The Recycle And Utility Of Alkali Deweighting Wastewater

Alkali deweighting is one of the important process in the course of polyester fabric peeling for silk-like effect. There are intermittent and continuous processes. Intermittent process is always carried out in groove or dying machine with high temperature and pressure. Continuous process is always carried out in continuous alkali peeling process machine. Intermittent process carried out in dying machine with high temperature and pressure is widely used in many township enterprises in our country. For the process is suitable for small batch and various fabrics while small investment is needed. Meanwhile, there are some shortcomings in the process, such .as low alkali utilized rate and serious pollution.Faced these problems affected enterprise' s sustained development, I researched factors affected alkali utilized rate in peeling process. These factors are alkali concentration, temperature, time, bath rate, promoter , recycle times of alkali. A cleaning alkali deweighting process was attained. That is promoter SN 1 g/L, NaOH 10 g/L, temperature 100癈, time 60 min, bath rate 1:30, alkali recycle 20 times. To those fabrics which cannot peeling with recycle alkali such as T/C fabrics, following process was used: promoter SN 1 g/L, NaOH 5 g/L, temperature 100癈, time 60 min, bath rate 1:30The method used for washing after alkali peeling process was investigated. A new washing method named set-back washing was used to wash alkali deweighting fabrics. It was proofed that the new method was efficient and more importantly, it consumed less water and produced less wastewater.As to inevitable effluent, in the view of using resource efficiently, I changed the main pollutant into TPA with acid sedimentation. Factors affected retrieve rate were researched. These factors are temperature, pH, flock promoter, stir time, sulphuric acid concentration and input speed. At last, I determined the parameter in retrieving process. That is flock promoter : Al2(SO4)3 50 mg/L, active carbon 2 g/L, stir time 5 min, pH=S, temperature 90,rapid input 30% sulphuric acid. Under the condition, the retrieve rate of TPA is up 80%, the ash in which is under 0.2%. So the TPA is fit for industrial application. Now TPA is selling like hot cakes in chemical material market. Good economic benefit is obtained. Meanwhile, after extracting TPA, CODcr dislodge rate of effluent is up 80%. The problem of effluent ejecting within criterion was dissolved. Good environment benefit is obtained.