Water Treatment and Purification

Abstract

This chapter describes water treatment methods used to partially remove and replace various impurities from a feedwater stream, water-conditioning additives used to neutralize impurities and inhibit corrosion, and pure water systems used to remove all impurities from the feedwater to a level at or below limits desired by the end user. Information is presented on basic water chemistry, impurities found in water, water analysis, and impurity measurement. Also discussed are general selection criteria for the removal or reduction of specific impurities from water. Separate sections cover water-conditioning systems for boiler feedwater, water-conditioning systems for cooling water, and the generation of purified water. For purposes of discussion only, the term water treatment is intended to mean only the removal and / or replacement of undesired impurities in feedwater with more desirable impurities. The resultant water is not pure. Water conditioning is intended to mean the addition of chemicals to water for the purposes of inhibiting corrosion and neutralizing undesirable impurities. Pure water systems is intended to mean the production of water pure enough for pharmaceutical and laboratory applications. The explanations and definitions given are simplified ones. CODES AND STANDARDS There are many codes and standards that apply to various systems. Among them are: 1. Potable water treatment shall comply with the 1986 Safe Drinking Water Act and Amendments. 2. Potable water treatment shall comply with EPA technologies describing contaminant removal. 3. Pure water treatment shall comply with the following, depending on the purity of the water desired: