RO stands for reverse osmosis, which is a sort of water purification technology that uses semipermeable membranes to exclude particles, germs, and colloids while allowing water molecules to freely move in relation to dissolved constituents (such as dissolved salts, silica, boron, and many organic impurities). The membranes allow passage of water while prohibiting passage of water contaminants under the influence of an applied hydraulic pressure and at a pressure difference greater than the osmotic pressure of the source water.
As fresh water supplies become scarce, using sea water becomes increasingly appealing. Reverse osmosis (RO) is becoming a more effective and cost-effective desalination technology thanks to new technologies. Using an effective pretreatment system to increase the quality of the feed water that passes through the RO membranes can help your membrane system function better.
REVERSE OSMOSIS MEMBRANE
An commercail RO plant membrane is at the heart of every Reverse Osmosis plant installation, and it is critical to the system's proper operation. If the membrane is damaged in any manner, it might result in decreased productivity, higher operating expenses, and poor water quality.It is consequently critical to keep the membrane safe, clean, and free of impurities so that it can perform at its best.
RO MEMBRANE COMPOSITION
The majority of RO membranes are made of hollow fiber or thin film composite sheets, with the membrane allowing purified water to pass through while rejecting any dissolved particles or pollutants in the feed water.
RO MEMBRANE POLLUTANTS
The solids concentration rises as the raw water flows over the membrane, and some sparingly soluble salts begin to exceed their solubility and precipitate.When these salts precipitate on the membrane surface, fouling occurs, resulting in decreased output and increased water conductivity.
COMMON CAUSES OF PREMATURE MEMBRANE FAILURE
Solids of many forms can cause membrane breakdown. Diatoms, often known as brown algae, are one of the most common causes. Diatoms can be spine-shaped, and the high operating pressure required for RO applications might cause them to pierce membranes. Algal blooms also add organic materials into the system, some of which sticks to the membranes and feeds bacteria development. As a result, an environment conducive to biofouling is created, which is exceedingly bothersome and difficult to control, not to mention expensive.
CALCIUM CARBONATE AND CALCIUM SULPHATE
Calcium carbonate and calcium sulphate are the most problematic of these solid membrane pollutants, therefore preventing their precipitation is critical if the membrane is to operate properly. Traditionally, the method for preventing calcium carbonate and calcium sulphate precipitation in the RO membrane was to pre-treat the feed water with sulphuric acid to "de-alkalize" it and therefore avoid calcium carbonate precipitation.
Sulphuric acid, on the other hand, is dangerous because it raises the sulphate concentration and makes the water more corrosive on both sides of the membrane. This reduced the RO plant's recovery rate, prevented calcium sulphate precipitation, but also reduced the plant's efficiency, resulting in higher operating costs.
RESIDUAL IRON LEVELS
It's also standard operating procedure to keep residual iron levels in RO supply water as low as possible, usually below the membrane manufacturer's maximum limit.Precipitated iron acts as a membrane foulant, reducing the effectiveness of many membrane scale inhibitors. With this in mind, it's critical to create chemical and reverse osmosis maintenance programs that can meet all of the aforementioned requirements in order to assure peak plant efficiency and trouble-free operation.
RO MEMBRANE ANTISCALANTS
NETSOL’s technical experts recommended using an appropriate RO membrane anti-scalant to overcome these issues and boost plant performance.
Anti-scalants for membranes should have the following characteristics-
- Safe to handle and utilize.
- Scale prevention that works
- Compatible with membranes
- Suitable for a wide pH range
- Other RO products are compatible.