Using coconut husks in a full-scale decentralized wastewater treatment system: The influence of an anaerobic filter on maintenance and operational conditions of a sand filter

The critical situation of domestic wastewater treatment in the rural areas of Brazil stimulates the development or improvement of on-site systems using cheap and sustainable materials that can be applied in small and isolated communities. Although this is an important theme, few real scale systems have been studied. This study investigated a full-scale on-site domestic wastewater treatment system composed of a septic tank, an anaerobic filter filled with green coconut husks (Cocos nucifera) and an intermittent sand filter. The experiment was conducted in a rural area located in the city of Campinas (Brazil) and the system was built to serve a small community. The quality of the effluent generated by this combination is in accordance with Brazilian and European legislation and even allows for its reuse in agricultural activities. The results also demonstrate the feasibility of using coconut husks in anaerobic filters, providing a new and more sustainable destination for this material, which is normally treated as solid waste. The combination was shown to be a viable technology for small communities.