Aecomix™ for efficient energy recovery from wastewater and waste streams

Abstract

Food and beverage production plants are major wastewater contributors and often have food waste. Particularly plants with wastewaters with a significant total suspended solids and/or fats, oils and greases like in the dairy, redmeat and chicken industry needs to pre-treat their wastewater before high rate anaerobic reactors can be applied. This pre-treatment generally includes undesirable chemical treatment and generates a concentrated side stream which needs to be dealt with. The Aecomix™ reactor is an anaerobic reactor with solids retention, particularly suited to treat such effluents, together with available organic wastes. In this manner two waste streams are dealt with in one system and a high level of conversion to biogas is achieved. The solids retention is achieved by Dissolved Biogas Flotation. A full scale Aecomix™ reactor treated the effluent of a chocolate/candy factory with a COD concentration varying between 10,000–60,000 mg/l at an average of 37,000 mg/l. The removal for COD and TSS was more than 95% on average. To meet with local discharge regulations a post aerobic biological treatment may be required. The excess sludge from this aerobic system can be returned to the Aecomix™ reactor, which is another advantage over high rate (UASB or EGSB type) reactors. The Aecomix™ is approximately 50% lower in yearly costs compared to a chemical treatment plant based on flocculation flotation followed by an EGSB reactor.