Biomass encapsulation for anaerobic resources recovery from wastewater

In addition to methane gas, there are high-value intermediates, such as hydrogen gas and medium chain fatty acids, produced during anaerobic process by microbial communities with specialized functions. In this study, a customizable alginate polymer matrix was used to selectively encapsulate the specialized biomass to achieve high-rate recovery of high-value resources. A composite coating can be applied to the encapsulant to enhance the biomass retention, but created permeation barrier for the substrate. In addition, different cross-linking agents that change the chemical stability of the alginate matrix altered the biomass retention ability and mass transport performances of the alginate matrix. Calcium cross-linked alginate had the highest permeability and the lowest biomass release rate, but also was reported to be the least stable against monovalent cations and phosphate compare to strontium and barium. High-rate hydrogen production was observed (up 6 L hydrogen/L reactor volume) from flow-through reactors containing encapsulated biomass feed brewery wastewater. Even when suspended biomass was washed out at the hydraulic retention time of 45 min, the reactor continued to produce hydrogen at 2.5 L/L reactor volume. The hydrogen production performance at different operating conditions can be predicted by a diffusion-reaction model adapted to describe the encapsulation system. The encapsulation system has shown to be a promising methods to achieve high-rate recovery of high-value intermediates from brewery wastewater. The customizability of the system suggested its potential to be optimized to treat other waste streams with various characterizations with different microbial communities.