Study On Recovering And Separating Of The Black Liquor Of Auto-catalyzed Ethanol Pulping Of Aspen

Aspen is planted abroad in China. The conventional pulping methods are acid and alkaliin pulping and paper making industry, and the waste liquor will get bad effects onenvironment. Auto-catalyzed ethanol pulping method is a new and environmental pulpingway. The ethanol，lignin and byproduct are easy to be recovered by dealing with the wasteliquor. The new pulping and recovering way can make full use of the economic value ofnatural resources.The components of waste liquor of Auto-catalyzed ethanol Pulping method are complex.The main components are lignin, ethanol, water and furfural, acetic acid, formate, syrup etc.Each component has high using value and economic value. If we can separate the differentparts from the waste liquor and use them fully, the whole pulping and paper making processwould become a close circulating system. It will reduce the environmental pollution and getmore and more profit to the corporation. The new methods control the environmentalpollution of waste liquor from source. This paper get the way of“distilling—filtration—ultrafiltration” to deal with the waste liquor of Auto-catalyzed ethanolPulp in order to recover the ethanol and lignin, at the same time, reducing the environmentalpollution of waste liquor. This study is still on the foundation phase, it will provide theory gistto the future industrialisation using.Consider the characteristic of the waste liquor of Auto-catalyzed ethanol pulping. First ofall, adopt distilling method to recover most ethanol and lignin. The experimental result showsthat it would recover the ethanol (the consistence of ethanol is21.61%) when thetemperature is93~95℃and the rate of concentrated volume is0.6, thereinto, the consistenceof acetic is0.45%. Adjust the PH of concentrate liquor after distilling; the PH is adjusted to1.44. Afterward, it would get the90%lignin in waste liquor by filtration of double filter paper.The COD of removal rate is79.77%. The BOD5of removal rate is32.81%. The viscosity isreduced to39.14%.The waste liquor is experimented after filtration of filter paper by ultrafiltration. Theoptimum conditions of ultrafiltration are: PES ultrafiltration membrane, trapped molecular weight10K, presses0.20MPa, stirring rate600r/min, temperature30℃, time2h. Thepollution of membrane is severe because there is no enough equipment of washing. Themembrane flux becomes smaller and smaller. It affects efficiency of concentrate andultrafiltration. In order to simulate the washing process of lab, must change the membranewhen it works two hours and gets the steady membrane flux. It would wipe off53.78%outgrowth of lignin,74.08%COD,44.19%BOD5.After the distilling and ultrafiltration experiment, the COD removal rate is94.89%, theBOD5removal rate is62.50%, and lignin removal rate is98.24%. The initial base of wasteliquor is too big, so the waste water can not be letted after “distilling—ultrafiltration”, it hasto be dealed with again.The waste liquor gets a distilling after ultrafiltration, cool the distilling liquor, recoverethanol liquor and mix the ethanol liquor with the ethanol liquor which is recovered at thefirst time. The final consistence of ethanol is19.60%, thereinto, the consistency of acetic acidis0.6441%. The96.78%lignin in waste liquor is recovered. This shows the experimentalproject can recover the liquor and lignin from the waste liquor. It can reduce theenvironmental pollution. The ethanol which is recovered from waste liquor can be used topulping. The lignin which is recovered can be used in different ways and gets better economicvalue.