Mass-Scale Algal Biomass Production Using Algal Biofilm Reactor and Conversion to Energy and Chemical Precursors by Hydropyrolysis

A pilot-scale algal biofilm reactor (P-ABR) was assessed for its potential to provide a continuous supply of high volume algal biomass to be utilized as feedstock for hydropyrolysis. The half-year long performance assessment showed significantly high productivity of 15–20 g m –2 d –1 with uniform biochemical composition. Hydropyrolysis (HyPy) using ZSM-5 was used to convert and partition ABR-grown algal biomass components into energy-rich biocrude (HyPyO), nutrient-rich aqueous condensate (HyPyA), carbon-rich solid residue (HyPyS), and gases. The effect of temperature on yield and composition of different HyPy products was quantified in terms of carbon and nitrogen recovery. The maximum yield of biocrude was 31% at 200 °C and decreased to 18% with an increase in temperature up to 300 °C. The influence of temperature on recovery of nitrogen showed preferential accumulation of nitrogen in the aqueous phase with increasing temperature. The highest carbon recovered was 41% in the form of biocrude (HyPyO) at 200 °C followed by 31% in HyPyA at 300 °C. In the context of energy and nutrient recovery potential of each of the HyPy products, applications of different fractions was explored for development of a sustainable algal biorefinery.