Biochar from food waste

I have a few Qs here...

• where does food waste best fit in a waste hierarchy? does it have better utility as animal feed or in a localised BSF industry
• what sort of H&MB numbers are going to work at scale, with all that water to remove? is hydrothermal carbonisation a better path for this type of waste stream
• recovering P from our industrial food and sewage systems is important... is biochar production going to become a key player?

Properties of Biochar from Anaerobically Digested Food Waste and Its Potential Use in Phosphorus Recovery and Soil Amendment

Shakib Alghashm ¹, Shiying Qian ¹, Yinfeng Hua ², Jian Wu ², Haitao Zhang ², Weihua Chen ² and Guoqing Shen ^1,*

¹School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China

²Shanghai Liming Resources Reuse Co. Ltd., Shanghai 201209, China

^*Author to whom correspondence should be addressed.

Received: 14 November 2018 / Accepted: 5 December 2018 / Published: 10 December 2018

Abstract

The disposal of a large amount of biogas residue from anaerobically digested food waste is a burden for biogas production. The aim of this work was to investigate biogas residue as a potential feedstock, by preparing biochar at a broad pyrolysis temperature range of 400–900 °C. The properties required for phosphorus recovery and soil amendment application were evaluated. Biogas residue collected from an urban food waste treatment plant was pyrolyzed in a laboratory scale reactor. It was found that by increasing the pyrolysis temperature, the yield of biochar decreased and the pH, electrical conductivity and Brunauer–Emmett–Teller surface area increased. The amount of phosphorus adsorbed onto the biogas residue-derived biochar (BRB) at 900 °C was larger than that of other kinds of biochar. The kinetics of phosphorus (P) adsorption on BRB could be described by the pseudo-second-order equation. The pot experiments showed that the resulting biochar is beneficial for the growth of cabbage. Overall, turning solid residue from the anaerobic digestion of food waste for biogas production into biochar shows good prospects as a means of solving the disposal problem, while creating new markets for food waste biogas residue.