Energy recovery and phosphorus phase behaviour from catalytic gasification of cyanobacterial biomass in supercritical water

Abstract

Hydrogen-rich gas has been successfully produced from cyanobacterial biomass by supercritical water gasification (SCWG). This study investigated the feasibility of energy recovery through cyanobacterial biomass gasification in supercritical water (SCW). During SCWG, a phosphorus (P) phase behaviour is generated from SCWG products, NaOH, Ca(OH)2, and low temperature (673 K). The results showed that both alkali additions had a positive effect on biogas production. The H2 yield could reach as high as 4.45 mol kg−1 with 1.0% NaOH loading. We also observed how additional NaOH improved the P bioavailability for plant growth. Furthermore, Ca(OH)2 could be considered a stabilizer for P, which would circumvent secondary pollution by preventing large quantities of P leaching in a relatively short amount of time. Liquid phase methods are used to treat wastewater by removing dissolved organic compounds, which have contaminated water sources. Therefore, liquid phase methods could serve as a desirable carbon source in wastewater treatment. The data illustrated that present technology provide a more effective way to convert waste cyanobacteria for H2 production and generate P activation or stabilization by alkali addition.