Pollution Evaluation Of Waste Water And The Optimized Process Of The Cotton Alkali Pretreatment

Through the detailed analysis about the value of COD under the conditions of different treatment methods and different prescription in the cotton pretreatment, we can get the data which can help manufacturers to reference (conducive to formulate, choose reasonable and effective process intensity and prescription), and decrease the COD in the cotton pretreatment in order to achieve the goal of lowering the cost of wastewater treatment. At the same time, we can get the main components which bring about the high COD through analyze the COD in different methods and different prescription in cotton pretreatment. Then, we can discuss the new process or new auxiliaries in pretreatment to reduce the COD value.This topic has the main research on the quality of cotton and the COD value of waste water in different pretreatment methods and different prescriptions. The quality includes weightlessness rate, capillary effect, and whiteness. Find out the main factors that make the different about the quality of cotton and factor which make the high COD value of the waste water from the pretreatment process, so as to make the pretreatment prescription and pretreatment methods in order to save energy and protect the environmental. Based on the quality of cotton and the wastewater COD value, combined with the principle of energy conservation and emissions reduction of cotton fabric pretreatment technology, comprehensive consider those factors, ultimately determine that the best technology of three-step pretreatment is at90℃*60min, the best technology of two-step pretreatment is at90℃*50min, the best technology of one step method pretreatment is at90℃*50min. Different prescription on cotton has great influences in semi-product quality and waste water COD, two of the biggest influences are the dosage of penetrate or refining agent and the dosage of hydrogen peroxide. The dosage of the penetrate agent or refining agent has a great relationship with the removal rate of impurities in cotton fabrics, and the dosage of hydrogen peroxide has a great influence about the whiteness of cotton. At the same time, the effect of the removal rate of impurities on cotton by the penetrate or refining agent, and hydrogen peroxide is closely related to the wastewater COD value in the cotton alkali pretreatment.Based on the analysis of the main pollutants (size, base, additives, and cellulose) in wastewater, consider the factors which make wastewater get high COD value. The main factors of wastewater COD are the dosage of the size from the fabric and the own COD value of the refining agent&penetrate agent which used in pretreatment. The main pollutants of cotton fabric pretreatment wastewater are size on the cotton fabrics and all kinds of penetrating agent and refining agent that used in the pretreatment process. To reduce the wastewater pollution of cotton pretreatment should be from the two aspects, as far as possible on the premise of meet the requirements of cotton pretreatment, reduce the value of COD in pretreatment waste water.