13 Jul Reverse Osmosis & Sustainability
Reverse Osmosis is the most advanced technology available for water treatment. Foodservice operators and hospitality vendors are keen on providing premium culinary experience to their clientele. This necessitates excellent food and beverage quality, which in turn requires adequately-treated water.
Reverse Osmosis, or RO for short, is the process of filtering water through a semi-permeable membrane under pressure. The pores of RO membranes are very small, typically in the order of 0.0001 microns, or 100,000 times finer than a standard sediment filter. The small pores reject virtually everything in water, including sediments, bacteria, viruses, proteins and even salts.
Typically, RO systems are installed in a package that includes a sediment prefilter, carbon filter for odour and taste control and sometimes a mineral adjustment cartridge for post-treatment. The RO system produces two streams: the product, also known as permeate, and the reject, or concentrate, which contains all the sediments, microorganisms and minerals. The concentrate stream is discharged to the drain.
Permeate water has low levels of total dissolved solids (TDS). TDS is a measure of dissolved salts and minerals in the water. TDS levels in municipal water supply typically range from 100 to 500 ppm, and groundwater can have even higher TDS levels. RO systems can reduce TDS levels to below 50 ppm. However, low TDS levels are not always desirable. For instance, TDS level around 150 ppm is considered adequate for proper flavour extraction and appreciable taste.
Another aspect of RO treatment is water and energy use. Reverse Osmosis systems require more energy and water than conventional sediment filtration. Foodservice operators and hospitality vendors are experiencing increased operating costs. Therefore, optimizing water and energy consumption becomes increasingly important.
The question that arises is how is it possible to provide the right level of water treatment without wasting water and energy? The answer to this question is twofold: 1- Know your equipment, and 2- Know the desired level of treatment.
Knowing your equipment is the first step in designing the right treatment system. Some appliances require higher water quality than others. For example, boiler-based steam ovens and espresso machines require low TDS water (around 50 ppm). However, coffee brewers can work with TDS between 100 – 200 ppm.
Knowing the requirements of each appliance helps in designing an optimized water system. A food service or hospitality vendor can save energy and water by providing the right level of treatment for each appliance.
Once you determine the requirements of your equipment, you can tailor the treatment system to provide the right mix for your application. If a reduction in TDS levels is required, you can use an RO system that is equipped with a blending valve. The blending valve mixes a preset amount of raw water with RO-treated water to achieve the desired TDS level. Afterwards, a sub-micron screen is used to remove taste, odours and any trapped sediments.
For equipment that does not require low TDS levels, the RO system can be bypassed and a taste and odour system installed. Using a blending valve reduces the amount of energy and rejects water that the RO system produces for each gallon of permeate water consumed.
Some innovative RO systems for foodservice and hospitality applications that come equipped with blending valves include the MRS-350BL and MRS-ENVI-RO 600 HE systems from Everpure.