Introduction:

Reverse osmosis filters play a crucial role in water treatment in various fields, from industrial production to drinking water treatment, from laboratory research to the food processing industry. However, different application scenarios have different requirements for reverse osmosis filters, so the correct selection is crucial for ensuring efficient system operation, ensuring water quality, and reducing costs. This article will elaborate on various aspects that need to be considered when selecting a reverse osmosis filter, including water source characteristics, treatment water volume, water quality requirements, equipment configuration, to help users make informed decisions.

Analysis of Water Source Characteristics:

1. Water source type

surface water

Surface water includes water from rivers, lakes, reservoirs and other water bodies. These types of water sources typically contain high levels of organic matter, microorganisms, suspended solids, and colloidal substances. For example, water in rivers may carry large amounts of sediment, humus, and pollutants from the surrounding environment.

When performing reverse osmosis treatment on surface water, the pretreatment system needs to focus on removing these impurities, which may require the configuration of more powerful multi-media filters and activated carbon filters to prevent fouling of the reverse osmosis membrane.

groundwater

Groundwater is relatively stable, but its hardness is often high, and it may contain a large amount of calcium, magnesium ions, and other minerals.

For the treatment of groundwater, the softener is particularly important in the pretreatment stage to avoid the formation of scale on the surface of the reverse osmosis membrane.

Municipal tap water

Municipal tap water has been treated to a certain extent, but it may still contain residual chlorine, small amounts of organic matter, and microorganisms.

At this point, the main function of the activated carbon filter is to remove residual chlorine while also taking into account the removal of organic matter.

2. Water quality indicators of water sources

hardness

Hardness is an indicator for measuring the content of calcium and magnesium ions in water. High hardness water is prone to scaling on the surface of reverse osmosis membranes, affecting their performance and service life.

According to the hardness, different types of softeners can be selected or the operating parameters of the reverse osmosis system can be adjusted (such as increasing the flushing frequency) to cope with it.

turbidity

Turbidity reflects the content of suspended solids and colloidal substances in water. Higher turbidity requires more efficient multi-media filters to reduce turbidity and protect the reverse osmosis membrane.

Organic content

The type and content of organic matter in water have a significant impact on reverse osmosis systems. If the organic content is high, it is necessary to choose activated carbon with better adsorption performance or consider adding other pre-treatment equipment for removing organic matter.

Microbial indicators

The presence of microorganisms may lead to biofouling of reverse osmosis membranes. For water sources with high microbial content, in addition to conventional pretreatment, it is also possible to consider adding sterilization and disinfection equipment to the pretreatment system, or installing ultraviolet sterilizers after the reverse osmosis system.

Processing water demand:

1. Determine the average and peak water treatment capacity

Average water treatment capacity

Calculate the average water consumption per unit time (usually in hours, days, or months) based on production processes, domestic water demand, or daily usage in other application scenarios.

This is one of the basic criteria for selecting the scale of reverse osmosis filters, ensuring that the system can meet daily basic needs

.

Peak processing water volume

Considering that in certain special circumstances, such as peak periods in industrial production and residential water usage (such as morning and evening), water usage may suddenly increase.

When selecting, it is necessary to ensure that the reverse osmosis system can operate normally at peak flow rates to avoid situations of insufficient water supply. Usually, the design flow rate of a reverse osmosis system should be greater than the peak flow rate.

2.Select equipment scale based on water treatment capacity

Small scale system

If the processing water volume is small (for example, below a few cubic meters per hour), a single-stage reverse osmosis system can be selected, equipped with smaller specifications of reverse osmosis membrane components and corresponding supporting equipment.

This type of small-scale system is typically suitable for small factories, small commercial spaces, or household use.

Medium sized system

For situations with moderate water treatment capacity (several tens of cubic meters per hour), it may be necessary to use a multi-stage reverse osmosis system or parallel multiple single-stage reverse osmosis membrane components to meet the requirements of water treatment capacity.

Medium sized systems are more common in medium-sized industrial enterprises, larger commercial buildings, and other places.

Large scale systems

When dealing with large amounts of water (hundreds of cubic meters per hour or even higher), it is necessary to design a large-scale reverse osmosis water treatment plant.

This may involve complex system layouts, including multiple reverse osmosis hosts, large pre-processing equipment, and sophisticated post-processing systems. Large scale systems are mainly applied in fields such as large-scale industrial production and urban water supply.

Analysis of Water Quality Requirements:

1. Water quality requirements for different industries

Electronic industry

In the electronics industry, especially in the semiconductor and integrated circuit manufacturing fields, there are extremely high requirements for water quality. The impurity content in water must be extremely low, usually requiring a resistivity of at least 18 megaohms per centimeter.

