Cleaning method of ultrafiltration membrane in sea water desalination by whole membrane technology

Abstract

The invention belongs to the technical field of sea water desalination and water treatment, and relates to a cleaning method of an ultrafiltration membrane in sea water desalination by the whole membrane technology. The cleaning method comprises the following steps of: transporting pre-treated sea water to a raw water inlet of an ultrafiltration device; mixing with ultrafiltration circulating concentrated water transported by an ultrafiltration circulating pump, wherein the mixture enters into the ultrafiltration device to be filtered to obtain ultrafiltration water entering into a closed ultrafiltration water buffer tank; then, transporting the ultrafiltration water by a low pressure pump, wherein one part of the water flowing through a security filter is pressurized by a high pressure pump and enters into a nanofiltration / reverse osmosis device through a check valve, while the residual water enters into an energy recovering device and exchanges energy with concentrated water of the nanofiltration / reverse osmosis device, then is transported to the nanofiltration / reverse osmosis device through the pressurizing pump to prepare nanofiltration / reverse osmosis water; feeding nanofiltration / reverse osmosis water after energy exchange into an ultrafiltration cleaning water tank, and discharging residual concentrated water through an overflow opening on the upper part of the ultrafiltration cleaning water tank. The cleaning method is reliable in process, simple and convenient to operate, lower in energy consumption, good in economic and social benefits and environment-friendly.

Description

Technical field: [0001] The invention belongs to the technical field of seawater desalination and water treatment, and relates to a method for cleaning an ultrafiltration membrane and realizing seawater desalination by using the concentrated brine discharged from nanofiltration / reverse osmosis seawater softening technology, in particular to a method for desalination of seawater by a full-membrane method Ultrafiltration membrane cleaning method. Background technique: [0002] The full-membrane method is a new seawater desalination technology that has emerged in recent years. Ultrafiltration (UF) is used as a pretreatment process, and the water produced is further separated by nanofiltration (NF) or reverse osmosis (RO). Industrial or domestic water. Ultrafiltration is a pressure-driven membrane filtration process. It mainly relies on the sieving mechanism to separate particulate matter and macromolecular organic matter in water. Substances and substances with a smaller pore...

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Problems solved by technology

[0003] Chinese patent application number CN200710116124.6 discloses a device for amplifying reverse osmosis concentrated water as ultrafiltration flushing water. The reverse osmosis concentrated water is used to flush the ultrafiltration device. Due to the certain pressure of the reverse osmosis concentrated water, when it passes through the injection device, Generate negative pressure and absorb water from the reverse osmosis water tank, thereby increasing the outlet water volume and strengthening the flushing effect. The advantage of this device is that it avoids the damage of the ultrafiltration cleaning water pump caused by the frequent start and stop of the pump, and can recycle low pressure at the same time. reverse osmosis concentrated water; Chinese patent application number CN200920313445.X discloses a self-cleaning continuous cross-flow ultrafiltration device. When the system detects that the outlet water pressure has dropped to a specific value, the backwashing program is started, and the valves are closed one by one. Perform backwashing, and the backwashing water is the water produced by other ultrafiltration components. The advantage of this device is that it can be operated completely automatically, and continuous operation avoids interruption of water production; these patents are the development of new devices to realize the use of reverse osmosis concentrated water as Ultrafiltration cleaning water. However, in order to reduce energy consumption, large-scale reverse osmosis devices generally use energy recovery devices. After the concentrated water pressure energy is recovered, the pressure is basically reduced to below 0.01MPa, and it is no longer possible to drive cleaning equipment through injection devices. , while backwashing the ultrafiltration membrane one by one with the produced water of other ultrafiltration components will still reduce the recovery rate of ultrafiltration water, so it is difficult to use in the actual process

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