Development of Environmental-friendly Cleaning Agents Utilizing Organic Acids for Removal of Scale on the Wall of Cleaning Beds and Distribution Reservoirs in the Waterworks

In this study, an environmental-friendly cleaning agent utilizing organic acids and various additives has been develop- ed and applied to the field for removal of scale deposited on the cleaning beds or distribution reservoirs of the waterworks. As an analytical result of scale on the cleaning beds, we found that it consists of mainly metallic oxides such as SiO2, Al2O3, Fe2O3, and MnO. Malic acid, malonic acid, and citric acid showed relatively better solvency on Al2O3, Fe2O3, and MnO except SiO2 among various organic acids. Mixed organic acid solutions of malic acid, malonic acid, and citric acid were prepared with certain weight ratios and their solvencies on mixed metal oxides of Al2O3, Fe2O3, and MnO were investigated. The experimental results showed that an 10% mixed organic acid solution prepared with weight ratio of malic acid : malonic acid : citric acid = 6 : 2 : 2 were found to have best scale solvency power of about 29%. The formulated cleaning agents with a small amount of nonionic surfactant showed