How To Choose Ro Membrane

How To Choose RO Membrane: Optimizing your water purification system depends on this key decision. Whether you are a homeowner, a business owner, or an industrial operator, selecting the right reverse osmosis membrane critically impacts performance, cost, and long-term durability.

What Is an RO Membrane?

The RO membrane is the core component of any reverse osmosis system, designed to remove contaminants such as dissolved salts, bacteria, viruses, and heavy metals from water. It operates on a simple principle: pressure forces water through a semi-permeable membrane, while microscopic pores trap impurities. These trapped contaminants are then flushed away as wastewater. Widely used in residential, commercial, and industrial settings, the performance of the RO membrane determines the entire system’s effectiveness. Therefore, selecting the right membrane is essential when designing or upgrading a water purification system.

How To Choose RO Membrane：Selection of Membrane Elements Based on Inlet Salinity

How To Choose RO Membrane：Selection of Membrane Elements Based on Water Source Quality

How To Choose RO Membrane：Selection Guide

◇ How to Choose an RO Membrane: The Complete Guide to Enhanced RO Membrane Elements

The LP400-LD and ULP400-LD membrane elements feature a new low-pressure-drop 34-mil feed spacer. This design improves surface turbulence, effectively reducing colloidal fouling risk and cleaning frequency.

The ULP440-MAX and LP440-MAX elements maintain original salt rejection while boosting water production by 15% and 20%, respectively, versus conventional products.

The PURO-I element enhances the polyamide layer’s cross-linking strength. This provides a broader chemical cleaning pH range and improves fouling resistance.

The PURO-II element offers increased chemical cleaning resistance. Its new LD low-pressure-drop spacer design further enhances fouling resistance.

The PURO-FRLE is an ultra-low-pressure, fouling-resistant RO membrane. It maintains anti-fouling performance while offering low energy consumption, making it suitable for purifying industrial water like electronics wastewater and surface water.

Model	Water yield		Steady removal rate	Membrane area		Inlet screen
	GPD	m3/d	%	ft2	m2	mil
LP440-MAX	12500	47.3	99.7	440	40.9	28
LP400-LD	10500	39.7	99.7	400	37.2	34-LD
ULP440-MAX 1	12000	45.4	99.5	440	40.9	28
ULP400-LD 1	10500	39.7	99.5	400	37.2	34-LD
PURO-I	10500	39.7	99.75	400	37.2	34
PURO-II	11500	43.5	99.8	400	37.2	34-LD
PURO-FRLE2	10500	39.7	99.6	400	37.2	34-LD

Test Conditions:

• LP440-MAX, LP400-LD, PURO-I, PURO-II: Operating Pressure 225 psi (1.55 MPa), 2000 mg/L NaCl, Temperature 25°C, pH 7.0 ±0.5, Recovery 15%
• ULP440-MAX¹, ULP400-LD¹: Operating Pressure 150 psi (1.03 MPa), 1500 mg/L NaCl, Temperature 25°C, pH 7.0 ±0.5, Recovery 15%
• PURO-FRLE²: Operating Pressure 150 psi (1.03 MPa), 2000 mg/L NaCl, Temperature 25°C, pH 7.0 ±0.5, Recovery 15%

Operating Limits:

• Maximum Operating Pressure: 600 psi (4.14 MPa)
• Maximum Feedwater Temperature: 45°C
• Maximum Feedwater SDI₁₅: 5
• Feedwater Free Chlorine Concentration: <0.1 mg/L
• Maximum Pressure Drop per Element: 15 psi (0.1 MPa)
• Chemical Cleaning pH Range: 1-13 (Operating Feedwater pH Range: 2-11)
  • Note for ULP440-MAX/ULP400-LD¹: Chemical Cleaning pH Range: 2-12 (Operating Feedwater pH Range: 3-10)

Note:

• Single element water production tolerance: ±15%
• Note for ULP440-MAX/ULP400-LD¹: Single element water production tolerance: ±20%

◇ How to Choose an RO Membrane for Zero Emissions: The ZERO Series Guide

The ZERO-FR10 is a highly fouling-resistant membrane designed for zero-discharge wastewater reuse with high TDS (5-15 g/L) and COD. It utilizes next-generation separation technology and module design, offering low pressure drop, extended cleaning cycles, and strong chemical resistance.

