## 3 Results and Discussion
### Analysis of Effluents from Anaerobically Digested Food Waste and Dairy Manure  
The physical properties of both the anaerobically digested flush dairy manure and food waste effluents before and after autoclaving are presented in Table 5. The majority of nitrogen in anaerobically digested waste effluents is in the form of ammonium and nitrate salts and magnesium or calcium phosphate salts. The majority of N-ammonia did not volatilize during high temperature autoclaving. It is possible that high ionic strength [45] from additionally supplemented NaHCO\({}_{3}\) salts and alkalinity used to supply inorganic carbon and limit contamination, as well as the microalgal sorbent properties [46], can further help reduce ammonia volatilization during the proposed outdoor phototrophic second-stage cultivation at high outdoor summer temperatures and high pH 10. An initial and final effluent total nitrogen volatilization rate of 16.15 mg L\({}^{-1}\) day\({}^{-1}\) and 3.66 mg L\({}^{-1}\) day\({}^{-1}\) were measured for a foam-capped 0.25 L flask containing 16.8 g L\({}^{-1}\) NaHCO\({}_{3}\) and 5% (\(v/v\)) of anaerobically digested food waste effluent in this study based on a plot of media nitrogen as a function of time (Figure 7). For a similar culture flask, a relatively low overall equivalent gas-liquid O\({}_{2}\)-mass transfer coefficient of 24 h\({}^{-1}\) was previously estimated for similarly foam-capped 0.25 L shaker flasks [47]. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Food Waste** & **Dairy Manure** \\ \hline \multicolumn{3}{c}{**Effluent Properties (g L\({}^{-1}\))**} \\ \hline
**Pre-Autoclave** & & \\ Ammonia-N & 0.89 & 0.63 \\ Total-N & 1.07 & 0.71 \\ Alkalinity & 7.04 & 2.35 \\ pH & 7.79 & 7.32 \\ PO\({}_{4}\)\({}^{3-}\) & 0.08 & 0.42 \\ COD & 6.64 & 15.00 \\
**Post-Autoclave** & & \\ Ammonia-N & 0.66 & 0.24 \\ Alkalinity & 5.90 & 2.29 \\ pH & 9.26 & 9.23 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Measured properties of anaerobically digested effluents. Figure 6: \({}^{1}\)H NMR spectra of wheat-straw torrefraction condensate before (**bottom**) and after (**top**) purification and de-toxification. The ammonia volatilization rate in a microalgal open-pond can be predicted via a convective mass transfer model dependent on ambient temperature, airflow over the surface, pH, ionic strength, and the \(NH_{3}\) concentration gradient between the ammonium (\(NH_{4}\)\({}^{+}\)) solution and the ambient air estimated as per Equation (10). \[J_{NH3}=-K_{m}\Big{(}[NH_{3}]_{gas}-[NH_{3}]_{ambient}\Big{)} \tag{10}\]  
where \(J_{NH3}\) is the \(NH_{3}\) volatilization flux (g \(NH_{3}\)\(-\)\(N\) m\({}^{-2}\) s\({}^{-1}\)), \(K_{m}\) is the convective mass transfer coefficient (m s\({}^{-1}\)), \([NH_{3}]_{gas}\) is the concentration of gaseous \(NH_{3}\) in equilibrium with dissolved \(NH_{3}\) in solution (g \(NH_{3}\)\(-\)\(N\) m\({}^{-3}\) air), and \([NH_{3}]_{ambient}\) is the concentration of \(NH_{3}\) in ambient air (g \(NH_{3}\)\(-\)\(N\) m\({}^{-3}\) air), which is normally very small and assumed to be negligible. The concentration of gaseous \(NH_{3}\) at equilibrium with the dissolved \(NH_{3}\) in solution is determined using [PERSON]'s law relating to the concentration of dissolved \(NH_{3}\) in the BG-11 medium supplemented with food waste effluent to an equilibrium concentration of \(NH_{3}\) in the air space immediately above the liquid surface following Equation (11). \[K_{H}=\frac{[NH_{3}]_{gas}}{[NH_{3}]_{solution}}=\bigg{(}\frac{0.2138}{T} \bigg{)}10^{6.123-1825} \tag{11}\]  
where \(K_{H}\) is the [PERSON]'s law constant, (g \(NH_{3}\)\(-\)\(N\) m\({}^{-3}\) air)/(g \(NH_{3}\)\(-\)\(N\) m\({}^{-3}\) solution) and \(T\) is absolute temperature of BG-11 media (K). Ammoniacal N in the BG-11 media consists of both \(NH_{3}\)\(-\)\(N\) and \(NH_{4}\)\({}^{+}\)\(-\)\(N\). The fraction of total ammoniacal N present as \(NH_{3}\) is estimated using equilibrium thermodynamic principles as per Equation (12).