Pilot-Scale Experiments in Water Hyacinth Lagoons for Wastewater Treatment

Abstract

Based on some information collected in foreign bibliography which classifies water hyacinth as one of the possible interesting alternatives for the treatment of some types of domestic sewage, CETESB has since 1980 been developing, in participation with other institutions, a series of pilot-scale experiments in order to evaluate the real applicability of this system of wastewater treatment in Brazil. The conclusions that can be drawn from the experiments that have been carried out up to the present have indicated that the water hyacinth lagoon presents a better performance when it is integrated with other treatment systems, mainly at tertiary level, instead of its direct application to raw sewage treatment. One of the operational problems of this system, which has been observed during the experiments, refers to the intense proliferation of mosquitos, the control levels of which were not satisfactory even with the periodical application of larvicide. The problem of water hyacinth removal and its use as biomass has not been solved at industrial level yet. In pilot-scale experiments carried out by CETESB, the use of water hyacinth as an organic compost has proved to be economically unfeasible, on an industrial scale, considering that there are many other residues which offer better alternatives both from the economical point of view and the available amounts.