Lead and Zinc Stabilization of Soil Using Sewage Sludge Biochar: Optimization through Response Surface Methodology

Abstract

In this study, the effect of biochar produced from municipal sewage sludge on the stabilization of potentially toxic elements (PTEs), including lead (Pb), and zinc (Zn) in a mining polluted soil, is investigated. Biochar is produced through the pyrolysis process at three temperatures of 300, 400, and 500 C. The results of the biochar characterization shows that the pH and surface area of the samples increases with increasing pyrolysis temperature whereas the biochar yield decreases. Response surface methodology (RSM) is used to design and optimize the experiments. Three factors are considered, including biochar pyrolysis temperature, biochar/soil ratio, and time of incubation in the experimental design. The incubation time is the most effective parameter in the stabilization of both metals and shows a direct effect on the responses. However, the pyrolysis temperature has the lowest effect among the investigated parameters. The optimum conditions from RSM shows that biochar is able to stabilize each metal up to 70%, which presents the high potential of produced biochar to be used in the remediation of soils polluted with PTEs. Figure 5. Response surface and contour plot for interactive factors for Pb stabilization. a) Temperature and biochar/soil ratio (incubation time ¼ 60 days), b) biochar/soil ratio and incubation time (temperature ¼ 400 C).

Effect of biological sewage sludge and its derived biochar on accumulation of potentially toxic elements by corn (Zea mays L.)

“…Depends on the PTEs functionality, positive surface biochars can stabilize anionic contaminants while negative surface biochars have a large capacity to interact with cationic contaminants and thus reduce their bioavailability 30 . The results were well consistent with Fathianpour et al 60 who reported remarkable stabilization of PTEs in soil using biochar. They also deduced the longer the time of biochar in contaminated soil, the more elements were stabilized.…”

A critical review on the biochar production techniques, characterization, stability and applications for circular bioeconomy

“…The thermochemical methods employed for producing biochar particularly in rural areas enhances development of that specific region and also small and medium enterprises producing enough energy thus increasing farmer’s income, providing solutions for managing waste in agricultural sector. Through this, small-scale production systems can be connected with other systems creating a closed system models so that waste from one process can be utilized as an input for the other with high social, economic and ecological outcomes in circular economy [ 145 ]. Similar interactions between different methodologies of biochar production and reusing waste are required for developing new opportunities.…”

Investigating the carcinogenic and non-carcinogenic health hazards of heavy metal ions in Spinacia oleracea grown in agricultural soil treated with biochar and humic acid

“…7.0). The optimal design allows the statistical model to be estimated with a minimal number of runs of the experiment (Fathianpour, Taheriyoun et al 2018, Ghorbani, Kamari et al 2020.…”