Biological degradation of catechol in wastewater using the sequencing continuous-inflow reactor (SCR)

Ali Ahmad Aghapour,Gholamreza Moussavi,Kamyar Yaghmaeian

doi:10.1186/2052-336x-11-3

Abstract

Catechol is used in many industries. It can be removed from wastewater by various methods but biological processes are the most superior and commonly used technology. The SCR is a modified form of SBR used to degrade catechol. The objective of this study was to investigate the performance of SCR for biodegradation and mineralization of catechol under various inlet concentrations (630–1500 mg/L) and hydraulic retention times (HRT) (18–9 h). This study used a bench scale SCR setup to test catechol degradation. The acclimation time of biomass for catechol at degradation at 630 mg/L was 41 d. The SCR operating cycle time was 6 h and the consecutive times taken for aerating, settling and decanting were 4, 1.5 and 0.5 h, respectively. This study investigated the effects of inlet catechol concentration (630–1560 mg/L) and HRT (18–9 h). The average catechol removal efficiencies in steady-state conditions of 630, 930, 12954 and 1559 mg/L of catechol were 98.5%, 98.5%, 98.2% and 96.9% in terms catechol and 97.8%, 97.7%, 96.4% and 94.3% for COD, respectively. SCR with acclimated biomasses could effectively remove the catechol and the corresponding COD from wastewater with concentrations of up to 1560, at the loading rate of 5.38 kg COD/m3.d and at a HRT of up to 13 h. The HRT was determined as an important variable affecting catechol removal from wastewater. Reducing the HRT to below 13 h led to reduced removal of catechol and COD.

Highlights

Catechol, it has many applications in industry for example as a photographic developer, lubricating oil, polymerization inhibitor and in pharmaceuticals [1,2]
The bioreactor was operated in two phases, the first phase of operation evaluated the effect of inlet concentrations at a constant hydraulic retention times (HRT) of 18 h and the second phase of the operation evaluated the effect of HRT (18, 13 and 9 h) at the constant catechol concentration of 1560 mg/L
During the acclimatization process certain enzymes are induced in the microorganisms that participate in the biodegradation reaction

Summary

Introduction

Catechol, (a derivative of benzene and a phenolic compound) it has many applications in industry for example as a photographic developer, lubricating oil, polymerization inhibitor and in pharmaceuticals [1,2]. The International Agency for Research on Cancer (IARC) has classified catechol in terms of a carcinogenic risk to humans (Group 2 B) [1]. Phenolic compounds such as catechol have been listed as prioritypollutants by EPA, USA [2,3]. Catechol is fatally toxic to fish at concentrations of 5–25 mg/L and it inhibits biological growth in microorganisms [4,5]. It has been detected in wastewater from coal conversion processes, crude wood tar, and drainage water from bituminous shale and

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