The removal of iron-organic complexes from drinking water using coagulation process

Abstract

The main problem of drinking water in Lithuania is high iron concentrations. Traditional methods can be used to remove iron from water; however, if drinking water contains organic matters, these matters have a negative effect on the process of iron removal from it. Because of the organic matters on the grain surface of screen filler, a membrane, which reduces the possibility of iron removal, is formed. There are also humus-iron complexes of organic origin that hinder iron removal. The article discusses the possibilities of removal of iron-organic complexes using the coagulant poly-aluminium chloride (PAC). During the investigation, different dose of coagulant was added into each drinking water sample; the process of coagulation was carried out, and then water was filtered. Measurements of concentration of total iron, permanganate index, pH and residual aluminium were conducted after the process of coagulation. The aim of this study was to establish the conditions under which the process of coagulation is most effective, iron organic complexes are removed from drinking water and its quality is maintained. The study established that water pH has the greatest impact on the removal of iron-organic complexes from drinking water. Iron-organic complexes are best eliminated from drinking water when its pH is from 6.8 to 6.5.