Skip to main content

Advertisement

Log in

Efficient phosphate recycling by adsorption on alkaline sludge biochar

  • OriginalPaper
  • Published:
Environmental Chemistry Letters Aims and scope Submit manuscript

Abstract

Large amounts of septic tank sludges from sanitation facilities are either landfilled or illegally dumped into the natural environment, leading to environmental pollution and waste of resources. This issue calls for advanced methods to recycle septic tank sludges such as sustainable adsorbents to recycle phosphorus, e.g., in agriculture, in the context of the circular economy. Here, we hypothesized that alkaline septic tank sludge biochar could be an efficient adsorbent to recycle phosphate from wastewater. We first prepared raw biochar by pyrolysis of septic tank sludge at 500 °C. Then, we prepared alkaline biochar by pyrolysis at 800 °C of mixtures of potassium hydroxide (KOH) and raw biochar at 3/1, 4/1 and 5/1 mass ratios. We studied biochar properties by scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy, and we quantified adsorption of phosphates by biochars. Results show that phosphate adsorption highly increases with KOH content, from 27.83 mg/g for the raw biochar to 42.51 mg/g for the 5/1 KOH-biochar. This trend is explained by the increase in biochar surface area from 64.214 m2/g for the raw biochar to 82.901 m2/g for the 5/1 KOH-biochar, and by the improvement of the structural properties and surface morphology of KOH-biochars. Overall, alkaline biochar appears as a promising adsorbent to recycle phosphates from wastewaters.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3

Similar content being viewed by others

Abbreviations

KOH-free (raw) biochar:

Biochar obtained by pyrolysis of septic tank sludge at 500 °C

3/1, 4/1, 5/1 KOH-biochars:

Biochars prepared by pyrolysis of mixtures of potassium hydroxide and raw biochar at 3/1, 4/1, or 5/1 mass ratios

SEM:

Scanning electron microscope

XRD:

X-ray diffractometry

FTIR:

Fourier transform infrared spectroscopy

BJH:

Barrett–Joyner–Halenda

BET:

Brunauer–Emmett–Teller method

References

Download references

Acknowledgements

The authors would like to acknowledge the co-funding of this work by the National Natural Science Foundation of China (No.52070130) and the Natural Science Foundation of Shanghai (No.22ZR1443200).

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Hongbo Liu.

Ethics declarations

Conflict of interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary Information

Below is the link to the electronic supplementary material.

Supplementary file1 (DOCX 190 kb)

Rights and permissions

Springer Nature or its licensor holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Liu, Z., Liu, H., Zhang, Y. et al. Efficient phosphate recycling by adsorption on alkaline sludge biochar. Environ Chem Lett 21, 21–30 (2023). https://doi.org/10.1007/s10311-022-01527-5

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10311-022-01527-5

Keywords

Navigation