Characterisation of some South African water treatment residues and implications for land application

Abstract

Land application of water treatment residue (WTR) the by-product from the production of potable water, is becoming the preferred method of disposal, as there are environmental concerns and increasingly high costs associated with other disposal options. However, before WTR can be applied to land, consideration needs to be given to their chemical and physical charac teristics to determine potential impacts. Six WTR samples were obtained from five South African water treatment facilities (Faure Water Treatment Plant (two samples), Rand Water, Umgeni Water, Amatola Water and Midvaal Water Company). The Rand Water WTR was a CaO, FeCl 3, long-chain organic polymer (LCP) residue with activated silica and CO 2 being added. The Umgeni and Amatola Water WTRs were lime and LCP residues. The Midvaal Water WTR was an Al 2(SO4)3.nH20, FeCl3, lime and LCP residue and the Faure WTRs were Fe 2(SO4)3, activated charcoal, lime and LCP residues.

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