Incorporation of salinity, nitrogen, and shading stress factors into the Huesemann Algae Biomass Growth model

This research calibrates nitrogen, salinity and shading growth factors for The Huesemann Algae Biomass Growth (HABG) model. It continues the HABG approach of independently calibrating growth coefficients for specific strains prior to simulation of algal growth in open pond raceways. Several Regional Algal Feedstock Testbed (RAFT) had salinity stress, nitrogen limitation, and shading, which all reduced growth rate. The salinity effect appeared to be most significant in Scenedesmus obliquus experiments. In order to quantify these effects, laboratory experiments were carried out to measure growth response of S. obliquus to high salinity and limited nitrogen. In addition, the shading effect was estimated based on raceway geometry, solar angle, albedo, and measured light intensity data. The new salinity, shading, and nitrogen stress factors greatly improved the accuracy of the model with the observed growth conditions. Over-estimation was decreased from 90% to 22%. The methods developed in this study are straightforward and can be applied to other algae strains and raceways.