HTL-temperature, this study attempted to identify the optimal HTLtemperature
and the appropriate dilution of the AP for recycling to the
cultivation step so that eventually the net energy yield of the integrated
process could be maximized. Because the ammoniacal nitrogen levels
varied from 833–3833 mg L−1 across the six AP samples, it was decided
to normalize the all nitrogen levels to 4000 mg L−1 (by adding
(NH4)2SO4 to the samples) prior to initiating the growth studies. This
eliminated nitrogen availability as a variable in the growth experiments
intended to evaluate biomass growth on carbohydrates in the recycled
aqueous products of HTL.