DISSOLVED-OXYGEN IN SMALL WASTE-WATER COLLECTION SYSTEMS

This paper concerns the dissolved oxygen (DO) balance in sewers and describes the experimental work and results obtained under a research project undertaken on a small wastewater collection system. For prediction of oxygen balance in sewers, reaeration and DO consumption, both within the stream and within the biological slime layer on the pipe wall, must be computed. In this study special emphasis is given to DO uptake by the slime layer. Comparison of experimental results concerning the activity of the slime layer with the results calculated by the Pomeroy and Parkhurst equation, the only one available in the literature applicable to sewers, did not lead to a good agreement. Under low flow conditions and high DO concentrations, a significative correlation was found between velocity and DO consumption by the slime layer. No correlation was found between DO concentration within the stream and DO utilization by the slime layer.