EFFECT OF BIOAUGMENTATION ON AEROBIC DIGESTION OF BIODEGRADABLE ORGANIC WASTE

The effect of bioaugmentation on aerobic digestion of biodegradable organic waste using indigenous bacteria isolated from the waste is presented. The analysis involves twenty-five 500 mL bioaugmented flasks (bioreactors) and twenty-five 500 mL non-bioaugmented flasks (i.e. control bioreactors) charged with prepared liquid waste and aerated for a period of 50 days using air at a flow rate of 0.15 L.min-1 per 400 mL of the liquid waste in each flask. Every 2 days, one bioaugmented-bioreactor and one control-bioreactor are dismantled and the microbial density and chemical oxygen demand (COD) of liquid sample taken from each flask are measured, as well as the pH of the medium in each flask. During the first 20 days of the experiment, the microbial population in the bioaugmented bioreactors increases with time from an initial value of to a maximum value of and from an initial value of to a maximum value of in the control bioreactors; while the COD decreases with time from 58.35 mg.L-1 to 11.84 mg.L-1 with 80% conversion of the substrate in the bioaugmented bioreactors, and from 58.35 mg.L-1 to 16.91 mg.L-1 with 71% conversion of the substrate in the control bioreactors. After the 20th day of the experiment, the microbial population in both types of bioreactors decreases with time, while the COD increases with time until the last day of the experiment. The pH in the bioaugmented and non-bioaugmented bioreactors are close and vary from 4.59 to 5.63, and the temperature in two types of bioreactors lie within the range 27oC – 30oC.