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An affordable closed cycle process with added benefits
The cost of conventional wastewater treatment (anaerobic filters, activated sludge, and centralized piping systems) has proved too expensive for many countries, including Brazil, Tanzania, and China. Building costs are more than $1000 per inhabitant for smallscale treatment facilities that serve up to 10 000 people. Communities that can pay capital costs often find they cannot support the annual maintenance fees of more than $100 per capita. For these reasons, many international institutions, including the World Bank, have concluded that conventional approaches to managing human waste are inadequate for providing sanitation and clean water to the majority of the world's population.
The high cost of installation and maintenance is one reason more than 90% of the world's wastewater is discharged to oceans untreated. The World Health Organization reports that water contaminated by wastewater causes 8 of the 10 most frequent fatal diseases.
To address health and cost concerns, scientists have conducted studies of plant-based biological wastewater treatment. In the 1980s, Steve Serfling developed integrated systems involving digesters and fish using wastewater in California, while K.R. Reddy, who lectures at several universities in Florida, used water hyacinths for wastewater treatment and researched applications for the macrophytes. Eneas Salati improved soil bed filtration in Sao Paulo, Brazil, by analyzing and mixing local soils to improve biochemical oxygen demand (BOD) reduction. Little of this research, however, has measured the potential success of combined wastewater purification and recycling nutrients.
Researchers at Hamburger Umweltinstitut e.V., based in Hamburg, Germany, in 1990 started planning a biomass nutrient recycling project for 600 residents in a neighborhood of Silva Jardim, Rio de Janeiro, Brazil. The institute, in cooperation with the Brazilian nongovernmental organization O Instituto Ambiental, has constructed, modified, and tested biomass nutrient recycling in tropical zones of Brazil since 1991, including, for example, the city of Petropolis. The research was funded by the European Commission, Henkel chemical company, Bayer do Brazil chemical company, Ciba Geigy Foundation, the City of Petropolis, Silva Jardim, and private donors.
Biomass nutrient recycling is based on the efficiency of natural systems. The process purifies wastewater by reducing BOD, nutrients, and coliform and recovers nutrients for agricultural production by closing nutrient cycles, such as recycling fertilizer onsite instead of transporting...