Oxidant reduction and biodegradability improvement of paper mill effluent by irradiation

Abstract

Paper mill bleach processing wastewaters represent a large input of hazardous compounds to the environment and these compounds are usually non-biodegradable. A preliminary study using a 5000 Ci 60Co gamma radiation source as a surrogate for electron beam irradiation, potentially an emerging technology for wastewater treatment, to treat a paper mill bleach effluent showed that for an absorbed dose of 800 krads, chemical oxygen demand (COD) was reduced by 13.5% and 5 day biochemical oxygen demand (BOD 5) was increased 58.6%. These changes altered the value of COD/BOD 5 from 14 to 5. For the same dose, the absorbable organic halogen (AOX) was reduced 76.2%. These results suggested the possibility of using the electron beam process to detoxify paper mill effluent thereby generating a more biodegradable wastewater.