(587at) Comparing Hydrothermal Liquefaction of Algae Cultivated in Different Municipal Wastewater

Hydrothermal liquefaction (HTL) is a whole cell conversion pathway that converts algae biomass into a carbon rich biocrude.  Major benefits of using HTL over other biomass conversion methods, such as pyrolysis, is that it eliminates the need for drying because it uses subcritical water as the chemical driving force.  Wastewater (WW) cultivation addresses the main concerns of sustainable algal biofuelss (i.e lack of water, nutrients for growth and land use).  This paper reports the HTL conversion of WW-cultivated algae from effluent from Lawrence, KS and Fayetteville, AR.  HTL was performed at 6 % solids and 350 ºC with 60 minute reaction times.  Wastewater derived algae from the two locations resulted in very different biomass in terms of its proximate and ultimate analysis with KS WW-algae having higher lipid and carbon content [14 afdw% (ash free dry weight) and 48.9 afdw%, respectively)¹compared to AR WW-algae (3.0 afdw% and 39.2 afdw%, respectively).  However, after HTL >30% of organics above the initial lipid content was able to be converted to biocrude from each batch of WW-algae (biocrude yields: 44.5 afdw%- KS; 34.4 afdw%- AR).  Biochar and aqueous co-product fractions are also compared in terms of yield and energy and nutrient content.

References:

1)      Griffin W. Roberts, Marie-Odile P. Fortier, Belinda S. M. Sturm, and Susan M. Stagg-Williams, Promising Pathway for Algal Biofuels Through Wastewater Cultivation and Hydrothermal Conversion, Energy and Fuels,  27 (2), 857–867 (2013).