Efficient Adsorption of Nitrogen and Phosphorus in Wastewater by Biochar

Abstract

Nitrogen and phosphorus play essential roles in ecosystems and organisms. However, with the development of industry and agriculture in recent years, excessive N and P have flowed into water bodies, leading to eutrophication, algal proliferation, and red tides, which are harmful to aquatic organisms. Biochar has a high specific surface area, abundant functional groups, and porous structure, which can effectively adsorb nitrogen and phosphorus in water, thus reducing environmental pollution, achieving the reusability of elements. This article provides an overview of the preparation of biochar, modification methods of biochar, advancements in the adsorption of nitrogen and phosphorus by biochar, factors influencing the adsorption of nitrogen and phosphorus in water by biochar, as well as reusability and adsorption mechanisms. Furthermore, the difficulties encountered and future research directions regarding the adsorption of nitrogen and phosphorus by biochar were proposed, providing references for the future application of biochar in nitrogen and phosphorus adsorption.

Keywords: adsorption; biochar; eutrophication; nitrogen; phosphorus.

Figure 1

Preparation process of original biochar.

Figure 2

The process of preparing biochar with modification before pyrolysis.

Figure 3

Process of preparing biochar with postpyrolysis modification.

Figure 4

Analysis of influencing factors on the adsorption of nitrogen and phosphorus in water by biochar.

Figure 5

(a) SEM of BC, 10,000×, (b) SEM of BC, 50,000×. Reprinted with permission from Ref. [91]. Copyright 2023 Copyright Hui Hu, Min Gao, Tian Wang, Lei Jiang.

Figure 6

(a) SEM of MBC, 10,000×, (b) SEM of MBC, 50,000×. Reprinted with permission from Ref. [91]. Copyright 2023 Copyright Hui Hu, Min Gao, Tian Wang, Lei Jiang.

Figure 7

FTIR spectra original biochar (CS450 and RH550) and modified biochar (H-CS and H-RH). Reprinted with permission from Ref. [93]. Copyright 2021 Copyright Mei Chen, Fang Wang, De-li Zhang, Wei-ming Yi, Yi Liu.

Figure 8

Effect of different initial pH values on the adsorption of P by biochar (BC@Ca). Reprinted with permission from Ref. [117]. Copyright 2022 Copyright Zhihao Chen, Yonghong Wu, Yingping Huang, Linxu Song, Hongfeng Chen, Shijiang Zhu, Cilai Tang.

Figure 9

The impact of different pH values on the adsorption of NH₄⁺ by four types of biochar (BC, NBC, MBC, and NMBC). Reprinted with permission from Ref. [48]. Copyright 2023 Copyright Meitao Tan, Yanqi Li, Daocai Chi, Qi Wu.

Figure 10

Effect of coexisting anions on the phosphate adsorption capacity of N/CaO/BC. Reprinted with permission from Ref. [122]. Copyright 2022 Copyright Yunwen Liao, Si Chen, Qian Zheng, Bingyuan Huang, Juan Zhang, Hongquan Fu, Hejun Gao.

Figure 11

Influence of coexisting ions on the adsorption of ammonium salt. Reprinted with permission from Ref. [12]. Copyright 2022 Copyright Zhipeng Zhao, Bing Wang, Qianwei Feng, Miao Chen, Xueyang Zhang, Ruohan Zhao.

Figure 12

Effect of temperature on the adsorption of PO₄³⁻-P (a) and NH₄⁺-N (b) by CS-MgCBC. Reprinted with permission from Ref. [123]. Copyright 2022 Copyright Lei Li, Qingfeng Chen, Changsheng Zhao, Beibei Guo, Xiaoya Xu, Ting Liu, Lingxi Zhao.

Figure 13

The influence of the dosage of biochar CaBC800 on the efficiency of phosphate removal. Reprinted with permission from Ref. [71]. Copyright 2022 Copyright Sheng-Nan Zhuo, Tian-Chi Dai, Hong-Yu Ren, Bing-Feng Liu.

Figure 14

Effect of cycle times on NH₃-N (a) and PO₄³⁻-P (b) adsorption in pig biogas slurry by C@Mg-P. Reprinted with permission from Ref. [79]. Copyright 2023 Copyright Lintong He, Dehan Wang, Tianlang Zhu, Yongzhen Lv, Sicheng Li.

Figure 15

Adsorption mechanisms of ammonium and phosphate onto EBC. Reprinted with permission from Ref. [3]. Copyright 2021 Copyright Ning Cheng, Bing Wang, Qianwei Feng, Xueyang Zhang, Miao Chen.

Figure 16

The primary adsorption mechanism of Ca-MB for phosphate and ammonium. Reprinted with permission from Ref. [125]. Copyright 2021 Copyright Qianwei Feng, Miao Chen, Pan Wu, Xueyang Zhang, Shengsen Wang, Zebin Yu, Bing Wang.

Figure 17

Comparison of fresh biomass of lettuce seedlings between the control group and LDHs/biochar. Reprinted with permission from Ref. [135]. Copyright 2016 Copyright Stefan Wana, Shengsen Wang, Yuncong Li, Bin Gao.

Figure 18

Adsorption mechanism of N and P co-doped porous biochar on Pb (II). Reprinted with permission from Ref. [137]. Copyright 2020 Copyright Jianqiu Li, Feifei He, Xiaoyang Shen, Dongwen Hu, Qiang Huang.

Figure 19

Proposed mechanism of PMS activation and MB degradation over NC-700. Reprinted with permission from Ref. [138]. Copyright 2019 Copyright Wanrong Hu, Yi Xie, Shan Lu, Panyu Li, Tonghui Xie, Yongkui Zhang, Yabo Wang.