2.3.2. Liquid Phase

The HTL liquid phase, as well as liquid streams from the nutrient recovery (Figure 1), underwent analysis for pH, elemental concentration, and ammonium nitrogen (NH4-N). NH4-N was determined with the Hach-Lange cuvette test LCK 304. The inorganic element content was measured with ICP-OES (Agilent 715) by injection diluted 1-to-10 with 1% HNO3 HTL liquid samples. The nitrogen content was determined by an elemental analyzer (HekaTech, Euro EA), and the pH was measured by HACH HQ40d. The analyses were conducted twice.
