Reverse Osmosis Membrane Biocides & Disinfectants Print E-mail

Reverse Osmosis Biocides  - Non-oxidizing, non-ionic biocides can be used either on line or as part of a cleaning program to control biofouling in reverse osmosis (RO) 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.

biocidesApplication 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).

The two ROC products widely used are 2,2-dibromo-3-nitrilopropionamide (DBNPA) and isothiazolone. These products are fully compatible with polyamide (PA) and cellulose acetate (CA) membranes. We also offer two high performance alternatives, chlorine dioxide and a hydrogen operoxide solution synergised with colloidal silver.


DBNPA 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 DBNPA is reduced with the increase of pH. In high pH feed waters (> 8.5) the dose rate and contact time should be doubled.

DBNPA biocide should not be dosed with stainless steel injection quills as corrosion of the injection assembly will occur.

ROCbio DBNPA -  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 pipework ... DBNPA based biocide >>


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

ROCbio 50 -  non-oxidising, non-ionic antimicrobial reverse osmosis disinfectant formulation based on 0.5% isothiazalone for use in membranes and pre-treatment plant ... isothiazalone based biocide >>

ROCbio 150 - non-oxidising, non-ionic antimicrobial reverse osmosis biocide formulation based on 1.5% isothiazalone for use in membranes and pre-treatment plant ... isothiazalone based biocide >>

ROCbio 300 - non-oxidising, non-ionic antimicrobial RO disinfectant formulation based on 3.0% isothiazalone for use in membranes and pre-treatment plant. It has a broad spectrum of activity ... isothiazalone based biocide >>

Hydrogen peroxide silver

ROCbio Silver, an innovative blend of hydrogen peroxide and silver, is an eco-friendly, multi-component oxidising 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 hydrogen peroxide alone.

ROCbio Silver - eco-friendly, multi-component oxidising biocide utilising a stable combination of hydrogen peroxide and silver (H2O2/Ag) ions to form a highly effective sanitising solution ... hydrogen peroxide silver biocide >> 

Chlorine dioxide

ROC produce a range of chlorine dioxide products that are ideal for use in reverse osmosis systems. Chlorine dioxide is a highly effective biocide that carries a number of important regulatory approvals including US EPA, FDA and UK Government for many of its uses. It is effective at concentrations as low as 0.1 ppm and will eliminate both planktonic and sessile bacteria.

ROC Chlorine dioxide - Reverse Osmosis Chemicals International offer several alternative products that will deliver varying amounts of high purity chlorine dioxide suitable for reverse osmosis applications ... chlorine dioxide >> 

Technical support and advice

Reverse Osmosis Chemicals International work closely with a diverse range of global organisations, intelligently combining advanced treatment technologies with practical solutions to resolve complex issues. If you have a project you would like to discuss, or you require technical support and assistance; or if you simply have a question about our reverse osmosis membrane biocides and disinfectants please contact one of our specialist advisors using our Technical Support page or call us on +44 (0) 330 223 31 31.