*2.1.1 NH3 recovery*

For the NH3 recovery, we used a formulated dairy digestate liquid sample by preparing an NH4 <sup>+</sup> solution with the NH4 <sup>+</sup> concentration of 2100 mg/L and alkalinity *Mitigation of Environmental Impact of Intensive Animal Farming through Conversion… DOI: http://dx.doi.org/10.5772/intechopen.105131*

of 8800 mg/L by mixing NH4OH and NaHCO3, respectively, with 1 L of distilled water. This was to simplify numerous experiments anticipated to be performed to optimize the recovery conditions. Once optimized, the real digestate liquid will be used for validation of our results. The above concentrations were obtained by analyzing samples of the digestate liquid taken from a centrifuge effluent of the dairy digestate on a dairy farm with 5000 Holstein cows. The chemicals used were ammonium hydroxide (28% NH3 in H2O, Sigma Aldrich), sodium bicarbonate ((≧99.7%, Sigma Aldrich), sodium carbonate (≧99.5%, Sigma Aldrich), and sulfuric acid (≧99.99%, Sigma Aldrich), all without further purification.

#### *2.1.2 Protein recovery*

The manure digestate solid (DS) sample was collected from the solid separated by a screw separator from the digestate effluent of AD using as the feed the dairy manure from a dairy farm in California Central Valley. The DS sample had a 50% water content. 24.8 g of DS sample was mixed in 1 L of distilled water and treated by THP without any pretreatment. The chemical composition of the dried DS sample is listed in Section 3.

#### **2.2 Methods**
