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

Production of Ethanol and Biomass from Thin Stillage Using Food-Grade Zygomycetes and Ascomycetes Filamentous Fungi

“…The latter was further shown to perform better in 50% diluted thin stillage. The need for the dilution of thin stillage containing 8% or more total solids has been reported when using Rhizopus oligosporus [5]. In this work, Rhizopus sp.…”

“…The thin stillage from corn-based ethanol production has previously been shown to be a good growth medium for production of nutritionally rich biomass using filamentous fungi [5]. However, research performed on thin stillage derived from ethanol production using other cereals such as wheat is scarce in literature.…”

“…Recently, research on the overall process leading to the production of feed products has been triggered. Thin stillage, in particular, has been considered to be a potential source of further improvement of the overall ethanol process via production of other products such as protein-and lipid-rich biomass [5,6]. Filamentous fungi have been prime catalysts in biotechnological processes towards valorisation of a wide range of by-products.…”

“…On the other hand, the Ascomycetes include Fusarium venenatum, which under the trade name Quorn ® might be the most studied microorganism for the production of human food [9]; Aspergillus oryzae, which is one of the most studied fungal species at the industrial scale for production of various fungal products [10]; Monascus purpureus, which has been used for production of red fermented rice for over a thousand years in Asian countries [11] and Neurospora intermedia, which is used for the preparation of oncom, an indigenous Indonesian food [12]. Thin stillage from corn-based ethanol industries has already been researched for production of several products, such as high-value biomass made using Rhizopus oligosporus [5,13], butanol using Clostridium pasteurianum [14], single-cell oil using Mucor circinelloides [6], eicosapentaenoic acid (EPA) using Pythium irregulare [15], and biogas [16] and ethanol using metabolically engineered Escherichia coli [17]. The production of ethanol from thin stillage is greatly interesting from a process economics standpoint since it could be recovered without needing additional steps: the produced ethanol left after the series of evaporations can be sent back into the process and follows the general stream towards the distillation column ( Figure 1).…”

Characterizing compositional changes of Napier grass at different stages of growth for biofuel and biobased products potential

“…The organic content of Napier grass juice was quantified and reported holistically as COD; a parameter known to be valuable for high value co-product generation like protein-rich fungal biomass (Nitayavardhana and Khanal, 2010;van Leeuwen et al, 2012;Nitayavardhana et al, 2013). Microbial cultures are able to utilize the organic constituents in liquid substrates, consequently reducing COD concentrations while simultaneously producing microbial biomass and/or high value biobased products.…”