Biosynthesis of Utilizable Microbial Biomass in the Treatment of Milk Wastes in High-Rate Filters

Abstract

The feasibility of producing utilizable microbial biomass while treating dairy wastes in a pilot-scale high-rate Flocor tower was examined. The literature on different methods of utilizing organic wastes and on the growth and control of fungi in bacteria beds was reviewed. A survey of dairies using Flocor high-rate filters to treat their waste was carried out and samples of bios were removed from the filters for microbial analysis. Fungi dominated all the film samples and three species were selected from twenty-nine for further studies based on their frequency of isolation. Laboratory studies established the optimum growth conditions for these fungi in batch culture. The effects of temperature, pH and feed strength on fungal growth were determined using agar plates, flask cultures and horizontal plastic screens. The method of culture turbidity as a measure of mould growth was assessed. One of the selected fungi, Fusarium aquaeductuum, was excluded from further studies because of its potential toxicity. A continuous culture apparatus was devised and developed to produce sufficient fungal biomass for analysis and assessment of the nutritive value of two fungi. The results of the analysis compared favourably with commercially-based fungal products and pilot plant studies commenced. One of the selected fungi, Fusarium aquaeductuum, was excluded from further studies because of its potential toxicity. A continuous culture apparatus was devised and developed to produce sufficient fungal biomass for analysis and assessment of the nutritive value of two fungi. The results of the analysis compared favourably with commercially-based fungal products and Pilot plant studies commenced. The pilot plant was sited at a dairy, which already possessed a full-scale Flocor tower, and was commissioned in October, 1978. The temperature and strength of the effluent from the dairy were governed by the products being manufactured. The feed was acidified to encourage the growth of the selected fungi. Equipment failures prevented the plant from operating consistently and reliably but results obtained have shown that the production of fungal biomass is feasible. Analysis of pilot plant biomass revealed amino acid levels lower than those obtained from the fungi grown in the laboratory. The need for continued investigations was discussed.