Pacific Water Technology supplies turnkey equipment package solutions for a whole host of applications utilising worldclass cross-flow membrane filter technology.
We design and build Industrial Reverse Osmosis systems (RO Systems) ranging in size from 5000 litre/ day 500 000 litre/day and that can remove up to 99.5% of dissolved salts and virtually all colloidal and suspended matter from the most challenging feed water including municipal, brackish, and sea water applications. RO units produce a high quality water yield at a low cost compared to other purification processes.
Our Industrial Reverse Osmosis systems are custom designed specifically for your water treatment needs by an experienced team of application, mechanical and chemical engineers. We build the RO system using only high quality components that will provide reliable long-term operation. They arrive at your site hydrostatically tested and ready to produce water with complete documentation and operator training. We also provide the pre-treatment equipment and chemistry required to ensure optimal performance and life span of your RO membranes.
we also offer fully self contained Reverse Osmosis systems that are built inside an ISO intermodal shipping container that has been specifically modified for water treatment applications. These units are easy to ship and are fast and inexpensive to install.
What is Reverse Osmosis(RO)?
Reverse Osmosis RO is a technology used to remove dissolved solids and impurities from water using a semi-permeable RO membrane which allows the passage of water but leaves the majority of dissolved solids and other contaminants behind. The RO membranes require water to be under high pressure (greater than osmotic pressure) to do this. The water that passes through the RO membrane is referred to as the “permeate” and the dissolved salts that are rejected by the RO membrane is referred to as the “concentrate”. A properly run RO system can remove up to 99.5% of incoming dissolved salts and impurities.
It is important to understand that an RO system employs cross filtration rather than standard filtration where the contaminants are collected within the filter media. With cross filtration, the solution passes through the filter, or crosses the filter, with two outlets: the filtered water goes one way and the contaminated water goes another way. To avoid build up of contaminants, cross flow filtration allows water to sweep away contaminant build up and also allow enough turbulence to keep the membrane surface clean.
What will Reverse Osmosis remove from water?
Reverse Osmosis is capable of removing up to 99%+ of the dissolved salts (ions), particles, colloids, organics, bacteria and pyrogens from the feed water (although an RO system should not be relied upon to remove 100% of bacteria and viruses). An RO membrane rejects contaminants based on their size and charge. Any contaminant that has a molecular weight greater than 200 is likely to be rejected by a properly running RO system (for comparison a water molecule has a MW of 18). Likewise, the greater the ionic charge of the contaminant, the more likely it will be unable to pass through the RO membrane. For example, a sodium ion has only one charge (monovalent) and is not rejected by the RO membrane as well as calcium for example, which has two charges. Likewise, this is why an RO system does not remove gases such as CO2 very well because they are not highly ionized (charged) while in solution and have a very low molecular weight. Because an RO system does not remove gases, the permeate water can have a slightly lower than normal pH level depending on CO2 levels in the feed water as the CO2 is converted to carbonic acid. The total alkalinity can also be reduced by the RO process and hence yielding aggresive water that can be corrosive to most metals.
Reverse Osmosis is very effective in treating brackish, surface and ground water for both large and small flows applications. Some examples of industries that use RO water include pharmaceutical, boiler feed water, food and beverage, metal finishing and semiconductor manufacturing to name a few.
We supply standard equipment packages that comply to raw water specifications as outlined below. For water specifications that do not comply these specifications, we add a pre-filtration package to ensure optimum performance of the RO-system and limit membrane fouling.
Membrane fouling is the main cause of permeate flux decline and loss of product quality in reverse osmosis (RO) Systems, so fouling control dominates RO system design and operation. Sources of fouling can be divided into four principal categories: scale, silt (particular), bacteria (bio fouling, growth of bacteria) and organic fouling (oil, grease).
Fouling control involves pre-treatment of the feed water to minimize fouling as well as regular cleaning to handle fouling that still occurs. Fouling by particulates (silt), bacteria and organics generally affects the first modules in the plant the most. Scaling is worse with more concentrated feed solutions, therefore the last modules in the plant are most affected, because they are exposed to the most concentrated feed water.
Silt density Index( SDI)
Silt is composed by suspended particulates of all types that accumulate on the membrane surface. Sources of silt are organic colloids, iron corrosion products, precipitated iron hydroxide, algae, and fine particular matter. Silt Density Index testing is a widely accepted method for estimating the rate at which colloidal and particle fouling will occur in water purification systems, especially using reverse osmosis (RO) or Nanofiltration membranes.
Feed Water Quality Requirements: