## Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

## If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

# Molecular Size Distributions of Dissolved Organic Matter in Wastewater Transformed by Treatment in a Full-Scale Trickling Filter

Bruce E. Logan and Gretchen A. Wagenseller
Water Environment Research
Vol. 72, No. 3 (May - Jun., 2000), pp. 277-281
Stable URL: http://www.jstor.org/stable/25045376
Page Count: 5
The performance of biofilm reactors is primarily limited by the rate of diffusion of biodegradable molecules into the biofilm. Wastewater entering and leaving a trickling filter was therefore separated into three molecular weight size fractions of <1000 daltons (<1K), 1 to 10K, and >10K to <0.45 μm, and the concentration of 5-day soluble biochemical oxygen demand (${\rm sBOD}_{5}$) and dissolved organic carbon (DOC) were measured for each size fraction. On average, a large percentage of both the ${\rm sBOD}_{5}$ (82%) and DOC (78%) was contained in the smallest size fraction (<1K). Removal rates of ${\rm sBOD}_{5}$ were high. Influent ${\rm sBOD}_{5}$ values were reduced from 27.3 to 33.3 mg/L to 4 mg/L in the effluent. A comparison of a trickling filter model (TRIFIL2) indicated that removal rates of ${\rm sBOD}_{5}$ were much greater at this site than was typical of other trickling filters treating domestic wastewater. The large concentration of this small molecular weight fraction was believed to account for greater than normal removal rates. To demonstrate this, the molecular size distributions assumed in the trickling filter model TRIFIL2 were adjusted to fit the measured size distributions. The measured average removal of 92% compared well to the 93% removal predicted by the TRIFIL2 model with these measured molecular size distributions. These measurements and model simulations demonstrate that the performance of trickling filters can be linked directly to physical characteristics of the wastewater such as the molecular size distribution of biodegradable organic matter.