ASSESSMENT OF THE AVAILABILITIES OF ORGANIC WASTES AS AN EXTERNAL CARBON SOURCE FOR DENITRIFICATION

Lee, Jae Woo; Yoo, Ung Joon; Chung, Tai Hak

Environmental Engineering Research 2000;5(4): 193-198.

Jae Woo Lee^†, Ung Joon Yoo, and Tai Hak Chung

School of Civil, Urban and Geosystem Engineering, Seoul National University, Seoul 151-742, Korea

Corresponding Author: Jae Woo Lee ,

Received: August 6, 2000; Accepted: October 8, 2000.

ABSTRACT

Volatile fatty acids (VFAs) produced from fermentation of organic wastes can be effectively utilized for improvement of the biological denitrification efficiency. Effectiveness of the organic wastes was evaluated by the VFAs production potential and consumption potential by nitrogen. The gross specific VFAs production (GSVP) has been frequently adopted in the assessing the availability of organic wastes as an external carbon source for denitrification. However, it is insufficient to use GSVP only in the evaluating the organic wastes as a carbon source for denitrification because additional nitrogen loads from organic wastes to denitrification system is excluded in the evaluation. While, the net specific VFAs production (NSVP) can be a useful indicator because it includes not only the VFAs production potential but also the VFAs consumption potential by nitrogen. Even if a relatively large fraction of organic matter was converted to gas in the batch experiment, active acid fermentation resulted in the significantly high concentration of VFAs accumulation. Fermented liquor after liquid-solids separation significantly increased the NSVP of the organic wastes by lowering the VFAs consumption potential, so adoption of the liquid fraction only in the biological denitrification system is strongly recommended. The food residue mixture showed the greatest potential as a carbon source because of the highest NSVP. In spite of extremely high GSVP, the molasses waste may be useless in the improvement of denitrification efficiency due to its much higher VFAs consumption potential than the VFAs production potential. Assessment of determination of available organic waste as a carbon source required for enhancement of denitrification efficiency can be effectively carried out by use of a dimensionless indicator, NSVP.

Keywords: fermentation | net specific VFAs production (NSVP) | organic waste | VFAs consumption potential | VFAs production potential