Eco-Efficiency of Drinking Water Treatment

Problem statement:In the water treatment processes, the chemicals (aluminum sulfate AS, chlorine, and polyelectrolyte) are required in the different steps of treatment (coagulation, flocculation, settling, disinfection…). The chemicals residues can affect the human healthy and the environment. The treatment process produces sludge according to the level of the water turbidity. However, the sludge management increases the monitoring expenses. Moreover, this water treatment sub-product constitutes a threat for the environment and the downstream water users.Approach:In this study, the effectiveness of chemicals uses and sludge reuse was evaluatedin order to find optimal operational conditions and reduce its residues. The influence of the chemicals consumption on the cost of treated water was also studied. A set of jar test experiments was conducted to find the sludge and aluminum sulfate dosages in order to improve the produced water quality for different turbidity levels. Results: Results demonstrated that the consumption of chemicals could be reduced by 10 to 15%. The sludge reuse improve the water quality and decrease the AS consumption by 50 to 60%. The turbidity removal is increasing and the aluminum residues is decreasing by 50%. Conclusions/Recommendations:Results show that the sludge reuse plays a very important role in reducing the aluminum sulfate dosage, improving the treated water quality and reducing water cost. The AS control and modeling reduce the chemicals consumption. This approach contributes in preserving the environment and opens income-earning opportunities for local population by promoting local products made from water treatment sludge.