New Standard from Last Update.

NATIONAL FOREWORD

This Indian Standard (Part 1) which is identical with ISO 21939-1 : 2019 ‘A method to calculate and express energy consumption of industrial wastewater treatment for the purpose of water reuse - Part 1: Biological processes’ issued by the International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards on recommendation of the Environment Protection Sectional Committee and approved by the Chemical Division Council. Biological wastewater treatment is a major process step in many cases of industrial wastewater treatment for reuse. In the field of biological wastewater treatment, the energy consumption of the process is commonly normalized in order to account for difference in flow and concentration when comparing different treatment options. Considering the importance to develop standard method for energy consumption for biological waste water treatment and to follow the uniform practices globally, the Committee felt that it would be more convenient to prepare this standard by adoption of ISO 21939-1 on dual numbering system.

The text of ISO Standard has been approved as suitable for publication as an Indian Standard without deviations. Certain terminologies and conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following:

a) Wherever the words ‘International Standard’ appears referring to this standard, they should beread as ‘Indian Standard’.

b) Comma (,) has been used as a decimal marker, while in Indian Standards, the current practiceis to use a point (.) as the decimal marker.