Assessment of the efficiency of water treatment plants in Vhembe District, South Africa
Abstract
Various studies have indicated that most rural and small-scale water treatment plants in South Africa face diverse operational challenges. Consequently, the majority of the plants are unable to meet the goal of delivering a reliable supply of safe drinking water. This study aimed to assess the efficiency of two small water treatment plants in the Vhembe District Municipality, in the Limpopo province. Raw and treated water quality at the plants and at the selected villages supplied by each plant was evaluated based on secondary data provided by the Vhembe District Municipality. This data included results of physicochemical and bacteriological water analysis for seven months categorized into dry and wet seasons. A questionnaire survey was also used to assess the operational practices at the plants and the perceptions of consumers about the quality of the water delivered.
The study found that the raw water used in both Vondo water treatment plant (VWTP) and Mutale water treatment plant (MWTP) was of poor quality in relation to turbidity, pH, fluoride, iron, manganese, electrical conductivity, total dissolved solids, and total coliform. On the other hand, the values of free chlorine, fluoride, and sulfate were higher in the treated water at the Vondo water treatment plant. A seasonal analysis of the quality of raw and treated water showed that the raw water quality was better in the wet season at the Vondo water treatment plant. However, in the Mutale water treatment plant, the raw water quality was better in the dry season. For the treated water, the wet season had better water quality in both plants. The results from both water treatment plants indicated that there was no statistically significant seasonal difference between the quality of water produced by the plant and transmitted to the villages as a whole in each season. The study also found no significant seasonal difference between the quality of water produced by the plant and transmitted to village taps. A comparison of the water quality parameters with the SANS 241, DWAF, and WHO water quality guidelines revealed that electrical conductivity, pH, fluoride, total dissolved solids, sulfate, E. coli, and total coliforms fell within the SANS 241, DWAF, and WHO drinking water quality limits during the wet and dry seasons for treated water at both plants and villages. However, free chlorine, turbidity, iron, and manganese exceeded WHO standards’ limits during the wet seasons for treated water at the plants. Similarly, the values for iron were above the WHO maximum permissible limit for treated water at Tap 2 and 3 for the Mutale water treatment plant.
At the operational level, both water treatment plants were operating below design capacity. Although the water treatment plants were generally performing well in terms of the water treatment process, poor management of chemical dosage, monitoring process and equipment repairs was observed. The study also found that most of the operators and supervisors interviewed did not have specific skills or training on water treatment and water reticulation. This can impact water treatment processes negatively. The majority of surveyed households indicated that they were generally satisfied with water quality. However, one major problem was intermittent water supply and irregular water pressure.
The study offered recommendations to the district municipality and other researchers. Firstly, although the water quality was generally of acceptable quality, there is a need for continuous monitoring of the water treatment processes to address any challenges on time. Similarly, there is a need for continuous maintenance of the equipment. The above will have a positive impact on selected water quality parameters that were found to be not meeting selected guidelines. There is a need for the district municipality to enhance the technical level of the plant managers and operators at each plant. This can go a long way to improve the operational practices at each plant. For researchers in water quality, the use of secondary water quality data kept by the water treatment plants reduces research costs. However, it is recommended that researchers undertake their own water sampling and analysis to provide a more independent water quality assessment that does not depend on the data produced by the same plants being assessed.