The zeta potential of the WAS samples was analyzed using a Zetasizer Nano (Nano-ZS90, Malvern Instrument Ltd., UK). The particle size distribution was measured by a laser particle size analyzer (LAP-W2000H) using ultrapure water as the dispersant. The Fourier transform infrared spectroscopy (FTIR) analysis of sludge samples was recorded in a wavenumber range of 4000–400 cm−1 by a Nicolet 6700 spectrometer (Thermo, USA).
Given the difficulty in separating the formed solids from the conditioned WAS samples, the extracted EPS solution was used and treated with the KMnO4/PMS process to monitor whether manganese oxides (MnOx) formed after KMnO4 oxidation of the organics in EPS. Briefly, after the extracted EPS solution was treated with the KMnO4/PMS process, the reaction solution was filtered through a 0.45 μm cellulose acetate membrane to collect the brown-red solids. Then, the collected solids were rinsed alternately several times using ethanol and ultrapure water, and vacuum-dried at 60 °C overnight. Finally, the dried solid samples were scanned by transmission electron microscopy (TEM) to capture the microscale crystallization and structure and energy dispersive X-ray spectroscopy (EDX) to analyze the elemental composition.
Given the difficulty in separating the formed solids from the conditioned WAS samples, the extracted EPS solution was used and treated with the KMnO4/PMS process to monitor whether manganese oxides (MnOx) formed after KMnO4 oxidation of the organics in EPS. Briefly, after the extracted EPS solution was treated with the KMnO4/PMS process, the reaction solution was filtered through a 0.45 μm cellulose acetate membrane to collect the brown-red solids. Then, the collected solids were rinsed alternately several times using ethanol and ultrapure water, and vacuum-dried at 60 °C overnight. Finally, the dried solid samples were scanned by transmission electron microscopy (TEM) to capture the microscale crystallization and structure and energy dispersive X-ray spectroscopy (EDX) to analyze the elemental composition.