Each sample was assigned a number 1–7 to indicate the sampling location, and samples from locations 1, 2, 3, 4, and 5 were assigned either letter A or B to indicate a draw from the acid slurry or base slurry system, respectively. Samples (≥10 mL) were drawn weekly for 10 weeks (120 samples total). These samples were stored in screw-cap polyethylene tubes at 4 °C until imaging
was conducted.