Pilot plant experience in the treatment of industrial and municipal waste-water by means of radiation-induced oxidation

Gamma-radiation-induced oxidation of organics adsorbed on activated carbon was studied for more than a year in a pilot plant having a design flow rate of 5000 gallons daily of waste effluents with organic concentrations of 100 ppm. Oxygen requirements, methods of injecting the oxygen and the economics involved for the process are presented. COD and BOD reduction, as well as colour and odour elimination, are shown to be directly related to the quantity of oxygen dissolved in the waste-water and the radiation dose. Greater than 90% reduction in COD was regularly accomplished during continuous large-scale runs. Dissolved oxygen in the plant feed is consumed in this process, and the carbon dioxide yield is measured in the effluent. More than 99% of the coliform bacteria present are killed. Other bacteria kills range from 95% upward. This study confirmed a new process for in-situ reactivation of charcoal by gamma-induced oxidation which is both highly efficient and economically favourable. A new method of injecting oxygen into the waste-water was developed using air as the oxygen source. This method is capable of producing oxygen concentrations of 11.5 mg/1 in industrial and municipal effluents used as pilot plant feed. At this level of dissolved oxygen the process efficiency appears to reach its peak. The primary object of this work was to reduce COD, BOD and bacteria concentration in effluents to a level acceptable for discharge into navigable waters. It was found, however, at high dissolved oxygen levels in the feed, the process yields a water product suitable for recycle. Hence recycle became a prime object and accomplishment. The economics of this method of waste-water treatment were found to be highly favourable, substantially lower in cost than other methods of obtaining comparable results. (Author)