Zeolite biofilm aeration filter plays a pre‐nitritation role in autotrophic nitrogen removal from iron oxide red wastewater

Abstract

BACKGROUND: The completely autotrophic nitrogen removal over nitrite (CANON) system has excellent performance in treating ammonium-rich wastewater and it depends on ammonia oxidizing bacteria (AOB) working together with anammox bacteria in a reactor. Higher ammonium nitrogen loading requires higher aeration to provide sufficient dissolved oxygen (DO) for nitritation, whereas high-strength aeration in theCANON will destroy the sludge structure and inhibit the activity of anammox bacteria. The present study uses a stable pre-nitritation system to reduce a part of nitritation and also decrease aeration intensity in the CANON. RESULTS: Continuous aeration to maintain the DO concentration between 1.5 and 4.3 mg L-1 in the CANON achieved a stable nitrogen removal rate (1.22 kg N m-3 d-1) from iron oxide red wastewater with 400-1016 mg N L-1 after 183 days of operation. Using a mixed alkalinity donor [sodium carbonate (Na 2 CO 3) and bicarbonate (NaHCO 3)] in the combined system can save ≈14.1-28.2% of the alkalinity cost compared with using NaHCO 3 only. CONCLUSIONS: A zeolite biofilm aeration filter (ZBAF) used in a pre-nitritation process can tolerate high DO concentration of ≤6.5 mg L-1 for nitritation and avoid all of the nitritation taking place in the CANON system. This can protect the sludge structure and anammox bacteria from high-strength aeration erosion.

Preparation and Application of a Natural Microspheric Soil Conditioner Based on Gelatin, Sodium Alginate, and Zeolite

“…However, the characteristic peak of iron oxide crystalin in PZ/GL-SA-Urea microspheres did not appear. It could be concluded that the PZ­(Fe)/GL-SA-Urea microspheres were successfully prepared . As shown in Figure d, according to the three thermogravimetric curves of PZ, FeOOH, and PZ­(Fe), the stability of PZ was the highest, the stability of FeOOH was the lowest, and the stability of PZ­(Fe) was the middle, which indicated that the loading of FeOOH was successful.…”

“…It could be concluded that the PZ(Fe)/GL-SA-Urea microspheres were successfully prepared. 30 As shown in Figure 2d, according to the three thermogravimetric curves of PZ, FeOOH, and PZ(Fe), the stability of PZ was the highest, the stability of FeOOH was the lowest, and the stability of PZ(Fe) was the middle, which indicated that the loading of FeOOH was successful. The decrease of the curves was ascribed to the evaporation of water and the decomposition of organic matter on the surface at the initial stage of about 200 °C.…”

“…As shown in Figure , PZ was obtained by pickling NZ to increase the loading ability. The FeOOH was prepared and loaded on the PZ surface to obtain the PZ­(Fe) . Then, the GTA crosslinker was added to GL solution, in which the −CHO group could react with the −NH 2 group to form Schiff base with a CN bond.…”

“…The FeOOH was prepared and loaded on the PZ surface to obtain the PZ(Fe). 30 Then, the GTA crosslinker was added to GL solution, in which the −CHO group could react with the −NH 2 group to form Schiff base with a C�N bond. Thus, the PZ(Fe)/GL microspheres were formed by the emulsion crosslinking method.…”