AGRICULTURAL USE OF STILLAGE

Abstract

Stillage is a liquid residue from the distillation of wine, resulting from alcoholic fermentation of cane juice, molasses, or a mix of both, to obtain alcohol. It has a high biochemical oxygen demand (BOD), and includes several soil borne chemical elements absorbed by sugarcane. Among them, stillage is rich in potassium and sulfur, containing sizeable amounts of phosphorus, nitrogen, calcium, magnesium, and micronutrients. Each liter of alcohol generates about 10 to 15 liters of stillage. Due to its high polluting power, its disposal was a problem for industries. Concern about its environmental impact is ancient. There are reports of high fish mortality when stillage was directly dumped in rivers, in the 1950s. Due to its organic nature, and the absence of contaminants, metals, or other undesirable compounds, it lead to the idea of using it on soil, however its pH being extremely acid, some care had to be taken. The first studies on applying stillage on soil were carried out by Professor Jaime Rocha de Almeida’s team in the 1950s, at Esalq/USP, in Piracicaba, São Paulo. However, the concern regarding environmental impacts and continuous high fish mortality resulting from stillage disposal in rivers led to Decree-Law n. 303, of February 28th, 1967, which definitively ban on the discharge of such residue to rivers, lakes and water courses.