Encapsulation technology for decentralized brewery wastewater treatment: A small pilot experiment

Abstract

The feasibility of implementing encapsulation technology for the biological anaerobic treatment of high-strength wastewater was investigated. The small pilot-scale wastewater treatment process, deployed at a local brewery, consisted of a 4-L fermenting first-stage reactor containing alginate-encapsulated fermenting microorganisms and a 30-L methanogenic second-stage reactor containing alginate-encapsulated anaerobic digester sludge (CH4E reactor). A parallel second-stage 30-L anaerobic membrane bioreactor (AnMBR) was operated for comparison. The first-stage reactor produced 40.4 ± 47.3% more volatile fatty acids than present in the influent wastewater. The CH4E reactor stared rapidly, with an off-gas methane content >60% after 14 days. It took >1 month for the AnMBR to achieve this performance. Nevertheless, the CH4E reactor performance declined relative to the AnMBR over time. This was thought to be a result of encapsulant leakage and the encapsulation of a non-ideal initial community. Further optimization is needed, but encapsulation shows promise for small-footprint anaerobic biological treatment applications.

Keywords: Anaerobic digestion; Anaerobic membrane bioreactor; Brewery wastewater; Decentralized wastewater treatment; Encapsulation technology.