Biological treatment of Schochu distillery wastewater

Abstract

An efficient method for the treatment of distillery wastewater from Shochumaking, which has high organic matters and suspended solids, must be developed as soon as possible as an alternative to sea dumping. First of all, Aspergillus awamori var. kawachi was cultivated aerobically at 35°C for a day in a 30-litre jar-fermentor (working volume; 18 litres) with an agitator, using the distillery wastewater as a medium. The specific resistance of the cultivated broth drastically decreased from 1.17×10 13 m kg −1 to 2.82×10 11 m kg −1, which facilitated filtration. The concentrations of BOD and PO 3− 4 in the filtrate of the cultivated broth also decreased drastically to 48 400 and 235 litre −1, respectively. After the filtrate was diluted three times with tap water, it was treated by an anaerobic fluidized-bed reactor at 37°C. By addition of Ni 2+ and Co 2+ to the diluted wastewater the maximum volumetric TOC loading rate of 22 g litre −1 day −1 could be achieved. However, the concentration of NH + 4 increased up to 1800 mg litre −1 during the anaerobic treatment. The NH + 4 was removed easily in a denitrification reactor by using volatile fatty acids remaining during the anaerobic treatment as electron donors. The quality of effluent from a nitrification reactor was suitable to be discharged to a river.