CAREER: Uncertainty Analysis and Modeling of the Biodegradation of Synthetic Organic Compounds in Activated Sludge Biotreatment Systems

Mississippi State University, Mississippi State MS

Investigators

Abstract

0348161 Magbanua Intellectual merit. The activated sludge (AS) process was originally developed for the removal of oxygen demanding material and suspended solids, and later applied also to nutrient removal, from wastewater. More recently, effluent limits have been placed on specific chemicals of industrial and environmental significance, referred to as priority pollutants. Biotreatment has been designated the best available treatment technology, against which alternative treatment options are measured, for priority pollutants that are potentially biodegradable synthetic organic chemicals (SOCs). Consequently, the development of approaches to accurately predict SOC degradation in activated sludge systems has become a major research focus in environmental engineering. The current modeling approach combines traditional microbial growth kinetics with reactor engineering principles to derive a deterministic model of SOC degradation. Experience has shown, however, that bio kinetic parameters derived from laboratory experiments are poor predictors of SOC removal performance, even in controlled laboratory reactors. Therefore, a modeling approach that accounts for process uncertainties would be more appropriate. The PI further suggests that an understanding of the sources of uncertainty in wastewater bio treatment would facilitate the design of more efficient and reliable bioprocesses for priority pollutant removal. The PI hypothesizes that uncertainty in wastewater bio treatment, and the disparity between field performance and laboratory-derived kinetics, arises principally from the concentration and activity of the competent biomass, the diversity of the microbial community, and the size distribution of the microbial flocs. Broader Impacts. Priority pollutants have been identified as imminent threats to public health and the environment. Strict limits have consequently been established for effluent concentrations of priority pollutant. The kinetics of SOC removal are poorly understood, however, so engineers tend to use very conservative safety factors and grossly over design treatment systems to ensure that SOC removal goals are met. A better understanding of the uncertainties related to SOC bio treatment, and models incorporating uncertainty, would permit more realistic assessment of uncertainty risk, and facilitate the development of design and operational strategies that minimize such risk. In addition to the usual scientific channels, The PI plans to disseminate these models and other project results through an interactive web site, which will be promoted to practitioners through professional associations. The PI is also committed to enhancing science and engineering education at all levels, particularly by providing opportunities for research. Mississippi is a state in which research expenditures have traditionally lagged the rest of the country, so availability of research experiences at the undergraduate and secondary levels has been severely limited. The PI is committed to providing such opportunities, particularly to persons from groups traditionally underrepresented in science and engineering.