Study On Reuse Of Waste Alkali Liquid Of Black Liquor By Nan Filtration Membrane Technology

The wastewater of papermaking industry has become a major source of environment pollution, which has threaten to the people's production, life and health.According to the statistics, the sewage discharge of national develapment accounts for about 10% to 12% of the national total sewage emissions, ranking third; the chemical oxygen demand (CODcr) of discharged sewage accounts for about 40 % to 45% of the national total emissions, ranking first. The main hazards are: Paper effluent contains large amounts of cellulose, pigment, and inorganic salts, can make the water black, and have a special odor; the BOD load of up to 5000 ~ 40000g / L, consumption of large amount of dissolved oxygen in water, so that deterioration of water quality; There are a lot of paper waste water alkaline substance, is the entity sharp increase in pH value, undermining the balance of who put the environment.The waste alkali liquor produced in the stage of alkali solution soaking during the papermaking process is not only the main part of COD in black liquor, but also the large expenditure of pharmaceutical investment in papermaking industry. COD load of spent caustic is about 20000-30000 g / L, half-fiber content:≤18.39g / L Color:≤550 times. Nanofiltration of paper waste lye in the night have a good treatment effect, the use of nanofiltration membrane technology for black liquor recycling in the waste lye, can effectively remove most of the COD, and the recovery of alkali Section soaking liquid can be used directly, in full compliance with the standard back, the resulting concentrated liquid waste lye can provide alkali flue gas desulphurization plant material, not only the effective use of the black liquor concentrate, but also for black liquor concentration Disposal of liquid provides a new way. After Nan filtration membrane separation enrichment technology to effectively cut and keep most of the COD, color, hemi cellulose COD removal rate of≥95%, water yield:≥37.5 m3 / d, lye recovery:≥75%, alkaline water production capacity: 20% -23%, a half-fiber content of produced water:≤3g / L, color Degree:≤7 times, adding lye is the paper industry, a large pharmaceutical investment in expenditure, so the waste alkali liquid treatment, recycling and energy saving benefits the country by a project.