Integrated anammox-biochar in synthetic wastewater treatment: Performance and optimization by artificial neural network

Recently, anammox bacteria have been applied for nitrogen elimination from wastewater. However, anammox is not effective for other kinds of pollutants. Therefore, in this study, the treatment of synthetic wastewater via combining anammox and biochar in a fixed-bed column was considered to improve performance. Two reactors, Reactor 1 (containing biochar and anammox bacteria) and Reactor 2 (containing biochar as a control), were run for four months. The nitrogen concentration (mg/L) and nitrogen loading rate (g-N/L/day) ranged from 100 to 500 and 5 to 20, respectively. Reactor 1 showed better performance in removing nitrogen from wastewater than Reactor 2. For Reactor 1, the optimum nitrogen removal effectiveness and nitrogen removal rate (g/L/day) were 82.3% and 8.2 (phase 1, 0–29 days), 90.9% and 12.7 (phase 2, 30–59 days), 72.3% and 13.0 (phase 3, 60–89 days), and 69.5% and 6.9 (phase 4, 90–119 days), respectively. An artificial neural network was applied for optimization. After finding the optimum performance conditions for the Reactor 1, COD (200 mg/L to 500 mg/L) was added to the influent. Adding up to 275 mg/L COD did not significantly affect N elimination, but after this point, N elimination was dramatically decreased.