Microbial decontamination of urea formaldehyde bonded medium density fiberboard

Abstract

Urea-formaldehyde (UF) is a resin commonly used as an adhesive for medium density fiberboard (MDF). Diverting MDF from Canadian landfills is important to decrease annual methane emissions. The use of anaerobic digestion and aerobic fungi were investigated as potential decontamination methods for the decontamination of toxic UF resins; specifically the formaldehyde (FA) component. For anaerobic digestion batch reactors with three inoculum types were used; diluted cow manure (DCM) inocula and decaying sea weed (DSW). FA concentration, gas production, and reactor conditions were measured. Reactors with 10 g L[superscript -1] MDF (1.1 – 1.4 g UF) were used with retention times of 38 days. Thermophilic (55 °C) reactors with fresh DCM as an inoculum had the greatest UF decontamination and gas production. Final FA concentration was 5.523 (SD = 1.516) ppm. GC-FID suggested partial UF resin un-hydrolyzed still in solution. The aerobic fungus Paecilomyces variotii was tested at various temperatures for its FA degrading potential. At 40 °C P. variotii could decontaminate autoclaved MDF with FA concentrations dropping from 400 ppm to 3.970 ppm (SD 3.832) ppm in 7 days, but pH rapidly increased and fungal death occurred.