METHOD FOR REUSING WASTED MERCERIZING LIQUID

摘要

PURPOSE: A reuse method of mercer wastewater is provided, which can recover the whole amount of sodium hydroxide from mercer wastewater and reuse as padding liquid of mercer processing, so that a complete reuse system of mercer wastewater is achieved. The main reason of pH problem of dying wastewater is sodium hydroxide delivered from mercer process and most of dying plant costs to buy sulfuric acid and pay the amount imposed for pH to treatment plant, thereby the method of reuse can save much and invest the saved money to install this membrane. CONSTITUTION: The method is as follows: (i) separating step of sodium hydroxide solution by passing through a nanofilter separating membrane the mercer wastewater that is disposed after used as padding liquid at a mercer process of fiber industry; (ii) concentrating step of the separated sodium hydroxide to 20-25 %; and (iii) a reusing step of the recovered sodium hydroxide as water for producing the mercer padding liquid that is adjusted to 50 % concentration.