Biostimulation of Immobilized Microbes in a Fixed-Bed Bioreactor towards Hydrocarbon-Contaminated Water Remediation Using Compost Tea and Egg Shell Powder

The need to satisfy the ever increasing petroleum demand coupled with the availability of enough crude oil reserves to meet demand for several decades to come makes petroleum contamination a globally important subject. Bioremediation has emerged as an efficient treatment option for the remediation of organic contaminants including petroleum owing to the failure of physico-chemical treatment options to address petroleum contamination. The current study targeted the application of compost tea (CT) and egg shell powder (ESP) solution at various levels as nutrient amendments/bio-stimulants for hydrocarbon-eating microbes attached to support media surfaces in a fixed-bed bioreactor system. CT and ESP were characterized to be rich in essential nutrients including N, P, K, Ca, Mg, Na and C. CT and ESP application at four levels each recorded appreciable boosts in microbial numbers and TPH removal across applied levels. CT application recorded 23.49±2.20 to 29.36±0.79 % boost in TPH removal and 17.03±3.01 to 61.07±2.26 % boost in microbial mass. Boosts in TPH removal assumed the order 3200 ml > 1600 ml > 800 ml > 400 ml. ESP application similarly recorded 27.56±2.62 to 29.57±0.90 % boost in TPH removal and 17.50±1.60 to 24.43±2.05 % boost in microbial mass. Recorded TPH removal boosts assumed the trend 20 g/l >10 g/ l > 2.5 g/l >5 g/l.