Abstract

The optimum mixing pattern in anaerobic reactorsis a subject of much debate. Under plug flow conditionsincoming substrate remains in the reactor for one retention time,allowing maximum time for conversion. However, the highsubstrate concentrations resulting from lack of dispersion mayinhibit bacterial activity. On the other hand, excessivedispersion may result in short -circuiting of substrate and wouldnot be ideal for granule formation in some anaerobic reactorconfigurations. Excessive substrate feeding during start-up canlead to the accumulation of volatile fatty acids and aconcomitant decrease in pH in anaerobic baffled reactorsbecause of their plug flow characteristics. In addition, plug flowreactors fed with high strength wastewater are more likely toexpose sensitive bacteria to toxic levels of inorganic and organiccompounds at inlet area. To overcome these difficulties,substrate feeding pattern to the reactor could be manipulated.Such a configuration, the split fed anaerobic baffled reactor(SFABR), has been developed in the Environmental EngineeringLaboratories of Newcastle University in 2001. During thedevelopment of this reactor, tracer study was used to decide splitratio of the reactor. As a result of the tracer study, it wasconcluded that a split ratio of 0.4, 0.3, 0.2, and 0.1 should beideal for the SFABR.