Closed system for local reuse of blackwater and food waste, integrated with agriculture

Abstract

To increase the recycling rate of blackwater and food waste to farm land, a small scale system, independent of sewer pipelines and sewage works, has been developed. It reduces water and air pollution, allows for source control of the recycled material, integrates farmers into the waste handling business, and reduces domestic water consumption. Parts of the system have been implemented in four Norwegian communities. Greywater is treated in local nature-based systems or in a new compact filter unit. Food waste and blackwater from new water saving toilets is stored in sub-surface tanks close to the house for one to two years, and then treated in a closed system. By combining the separate blackwater and food waste streams into one, logistics are greatly simplified. After collection by a tanker, the material is sanitised and stabilised in a thermophilic aerobic reactor, especially suited for decentralised solutions. No ammonia is lost, and the product has the highest possible agronomic value, with respect to nutrient content and organic matter. The treated material is spread onto farm land during the growing season. The different parts of the system can be implemented step by step over a longer time period.