quarter alone, 70 cases of diarrhoea were recorded and of those 70, 71% of the cases came from the peri urban area which surrounds the ponds. Figure 2 The problem is thus, there is no evidence on the role the ponds play in the progression of diarrhoea as there has been no study done to determine whether the ponds affect the quality of groundwater around the ponds which is used by the community for consumption. The study will help to determine the actual efficiency level of the waste stabilization ponds in treating waste water before it is released to the environment. The findings of this study could increase knowledge on the dangers of living near the waste stabilization ponds amongst the people of the community. The findings will act as a basis in which the local authority may come up with strategies targeting the problems to be identified by the study.
These findings can also help to influence the prioritization of sewage management on the list of council activities. This can then help reduce disease burden and related costs to the community. The research is to contribute on goal number six of the sustainable development goals which focuses on clean water and good sanitation in the environment. The study was done in order to produce information that could be used by local authorities or wastewater managers to develop or review effective policies on wastewater treatment plant management with the goal of meeting standard requirements for discharge of effluents into the environment. The study would help in revealing other underlying problems that may help future researchers on what to study. To determine the impact of waste stabilization ponds on underground water sources and aesthetics in the surrounding community 1.51 Specific objectives To determine the physico-chemical and biological quality of the wastewater effluent from the waste water ponds.
To determine the physico-chemical and biological quality of the groundwater that surrounds the ponds. To determine the aesthetic effects of the waste stabilization ponds to the surrounding environment. Are the waste stabilization ponds efficient in treating the waste water before it is released into the environment? Are the water sources found in the nearby community contaminated by organisms that are also found in the waste ponds? Are the people living around the ponds aware of the functions and effects of the ponds within their vicinity? The research was done in Gokwe Town which is located in Gokwe South District of the Midlands Province and was limited to the peri urban area of Miti village where the waste stabilization ponds are located. The study mainly focussed on how the waste water ponds affected the quality of surrounding water sources and the people who live around the ponds. People who live in the town of Gokwe were excluded from the study as they lived further and used reliable water provided by the local authority. Data was collected from the surrounding water sources through water sampling and from 30 respondents who were residents in the surrounding community.
