Building a low-cost domestic wastewater reclamation system using local agricultural waste in Kinmen islands, Taiwan

Abstract

The ongoing processes of climate change and natural resource exhaustion have an especially great impact on small islands. Kinmen is an archipelago of several islands of approximately 150 km2 in area located off the southeast coast of mainland China. Kinmen does not have an abundance of natural resources, and therefore, its development is restricted by the ecological environment and reflected in cultural fragility. After the end of military administration in 1992, Kinmen transformed into a famous tourist attraction. The rapid development of tourism has attracted a large number of tourists, but also worsens the long-standing scarcity of freshwater resources. As Kinmen is currently aiming to move toward becoming a low-carbon demonstration island, installation of a water reclamation system with a low carbon consumption would be the best choice for the islands. A wastewater reclamation system that considers local conditions and uses local materials to reduce the carbon footprint was therefore proposed in this study. To reduce the carbon footprint, the system uses local agricultural waste, including sorghum stalks and oyster shells, as filter media to construct a water purification system that can purify domestic wastewater by reclamation. The results demonstrated that the reductions in suspended solids, biochemical oxygen demand and NH4-N using this system reached 95.3, 97.0 and 99.3%, respectively, achieving the standards required for tertiary wastewater treatment. In addition, oyster shells after burning absorbed around 50% of the phosphorus in wastewater. The findings demonstrated that this low-carbon water reclamation system can achieve waste reduction, recycling wastewater to a quality suitable for irrigation.