title: Selective enrichment of a methanol-utilizing consortium using pulp and paper mill waste streams.
abstract: Efficient utilization of carbon inputs is critical to the economic viability of the current forest products sector. Input carbon losses occur in various locations within a pulp mill, including losses as volatile organics and wastewater. Opportunities exist to capture this carbon in the form of value-added products such as biodegradable polymers. Waste-activated sludge from a pulp mill wastewater facility was enriched for 80 days for a methanol-utilizing consortium with the goal of using this consortium to produce biopolymers from methanol-rich pulp mill waste streams. Five enrichment conditions were utilized: three high-methanol streams from the kraft mill foul condensate system, one methanol-amended stream from the mill wastewater plant, and one methanol-only enrichment. Enrichment reactors were operated aerobically in sequencing batch mode at neutral pH and 25 degrees C with a hydraulic residence time and a solids retention time of 4 days. Non-enriched waste activated sludge did not consume methanol or reduce chemical oxygen demand. With enrichment, however, the chemical oxygen demand reduction over 24-h feed/decant cycles ranged from 79 to 89%, and methanol concentrations dropped below method detection limits. Neither the non-enriched waste-activated sludge nor any of the enrichment cultures accumulated polyhydroxyalkanoates (PHAs) under conditions of nitrogen sufficiency. Similarly, the non-enriched waste activated sludge did not accumulate PHAs under nitrogen-limited conditions. By contrast, enriched cultures accumulated PHAs to nearly 14% on a dry weight basis under nitrogen-limited conditions. This indicates that selectively enriched pulp mill waste activated sludge can serve as an inoculum for PHA production from methanol-rich pulp mill effluents.
authors.affiliation: Department of Civil and Environmental Engineering, University of California at Davis, 1 Shields Avenue, Davis, CA, 95616, USA.
authors.forename: Gregory R
authors.initials: GR
authors.lastname: Mockos
authors.forename: William A
authors.initials: WA
authors.lastname: Smith
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Loge
authors.forename: David N
authors.initials: DN
authors.lastname: Thompson
mesh_terms: D001419:Bacteria / Q000302:isolation & purification* / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology*; D018929:Cell Culture Techniques / Q000379:methods*; D007220:Industrial Waste / Q000517:prevention & control*; D000432:Methanol / Q000378:metabolism*; D010209:Paper; D012722:Sewage / Q000382:microbiology*
chemical_list: D007220:Industrial Waste; D012722:Sewage; D000432:Methanol