Biochar as a sustainable alternative to acai waste disposal in Amazon, Brazil

The acai palm (Euterpe oleracea Mart) is native to the floodplains of central and South America and is cultivated in Brazil for its berries, which are considered to be a 'superfood'. The waste acai fiber and seeds obtained after fruit processing pose a challenge since they remain unutilised despite being an abundant waste by-product of acai processing.This leads to a build-up of waste, regular dumping and environmental management challenges. Here we examine the potential use of acai seed biochar as a soil conditioner. The biochar was produced from waste seeds in a handmade kiln, incorporated into two soils of different textures and then compacted in volumetric rings with a hydraulic press. The samples were kept in a greenhouse for a 270-day incubation period. After this, the samples were evaluated for their soil physical and chemical attributes. Nine months after the application of the acai seed biochar, soil physical properties were not affected, except for the soil aggregate size distribution, for which the highest dosage resulted in a larger weighted average diameter. However, biochar increased phosphorus, potassium and magnesium contents, and reduced the aluminum content, which was reflected in an increase of the base saturation and a reduction in aluminum saturation. Therefore, within a relatively short time period, the biochar was found to improve soil chemical quality more so than soil physical properties, thus offering potential as a sustainable solution to manage acai waste in the Amazon region. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.