Physicochemical Characteristics of Dissolved Organic Matter in Untreated and Treated Pulp and Paper Mill Wastewaters, 1998 Environmental Conference Proceedings

L. B. Sonnenberg, Director

J. C. Holmes, Research Technician Millar Wilson Laboratory for Chemical

Research Common approaches to evaluating pulp and paper mill effluents are to measure bulk water quality parameters (e.g., BOD), or to measure regulated compounds that are present in trace quantities (e.g., chlorophenols). While these types of measurements have their advantages and serve specific needs, fundamental chemical information about the structure and properties of the bulk organic material in wastewaters provides better information for predicting and controlling its behavior during treatment. Physicochemical characteristics of the dissolved organic carbon (DOC) in several types of waters and wastewaters were evaluated. The dissolved organic carbon was profiled by its distribution into chemical categories including hydrophilic acids, bases, and neutral compounds, and hydrophobic acids and base/neutrals. One goal of the study was to characterize untreated and treated pulp and paper mill wastewaters to determine which compounds were readily removed and which types were resistant to biological removal. Results indicated that there is a net production of hydrophilic compounds during microbial treatment and a net reduction in acids, probably reflecting microbial metabolism. A second goal of the study was to compare the characteristics of treated effluents with naturally-occurring organic matter. The DOC in untreated pulp and paper mill wastewaters had distributions of chemical classes similar to naturally occurring organic matter in the blackwater system in the study, probably due to similar DOC precursors and physicochemical processes. The ecosystem we studied appeared to readily assimilate the organic matter introduced by wastewater discharge into naturally occurring organic carbon cycles.