Reverse Osmosis Biocides – Non-oxidizing, non-ionic biocides and antifoulants can be used either on line or as part of a cleaning program to control biofouling in reverse osmosis membranes. When used as an on-line treatment, the biocide should be dosed prior to the RO system to control bio-growth in the membranes.

Application frequency of any selected biocide will normally depend on biological loading and biofilm growth rate. The program should be used to control differential pressures in the RO plant to reduce cleaning frequency.

Application rates and frequency of application (biocide program costs vs. effectiveness) vs. reduction in cleaning frequency, down time, membrane life (operating costs without biocide program) should be balanced to determine the most cost effective biocide dosing frequency.

Dosing biocide further back in the pre-treatment will help control bio-growth but will also greatly increase demand and application costs. The main goal of an effective biocide program is to control biofouling in the membranes to an acceptable and cost effective level compared to cleaning program costs (and other associated costs).

Dew products are fully compatible with polyamide (PA) and cellulose acetate (CA) membranes. We also offer two high performance alternatives.


DEWTREAT-900 is fast acting and readily decomposes to harmless by-products on discharge. On-line, it is dosed just prior to the RO system to control biofouling in the membranes. Dose rate is typically 100 ppm for 1 hour. Frequency of application depends on degree of biological contamination in the feed water and rate of biofilm growth in the membranes. Typically frequency of application can vary from every other day to once a month. The half-life of DEWTREAT-900 is reduced with the increase of pH. In high pH feed waters (> 8.5) the dose rate and contact time.

DEWTREAT-900 – fast-acting, non-oxidising, antimicrobial reverse osmosis bio-control formulation with a broad spectrum of activity developed to control the planktonic and sessile microorganisms that may form as biofilms on membrane surfaces and in pre-treatment vessels and pipe work.


DEWTREAT-901 has a longer contact time than DEWTREAT-900. Dose rate is typically 50 – 100ppm for 4 hours contact. DEWTREAT-901 is more effective than DEWTREAT-900 in waters with high organic loading. DEWTREAT-901 can also be used at low dose rates on a continuous basis (10 – 20ppm).


Oxypure Silver, an innovative blend of peroxide and silver, is an eco-friendly, multi-component oxidizing biocide utilising a stable combination of hydrogen peroxide (H2O2) and silver(Ag) ions to form a powerful sanitising solution. This synergistic combination is so effective it creates a biocide twenty times more powerful than that of peroxide alone.


We produce a range of DEWTREAT-CD products that are ideal for use in reverse osmosis systems. DEWTREAT-CD is a highly effective biocide that carries a number of important regulatory approvals. It is effective at concentrations as low as 0.1 ppm and will eliminate both planktonic and sessile bacteria.

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Dew work closely with a diverse range of global organisations, intelligently combining advanced treatment technologies with practical solutions to resolve complex issues.