Lettuce Fertigation with Domestic Effluent Treated with Orange Pomace Biochar

Abstract

The objective of this study was to evaluate the adsorption capacity of orange pomace biochar, applying its benefits in irrigated agriculture. For this, a low-cost system for tertiary treatment using biochar was developed. The objective was also to compare the physicochemical and microbiological attributes of irrigation water with the limits established by the legislation. The impacts of wastewater from the filtration system on the soil and on the agronomic and biological characteristics of the lettuce crop were assessed. Biochar was produced in a muffle furnace and characterized by thermogravimetry and scanning electron microscopy (SEM). The experimental design was randomized blocks, in a 5 (irrigation depths) × 5 (combinations of water sources and fertilization) factorial arrangement, with three replicates. It was found that the use of biochar as a filter material improved the microbiological quality of wastewater. The water sources used in irrigation did not cause changes in soil salinity. Fertigation using wastewater that passed through the filtration system positively affected the agronomic characteristics of lettuce, with no need for top-dressing fertilization. Lettuce leaves produced in the experiment were acceptable for human consumption, according to the standards of Resolution-RDC No. 12, of 2 January 2001, of the National Health Surveillance Agency (ANVISA).