The ZERO-HP70 is a high-pressure RO membrane developed for feedwater with 15-35 g/L TDS. It enhances pressure resistance while improving surface charge and hydrophilicity.

The ZERO-UHP120 ultra-high-pressure RO membrane concentrates brine with inlet TDS of 35-70 g/L. It operates at up to 120 bar and is suited for zero-discharge, high-salinity applications.

The ZERO-XS90 is a selective, anti-fouling nanofiltration membrane for low-energy recovery of NaCl and Na₂SO₄. It handles high-TDS (35-70 g/L) concentrated brine and supports denitrification in chlor-alkali, desulfurization, and dyeing wastewater.

Model	Water yield		Steady removal rate	Membrane area		Inlet screen
	GPD	m3/d	%	ft2	m2	mil
ZERO-FR10	11500	43.5	99.7	400	37.2	34
ZERO-HP70 1	8800	33.3	99.75	400	37.2	34
ZERO-UHP120 2	7400	28.0	99.7	330	30.7	28
ZERO-XS90 3	8300	31.4	99.0	400	37.2	34

Test conditions:

1.Operating pressure 225 psi (1.55 MPa), 2000 mg/L NaCl, temperature 25°C, pH 7.0 ± 0.5, recovery rate 15%

2.Operating pressure 800 psi (5.52 MPa), 32000 mg/L NaCl, temperature 25℃, pH 8, recovery 8%

3.Operating pressure 100 psi (0.69 MPa), 2000 mg/LMgSO4  solution, temperature 25℃, pH7.0 ± 0.5, recovery 15%

Operating conditions: Maximum operating pressure	600 psi(4. 14 MPa)   11200 psi(8.28 MPa)    21740psi(12.0MPa)
Maximum inlet temperature	45℃
Maximum intake SDI15	5
Free chlorine concentration in influent	<0.1 mg/L
Maximum   pressure   drop   of   a   single   membraneelement	15 psi (0.1 MPa)
Operating influent pH range	2-11             Chemical cleaning pH range 1-13
3 operating influent pH range	3-10 3 Chemical cleaning pH range 2-11

Note: The water production of a single membrane element is ±20%.

◇ How to Choose an RO Membrane: The UE Series for Ultra-Pure Water Systems

The LE-8040UE reverse osmosis membrane element is engineered for ultrapure water production. It provides excellent TOC removal efficiency with minimal TOC leaching. Certified under the Technical Requirements for Product Certification of Coiled Reverse Osmosis Membrane Elements for Ultrapure Water Production in Semiconductor Industry, it is ideal for semiconductor and pharmaceutical applications.

The LE440-UE features a larger effective membrane area. This design meets ultrapure water application requirements while reducing production costs.

The PURO-UE membrane is specifically designed for ultrapure water reuse processes. It offers superior resistance to contaminants in high-pollution wastewater, such as semiconductor industry cleaning effluents.

Model	Water yield		Steady desalination rate	TOC removal rate	Membrane area		Inlet screen
	GPD	m3/d	%	%	ft2	m2	mil
LE-8040UE	11500	43.5	99.5	90.0	400	37.2	34
LE440-UE	12000	45.4	99.3	90.0	440	40.9	28
PURO-UE 1	11500	43.5	99.6	95.0	400	37.2	34

◇ How to Choose an RO Membrane: The SP Series for Food and Beverage Applications

The LP400-SP and ULP400-SP reverse osmosis membrane elements are designed for the food and beverage industry. Their materials comply with the “Hygienic Safety Evaluation Specifications for Drinking Water Distribution Equipment and Protective Materials” (2001). The hygiene permit number is Qian Wei Shui Zi (2023) No.0009.

The VNF400-SPHL nanofiltration membrane removes sulfates while retaining minerals. It is suitable for processing functional beverages.

The VUF400-SP spiral-wound ultrafiltration membrane comes in four MWCO variants: 2K, 6K, 10K, and 20K. These meet different purification needs for functional beverages. The product holds Hygiene Permit No. Qian Wei Shui Zi (2023) 0011.

