Resource Recovery Of The Sea-island Fiber Wastewater

At present, sea-island fiber is an important material. A plenty of wastewater, brought from sea-island fiber process, contains disodium terephthalate salt (TA-Na₂) of some concentration, and is the difficulty and keystone to the wastewater-treating. Therefore, the study catches researcher's eye greatly and widely. The recovery of terephthalic acid (TA) from sea-island fiber wastewater is great of importance to reducing environment pollution and the full use of resource. The paper has researched how to recover TA from the wastewater to lay foundation for the future industrial application.The paper has also researched the influences that crystal conditions of acid eduction from sea-island fiber wastewater have on the quality of recovered TA. The research shows that if the reaction conditions of acid eduction are under control, then the crystals of great particle size will be formed. Thus, it not only has a purification effect, but also favors dehydrating washing-up. The technics conditions for recovering TA have been researched through the orthogonal experiment. The orthogonal experiment and analysis of variance show that when acid precipitating, all of the temperature of the wastewater, the concentration of the acid added, the mixing speed of acid-adding, and the speed of acid-adding, have effects on the results of the experiments. This research also probe into the mechanism of crystal in acid eduction through the system mensuration and analyses of the main performances of recovered TA.The paper has also researched some experiments of acid eduction to two wastewater of different concentration, and surveyed the influence that the changing of the wastewater quality has on the experiments of acid eduction. And the experiments show that after the wastewater quality hasbeen changed, the temperature is the factor which has the most obvious influence of the same tendency on the acid eduction. Little change almost happens to the optimal values of the concentration of the acid added and the speed of adding acid. The smaller the values of the speed of adding acid and the concentration of the acid added are, the better the performances of the recovered TA will be. As far as the mixing speed, one of the influencing factors, is concerned, with the rising of percentage of COD_Cr in the wastewater, the best mixing speed is also be reduce. With the rising of the concentration of the COD_Cr, TA and impurities in the wastewater, the performances of the TA recovered under the best conditions is also be levelled down.The F values in the orthogonal experiment of two kinds of wastewater show that with the concentration of the COD_Cr. in the wastewater rising, the impact that each influencing factor has on the experiments decreases. Thus, it can be concluded that when the concentration of the wastewater increases, the influencing factors which have obvious impact on the experiments will be reduced gradually. It is even harder to control the influencing factors when acid precipitating.This paper discusses the treatment of sea-island fiber wastewater, and shows that only recovering the useful resource of TA from the wastewater can meet the policy of recycling economy and sustainable developments, and meanwhile solve the difficulties of dealing with the wastewater, and recover resources.We wish it would be useful to the industrial production.