Experiencing the oil crisis as a child in the seventies is probably what drove my interest in alternative fuels, including methane from anaerobic digestion. In high school, I was building small anaerobic digesters at home and my advanced biology research report was titled The Effect of Substrate on Bacterial Production of Methane. I still have the report and my Biogas Handbook. So, I was thrilled to work on this project when I was at Bio-Technical Resources and consider it one of my best process development projects for the simplicity of the factorial design.

The idea for the project came from one of the DuPont researchers that had been involved with development of the PACT process to treat their chemical plant wastewater streams. At the time, the chlorinated lignins in pulp and paper mill wastewaters were significant contributors to both the biochemical oxygen demand (BOD) and the brown color of these wastewaters. The starting wastewater for the project was from a pulp and paper mill, with a portion of it passed through sintered stainless steel tubular supports with formed-in-place polymeric ultrafilter membranes. This ultrafiltration was used to remove the high molecular weight chlorinated lignins.

I built out multiple sets of small reactor trains and ran them in parallel to test the different combinations of ±ultrafiltration, ±activated carbon and ±anaerobic digestion. I ran these reactors continuously for several months to line them out. My group then regularly analyzed the treated wastewater for color, total organic carbon, and total organic chlorine to determine which of the trains gave the best overall treatment and the relative contributions of the different unit operations.