The process wastewater from a soy sauce fermentation plant was studied. Plant production has increased for the last 20 years, especially from 1989 to the present, with a resultant increase in average wastewater discharge of 284 m3 (75,000 gallons) per day.

Soybean fermentation wastewater is characterized by high concentrations of protein and starch. The increase in effluent releases resulted in increased surcharges in two waste discharge categories: Biochemical oxygen demand (BOD) and total suspended solids (TSS). The high concentrations of protein in the wastewater also contributed to strong odors in the treatment works. The plant instituted the use of a novel product, EcoSystem Plus (ESP), a proprietary enzyme surfactant mixture.

After treatment, effluent BOD levels decreased an average of 48% and TSS levels decreased an average of 51% from the period before treatment. Aeration tank dissolved oxygen (DO) increased by almost five fold from the period before treatment.

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