Bleaching Of KP Wheat Straw Pulp&Treatment Of Bleaching Waste Water

In this paper,combining with the practical production of Henan Yinge Industrial Investment Co.,Ltd,wheat straw pulp bleaching and bleached effluent treatment are studied.The technology accordance with factory practical production is determined and theoretical basis is provided for practical production.TCF bleaching method is used to bleach wheat straw pulp got in KP method,the brightness should attain above80%ISO and the bleaching effluent is treated by O3.Oxygen,peracetic acid and hydrogen peroxide are chosen as the bleaching aids of TCF bleaching.As a kind of high efficiency clean bleaching process,oxygen bleaching has the disadvantage of low delignification selectivity and inhomogeneous mixture of oxygen and pulp,so hydrogen peroxide and surfactant are selected to improve the oxygen bleaching effect; TAED potentialization treatment is used in peracetic acid bleaching stage and the potentialization treatment effect is discussed;MgOH which is a hot research is used instead of NaOH at hydrogen peroxide bleaching stage.OPaP is determined as a better bleaching sequence according to repeated experiments,then optimize each bleaching stage after determination of bleaching sequence.Optimal process condition of oxygen bleaching stage and peracetic acid bleaching stage are determined according to the condition experiment,the bleaching condition of hydrogen peroxide bleaching stage is determined by minitab software. The optimal process conditions of these three stages respectively are O stage:pulp consisency10%,sodium dodecyl benzene sulfonate (DBS) dosage0.3%,H2O20.3%, NaOH3%,MgSO40.5%,EDTA0.2%,time70min,temperature100℃,oxygen pressure0.6MPa;Pa stage:pulp consisency10%,C2H4O32.5%,TAED0.6%,EDTA0.5%,pH7,temperature65℃,time60min;P stage:pulp consisency10%,H2O22%,EDTA0.5%,NaOH/H2O2=1(molar ratio),MgOH substitution amount40%,time70min,temperature60℃,TAED/H2O2=0.06(molar ratio).Pulp performance treated by OPaP bleached are:brightness80.3%ISO,viscosity648mL/g,Kappa number2.9,yield89.65%,PC number1.8%,acid insoluble lignin3.2%,soluble lignin0.4%.The beating degree is50°SR,the paper performance are:tensile index50.992N·m/g,breaking length5.203km,folding endurance60times,tear index 6.0mN·m2/g,bursting index3.74kPa·m2/g.The optimal process conditions of mixed OPaP bleached effluent treated by ozone are:temperature23±2℃(room temperature),initial pH8,03flux624mg/L,time70min.Under these conditions,the bleached effluent’s CODcr9113mg/L,chroma705times,SS550mg/L.In addition,ozone significantly influence to chroma of the bleached bleached wastewater.