Green waste recycling of peanuts highly contaminated with aflatoxins in clay brick manufacturing

Abstract

Abstract Background The safe disposal of green waste is necessary for a clean environment, with the safe disposal of waste contaminated with aflatoxins being of particular importance. This work presents a novel route for utilizing contaminated grains in the production of clay bricks. In this work, the contaminated peanut (P) with aflatoxins (AFs) is divided into two categories: PA is the contaminated peanut kernel (without the outer shell), and PB is contaminated whole peanut grain (with the outer shell). Both of ground PA and PB were used to replace the clay in fired building bricks. The raw materials were characterized using X-ray fluorescence (XRF), X-ray diffraction (XRD), and thermo-gravimetric analyses (TGA). The effectiveness of this approach was evaluated by measuring the effect of the replacement percentage and firing temperature on the properties of the produced building bricks. Results The optimization of the process parameters was performed using central composite design as a tool in the response surface methodology. The ANOVA analysis of the predicted quadratic model elucidated significant models’ terms and adequate precision that emphasizes the applicability of the model to navigate the design space. The results revealed that the optimum conditions are 6% clay replacement and 725 °C firing temperature, resulting in a compressive strength of 109.85 kg cm−2 for clay bricks with PA and 126.33 kg cm−2 for clay bricks with PB. Conclusions The objective of clay replacement by the contaminated peanut is not to improve the clay brick properties but to perform safe disposal of the accumulated contaminated peanut without deviating from the standards. The design of experiment using response surface method enables studying the effect of several factors on the clay brick properties simultaneously. Subsequently, this approach elucidates a sustainable route for accumulated contaminated green peanut waste disposal as the other alternatives have realized risks.