Short-Term and Long-Term Effects of Tourmaline on Activated Sludge Viability and Performance

The study aimed to explore the short-term and long-term effects of tourmaline on activated sludge viability and biological nutrient removal performance. The experimental results indicated that ultrafine tourmaline particles (1 g/L) promoted sludge viability, the reaction rates, and relative enzyme activities in wastewater nitrogen removal. The difference between short-term and long-term effects of tourmaline was not significant. Although the NH₄⁺-N removal rate and NO₃⁻-N formation rate in the presence of 1 g/L ultrafine tourmaline particles were increased to 13.8 and 6.8 mg/L•h, which were higher than those in the control (11.0 and 6.0 mg/L•h), short-term and long-term exposure to 1 g/L ultrafine tourmaline particles did not change the effluent concentrations of ammonia nitrogen, nitrite, and nitrate because the relative substrate concentrations were low in the influent. Denaturing gradient gel electrophoresis (DGGE) analysis results indicated that the microorganism community structures including the whole bacteria community, ammonia-oxidizing bacteria community, or the whole fungi community were not changed after the long-term exposure to 1 g/L ultrafine tourmaline particles, and Shannon diversity indices (H′) assays revealed that the diversities of community structures were not changed after the exposure to 1 g/L ultrafine tourmaline particles.