【国外标准】 Standard Practice for Estimation of Chlorine Demand of Water

5.1 Chlorine is added to potable water, waste water, and industrial water for a variety of purposes. Some of these purposes are:5.1.1 To eliminate or reduce the growth of microorganisms in water,5.1.2 To destroy or modify decomposable organic substances so as to reduce the biochemical oxygen demand of the water,5.1.3 To eliminate or reduce taste, odors, and color in the water,5.1.4 To separate grease in waste water by eliminating the protective colloidal effect of proteins present, and5.1.5 To destroy or modify substances in the waste water that react directly by oxidation, such as ammonia, cyanates, cyanides, ferrous iron, nitrites, phenol, phosphorus, sulfides, sulfites, thiocyanates, and other oxidizable constituents.5.2 It is important to avoid over-chlorination in order to minimize chemical consumption, meet restrictions specified by regulatory agencies, and minimize equipment degradation.1.1 This practice provides a means of estimating the quantity of chlorine required to be added to a unit volume of water to accomplish a predetermined treatment objective or to completely react with all chlorine reactable substances in the water, or both.1.2 Temperature, pH, and initial chlorine dosage are all variables in estimating the optimum chlorination practice. The effects of these variables can be evaluated using this practice.1.3 Chlorine residual is determined using Test Method D1253.1.4 This practice is applicable to all types of water in which the stated treatment objective can be evaluated or residual chlorine can be measured, or both.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see 7.5.1.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.