Study On Separation Of Lignin And Inorganic Compounds From Wheat Straw Pulping Black Liquor

Black liquor from Pulping and paper making industry, is one of the main industry pollutants in the environment. The drainage badly pollutes our natural environment so that many countries consider it as a very important issue. Traditional alkaline recovery technique is available to those large-scale pulping corporations in which the raw material is wood. However, it meets many unconquerable problems on economy or technique when it is used in those corporations in which the yield is under 10,000 tons annual or the raw material is non-wood. The resolution of black liquor pollution is very important to these corporations, and also important to the development of pulping and paper making industry, as well as our national economy. In our country, wood material is short and wheat straw is the main material for pulping. The objective of this study is to treat the black liquor from wheat straw pulping. It includes: 1. Lignin is separated by acid treatment; 2. Inorganic compounds are separated and recycled by adding other chemicals. The optimal technical parameters are obtained by using orthogonality experiment plan. The waste water samples from pulping before and after treating are analyzed by ICP-AES, FTIR and UV. The results show: Lignin and inorganic compounds can be separated and recycled by adding acid and other chemicals. Thus, most pollutants in black liquor can be separated and it is possible that the treated water is eligible to drain.