The Industrial Water Purification Blog

Maintaining A Bacteria-Free Purified Water System

Posted by Peter Wood on 26-Apr-2019 10:56:13

Maintaining a Bacteria-Free Purified Water System

It is crucial for manufacturers to maintain the proper quality of water for their purposes and sector requirements. It is not enough to install the best water purification systems if there are no proper systems in place to keep the system free of bacteria. Pre-treatment devices and the reverse osmosis (RO) system are the systems most at risk from contamination, so require regular testing, cleaning and maintenance to prevent bacterial build-up.

Download our FREE Guide to Commercial Reverse Osmosis Systems

Maintenance Of Pre-treatment Devices

1) Filters

The sand and activated carbon filters used in pre-treatment requires the use of clean water. The quality of water used determines the backwash period intervals. For instance, if clean mains water is used, then the backwash period is about a week. If the water used is from underground sources such as wells, boreholes, or rivers, then the backwash period should be about three days. Ideally, the backwash process is aimed at ensuring all clogged slime and other impurities are removed from the system before they cause microbiological contamination.

2) Resin Tank

The resin tank should be placed away from direct exposure to sunlight, as this encourages bacterial growth.

3) Security Filter

The filter element of the security filter should be replaced whenever the difference between the inlet and outlet water goes beyond 0.06 Mpa. The element filter should be replaced every 2-3 months, depending on water quality.

Maintaining Ultrafiltration (UF) Systems

The UF system is made up of fine membranes that require regular cleaning to keep them bacteria-free. However, the sterilisation method depends on whether the system is meant to clean organic or inorganic impurities or a combination of both.

Cleaning Organic UF Systems

The tubular membranes should be cleaned using a low and a high alkaline cleaning agent at 0.06% and 1% respectively. The procedure is known as clean in place (CIP) and takes between 40 to 60 minutes. Some of the chemicals you can use to clean the membranes are: caustics, chelating, and surfactant agents.

Cleaning Inorganic UF Systems

Citric acid at 3% concentration is the best way to clean inorganic UF systems. Sulfuric, oxalic, nitric, and hydrochloric acids can also be used. To trap all inorganic impurities, the cleaning process should run for 1-3 hours.

Maintaining A Reverse Osmosis System

Anti-bacterial cleaning of RO membranes depends on the cause of contamination. One indication that your RO membranes require either cleaning or replacement is if the water recovery rate drops below 70%. Here are the processes used to keep an RO system free of bacteria:

1) Concrete Flushing

Those particles that have only attached themselves on the membranes and not on the feed side of the system can be flushed out using water at very high speeds.

2) Chemical Cleaning

With this method chemicals such as hydrogen peroxide and chlorine bleach are used to soak the membranes. The membranes are then subjected to a forward or backward flush which eliminates any remaining bacteria.

3) Backward Flushing

Reverse filtration is done to remove any bacteria embedded on the pores of the membranes.

Find Out More

Downtime necessitated by microbiological testing can cause severe disruption. Fortunately, an effective cleaning schedule is easy to implement and costs comparatively little. To find out more, please call 01993 892211.
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Topics: Purified Water Systems, Commercial RO System

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