Technical Support

Service Philosophy: Based on concept of service dedication, Keensen established an one-stop customer centralized service system, created a worry-free brand, providing the customer with characteristic, fast, high-quality and credible service through attentive service concept, concentrated service image, patient service attitude and careful service process. The customers can fully experience Keensen’s perseverance and responsibility.

Service Including:

• OEM or ODM Service for Flat Sheet and Membrane Element.
• Model Selection and Calculation for Flat Sheet Membrane and Element.
• Water Quality Analysis and Tests Training.
• Bug Diagnosis and Analysis of Membrane System.
• Designs and Evaluations of Membrane System.
• Membrane System Maintenance and Staff Training.

1. Application Fields

2. Guide to Design of RO and NF System

According to the water quality of feed and requirements of output, users need to design the membrane system with reasonable recovery rate and permeate flow in unit membrane area by applying suitable model membranes to achieve the high efficiency.

If the designed permeate flow of unit area is much higher than the reasonable value, it will greatly rises the membrane fouling rate and reduces the permeate flow, at the same, the membrane system will need much more extra cost for maintaining. To extend membranes service life, the recovery rate should be designed with 15%. However, some users need to design the higher recovery rate (over than 18%) to improve the system efficiency. Therefore, it is necessary to choose the reasonable array about membrane system to achieve the higher system recovery rate. Such as series or parallel design which can extend the membranes service life and also save the energy.

Detailed design advice:

1. As for the single membrane system, the system recovery rate can improved to 50% by adjusting the backflow device of concentrated water; if the membrane system designed recovery rate is higher than 18% without concentrated water backflow device, the membranes cannot achieve the best performance and it will lead to fouling or damage for membrane.

2. As for single stage membrane system (Single pressure vessel), it can adopt series design with two or more membranes to improve the membrane system recovery rate. But the system recovery rate should be higher than 50 %( Sea Water should be higher than 45%)

3. As for multi-stage membrane system, it can achieve the high recovery rate by designing membrane housing in series, or first connected in parallel then connected in series. The detailed suggestion as below:

For 1-2 core pressure vessels, recovery rate of membrane system can achieve to 40-60% by using three stage arrays (4:2:1)

For 3-5 core pressure vessels, recovery rate of membrane system can achieve to 55-70% by using 2 stage arrays (2:1).

For 6 core pressure vessels, recovery rate of membrane system can achieve to 75% by using 2 stage arrays (2:1).

For 6 core pressure vessels, recovery rate of membrane system can achieve to 85%-90% by using three stage arrays (4:2:1).

Note: It is normal the membrane element will be still fouled by contaminants and decrease

permeate flow and rejection rate of system after long period of correct running.

3. Feed Quality Requirements of RO and NF Membrane System

As a kind of new type physical desalination technology, membranes have special structure, material and desalination mechanism. So quality of feed has strict requirements, which is crucial to maintaining the good separation performance, extending the working life and economize the operating cost.

Note:

1. Membrane has a certain residual chlorine resistance capability (200-1000ppm HR), and when it’s in the different temperature, pH value and other conditions, the damage speed of residual chlorine is different to aromatic polyamide membrane. Hence, it must keep the residual chlorine of feed water under 0.1mg/L;

2. Iron and manganese in feed cannot higher than 0.05mg/L. They usually dissolved in water with bivalent or present with insoluble trivalent hydroxide. If the concentration of iron and manganese are higher than 0.05mg/L, and they are oxidized by air to form the Fe (OH) 3 and Mn(OH)2, precipitate will be existed in the membrane system when the pH value is higher than standard level.

3. Silicon usually exists in most of nature water with 1-100mg/L concentration. When the pH value is lower than 9.0, Silicon will be exist in Si (OH)4. When the pH value is too low, it will form colloidal silica. When the pH value is higher than 9.0, it will exist in SiO32- or form hydrate precipitation through combine with calcium, magnesium，iron, or plumbum.

4. Water alkalinity is mainly formed by HCO3-. When the pH Value is higher than 8.3, HCO3- will transfer to be CO32- . Raw water will be concentrated in the process of RO and NF system, so CaCO3 is easy to form the scaling matter in the system.

5. If one or more above indicators in non-compliance, which may have following influence for membranes or permanent damage.

• Membrane elements are oxidized by residual chloride or contaminated by metal oxide.
• Suspended solid may plug the membrane elements, even following with serious colloidal contamination.
• An increasing output of CODcr may occur as a result of organic and microbiological contamination.