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Highly synergistic effects on ammonium removal by the co-system of Pseudomonas stutzeri XL-2 and modified walnut shell biochar

Yu, Yang, An, Qiang, Zhou, Ying, Deng, Shuman, Miao, Yue, Zhao, Bin, Yang, Li
Bioresource technology 2019 v.280 pp. 239-246
Pseudomonas stutzeri, adsorption, ammonium, bacteria, biochar, biodegradation, denitrification, hydrophilicity, magnesium, moieties, surface area, synergism, walnut hulls
Pseudomonas stutzeri strain XL-2 presented efficient ammonium removal due to heterotrophic nitrification-aerobic denitrification. The modified walnut shell biochar also showed ammonium adsorption due to chemical interaction. The complex of modified biochar and strain XL-2 exhibited excellent synergistic effects on ammonium removal, especially in unfavorable environment. The maximum average ammonium removal rate of the complex was 4.40 mg·L⁻¹·h⁻¹, which was 3.01 times higher than that of pure bacteria and 5.57 times higher than that of biochar. A large number of irregular pores and hydrophilic functional groups promoted the immobilization of strain XL-2 on biochar. Adsorption of ammonium, high specific surface area and release of Mg²⁺ by biochar enhanced biodegradation of strain XL-2. Approximately 96.34%−98.73% of ammonium was removed in a sequencing batch reactor (SBR) inoculating with the complex of strain XL-2 and biochar, which was much higher than the treatment efficiency of free bacteria in SBR.