Ammonium removal efficiency of biochar-based heterotrophic nitrifying bacteria immobilization body in water solution

Abstract

In order to explore the performance of biochar-based microbial immobilization body in ammonium removal from water and potential mechanisms, a strain of heterotrophic nitrifying bacteria (HNB) was isolated from activated sludge, and the biochemical and molecular biological identification of HNB was carried out. Moreover, HNO<sub>3</sub>-, Mg<sup>2+</sup>-, NaOH<sub>-</sub>, and NaOH+Mg<sup>2+</sup>-modified rice husk-derived biochars were prepared. Then all the five kinds of biochars, including the original biochar, were used as carriers of HNB to remove NH<sub>4</sub><sup>+</sup><sub>-</sub>N from water. Results showed that HNB was classified as <i>Pseudomonas</i>, and the 72-h NH<sub>4</sub><sup>+</sup><sub>-</sub>N removal ratio of the free bacteria reached 80.24%. Compared with biochar itself, biochar-based HNB immobilization body showed a much stronger ability to remove NH<sub>4</sub><sup>+</sup><sub>-</sub>N, especially for NaOH<sub>-</sub> and NaOH+Mg<sup>2+</sup>-modified biochars. At the initial NH<sub>4</sub><sup>+</sup><sub>-</sub>N concentration of 100 mg/L and biochar addition dose of 10 g/L, NH<sub>4</sub><sup>+</sup><sub>-</sub>N removal ratio of NaOH<sub>-</sub> and NaOH+Mg<sup>2+</sup>-modified biochar-based HNB immobilization bodies reached 57.78% and 58.35% after 5 h, and reached 88.66% and 90.93% after 48 h respectively, which were obviously higher than the original, HNO<sub>3-</sub> and Mg<sup>2+</sup>-modified biochar-based HNB immobilization bodies. The phenomenon resulted from significantly higher bacteria adsorption ability of NaOH<sub>-</sub> and NaOH+Mg<sup>2+</sup>-modified biochars, which reached 773.75 and 941.17 nmol P/g biochar, respectively.

Effects of H₂O₂-modified Rice Husk-Derived Biochar on Nitrification and N₂O Emission from Water by an Isolated Heterotrophic Nitrifying Bacterium

“…HNB cell was prepared as the following procedures. The pre-saved HNB strain (Pseudomonas putida strain-N3, MN602471) [21] was selected from the slant culture medium, and then it was inoculated into 400 mL LB liquid culture medium (g/L, tryptone 10, yeast extract 5, NaCl 10) and cultivated to OD 600 = 1.0 (25ºC, 170 r/min). After dividing the liquid culture medium into 15 or 50 mL, respectively, the HNB cell was collected by centrifuging the liquid culture medium followed by washing the centrifugated deposit with sterile water twice.…”

Biochar application in biofiltration systems to remove nutrients, pathogens, and pharmaceutical and personal care products from wastewater

“…Both Freundlich (i.e., multilayer) and Langmuir (i.e., monolayer) adsorption have been reported in NH 4 + adsorption tests with both modified and unmodified biochar (Vu et al., 2017; H. I. Yang et al., 2018; Q. Yin et al., 2018). At neutral pH (∼7), biochar showed effective removal of NH 4 + , with a pH at the point of zero charge (pH pzc ) of 5.6–5.8, indicating that the negative surface charge of biochar was beneficial for NH 4 + removal (C. Wang et al., 2020; Xiao et al., 2020). No NO 3 − adsorption (1.5 g biochar in 30 ml) was observed in batch adsorption tests, and NO 3 − was even released to the solution (0.16–0.40 mg N g −1 ) (Gai et al., 2014).…”