DEVELOPMENT OF TRIHALOMETHANES FORMATION TOOL FOR OPERATIONAL MANAGEMENT OF WATER SUPPLY SYSTEM

Disinfection is a very significant water treatment process for drinking water safety, as it inactivates pathogens from drinking water. Chlorination is the most widely used method for disinfection of drinking water, but there are concerns about the formation of by-products, such as trihalomethanes (THMs), since chronic exposure to them may pose risks to human health. For these reasons regulations fix maximum acceptable THMs levels throughout distribution networks, so it is very important to be able to correctly reproduce their formation. Research has provided many predictive models for the formation of DBPs based on various water quality parameters and following different methodologies, many models for predicting THMs formation have been developed, both based on empirical relationships and kinetics involved during chlorine reaction. The study aimed at developing an operational management tool for the formation of DBPs in drinking water supply systems in Thyolo. Such management tools are helpful to the water utility managers during decision making, for example, setting a disinfectant dose, contact time, adjustment of pH, temperature, etc., to reduce the formation of DBPs and at the same time maintain the required disinfectant residual. Primary data from the water supply scheme was collected using grab sampling. Parameters such as PH temperature (°c), ORP, EC, TDs, were measured using the multi-parameter on-site to determine the water quality of the scheme. The residual chlorine (mg/L Cl2), TSS (mg/l) turbidity (NTU), and fecal coliform were measures in the laboratory using photometer and membrane filter technique respectively. Laboratory, experiments were carried out to assess possible effects of DBPs drivers (PH and temperature) that result in the formation of THM upon chlorination, after the experiments it was found that pH and temperature have an effect on residual chlorine which reacts with natural organisms to form THMs. a regression equation of RC = -3.2302 + 0.34923TURBIDITY -0.28699TSS + 0.035095 TEMP + 0.008081 TDs + 0.11475 PH + 0.011009 FC was developed as a management tool to monitor free residual chlorine concentration in the distribution systems.

Research has provided many predictive models for the formation of DBPs based on various water quality parameters and following different methodologies, many models for predicting THMs formation have been developed, both based on empirical relationships and kinetics involved during chlorine reaction. Such management tools are helpful to the water utility managers during decision making, for example, setting a disinfectant dose, contact time, adjustment of pH, temperature, etc., to reduce the formation of DBPs and at the same time maintain the required disinfectant residual. Laboratory, experiments were carried out to assess possible effects of DBPs drivers (PH and temperature) that result in the formation of THM upon chlorination, after the experiments it was found that pH and temperature have an effect on residual chlorine which reacts with natural organisms to form THMs. a regression equation of RC = -3.2302 + 0.34923TURBIDITY -0.28699TSS + 0.035095 TEMP + 0.008081 TDs + 0.11475 PH + 0.011009 FC was developed as a management tool to monitor free residual chlorine concentration in the distribution systems.

The study took place at the Mpeni water treatment plant in the Thyolo district. Thyolo district is located in the southern region of Malawi on the shire highlands. It borders Mulanje to the east, Blantyre to the north, and Nsanje to the south. The climate is dry and with savanna type of vegetation. Generally, the area terrain is sloppily surrounded by mountains and rivers/streams. The soil is roamed clay and some parts are rocky (Maoulidi 2012). This plant distributes water to not less than five thousand customers around Thyolo district. Mpeni water treatment plant uses a conventional method of treating water. Conventional Method treatment plants use a combination of coagulation, sedimentation, filtration, and disinfection to provide clean, safe drinking water to the public

District: Thyolo

Coordinates: -16.12965, 35.1166