Model	Water yield		Steady removal rate	Membrane area		Inlet screen
	GPD	m3/d	%	ft2	m2	mil
LP400-SP 1	10500	39.7	99.7	400	37.2	34-LD
ULP400-SP 2	10500	39.7	99.5	400	37.2	34-LD
VNF400-SPHL 3	10500	39.7	96.0	400	37.2	28
Model	Water yield		Molecular cut off	Membrane area		Inlet screen
	GPD	m3/d	Da	ft2	m2	mil
VUF400-SP/2K 4	5500	20.8	2000	400	37.2	31
VUF400-SP/6K 4	6500	24.6	6000	400	37.2	31
VUF400-SP/10K 5	7000	26.5	10000	400	37.2	31
VUF400-SP/20K 5	10500	39.7	20000	400	37.2	31

◇ How to Choose an RO Membrane: The Anti-Pollution FR Series Guide

The FR series anti-pollution RO membranes utilize a special manufacturing process to enhance surface hydrophilicity, charge, and roughness, thereby reducing the adhesion and growth of pollutants and microorganisms.

surface.

Model	Water yield		Steady removal rate	Membrane area		Inlet screen
	GPD	m3/d	%	ft2	m2	mil
FR12-8040	10500	39.7	99.5	400	37.2	34
FR22-8040PRO	11000	41.6	99.7	400	37.2	34
FR400-LD	10500	39.7	99.6	400	37.2	34
FR11-4040	2200	8.3	99.5	90	8.4	34

◇ How to Choose an RO Membrane: The Low-Pressure LP Series

Low-pressure series membrane elements are primarily designed for brackish water desalination, featuring low-pressure operation, high water output, and

excellent desalination performance. They demonstrate superior removal capabilities for dissolved salts, total organic carbon (TOC), and SiO2, making them

ideal for producing high-purity water in the electronics and power industries.

Model	Water yield		Steady removal rate	Membrane area		Inlet screen
	GPD	m3/d	%	ft2	m2	mil
LP22-8040-440	11500	43.5	99.7	440	40.9	28
LP22-8040	10500	39.7	99.7	400	37.2	28
LP22-8040PRO	11000	41.6	99.7	400	37.2	28
LP22-8040/31	10500	39.7	99.7	400	37.2	31
LP21-4040	2800	10.6	99.6	100	9.3	28

Test conditions: Operating pressure 225 psi (1.55 MPa), 2000 mg/L NaCl solution, temperature 25 °C, pH 7.0 ±0.5, recovery rate 15%

Usage conditions: Maximum operatingpressure  and  maxi-mum inflow rate	600 psi (4. 14 MPa)8040-75 gpm ( 17 m3/h)    4040-16 gpm (3.6 m3/h)
maximum inlet temperature	45℃
Maximum intake SDI15	5
free  chlorine  concentration  in
influent	<0.1 mg/L
pH range for chemical cleaningof   single-membrane   element	15 psi (0. 1MPa)
with maximum pressure drop	1-13
operating influent pH range	2-11

Note: The water production of a single membrane element is ±20%.

◇ Ultra-Low Pressure Reverse Osmosis Membrane Element ULP Series

Ultra-low pressure membranes deliver high water flux and removal rates comparable to conventional low-pressure membranes, but at significantly lower operating pressures.Their operating pressure is approximately 2/3 of that of conventional low-pressure membranes, with a removal rate reaching 99.5%.

Model	Water yield		Steady removal rate	Membrane area		Inlet screen
	GPD	m3/d	%	ft2	m2	mil
ULP32-8040-440	12650	47.9	99.3	440	40.9	28
ULP22-8040	12100	45.8	99.0	400	37.2	28
ULP32-8040	10500	39.7	99.5	400	37.2	28
ULP32-8040/31	10500	39.7	99.5	400	37.2	31
ULP21-4040	2600	9.8	99.5	100	9.3	28
ULP31-4040	2000	7.6	99.6	100	9.3	28
ULP21-40211	950	3.6	99.0	36	3.3	28
ULP21-2540	750	2.8	99.0	30	2.8	28
ULP21-25211	300	1.1	99.0	14	1.3	28

◇ How to Choose an RO Membrane: The Ultra-Low Pressure XLP Series

The ultra-low pressure series membrane element can achieve the same high water flux and high removal rate as the conventional low pressure membrane under the ultra-low operating pressure, and its operating pressure is about half of the operating pressure of the conventional low pressure membrane.

