Small-Scale Waste-Water Treatment Systems Utilizing Water Hyacinth

Opinion, by Alfonso Stefanini

RIO DE JANEIRO, BRAZIL – Rio’s Guanabara Bay, a geographically mountainous and aesthetically beautiful area, is polluted daily with domestic water and sewage coming from “subnormal agglomeration” housing. The term was coined by IBGE (Brazilian Institute of Geography and Statistics) to describe favelas or “slums” which house over 11 million people in Brazil, or about fourteen percent of the total population in Rio de Janeiro State.

Here, irregular housing and absence of basic sanitation, such as sewage collection, is the unfortunately well-known norm.

The uncontrolled release of waste-water effluents has negative effects on the environment, public health, and the fishing and recreational economy, creating a passive environmental and economic burden to all of Rio’s citizens.

The construction of small and low-cost waste-water treatment systems along the water courses, using a phytoremediation process, is a simple solution to clean the excess organic waste-water effluents in many of the communities in Rio that have open sewers.

The water hyacinth plant (Eichhornia crassipes), also known in Brazil as aguapé, jacinto-de-água-comum or gigoga, is an endemic Amazonian aquatic plant known for its exuberant growing characteristics and its ability to absorb nutrients (nitrogen and phosphorus), heavy metals, organochlorine, organophosphorus and phenols.

This plant was first studied by NASA, and than later studied by the Instituto Nacional de Tecnologia in Brazil (INT) and also has the ability to balance the acidity of the water and inject oxygen into hydric mediums.

The water hyacinth is considered an invasive plant in many parts of the world, and its eradication, rather than its utilization, is the present status quo. However it is worth noting that the plant growth excels because of the presence of organic nutrients coming from sewage and natural organic waste, like in wetlands.

Water hyacinth’s ability to remove domestic waste-water contaminants using the proper catchment systems among the nutrient rich rivers can provide biomass, energy and fibers. The plant has a higher energetic value, on a dry basis comparison, than sugarcane. Ethanol can be derived from water hyacinth and can be used in the biofuels mix-energy alternative options.

Besides having an ability to produce biofuels, water hyacinth utilization can provide jobs, improve sanitation, and provide benign energy options, such as biogas for cooking, to the many communities that need them around Brazil and the world.

Large-scale waste-water treatment facilities are capital-intensive to build and do not capture all the multitude of rivers and man-made canals discharging domestic waste-water from the hundreds of communities in Rio de Janeiro. Although sewer should be treated in waste-water treatments facilities, water hyacinth systems can be a quick and economical alternative to improve water quality in the communities that lack the most basic infrastructure.

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Alfonso Stefanini has an MA in International Environmental Policy from the Monterey Institute of International Studies in California and a BA from Hampshire College. Alfonso lives in Rio de Janeiro, and he can be reached at: [email protected].