Microbial reduction of the chemical oxygen demand of cottage cheese whey

The objective of the study was to analyze the microbial reduction of the Chemical Oxygen Demand (COD) of cottage cheese whey by Kluyveromyces fragilis, Geotrichum candidum, Streptococcus faecalis subspecies liquefaciens and a Candida species.

The four starter cultures were added singly and in combinations of two, three and four making 15 different culture treatments. A 10 per cent inoculum of the culture treatments was added to 400 milliliters of whey. The culture treatments were grown in the whey for 96 hours at 30°C.+ 1°C. on a Burrell shaker. Samples taken at 6, 12, 24, 48, and 96 hours were analyzed for pH, total solids and then centrifuged. The resulting supernatant was analyzed for total solids, titratable acidity, lactose, protein, cell weight and COD. The effects of culture treatment and time were studied. Using the analysis of variance data, regression equations were derived to follow the fate of the several parameters over time.

Effect of culture treatments was significant on all parameters except protein which overall averaged 50 percent reduction. Several treatments showed an outstanding ability to utilize the organic contents of whey and thereby reduce the COD of the whey. Up to 96 percent of the lactose was utilized. Typically titratable acidity was neutralized and pH approached 7. When these factors were combined with 50 percent utilization of protein, the COD was reduced by up to 82 percent. Six culture treatments reduced the COD to below 15,000 ppm. in 96 hours. One treatment reduced the COD to 16,000 ppm. in 48 hours.