Abstract
In the present work, removal of 4-chlorophenol (4-CP) by the mixed microbial consortium was evaluated in an airlift inner loop bioreactor. During the study, the effect of various reactor parameters such as hydraulic retention time (HRT), biogenetic substrate concentration, loading rate, and initial substrate concentration on the removal efficiency of 4-CP was investigated. Bioreactor showed a maximum removal rate of 16.59 mg/L/h at the optimum conditions of 24 h HRT, 400 mg/L initial 4-CP, and 0.2 g/L peptone. The optimum HRT found was 24 h after that the washout occured, and the degradation efficiency almost dropped to 50 % at 18 h HRT. Effect of peptone showed that lower concentration of peptone improves 4-CP removal efficiency of the bioreactor. Also, the mixed consortium had utilized 4-CP as a carbon source, as evidenced by the increasing biomass concentration with 4-CP at constant peptone concentration. The presence of 5-chloro 2-hydroxymuconic semialdehyde in the reactor infers that the mixed consortium has followed the meta-cleavage pathway for 4-CP degradation.
Highlights
With heavy industrialization and urbanization, activities polluting the environment and concomitantly sabotaging the inherent ecosystems have enormously increased
The bioreactor was filled with 12 L mineral salt medium (MSM) containing 20 mg/L of 4CP and inoculated with 10 % (v/v) mixed consortium
An airlift bioreactor was evaluated for the removal of 4-chlorophenol in synthetic wastewater using the mixed microbial consortium isolated from the dye industries
Summary
With heavy industrialization and urbanization, activities polluting the environment and concomitantly sabotaging the inherent ecosystems have enormously increased. Chlorophenols have been classified as priority pollutants by the US Environmental Protection Agency (ATSDR 2015) They are primarily found in the industrial effluent from pulp and paper, leather tanning, biocide, dyes, herbicide and chlorination of drinking and waste water (Olaniran and Igbinosa 2011; Field and Sierra-Alvarez 2008; Wang et al 2014). Chlorophenol compounds have been demonstrated to have mutagenicity, carcinogenicity, immunogenicity, and may cause fatalities (IARC 1986; Daniel et al 2001) Conventional methods such as adsorption, chemical oxidation, photo-degradation and solvent extraction have limitations due to their high cost of implementation, production of toxic by-products and low energy efficiency (Herrera et al 2008; Durruty et al 2011). It is eco-friendly and energy efficient treatment with assuring future (Field and Sierra-Alvarez 2008; Olaniran and Igbinosa 2011; Basak et al 2013, 2014; Chakraborty et al 2013)
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