Improved biogas generation from biomethanated distillery wastewater

Improved biogas generation from biomethanated distillery wastewater by pre-treatment with catalytic wet air oxidation. Ganesh M. Bhoite and Prakash D...
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Improved biogas generation from biomethanated distillery wastewater by pre-treatment with catalytic wet air oxidation Ganesh M. Bhoite, and Prakash D. Vaidya Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.7b04281 • Publication Date (Web): 01 Feb 2018 Downloaded from http://pubs.acs.org on February 3, 2018

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Industrial & Engineering Chemistry Research

Improved biogas generation from biomethanated distillery wastewater by pre-treatment with catalytic wet air oxidation

Ganesh M. Bhoite, Prakash D. Vaidya*

Department of Chemical Engineering, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga, Mumbai-400019, India.

* Corresponding author (Tel.: +91 22 3361 2014; Fax: +91 22 3361 1020; Email: [email protected])

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Abstract Catalytic wet air oxidation (CWAO) is a prospective method for the treatment of distillery effluents. In this work, the biodegradability of biomethanated distillery spent wash (BOD5=8100 and COD=40000 mg/L) was improved by oxidation over ferrous sulfate catalyst. The homogeneous CWAO process was optimized by investigating the effects of reaction variables such as temperature (150-225 0C), oxygen partial pressure (0.69-2.07 MPa) and catalyst loading (16-48 mg/L). After oxidation at T=175 0C for 1 h, adsorption over activated carbon (loading 5%) was performed at ambient temperature. As a result, 73% reduction in COD and substantial rise (from 0.2 to 0.45) in the BOD5/COD ratio was observed. This ratio further rose to 0.52, when anaerobic digestion was performed using 1% acclimatized biomass. For every m3 of wastewater, 1.1 Nm3 of biogas was formed (methane 69%). After a final polishing step by aerobic treatment, BOD5/COD was 0.58 and 91% COD was destroyed. Clearly, this work has provided a useful solution to the effective pre-treatment and valorization of biomethanated distillery wastewaters. Lastly, we employed a two-step power-law model to describe kinetics of COD conversion.

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Introduction In India, alcohol distilleries are widely regarded as one of the most polluting

industries. It is mandatory for distillery units to meet the minimal national standards for the discharge of distillery wastewater into surface waters (COD