Biological and photocatalytic treatment at pilot plant scale of synthetic coloured wastewater produced in university teaching laboratories

Abstract

Dyes and chemical additives, present in wastewater produced in Microbiology teaching laboratories generate high contamination. They are difficult to degrade and according to the Colombian regulation should be treated before final disposal. In this work, a pilot plant was used to treat synthetic wastewater (SWW) containing a mix of dyes (10 mg/L Crystal Violet, 10 mg/L Congo Red, 10 mg/L Malachite Green and 10 mg/L Fuchsin Gram). To remove this type of contaminants initially, the capacity of a fungal/bacterial sludge (FBS) on a 1 L scale was determined. Subsequently, the operating conditions that favor tertiary treatment were selected by using TiO2/UV photocatalysis at 0.25 L scale and finally the complete treatment plant was integrated and evaluated (Pre-treatment, secondary treatment and tertiary treatment). The SWW that entered the plant had the following characteristics: Chemical Oxygen Demand (COD): 4033 mg/L, Biochemical Oxygen Demand (BOD5): 2750 mg/L, Color Units (CU): 2010, BOD5/COD ratio: 0.68, 19_3 ºC and a pH of 7.0. After 37 hours of plant operation, overall removal was 98 _ 3%, 99 _ 6% and 99 _ 8%, for COD, BOD5 and CU. Demonstrating that integration of unitary operations in a sequential and orderly manner, are a novel alternative for treatment of this type of wastewater.