The operating experience of the treatment of washing & bleaching effluent from wheat staw pulping

The paper mill effluent in Xinya Paper Industry Group is the mixture of the washing bleaching effluent of wheat straw chemical pulping and the effluent from alkaline semichemical wheat straw pulping, which is high in SS content, low in BOD / COD ratio, difficult in biochemical treatment and varible in water quality. Under the above mentioned conditions, the hydrolytic-acidification oxidation ditch technology was chosen in which the anaerobic and aerobic processes were completed by turns in the same ditch with a higher COD removal rate, good operation effect and lower running cost. The measures were adopted to improve cooking quality for better alkali recovery condition and higher alkali recovery rate.