Sewage regeneration and zero discharge method

Abstract

The invention belongs to the technical field of environmental protection, especially belongs to the technical field of water treatment, and relates to a method for respectively removing the pollutants in sewage by using a plurality of membrane separation methods. The method comprises the steps of: 1, carrying out membrane enhanced chemical softening to remove the alkaline deposits in the water in a manner of a deposit (1); 2, filtering by using nanofiltration membrane to obtain organic pollutant concentrated solution (2) and nanofiltration produced water (3), wherein the recovery rate of the nanofiltration membrane is 80-95%; 3, carrying out reverse osmosis concentration on a small part of the nanofiltration produced water (3) to obtain reverse osmosis produced water (4) and dissolving salt concentrated solution (5), wherein the utilization rate of reverse osmosis can be up to 80-97%; 4, evaporating and concentrating the organic pollutant concentrated solution (2), reusing distilled water (6) and combusting organic matter strong liquor (7); and 5, carrying out evaporative crystallization on the dissolving salt concentrated solution (5) and reusing distilled water (8) to obtain solid salt. According to the method, the nanofiltration and the reverse osmosis can be stably carried out under high utilization rate to remarkably decrease the treating water quantity of an evaporative crystallizer, so that the operation cost is reduced, the scaling problem of crystallization equipment is avoided at the same time, the crystallization difficulty of mixture of inorganic salt and organic pollutant is solved and then the crystallizer can stably run in a long term.

Description

technical field [0001] The invention belongs to the technical field of environmental protection, in particular to the technical field of water treatment, and relates to a method for separately removing pollutants in sewage by using various membrane separation methods. technical background [0002] With the development of the economy, human beings have become more and more serious about water pollution, and the requirements for water purification, sewage treatment and sewage regeneration are getting higher and higher. Under this premise, new sewage treatment technologies and methods are becoming more and more crucial, especially the technologies and methods of zero discharge of sewage. [0003] Among the many methods of water treatment and water regeneration, filtration membrane technology is a key technology. Generally, a membrane with a filtration accuracy of 0.005-0.1 microns is called an ultrafiltration membrane, and a membrane with a filtration accuracy of 0.1-2 microns...

AI Technical Summary

Problems solved by technology

Insoluble salts cause serious fouling of evaporation and crystallization equipment; organic matter itself has no crystallinity, and it is difficult to discharge the system in solid form; organic matter interferes with the crystallization of soluble salts

These factors make the crystallizer unable to run stably for a long time

[0010] It can be seen that although the zero discharge of sewage has a wide market demand, there is a lack of practical and feasible technical solutions in the known technology