# The Use of Low-Rejection Nanofiltration Membranes as a Tool to Simplify Pretreatment, Escape Scaling and Radically Increase Recoveries

## TL;DR

A new water treatment system using low-rejection nanofiltration membranes improves water recovery and reduces scaling in industrial water reuse.

## Contribution

The use of low-pressure nanofiltration membranes in multiple stages enables high calcium removal and increased water recovery compared to traditional reverse osmosis systems.

## Key findings

- Low-pressure nanofiltration membranes achieve high permeability and recovery with reduced reagent consumption.
- The technology effectively prevents scaling by determining maximum recovery limits before homogeneous nucleation occurs.
- The system provides economic benefits through minimal discharge and efficient water reuse.

## Abstract

This article describes the results of research to develop a new technology to treat storm and drainage water generated on a territory of industrial enterprises and reuse it as a feed water for boiler feed and steam generation. To develop such a system, it is necessary to resolve issues related to pretreatment, scaling, and fouling, as well as to provide a minimal discharge in the company’s sanitation network. Principles of the new approach to reach high calcium removal are based on the use of two or three stages of low-pressure nanofiltration membranes instead of the conventional facilities that contain one stage of reverse osmosis membranes. High permeability, low pressure, high recovery, and reduced reagent consumption provide an economic effect. The technology uses low-rejection membranes “nano NF” developed and produced by “Membranium Co.” (Vladimir, Russia). In the article, the results of investigations on the evaluation of scaling rates in membrane modules and rates of homogeneous crystallization in concentrate flow are presented. Processing these results enables us to detect recovery values when scaling begins on the membrane surface as well as to determine the maximum recovery value for the beginning of homogenous nucleation in the concentrate flow.