Polyethylene glycol as a robust, biocompatible encapsulant for two-stage treatment of food and beverage wastewater

Abstract

This research investigates encapsulation of microorganisms for two-stage anaerobic treatment of industrial food and beverage wastewater. Encapsulants were tested in batch reactors to determine the potential for biological inhibition during encapsulation. Flow through reactors were constructed to test the leakage of microorganisms from the encapsulants over time. Five different reactor designs were explored to assess the effects of reactor conditions on encapsulant longevity and activity. It was found that polyethylene glycol (PEG) beads encapsulating biomass grown in suspension did not change in shape, activity, or protein concentration over one month in flow-through reactors. In reactors mixed by stir bars, PEG beads encapsulating suspended biomass were intact after 6–10 months; the PEG beads were not tested for longer periods of time, it is therefore unclear how long they can last. PEG beads encapsulating powdered activated carbon-supported biofilms improved methane production approximately 20 times compared to PEG beads encapsulating suspended biomass, but the beads were less robust, chipping and losing biomass over time. This study provides information on encapsulant performance that can be used to select encapsulants for implementation.