The chemical composition of cassava wastewater was analyzed
at the Laboratory of Agricultural and Environmental Chemistry,
University of Western Parana, Brazil, according to methods
described by Tedesco et al. (1995). The concentration of potassium
(K), calcium (Ca), magnesium (Mg), manganese (Mn) and iron (Fe)
were determined by nitropercloric digestion. Nitrogen (N) and
phosphorus (P) were determined by the distillation method of
Kjeldahl and the ammonium metavanadate method, respectively.
The values of chemical oxygen demand (COD) and pH were obtained
according to Silva (1998). Values of free cyanide were obtained
by using a colorimetric kit