Anaerobic-aerobic combined bioreactor (CBR) with fixed bed and intermittent aeration for organic matter and nitrogen removal in the treatment of sewage

Abstract

The treatment of sewage represents a major challenge for Brazil due to population growth, lack of infrastructure in sanitation, cost of implementation and operation, and compliance with environmental legislation. Activated sludge systems are widely used for sewage treatment in Brazil. However, various aspects of design, operation and economics have determined the search for other treatment processes. Upflow anaerobic reactors with sludge blanket (UASB) applied for the treatment of sanitary sewage have shown to be economically advantageous. However, other reactor types have been developed to reduce costs and minimize operational problems related to the sludge blanket. Bioproj Tecnologia Ambiental Ltda has developed, with great success and advantages over existing technologies, two types of reactors with the use material support for biomass adhesion (Biobob®). The hybrid anaerobic reactor (HAnR) which use fixed bed (Biobob®) and the Combined Bioreactor configuration (CBR) that places in the same reactor an anaerobic step followed by an aerobic step with the use of fixed bed (Biobob®). The CBR configuration made it possible to reduce the cost of installation and operation, comparing with the conventional configurations (anaerobic reactor + activated sludge) and greatly improved the quality of the final effluent in comparison with the anaerobic reactor effluent. Despite the advantages of the BRC configuration, some limiting aspects of this technology must be carefully studied and solved, such as incomplete denitrification, which maintains the nitrogen concentration in values many times above the legislation requirements and the high energy consumption due to the energy required for aeration. Aiming to attend the legislation requirements, Bioproj intends to develop a type of reactor with exclusive technology to control and establish nitrification and denitrification process with high performance. In addition, aiming to meet market demands, Bioproj intends to develop a compact, economical and efficient sewage treatment systems. This research project proposes the study a sewage treatment system composed by anaerobic / aerobic fixed bed reactor with intermittent aeration (CBR with intermittent aeration). The operating system will carry on in a pilot scale system consisting of sand and grease removal tank, sieve for removal of fine solids and CBR reactor with intermittent aeration followed by sedimentation tank. The company envisions with the development of this project to launch in the market high performance compact systems for sewage treatment capable of operating with reduced energy expenditure and maintaining high removal of organic matter and nitrogen with national technology. (AU)