Modelling energy efficiency of an integrated anaerobic digestion and photodegradation of distillery effluent using response surface methodology

Journal article

Authors/Editors

Ochieng, Aoyi

Research Areas

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Publication Details

Author list: Apollo S, Onyango MS, Ochieng A

Publisher: Taylor and Francis Group

Place: ABINGDON

Publication year: 2016

Journal: Environmental Technology (0959-3330)

Journal acronym: ENVIRON TECHNOL

Volume number: 37

Issue number: 19

Start page: 2435

End page: 2446

Number of pages: 12

ISSN: 0959-3330

eISSN: 1479-487X

Languages: English-Great Britain (EN-GB)

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Abstract

Anaerobic digestion (AD) is efficient in organic load removal and bioenergy recovery when applied in treating distillery effluent; however, it is ineffective in colour reduction. In contrast, ultraviolet (UV) photodegradation post-treatment for the AD-treated distillery effluent is effective in colour reduction but has high energy requirement. The effects of operating parameters on bioenergy production and energy demand of photodegradation were modelled using response surface methodology (RSM) with a view of developing a sustainable process in which the biological step could supply energy to the energy-intensive photodegradation step. The organic loading rate (OLRAD) and hydraulic retention time (HRTAD) of the initial biological step were the variables investigated. It was found that the initial biological step removed about 90% of COD and only about 50% colour while photodegradation post-treatment removed 98% of the remaining colour. Maximum bioenergy production of 180.5kWh/m(3) was achieved. Energy demand of the UV lamp was lowest at low OLRAD irrespective of HRTAD, with values ranging between 87 and 496kWh/m(3). The bioenergy produced formed 93% of the UV lamp energy demand when the system was operated at OLRAD of 3kg COD/m(3)d and HRT of 20 days. The presumed carbon dioxide emission reduction when electricity from bioenergy was used to power the UV lamp was 28.8kg CO(2)e/m(3), which could reduce carbon emission by 31% compared to when electricity from the grid was used, leading to environmental conservation.

Keywords

Anaerobic digestion, bioenergy, carbon dioxide emission reduction, response surface methodology, UV photodegradation

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