Integration treatment recovery method for alkali decrement waste water by film method

Abstract

The present invention discloses integrated membrane process of treating waste water from alkali weight reducing process includes flocculating, pre-filtering to eliminate particles larger than 10 micron, ultrafiltering and discharging ultrafiltered concentrated liquid, nanometer filtering the ultrafiltered filtrate in a nanometer filtering membrane assembly to obtain nanometer filtered filtrate accounting for 80-90 vol% and nanometer filtered concentrated solution accounting for 10-20 vol%, adding concentrated sulfuric acid solution to the nanometer filtered concentrated solution to regulate pH value to 2-3 to separate out terephthalic acid, and filtering out terephthalic acid before post-treatment. The present invention has the advantages of recovering and reusing most of NaOH in the waste water, recovering and reusing 80-90 % of water resource, reduced acid adding amount, and lowered cost.

Description

technical field [0001] The invention relates to the field of waste water treatment, in particular to a method for integrated treatment and recovery of waste water in an alkali reduction process of textile printing and dyeing enterprises. Background technique [0002] The alkali weight reduction technology of textile printing and dyeing enterprises is a new production process adopted in the past 10 years to improve the comfort and softness of polyester fabrics. Due to the high pH value and high COD value of the wastewater discharged during the production process, it is difficult to use biochemical and physical chemical treatment, thus seriously affecting the discharge of wastewater up to the standard. [0003] Alkali reduction wastewater is produced during the alkali reduction process of polyester imitation silk, and contains polyester decomposition products, swelling agents, accelerators, surfactants, etc. The main components are sodium terephthalate, ethylene glycol, etc. ...

AI Technical Summary

Problems solved by technology

[0009] The above two methods are the main ways to control alkali reduction wastewater at present, and the treatment effect is better, but there are still some problems as follows: (1) the optimum pH value of the pretreatment process is in the range of 3 to 5, while the alkali reduction The pH value of wastewater is 12-14, and reducing the pH value will consume a large amount of acid, thereby increasing the operating cost. It has been reported that the treatment cost per ton of wastewater is 10 yuan; (2) NaOH in the wastewater is neutralized by sulfuric acid instead of Recycling is a waste of resources; (3) The crude terephthalic acid produced by pretreatment has industrial recycling value, but due to its tiny particles (particle size is about 5 μm), precipitation and separation are relatively difficult, and the dehydration amount is large and dehydration is poor , the cost and quality of recyclables need to be improved; (4) as a desulfurizer, only the residual alkali in the wastewater is used, and the COD of the organic wastewater is not reduced at all, and the consequences are the same as those directly mixed into the sewage main network

This technical route consumes an extremely limited amount of alkali reduction waste water (usually designed to be compatible with the flue gas wet desulfurization device of the boiler heating system of our factory)