Fungal Treatment of Crop Processing Wastewaters with Value-Added Co-Products

Abstract

Conventional biological wastewater treatment generates large amounts of low-value bacterial biomass. The treatment and disposal of this excess bacterial biomass accounts for about 40-60% of wastewater treatment plant operational costs. A different form of biomass with a higher value could significantly change the economics of wastewater treatment. Fungi could offer this benefit over bacteria in selected wastewater treatment processes. The biomass produced during fungal wastewater treatment has, potentially, a much higher value than that from the bacterial activated sludge process. The fungi can be used as a protein source and to derive valuable biochemicals. Various high-value biochemicals are produced by commercial cultivation of fungi under aseptic conditions using expensive substrates. Food processing wastewater is an attractive alternative as a source of low-cost organic matter and nutrients to produce fungi with concomitant wastewater purification. This chapter summarizes various findings in fungal wastewater treatment, particularly focusing on creating new byproducts. This chapter also provides an overview on performance of fungal treatment systems under various operational conditions. Important factors such as pH, temperature, hydraulic and solids retention time, nonaxenic and axenic operation, bacterial contamination and others that affect the fungal treatment system are discussed. The work described culminates in the design and operational experience in operating a pilot plant for beneficiating leftovers from ethanol production from corn. Lastly, production of other valuable biochemicals from fungi as further byproducts is discussed. © Springer-Verlag London Limited 2012.