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Converting corn wet‐milling effluent into high‐value fungal biomass in a biofilm reactor
Author(s) -
Jasti Nagapadma,
Khanal Samir K.,
Pometto Anthony L.,
van Leeuwen J. Hans
Publication year - 2008
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.22007
Subject(s) - chemical oxygen demand , effluent , biomass (ecology) , bioreactor , chemistry , pulp and paper industry , nutrient , biofilter , chitosan , wastewater , food science , agronomy , biology , environmental engineering , environmental science , organic chemistry , engineering
Rhizopus microsporus was grown in an attached growth system using corn wet‐milling effluent as a growth medium. This strain was chosen due to its ability to effectively degrade organic matter in corn wet‐milling effluent and for its properties to produce significant levels of protein, chitin and chitosan. Fungal growth and organic removal efficiency were examined under both aseptic and non‐aseptic conditions with and without nutrient supplementation. Plastic composite support (PCS) tubes, composed of 50% (w/w) polypropylene (PP) and 50% (w/w) agricultural products were used as support media. Significantly higher organic removal measured as chemical oxygen demand (COD) and biomass yield were observed in the bioreactor with PCS tubes than in two control bioreactors; that is with PP tubes alone and suspended growth (without support media). This confirmed that the PCS support medium with agricultural components enhanced fungal growth and organic removal. The results showed that supplementation of nutrients (e.g., mineral salts) under aseptic conditions enhanced the COD removal from 50% to 55% and observed biomass yield from 0.11 to 0.16 g (dry‐weight)/g COD removed (i.e., from 0.10 to 0.14 g volatile solids (VS)/g COD removed approximately). Non‐aseptic operation without nutrient supplementation resulted in an observed biomass yield of 0.32 g volatile suspended solids (VSS)/g COD removed with no significant improvement in COD removal (∼53%); whereas with nutrient supplementation, the observed biomass yield increased to 0.56 g VSS/g COD removed and COD removal improved to 85%. The fungal system was able to degrade the organic matter with concomitant production of high‐value fungal biomass. This is the first study that examined the conversion of corn milling waste stream into high value fungal protein. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc.