Thermophilic aerobic reactor for processing organic liquid wastes

Since 1990 the Agricultural University of Norway and Alfa Laval Agri Ltd have developed a small scale thermophilic aerobic reactor for processing liquid organic wastes and turning them into a stable and hygienic product. The reactor has proven to be a multipurpose reactor, that can process a wide range of organic substrates with VS-contents from about 1.5–9%. It is a prefabricated, compact and self contained unit with all parts mutually adapted to each other, and suitable for local operation. A control system runs the process based on given set values to predict the product quality. The most unique results obtained are high oxygen utilisation, low air flow, no ammonia loss and very low odour release. The reactor causes no atmospheric pollution. The degradation of organic matter is moderate, and the processed substrate has the highest possible agronomic value. The hygienic quality of the product satisfies the criteria set by the Norwegian authorities. The stability of the product proved to be sufficient for a storage period of 10 months. By controlling the process carefully, same results are obtained in this one-stage reactor as in two-stage reactors. Use of one-stage instead of two-stage reactor means reduced investments and simplified operation.