The advantage of a two-stage nitrification method for fertilizer recovery from human urine

Zhiqiang Zuo; Yan Chen; Yaxin Xing; Siqi Li; Shaolin Yang; Guangming Jiang; Tao Liu; Min Zheng; Xia Huang; Yanchen Liu

doi:10.1016/j.watres.2023.119932

The advantage of a two-stage nitrification method for fertilizer recovery from human urine

Water Res. 2023 May 15:235:119932. doi: 10.1016/j.watres.2023.119932. Epub 2023 Mar 29.

Authors

Zhiqiang Zuo¹, Yan Chen², Yaxin Xing³, Siqi Li³, Shaolin Yang³, Guangming Jiang⁴, Tao Liu⁵, Min Zheng⁵, Xia Huang³, Yanchen Liu⁶

Affiliations

¹ State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Australian Centre for Water and Environmental Biotechnology, The University of Queensland, St Lucia, QLD 4072, Australia; Engineering Research Center of Beijing, Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, China.
² State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; School of Civil, Mining and Environmental Engineering, University of Wollongong, Wollongong, NSW 2522, Australia.
³ State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
⁴ School of Civil, Mining and Environmental Engineering, University of Wollongong, Wollongong, NSW 2522, Australia.
⁵ Australian Centre for Water and Environmental Biotechnology, The University of Queensland, St Lucia, QLD 4072, Australia.
⁶ State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: liuyc@mail.tsinghua.edu.cn.

PMID: 37011577
DOI: 10.1016/j.watres.2023.119932

Abstract

Recycling nutrients (nitrogen, phosphorus, and potassium) from human urine can potentially offset more than 13% of global agricultural fertilizer demand. Biological nitrification is a promising method for converting volatile ammonia in high-strength human urine into stable ammonium nitrate (a typical fertilizer), but it is usually terminated in the intermediate production of nitrite due to the inhibition of nitrite-oxidizing bacteria by free nitrous acid (FNA). This study aimed to develop a stable nitrification process in a unique two-stage bioreactor by removing critical barriers associated with FNA inhibition. Experimental results show that half of the ammonium in high-strength urine was successfully converted into nitrate, forming valuable ammonium nitrate (with a nitrogen concentration greater than 1500 mg N/L). The ammonium nitrate solution could retain most phosphorus (75% ± 3%) and potassium (96% ± 1%) in human urine, resulting in nearly full nutrient recovery. Once concentrated, the liquid compound fertilizer of ammonium nitrate was generated. Based on an assessment of economic and environmental impacts at the urban scale, urine diversion for nutrient recovery using a technical combination of nitrification and reverse osmosis could reduce total energy input by 43%, greenhouse gas emission by 40%, and cost by 33% compared to conventional wastewater management. Further research is needed to optimize the two-stage nitrification method on a larger scale.

Keywords: Fertilizer; Free nitrous acid; Nitrification; Two-stage method; Urine.

MeSH terms

Ammonia
Bioreactors / microbiology
Fertilizers
Humans
Nitrification*
Nitrites*
Nitrogen
Nitrous Acid
Phosphorus

Substances

ammonium nitrate
Nitrites
Fertilizers
Ammonia
Nitrous Acid
Nitrogen
Phosphorus