Membrane treatment for reverse osmosis systems
Membrane units, these days are widely used in the water pre-treatment preparation and are becoming one of the most important technologies in the production of highly purified water. Nevertheless, these systems often face problems with scaling and fouling and are therefore limited by frequent maintenance, downtime and high costs. Our membrane treatment solution programs are specifically designed for membrane units like reverse osmosis, ultrafiltration and nanofiltration and enable the removal or prevent scale and fouling deposits. Our main target is to run these plants under environmentally friendly and beneficial economic conditions. Special attention is given to an efficient utilization of energy as well as saving precious water. Kurita develops an efficient and effective treatment concept achieving an optimal economic operation and a maximum operational reliability of a plant.
Membrane units are used in various sectors of industry:
- Surface technologies (cutting fluids, tooling oils, emulsions, cataphoresis baths, phosphating baths, painting, cleaning baths)
- Seawater desalination
- Waste water recovery system
- Boiler water preparation
- Food and Beverage
- Metals and Mining
- Municipal Drinking Water
What kind of products does Kurita offer?
Our comprehensive product range enables Kurita to specifically target contaminants that would otherwise impact system operation.
Biocides control agents
Why choose Kurita?
Our solutions prevent deposition, reduce the cleaning frequency and downtime and help you save costs. Our strength is our ability to offer you not only the chemicals but also procedures designed to give you the benefit of more than 65 years of experience. Our field experience and our technical facilities with the most advance equipment and facilities in membrane autopsy will help you to find a customized solution for your system.
Consultancy and Service
A thorough understanding of the design and the operation of a reverse osmosis installation is the basis for a successful treatment concept. According to this principle, we perform the following investigations in our scientific research laboratories:
Based on these comprehensive preliminary investigations it is possible to select the most suitable biocides, antiscalants and cleaning chemicals, and thus to operate a plant in an economical and environmentally friendly way.
*Attention: Use biocides safely. Always read the label and product information before use.
A regular monitoring of the operational plant performance, as well as a regular maintenance, are basic preconditions for a trouble-free operation. Scaling within reverse osmosis (RO) membranes is a serious matter, scaling can drastically reduce system performance and the abrasive scale deposits may case irreversible damage to the rejecting membrane surface. Furthermore, the membranes need to be protected against fouling and scaling in order to maximize their lifetime and avoid unnecessary and undesired stops.
We select the most effective antiscalant for each specific application and supply water quality. Our antiscalants offer excellent inhibiting effects for:
- Colloids and suspended matter
- Iron and manganese
- Calcium carbonate
- Calcium sulfate
- Strontium sulfate
- Barium sulfate
Our product portfolio includes antiscalants with NSF certification.
Biological, organic and inorganic contaminants present in the supply-water deposit on the surface of membranes. The deposition of the contaminants from an impure supply water on a membrane surface is generally referred to as “fouling”. The adsorption of micro-organisms to the surface of membranes is designated as “biofouling”. Biofouling is particularly problematic since micro-organisms can reproduce and grow in an exponential way over the membrane surface. The consequences: the efficiency of the plant suffers significantly and can produce irrecoverable damage to the membranes.
In order to prevent the process of biofouling effectively, the addition of biocides and biofouling daily control agents are essential and highly recommended. Kurita has developed special biocides* which substantially contribute to the economical operation of reverse osmosis plants. Our technology is characterized by:
- Low dosing rates
- Dispersion of existing biofilms
- Prevention of germ resistance
The stress-load of a plant should be reduced as much as possible by an effective pre-treatment of the feed water. Depending on the raw-water quality suitable pre-treatments are coagulation, flocculation, sedimentation, filtration etc.
Colloids and silt fouling are major causes of performance decline in RO membrane systems. As a result, many system designs include upstream Multimedia Filtration (MMF) to enhance particulate removal and improve the feedwater quality to downstream membranes systems. Membrane compatible coagulants improve efficiency of MMF equipment by increasing particulate removal.
Kurita has a broad and deep expert-knowledge as well as specifically developed and innovative products for these treatment steps. With various analytical methods, e.g. SDI-measurements, the appropriate products can be selected already in specific lab-tests.
An effective pre-treatment of water is the basis for a smooth operation of the reverse osmosis plant. However, it cannot completely prevent the membranes from fouling and scaling, which decreases the membrane’s performance. This, in turn, increases the energy demand of the plant substantially while the quality of the produced water diminishes. This performance loss results from colloidal and microbiological depositions as well as from deposits of metal hydroxides. Also, deposits of CaCO3, CaSO4, SIO2, BaSO4 and CaF2 reduce the yield of permeate.
It is, therefore, necessary to clean the membranes regularly. Cleaning membranes in RO systems removes mineral scale, organic matter, biological growth, colloidal particles, and/or insoluble constituents which build on or in a membrane element. Specific demands require individual solutions for the proper cleaning procedure. Kurita performs a range of preliminary investigations, like membrane autopsy, in order to develop a suitable cleaning procedure for your system in order to extend reverse osmosis membranes live and avoid unnecessary replacements. The following aspects are of importance:
- Avista Membrane Autopsy
- Performance tests
- Analyses of water
- Purification tests
- Analyses of deposits