PILOT-PLANT INVESTIGATIONS OF THE TREATABILITY OF ETHYLENE-GLYCOL BY ACTIVATED-SLUDGE

Activated sludge pilot plant studies were carried out in order to inve stigate the treatability of ethylene glycol, an organic chemical commo nly used as a coolant in the pharmaceutical industry. Four completely mixed, single-stage, activated sludge units, with a capacity of 80-lit res were operated in parallel. The effect of various concentrations of the test chemical on the sludge settleability, the sludge growth, and the plant performance in terms of BOD and COD removal were examined d uring the study. It was concluded that a concentration of 0.1% ethylen e glycol in the raw wastewater of the full-scale plant was treatable, as higher concentrations appeared to cause a deterioration in the floc structure and to enhance Nocardia scum formation on the surface of th e aeration basin.