Reverse osmosis water treatment system and water treatment method

Abstract

The invention relates to a reverse osmosis water treatment system. The reverse osmosis water treatment system comprises a reverse osmosis treatment device and a filtration device, wherein a water inlet end of the filtration device is connected with a concentrated water outlet end of the reverse osmosis treatment device; a produced water outlet end of the filtration device is connected with a water inlet end of the reverse osmosis treatment device. The invention also relates to a method for performing water treatment by using the water treatment system. According to the reverse osmosis water treatment system and the water treatment method, the treatment load of the filtration device can be obviously reduced, the energy consumption is reduced, the cost is greatly reduced, and the water treatment system runs more relatively.

Description

technical field [0001] The invention relates to the field of water treatment, in particular to a water treatment system and a water treatment method using the water treatment system. Background technique [0002] At present, commonly used water treatment technologies include ultrafiltration, microfiltration, nanofiltration and reverse osmosis. Among them, the reverse osmosis (RO) desalination process drives water through a semi-permeable membrane through pressure, and traps ions in the water on the other side of the membrane, thereby realizing the separation of water and soluble salts in the water. The entire process of reverse osmosis desalination has no phase change, no heat source is required at room temperature, and no regeneration agent is added. The desalination rate can reach more than 97%, the filtration accuracy is extremely high, and the safety is the best, so it is widely used. [0003] However, the conventional water recovery rate of reverse osmosis desalination...

AI Technical Summary

Problems solved by technology

However, the HERO system still has the following main problems: 1) It operates under alkaline conditions such as pH 8.5-11, which makes the reverse osmosis membrane in alkaline chemical cleaning conditions for a long time, so the service life will be significantly shortened and the system economy will be reduced; 2) The conventional aromatic polyamide reverse osmosis membrane generally achieves the highest desalination rate when the pH value of the reverse osmosis feed water is in the neutral range. When the pH of the feed water is low or high, the desalination rate will drop and affect the reverse osmosis. The effluent water quality of the membrane, especially for the reverse osmosis membrane of the HERO system operating under alkaline conditions, the higher the recovery rate of the system, the more obvious the decline in the desalination rate; 3) When applied to sewage reuse, the influent water of the reverse osmosis membrane contains a small Ammonia nitrogen, or NH 4 + and NH 3 The water balance system, in this case, adjust the feedwater to be alkaline. On the concentrated water side of the reverse osmosis membrane, the pH value of the effluent of the reverse osmosis will be higher than the pH value of the feedwater due to the influence of ammonia nitrogen, while the pH value of the concentrated water will be lower than that of the reverse osmosis membrane. The pH value of the influent water, and the higher the recovery rate of RO, the more obvious this trend is, which makes the alkaline operating conditions required by the system unable to be guaranteed; 4) The system uses a roll-type reverse osmosis membrane, which is limited by the current reverse osmosis membrane At present, the maximum water pressure that the membrane can withstand is 69-83bar, and the salt content on the concentrated water side of the reverse osmosis membrane reaches 50000-70000ppm. Under normal circumstances, the salt content on the concentrated water side of the HERO system will reach 100,000ppm or above, and the osmotic pressure is too high for the system to withstand

The disadvantage of this treatment process is that both nanofiltration and reverse osmosis require pressurization and high energy consumption; the pre-nanofiltration treatment needs to handle 100% of the influent load, and the number of nanofiltration membranes required is large, and the investment is relatively high. Larger; the greater the reverse osmosis concentrated water return flow, the greater the processing load of the nanofiltration membrane, which may be greater than 100% of the influent load. If the concentrated water from the RO process and the NF process are both discharged, only the water produced by the RO process is recovered. The feed water load of the filter membrane can be reduced, but the total recovery rate of the system is also significantly reduced

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