Removing Total Organic Carbon from Raw Water using Direct Nano-Filtration

Degradation of vegetative matter in surface water sources can lead to the formation of humic substances into water supplies. The humic material is often referred to as natural organic matter, or NOM in water treatment systems. These natural degradation processes result in elevated colour and increased total organic carbon (TOC). The presence of organic carbon creates challenges in the generation of drinking water.

To protect human health against a variety of pathogens present in natural water sources, as well as to prevent the formation of biofilms within drinking water supplies pipelines, oxidants are used as part of the drinking water treatment process. Chlorine and chloramine are two oxidants used widely both in Australia and around the world to provide this protection.

When oxidising high TOC raw water for pathogen control, disinfection byproducts such as trihalomethane (THM) can form. THM impacts human health and is tightly regulated within drinking water supplies in Australia.

To limit the generation of disinfection byproducts such as THM, TOC values need to be controlled prior to the oxidation step in order to meet the required THM values in the Australian Drinking Water Guidelines (ADWG).

One technology which is having a significant impact globally on the reduction of TOC is NX Filtration’s direct hollow fibre nanofiltration. Nanofiltration provides a physical barrier to TOC, producing a high-quality water source prior to oxidation. The nanofiltration is generally ideal for targeted removal of colour and NOM.

The benefit of NX Filtration’s direct hollow fibre design is the robust membrane structure allows direct treatment of raw water sources without the need for extensive pre-treatment generally required for other nanofiltration membranes. This reduces both operating and capital costs, as well as lowering the carbon footprint required for the production of drinking water.

Long Term Trials – Queensland

Hydroflux recently conducted a long-term trial on behalf of a regional water authority to determine the effectiveness of TOC removal using NX Filtration’s direct hollow fibre nanofiltration. The site had an existing water treatment plant that used physical chemical treatment to meet drinking standards.

The trial operated for a period of three months. The plant was left to operate automatically whilst being monitored by water authority engineers on site and the Hydroflux team via a remote access system. The remote monitoring system simplified running the trial over an extended period.

Trial Results

The pilot system, which was a fully contained automated dNF unit with HMI, was tested at three different locations within the existing treatment plant. This included direct raw water without pre-treatment by existing site processes, as well as after primary clarification.

For all three test locations an average of 96% TOC removal was achieved, whilst outperforming competing nanofiltration membranes both in terms of TOC removal and net recovery. During the trial the crossflow velocity, flux and operating pressure was optimised to achieved the highest recovery rate.

The flexibility and performance of NX Filtration’s dNF technology for TOC reduction on both raw effluents, as well as after primary clarification provides water authorities with options to reduce THMs in the final product water whilst lowering total lifecycle costs and carbon footprint of drinking water production.

To learn more about the use of dNF technology for raw water treatment, please contact our team on 1300 417 697 or visit www.hydrofluxepco.au.

About the Hydroflux Group

The Hydroflux Group aims to deliver the highest level of engineering and scientific know-how to the emerging issues of sustainability, climate adaptation and environmental protection with a specific focus on water and wastewater.

As part of its vision and mission, Hydroflux has always taken its climate responsibility seriously. In 2022, Hydroflux became Australia’s first water treatment and technology company to achieve Climate Active carbon neutral certification for its organisation and products. It knows that partnering with customers and clients is the most significant impact it can have in its journey. The Group employs over 100 staff and operates throughout Australia, New Zealand and the Pacific Islands, with office locations in Sydney, Melbourne, Brisbane, Perth, Auckland, Suva and Portsmouth.