The present study examined novel wheat straw biochar (WSB) and acid treated wheat straw biochar (AWSB) for cadmium removal from contaminated water. A series of batch and column scale experiments was conducted to evaluate the potential of WSB and AWSB for cadmium removal at different biochar dosage (0.5–8 g/L), initial cadmium concentration (5–100 mg/L), solution pH (2–8) and contact time (5–180 min). Results revealed that cadmium adsorption decreased by increasing biochar dosage from 0.5 to 8 g/L; however, optimum dosage for maximum (99%) removal of cadmium was 2 g/L by WSB and 1 g/L by AWSB. Enhanced cadmium removal potential by AWSB is attributed to increased surface area, microporosity and variation in functional groups. Equilibrium experimental data was well described by Freundlich adsorption isotherm whereas kinetic data were better explained with pseudo-second order model. Both WSB and AWSB have shown good adsorption capacity of 31.65 mg/g and 74.63 mg/g, respectively, that is comparable with other costly adsorbents. Columns packed with WSB and AWSB at laboratory scale have also shown good retention of cadmium with excellent reusability. These findings indicate that WSB especially AWSB could be a promising, cost-effective and environmental friendly strategy for the removal of metals from contaminated water.

Biochar produced from transforming bioresource waste can benefit sustainable agriculture and support circular bioeconomy. The objective of this study was to evaluate the effect of the application of biochar, produced from wheat straws, and a nitrification inhibitor, sourced from neem (Azadirachta indica), in combinition with the recommended synthetic fertilizer on soil properties, maize (Zea mays L.) plant growth characteristics, and maize grain yield and quality paramters. The nitrification inhibitor was used with the concentrations of 5 and 10 mL pot⁻¹ (N₁ and N₂, respectively) with four levels of biochar (B₀ = 0 g, B₁ = 35 g, B₂ = 70 g, B₃ = 105 g, B₄ = 140 g pot⁻¹), one recommended nitrogen, phosphorous, and potassium syntactic fertilizer (250, 125, and 100 kg ha⁻¹, respectively) treatment, and one control treatment. The results showed that the nitrification inhibitor enhanced crop growth while the application of biochar significantly improved soil fertility. The application of biochar significantly enhanced soil organic matter and soil nitrogen as compared with nitrogen–phosphorus–potassium treatment. The highest root length (65.43 cm) and root weight (50.25 g) were observed in the maize plants treated with B₄ and N₂ combinedly. The grain yield, total biomass production, protein content from biochar’s B_4, and nitrogen–phosphorus–potassium treatments were not significantly different from each other. The application of 140 g biochar pot⁻¹ (B₄) with nitrification inhibitor (10 mL pot⁻¹) resulted in higher crop yield and the highest protein contents in maize grains as compared to the control treatments. Therefore, the potential of biochar application in combination with nitrification inhibitor may be used as the best nutrient management practice after verifying these findings at a large-scale field study. Based on the experimental findings, the applied potential of the study treatments, and results of economic analysis, it can be said that biochar has an important role to play in the circular bioeconomy.