To meet such requirements, it is necessary to choose high-performance reverse osmosis membranes and equip them with a combination of multiple water treatment processes such as multi-stage reverse osmosis and ion exchange.

Pharmaceutical industry

The pharmaceutical industry also has very strict requirements for water quality, not only to remove impurities, salts, and microorganisms from the water, but also to ensure that there are no heat source substances in the water.

In addition to conventional reverse osmosis treatment, it is also necessary to add process steps such as ultrafiltration and sterilization after reverse osmosis, and have higher requirements for the material and quality of the reverse osmosis membrane.

In the field of drinking water

For drinking water, the main requirement is to remove harmful substances such as heavy metals, organic matter, bacteria, and viruses from the water, while ensuring a good taste.

General reverse osmosis filters can meet basic drinking water treatment needs, but if there are higher requirements for taste, equipment that improves taste can be added to the post-treatment system.

2.Select reverse osmosis membrane according to water quality requirements

Desalination rate of reverse osmosis membrane

Desalination rate is one of the key performance indicators of reverse osmosis membranes. For industries with high water quality requirements, such as electronics and pharmaceuticals, it is necessary to choose high desalination rate reverse osmosis membranes with a desalination rate of over 99%.

For some fields with relatively low requirements for salt removal, such as certain industrial flushing water, reverse osmosis membranes with slightly lower desalination rates can be chosen to reduce costs.

Material of reverse osmosis membrane

At present, common materials for reverse osmosis membranes include polyamide, cellulose acetate, etc. Polyamide membranes have high desalination rates and good mechanical strength, but are sensitive to residual chlorine; Cellulose acetate membrane has good tolerance to residual chlorine, but its desalination rate is relatively low.

According to the residual chlorine content in the water source and water quality requirements, suitable materials for reverse osmosis membranes can be selected.

Equipment configuration selection

1.Preprocessing system configuration

Multi media filter

Select the appropriate specifications for the multi-media filter based on the turbidity and suspended solids content of the water source. If the turbidity is high, the filter layer thickness can be increased or multi-stage multi-media filtration can be used.

At the same time, the backwashing method and frequency of the filter should also be considered to ensure its long-term stable operation.

Activated carbon filter

Determine the amount and type of activated carbon filling for the activated carbon filter based on the content of organic matter and residual chlorine in the water. For water sources with high organic content, coconut shell activated carbon with stronger adsorption performance can be chosen.

Regularly monitor the adsorption performance of activated carbon and replace it in a timely manner to ensure its removal efficiency.

Softener

Choose a suitable capacity softener based on the hardness of the water source. The amount of ion exchange resin used in the softener can be determined by calculating the content of calcium and magnesium ions in the water.

For water sources with large fluctuations in hardness, automatic regeneration softeners can be considered to ensure the stability of the softening effect.

2. Reverse osmosis host configuration

High pressure pump

Select a high-pressure pump with appropriate power and flow rate based on the scale of the reverse osmosis system and the required operating pressure.

Considering energy conservation and operating costs, a variable frequency high-pressure pump can be chosen to adjust the pump's speed and power according to actual operating conditions.

Reverse osmosis membrane module

Select appropriate quantities and specifications of reverse osmosis membrane components according to the requirements of water treatment capacity and quality. At the same time, the arrangement of membrane components (such as one-stage, one-stage, multi-stage, multi-stage, etc.) should be considered to optimize system performance and reduce costs.

Membrane shell

The selection of membrane shell should match the reverse osmosis membrane components to ensure that the membrane components can be safely and stably installed inside the membrane shell. At the same time, the pressure resistance and material of the membrane shell should be considered to adapt to different operating environments.

3.Post processing system configuration

Pure water tank

Select a pure water tank of appropriate capacity based on the user's water demand and the system's water production capacity. The material of the pure water tank should comply with food hygiene standards or relevant industry standards.

UV sterilizer

If there are strict requirements for microbial indicators, a UV sterilizer with appropriate power and flow rate can be selected. Regularly replace ultraviolet lamps based on their sterilization effect and lamp lifespan.

Precision filter

Select a precision filter with appropriate precision according to the requirements for effluent clarity. Usually, setting a precision filter of 0.1-1 micron after the reverse osmosis system can effectively remove residual small particles.

Conclusion:

The selection of reverse osmosis filters is a complex process that requires comprehensive consideration of water source characteristics, treatment water volume, water quality requirements, and equipment configuration. Through detailed analysis and evaluation of these factors, combined with the needs of practical application scenarios, the most suitable reverse osmosis filter can be selected to ensure that the system can operate efficiently, stably, and economically, providing users with high-quality water resources. During the selection process, users can consult professional water treatment equipment suppliers and technical experts to obtain more information and advice, in order to make more informed decisions.

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