Low-pressure membrane water treatment technology based on "sandwich" loose floc protection layer

Abstract

A low-pressure membrane water treatment process based on a sandwich type loose floc protective layer is disclosed. An integrated type membrane coagulation reactor is adopted by the process, and mainly includes a membrane tank, a low-pressure membrane assembly arranged in the membrane tank and an aeration device arranged in the same membrane tank. The membrane tank is in series connection with a suction pump and a coagulant adding tank through a pipeline. The bottom of the membrane tank is provided with a sludge discharging valve. The coagulant is injected into the membrane tank through the coagulant adding tank through a batch-type manner so that coagulant hydrolyzed floc forms the sandwich type loose protective layer on the membrane surface. Raw water is fed into the membrane tank, treated by adsorption by the floc layer and membrane treatment, and then discharged. The process can ensure water quality of discharged water, and can effectively reduce membrane pollution at the same time, especially membrane pollution caused by low-molecular-weight organic matters. The treatment device integrating an adsorption process and a membrane process is adopted by the water treatment process, thus effectively reducing the occupied space.

Description

technical field [0001] The invention belongs to the technical field of water treatment and membrane pollution control, and in particular relates to a low-pressure membrane water treatment technology based on a "sandwich" loose floc protection layer. Background technique [0002] Membranes are increasingly used in water treatment. As of now, the applications of membranes are growing almost exponentially. However, as the running time increases, pollutants will gradually accumulate in the membrane pores or membrane surface, resulting in inevitable membrane fouling, especially small molecular organic pollutants. After membrane fouling, not only the hydraulic resistance increases, but also the transmembrane pressure difference increases rapidly, which greatly increases the energy consumption in the membrane filtration process. [0003] Previous studies have shown that membrane pore adsorption, membrane pore clogging and filter cake layer on the membrane surface are important ca...

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Problems solved by technology

[0006] For the integrated membrane combination process, on the one hand, it is currently reported that the price of the adsorbent used is relatively high, such as activated alumina, activated iron oxide, carbon nanotubes, nano-zero-valent iron, etc.

On the other hand, some adsorbents are easy to scratch the ultrafiltration membrane during long-term operation, such as powdered activated carbon

In addition, although a large number of adsorbents are injected into the membrane pool, it is difficult to form a protective layer on the surface of the membrane because most of the adsorbents used are granular, or only a single protective layer is formed on the surface of the ultrafiltration membrane.

With the increase of running time, small molecular organic pollutants can still pass through the adsorbent protective layer to reach the membrane surface, and at the same time, the pollutants gradually form a denser pollution layer on the surface of the adsorbent protective layer, which intensifies membrane fouling.

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