BOD contribution by benthalsludge deposits-Part II: Effect of stream characteristics

Abstract

Organic matter that settles to the river bottoms is the benthalsludge deposits. Decomposition of benthalsludge deposits in streams affect the overlying waters by removal of the dissolved oxygen (DO) from the overlying waters as well as by the benthos and periphytons in the aerobic top layers of the overlying waters and by the immediate oxygen demand of the reduced substances emanating from the deeper anaerobic layers. Secondly, the benthalsludge deposits can also release organic substances and various nutrients into the overlying waters. The oxygen utilisation rate by the benthalsludge deposits may also depend on the stream characteristics as well as the sludge characteristics. In this second part of the paper, the variations of the total oxygen uptake rate in any one days duration and the rate of BOD contribution in respect of different stream characteristic parameters have been correlated and discussed. The flow rate of overlying waters influenced the BOD contribution rate significantly, both at the top and bottom most layers of overlying waters. The rate of BOD contribution manifested optimum values affected by h/d ratios, at the top layers of overlying waters. Predictive models involving all the sludge and stream characteristic parameters have been developed. 2008 - Kalpana Corporation.