The biosynthesis of ammonium lactate, a product of lactic acid fermentation was studied from corn and glucose at five different pH values of 5.4 to 7% In the glucose fermentations, a 100 % conversion of substrate was obtained resulting in a maximum lactic acid production yield of 93-2 %. The optimum pH for the maximum volumetric rate of lactic acid biosynthesis (1.56 g dm-3 h-l) was between 6 0 and 65. The corn fermentations were slower than the glucose fermentations with a resulting lactic acid yield of 67.5 %. Hydrolysis of corn by enzymatic or chemical methods as well as the use of ammonium hydroxide for pH control increased both the final concentration and the rates of lactic acid production. An enhanced yield of more than 90 "LO was finally obtained in the corn fermentations. A logistic model adequately described the kinetics of biomass growth, lactic acid production and sugar utilization in the glucose fermentations at different pH values. The dynamics of lactic acid formation in the corn fermentations were also successfully described by the developed model. The dependence of the model parameters on pH was investigated.

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The white-rot fungus Coriolus versicolor, used in the form of mycelial pellets, provided an effective means to decolorise lignin-containing kraft El-stage effluent from wood treatment processes. The mycelial pellets adsorbed the chromophores of the liquor and oxidised them in the presence of glucose. For an original liquor containing 7000 colour units (CU), the mean colour removal in batch experiments was estimated to be 300 CU g-' mycelium h-I. The adsorption process and the oxidation process (following glucose addition) generally operated best at between pH 4 and 5, and at temperatures of 25 to 3 0 T , with a ratio of glucose to mycelium of 0.36. for a 2 4 h experiment. Magnesium ions accelerated the oxidation process. Decolorisation was then tested in a continuous reactor. The rate of loss of activity of the pellets was 1% per day and no mechanical damage to the pellets was observed in the reactor. With a liquor of 5600 CU a 50% decolorisation was attained in 15 to 30 h using 4.64 g dm-' mycelium. This represents a rate of chromophore consumption of 30 CU g-' mycelium h-'.

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