Improve water recycling rate of poly aluminum chloride

Paper industry wastewater treatment focused on improving water recycling rate of poly aluminum chloride mass.

Paper industry in the production of two pulp and papermaking processes, will generate a lot of waste paper, poly aluminum chloride is mainly derived from the papermaking pulp dilution, forming, pressing, drying, made ​​of paper; pulping is to fibrous plant material separated from a slurry, and then bleached. Large volumes of wastewater in these two processes are discharged, pulping wastewater generated the most polluted wash pulp wastewater effluent was dark brown, called Blackwater, Blackwater high concentrations of pollutants, BOD up to 5 - 40g / L , contains a lot of fiber, salts and pigments. Waste water discharged from the bleaching process contains a large amount of acid substances, wastewater paper machine, known as white water, which contains a large number of fibers in the production process and add the filler and rubber material.

In addition, there is also domestic reverse osmosis, ultra filtration, electrodialysis and other processing methods, using polyaluminum chloride for papermaking wastewater coagulation tests through them at different pH values ​​and the dosage in case of wastewater color, CODCr removal rate were analyzed to choose the best coagulant and coagulation conditions, the experimental results show that at pH 8, coagulant dosage of 30 mg / L, the use of PFC coagulant papermaking wastewater treatment PAC and more effective than the economy, the decolorization rate reached 90%, CODCr removal rate of 43%.

Paper industry wastewater treatment should focus on improving water recycling rate, reduce water consumption and wastewater discharge, but should also actively explore various reliable, economical and useful to be able to take full advantage of the resources in waste water treatment. For example flotation recyclable whitewater fibrous solids recovery of up to 95%, to clarify water reuse; combustion recyclable blackwater sodium hydroxide, sodium sulfide, sodium sulfate and sodium with other organic binding. Neutralization adjust pH value of wastewater; coagulating sedimentation or flotation removes suspended solids in wastewater; chemical precipitation decolorizable; biological treatment can remove BOD, wastewater more effectively on kraft paper; polyaluminum chloride wet oxidation Asia sulphate pulp wastewater more successful. 

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