Biological Treatment of Agro‐Industrial Wastewater for the Production of Glucoamylase and Rhizopus Biomass

Abstract

The present work concerns the biological treatment of a starch wastewater, coupled with the production of microbial biomass and glucoamylase. Every unit operation of the process was tested in a laboratory scale, in order to perform a feasibility analysis. Fermentation tests confirmed that a stirring rate of 300 rpm was the optimum (in the investigated range) as concerns biomass growth and enzyme activity. Ultrafiltration tests showed that the best operating conditions in the investigated range for enzyme recovery were: temperature 25°C, transmembrane pressure 100 kPa, membrane cut off 30 kDa. Diafiltration tests evidenced that an effective enzyme washing (about 85% reduction of chemical oxygen demand) was achieved with 3 volumes of water per volume of feed and no significant enzyme deactivation was observed.

Keywords:

• Wastewater
• Rhizopus
• glucoamylase
• fermentation
• ultrafiltration
• diafiltration

Acknowledgements

Authors are grateful to Mrs. Lia Mosca and Mr. Marcello Centofanti for their helpful collaboration in the experimental work.