Picture of what this could look like from a prior experiment done in Finland.

Ammonia Sulfate Extraction & Analysis

• Suspended solid (SS) was determined using a Whatman membrane (pore size 0.4µm) with a drying method at 105C for 2 hours (SFS-EN 872, year 2005). The harvested ammonium sulfate and phosphorus compounds (sediment) were determined or confirmed by XRD (X-ray diffraction) using an X-ray powder diffractometer (PANalytical X'Pert Pro MPD α1)

Experiment Environment & Optimization

• Air Flow Rate → increase ammonia stripping
  • Should be < 1.1 +/- 0.1 L/min
  • Anything greater will cause a foaming issue
• Temperature → where experiment is being conducted
  • 40°C for 28 hours

Experiment 1 → Pure urine where pH is not maintained

• Materials

  • 700 mL in 1L glass bottle
  • 14 g of Ca(OH)2 added to achieve pH of 12 +/- 0.3
  • Two aliquots of 1M H2SO4 (i.e., 100 mL and 50 mL) were taken in two different bottles

• Procedure

  • The urine containing bottle was placed in a water bath to control the temperature and it was aerated by compressed ambient air with a flow rate of 1100 - 1200 mL/min (calculated using Equation 3) via a ceramic diffuser (30 mm long and 16 mm diameter) for NH3 (ammonia) stripping
  • The stripped air/NH3 from the urine containing bottle was passed into the 100 mL H2SO4 in the first bottle and the exhausted air was passed into the 50 mL of H2SO4 in the second bottle
  • The pH of the H2SO4 was kept under 2 by adding 9M H2SO4 when needed so there was enough H2SO4 to react with NH3 to form (NH4)2SO4.
  • All the experimental condition and setups were similar to Experiment 1, but the pH of the urine was maintained above 11 for the entire experiment. The pH was maintained for the entire experiment by supplementing 2.5 g of Ca(OH)2 after 12 h (i.e. after the 3rd 146 sampling of the experiment).

  

  

  • Extraction: After the completion of the experiment, the urine was left overnight and the supernatant (later referred to as the effluent) was carefully separated from the sediment. The sediment and the (NH4)2SO4 solution (NH3 adsorbed H2SO4 solution) were dried at 60 oC for 24-48 h, and the phosphorus-rich sediment and the crystallized/solid (NH4)2SO4 compound were recovered. The sediment was analyzed for N, P, and K, and the effluent was analyzed for SS, N, P, and K.

• Calculation of free ammonia (IF needed)