Standards Development

Scope

This document provides guidance for deep purification of secondary effluent for non-potable reuse by using biological filtration systems in urban areas. It specifies general requirements, system selection, biological filtration system components, technical requirements of each component, water reuse applications and system design considerations.

This document is applicable to: a) engineers that intend to implement biological filtration systems for deep purification of secondary effluent for reuse purposes in terms of design and implement, under safe and stable circumstances; b) enterprises who assist spreading high-efficiency water reuse technology among different countries and accelerate the technological progress in the field of secondary effluent reuse.

Purpose

Global water consumption has been increasing by approximately 1% annually since the 1980s, due to population growth, socio-economic development and the change of consumption patterns. It is expected that global water demand will keep a similar growing rate of 20%-30% of water use compared with the current usage level by 2050. Water reuse is an efficient measure to alleviate the global water shortage problem and is a common action for many countries in the world. "Fit for purpose" is a consensus in the field of water reuse, which reduces the demand for fresh water by reusing treated secondary effluent in different scenarios, such as urban miscellaneous water, circulating cooling water, process and product water, etc. Treated secondary effluent acts as an important source of water supply, which provides opportunities to strengthen traditional water supply in some cities, particularly where long-distance transfer is required to meet the water demands. However, organics and nutrients such as nitrogen in wastewater are the key indicators in various countries for the management and control of water reuse.

Biological filtration system, as a mainstream technology for wastewater treatment and reuse, is widely used for deep purification of secondary effluent to achieve cost-effective carbon, nitrogen and solid substances removal. However, due to differences in technological, economic, social and environmental conditions, there is no unified guideline on technical requirements for biological filtration system on a global scale, which hinders the secondary effluent “fit for purpose” practice by biological filtration system.

This proposal is intended to provide cost-effective and high-efficiency technology to control excessive discharge of carbon, nitrogen and solid substances, and maintain sustainable and healthy development of water environment. In addition, it is beneficial to reduce investment and operational costs, as well as establish a favourable market order and promote the technological progress in the field of biological filtration for water reuse.