Model	Water yield		Steady removal rate	Membrane area		Inlet screen
	GPD	m3/d	%	ft2	m2	mil
XLP12-8040	12800	48.4	99.2	400	37.2	28
XLP11-4040	2600	9.8	99.2	100	9.3	28

Test conditions: Operating pressure 100 psi (0.69 MPa), 500 mg/L NaCl solution, temperature 25 °C, pH 7.0 ±0.5, recovery rate 15%

Usage conditions: Maximum operatingpressure   and   max-imum inflow rate	600 psi (4. 14 MPa)8040-75 gpm ( 17 m3/h)    4040-16 gpm (3.6 m3/h)
maximum inlet temperature	45℃
Maximum intake SDI15	5
free  chlorine  concentration  in
influent	<0.1 mg/L
pH range for chemical cleaningof   single-membrane   element	15 psi (0.1 MPa)
with maximum pressure drop	2-12
operating influent pH range	3-10

Note: The water production of a single membrane element is ±20%.

◇ HOR Series of Anti-Oxidation Reverse Osmosis Membrane Elements

The anti-oxidation  series membrane element is an anti-oxidation polyamide reverse osmosis membrane element independently developed by Wotong Technology. To address the drawback of conventional polyamide reverse osmosis membranes being susceptible to oxidation, a specialized synthesis process was employed to enhance the anti-oxidation properties of the membrane element. This allows for the direct online addition of biocides into the membrane element, enabling the reverse osmosis system to achieve complete sterilization.

Model	Water yield		Steady removal rate	Membrane area		Inlet screen
	GPD	m3/d	%	ft2	m2	mil
HOR22-8040	9000	34.0	99.5	400	37.2	28
HOR21-4040	2200	8.3	99.5	90	8.4	28

◇  How to Choose an RO Membrane: The SW Series for Seawater Desalination

The  series  of seawater  desalination membrane  elements  achieve  a performance balance between  desalination  efficiency  and water production through precise control of the separation layer. The optimized design of the membrane element configuration enhances the pressure-bearing capacity of the components. These elements feature stable performance, low-pressure energy efficiency, and a comprehensive range of specifications. They are suitable for small-scale seawater desalination equipment, large-scale seawater desalination projects, high-salinity water concentration reduction, and the concentration of high-concentration materials.

Model	Water yield		Steady removal rate	Membrane area		Inlet screen
	GPD	m3/d	%	ft2	m2	mil
SW8040XHR-400	6000	22.7	99.85	400	37.2	28
SW8040XHR-440	6600	25.0	99.85	440	40.9	28
SW8040FR-400	8200	31.0	99.8	400	37.2	34
SW8040HR-400	7500	28.4	99.8	400	37.2	28
SW8040HR-440	8250	31.2	99.8	440	40.9	28
SW8040LE-400	9000	34.0	99.8	400	37.2	28
SW8040LE-440	9500	35.9	99.8	440	40.9	28
SW8040XLE-400	11000	41.6	99.7	400	37.2	28
SW8040XLE-440	12100	45.8	99.7	440	40.9	28
SW4040HR	1600	6.1	99.8	90	8.4	28
SW4040LE	1900	7.2	99.7	90	8.4	28
SW11-40211	750	2.8	99.5	33	3.1	28
SW11-25211	270	1.0	99.5	12	1.1	28
SW11-2540	600	2.3	99.5	28	2.6	28
SW21-2540	800	3.0	99.7	28	2.6	28

◇ Hot Disinfection Reverse Osmosis Membrane VHD Series

The VHD thermal disinfection reverse osmosis membrane is designed for pasteurization in the food and pharmaceutical industries. It features a hygienic mesh outer shell and accessories to eliminate stagnant water zones between the membrane element and its housing.The product has obtained the “Hygienic License Approval for Products Involving Drinking Water Hygiene Safety”.

Model	Water yield		Steady removal rate	Membrane area		Inlet screen
	GPD	m3/d	%	ft2	m2	mil
VHD-8040/34G	9000	34.0	98.0	400	37.2	34
VHD-4038G	2100	7.9	98.0	90	8.4	28