Technology of wastewater treatment production of vegetable oils and fats and evaluation of aeration tank efficiency on the basis of microanalysis of activated sludge

Abstract

This article discusses the main stages and features of wastewater treatment at "Food Ingredients" LLC (Russia, Krasnodar region) involved in vegetable oils and fats refining. The experimental data on averaged qualitative composition of industrial wastewater involving the period from January to June, 2018 were presented. The indicators of the quality of averaged waste did not exceed: 20 mg/l for ammonium nitrogen; 20 mg/l for phosphates; 800 mg/l for suspended solids; 700 mg/l for fatty substances. The operation of biological aeration tank was analyzed from January to June, 2018. The graphic dependences of the change of sludge index, phosphate ions, chemical oxygen demand (COD), and temperature were given. The species composition of microorganisms and their amount were determined by means of optical microscopy. Absolute quantity of microorganisms in activated sludge was determined with the "calibrated droplet" method. As of October 31, 2018 the quantity of microorganisms was as follows, U/ml: small flagellates - 44,015; free swimming infusoria - 34,233; Euglypha - 6,520; Vorticella - 27,713; Rotatoria - 29,343; Aspidiska - 36,950; Aelosoma - 2,173; Heliozoa - 1,086. No filamentous microorganisms were detected. After treatment, the recovered water was characterized by the following indicators of the quality: transparent, ammonium nitrogen content in water was less than 0.1 mg/l, phosphate ion content was no higher than 0.2 mg/l; COD was no higher than 30 mg O2/l, hydrogen index was about pH = 7. These indicators comply with the requirements for water in technical water supply systems of industrial enterprises (Russia), as applied to recovered water produced of wastewater for subsequent use in recycled water supply system. The treated water is reused in the production processes, which evidences high quality of water treatment and reliable operation of the equipment in local treatment facilities at "Food Ingredients" LLC during 10 years of operation.