Removal of organic compounds from water at the Luweero Industries Treatment Plant using granular activated carbon
Kagoya, Catherine Joy
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In this report, the study on the water treatment process at Luweero Industries limited is presented. Emphasis was put on the disinfection process. The process was noted to be consuming plenty of the calcium hypochlorite reagent. The great amounts of the reagent added to the water for disinfection resulted into a number of economic and physical challenges. Economically, there was increased cost of production. Physically, pipes and reservoirs’ surfaces were damaged due to massive corrosion. The presence of organic compounds in the water resulted into large amounts of calcium hypochlorite consumption during their oxidation chemical reactions as well as the oxidation of the formed byproducts.Filtration over granulated activated carbon filter was employed in the study. The filtrate was analyzed for the total, free and combined residual chlorine. This was done using DPD (N, N diethyl-1,4 phenyl diamine) tablets. Experiments were conducted to remove organic compounds from the water sample determine its chlorine demand and the quantities of free and combined residual chlorine. These were done by filtering the water sample over granular activated carbon. A quantitative analysis was carried out using high test hypochlorite to determine the chlorine demand. This analysis helps us to determine the chlorine dosage required to obtain a predetermined chlorine residual. The amounts of free residual and total chlorine were also obtained using DPD 1 and 3 reagents. The values of free residual and total chlorine were then used to calculate the amount of combined residual chlorine. A control experiment was also carried out where the water sample was analyzed by the same procedures without removal of the organic compounds. The experimental group results when compared with those of the control group showed that the amount of free chlorine required to reach breakeven point reduced. This was because in the experimental group some of the organic compounds which were initially consuming the free chlorine had been removed. Therefore, less calcium hypochlorite in form of free chloride ions was used to optimum obtain disinfection. The results of combined residual chlorine were computed for both control and experimental group by getting the difference between the total free and free residual chlorine. The computed figures showed a decrease in the amount of combined residual chlorine. It was found that the amount decreased by 31.68%. The combined chlorine reduction shows the efficiency of the activated carbon in adsorbing the organic compounds. The amount of free residual chlorine increased by viii 32%. The overall amount of reagent used for disinfection reduced and therefore the cost of disinfection reduced. Also, because there was less reagent being added to the water after the activated carbon filtration, the degree of corrosion was reduced.