Sewage sludge biofertilizer impacts the accumulation of heavy metals in the leaves and fruits of sweet passion fruit (Passiflora alata Curtis)

Abstract

Treatment of industrial sewage results in the production of a solid residue, sewage sludge, whose rich organic matter and chemical content makes it useful in agriculture. However, some soil components can be potentially toxic to humans if they enter the food chain. The aim of this study was to analyze the accumulation of heavy metals in the leaves and fruits of Passiflora alata Curtis grown on sewage sludge. Sweet passion fruit plants were cultivated in plain Oxisol soil and in lime-adjusted Oxisol enriched with sludge. After fruit maturation, the leaves and fruits were collected, growth variables were measured, and the concentration of arsenic, barium, cadmium, chromium, and lead was determined. The use of sewage sludge increased the concentration of essential elements and organic matter in the soil, thereby favoring plant growth and development. However, the sludge caused also the differential accumulation of heavy metals in the leaves and fruits of sweet passion fruit.