Besides biogas production, the following processes and technologies are available in practice for microbiological processing: 1) Lactic acid Using thermophilic lactic acid bacteria, such as Lactobacillus bulgaricus, the procedure is economically performed at 45-50/sup 0/C. Since the bacteria are sensitive to high lactate concentrations, buffering with CaCO/sub 3/ or lime-milk is necessary. 2) Ethanol Using lactose-fermenting yeasts, such as Kluyvermyces fragilis, alcohol production is easily performed at 25/sup 0/C and at pH-values between 4 and 6, the dry matter contents varying between 5 and 15% (concentrated whey or permeate). Addition of ammonium sulphate is necessary. 3) Single Cell Protein One-stage production of single cell protein (SCP) is possible using lactose-fermenting aerobic yeasts (K. fragilis, Candida utilis etc.). The yeast procuced and utilized in animal feeding (as Milke replacement in calf rearing) is currently offered in the Federal Republic of Germany at a price of approximately DM 1.40/kg. Two-stage fermentation of Saccharomyces cerevisiae following lactic acid fermentation and addition of enzymatically hydrolyzed starch can be performed effluent-free.