What should be considered when purchasing surface water reve

DAWT·2022-03-28

With the entry into a well-off society in an all-round way, the problem of food and clothing has been solved, people's living standards have improved, and a healthy lifestyle has been advocated. Water health issues have received attention. The reverse osmosis system is an effective pure water purification technology today, which is widely used in urban drinking water, enterprises and institutions, electronic industry, medical industry, seawater, brackish water desalination and other process water. As we all know, if the reverse osmosis water treatment equipment is used for a long time, it will be polluted, the quality of the effluent will be deteriorated, and it needs to be cleaned and maintained. Therefore, when selecting reverse osmosis equipment, the balance between equipment investment and operating costs should be considered, which can not only ensure the water production and water quality, but also reduce energy consumption and cleaning frequency.

The main factors affecting the pollution rate of surface water reverse osmosis water treatment equipment are:

1. Type of membrane material (cellulose acetate membrane or polyamide membrane)

Common reverse osmosis membranes on the market are divided into: CAB series (cellulose acetate) membrane elements or CPA series (aromatic polyamide) membrane elements. For difficult-to-treat surface water or wastewater systems, CAB membranes are often used instead of CPA membranes. The advantages of CAB membrane are that the membrane surface is smooth and uncharged, which can reduce the deposition of pollutants during use, and microorganisms are not easy to stick to its surface. The CAB membrane also has the advantage that the feed water can contain 0.3-1.0 ppm free chlorine during operation. Chlorine acts as a disinfectant to protect CAB membranes from harmful bacteria and also prevents fouling due to microbial and algal growth. The CPA film itself is resistant to chlorine, but not its oxidizing properties. Therefore, chlorine removal is required.

2. Water flux:

Permeate flux is the amount of permeate per effective area of ​​membrane surface, expressed in GFD (gallons per square foot per day) or LMH (liters per square meter per hour). There is a proportional relationship between the water flux of reverse osmosis equipment and the pollution rate. When the water flux is low, the pollution rate is low; on the contrary, when the water flux increases, the pollution rate increases. To reduce the water flux, a reverse osmosis membrane element with a larger membrane area can be selected.

According to the experience of Zhongdio's manufacturers, if it is cleaned every three months or longer, it indicates that the design of the pretreatment and reverse osmosis system is reasonable. If the equipment needs to be cleaned every 1 to 3 months, the process should be improved or the equipment should be added.

3. Transverse flow velocity:

Lateral flow velocity is also an important factor affecting the fouling rate of reverse osmosis equipment. The higher the lateral velocity of the surface feed water and the concentrated water produced by it on the membrane surface, the lower the membrane fouling rate. This is because the high lateral flow rate of influent reduces the precipitation and accumulation of particulate matter on the membrane surface, and at the same time accelerates the diffusion rate of high-concentration salts on the membrane surface to the bulk solution, reducing the risk of insoluble salt precipitation.

Fourth, reverse osmosis cleaning:

Cleaning and maintenance of reverse osmosis water treatment equipment can effectively prevent the speed of equipment pollution. The methods include concentrated water recirculation, low-pressure flushing out of operation, and regular disinfection.

The RO equipment produces water for rinsing and short-term soaking of the membrane elements, which can inhibit bacterial growth, dissolve contaminants on the membrane or loosen it.

Recirculation of concentrated water can increase the lateral flow rate and wash away the pollutants on the membrane surface; but it increases the capacity of the RO feed pump and increases the salt content of the water produced by the equipment.

Low-pressure cleaning when the equipment is out of service can flush pollutants and concentrated water from the membrane elements to prevent the growth of microorganisms.

The purpose of regular disinfection is to control microbial growth between cleanings.

5. Structure of reverse osmosis membrane element:

Reverse osmosis water treatment equipment is used for the purification of well water and surface water. The membrane elements selected for the equipment are mainly roll-type membrane elements. Under the comprehensive consideration of the anti-pollution ability of the water supply channel, equipment space requirements, investment and operation costs and procurement, the roll-type membrane elements Elements outperform hollow fiber and plate-and-frame structures. Designing a large membrane area is beneficial to reduce the water flux and increase the lateral flow velocity, and suppress the speed of equipment fouling.

The selection of reverse osmosis water treatment equipment has many considerations, professional things, let professional people do it, welcome to consult Xi'an Dior Environmental Protection Technology, telephone 400-63-8018, you provide your needs, I will provide equipment.