Attenuation of phosphate from municipal wastewater using biochar derived from co-pyrolysis of Amarula peel and chicken eggshell: Adsorption and precipitation process

Herein, lignocellulosic biomass waste has been explored and reported for the development of an adsorbent for the removal of phosphate from real municipal wastewater (MWW) effluent. Specifically, there is a lack of knowledge on the use of Amarula peels to produce an adsorbent for wastewater treatment, hence the pursuit of the current study. The chicken eggshell (ES) and Amarula peel (AMAP) were mixed in a 1:1 solid-to-solid ratio and synthesized via co-pyrolysis in the presence of nitrogen gas at 600 and 800 ℃, and they were labelled AMAP-ES-600 and AMAP-ES-800, respectively. Fourier Transform Infrared and X-ray Diffraction shows that the composite pyrolyzed at 600 ℃ was mainly consists of calcite. Whereas after 800 ℃ pyrolysis, the lime (CaO) and portlandite (Ca (OH)₂) was the most dominant compounds. X-ray Fluorescence techniques confirm the predominant of CaO (49.83%) at 800 ℃. Results registered phosphate removal efficacy of 7% and 100%, for biochar synthesized at 600 °C and 800 °C, respectively. High removal recorded at higher pyrolysis temperature could be attributed to the adsorption and precipitation between CaO or Ca (OH)₂ and phosphate from aqueous solution. In light of performance, the AMAP-ES-800 material was then employed in real MWW to ascertain its effectiveness and robustness in removing phosphate from aqueous matrices. The application of AMAP-ES-800 in MWW yielded 90.87% removal of phosphate from aqueous solution within 5 minutes of contact time at room temperature and ambient pH. Therefore, this material has demonstrated the potential to be applied in real practice, which will contribute to national and global efforts on water security. However, future work is recommended to investigate other water parameters listed by the South African National Standard or World health organization water quality guideline. Furthermore, future research shall consider techno-economic evaluation of the developed process along with the market analysis.