Fungal Purification of an Industrial Effluent Containing Volatile Fatty Acids by Means of a Crossflow-Microscreen Technique

An industrial effluent containing C₂ to C₅ monocarboxylic acids was successfully treated by the fungus Geotrichum candidum using the selective mechanism of the crossflow-microscreen method. Due to the cell separating capacity of the microscreen the system could be operated as a cell recycle reactor with the hydraulic residence time (θ) independent of the mean cell residence time (θ_x). At θ = 1.25 h and θ_x = 7.5 h, 89.5% COD reduction was obtained. The excess biomass could be harvested by simple screening and contained a crude protein content of 50.2%, which may be used as a feed supplement.

The growth kinetic values obtained for a monoculture of G. candidum grown on the industrial effluenf were as follows: ^µmax = 0.26 h⁻¹, Y = 0.38 g cells g⁻¹ COD, K_s = 201 mg COD ℓ⁻¹, k_d = .009 h⁻¹, indicating the potential use of this micro-organism for the treatment of several industrial effluents.