Microscopic observation of anaerobic microorganism in a modified anaerobic hybrid baffled (MAHB) reactor in treating recycled paper mill effluent (RPME)

activities of various kinds of microorganisms are the key factor for anaerobic digestion which produces methane gas. Therefore, anaerobic digestion process is known as an alternative methods to convert waste into methane. In this present study, a modified anaerobic hybrid baffled (MAHB) reactor with a working volume of 58 L were used to treat recycled paper mill effluent (RPME) wastewater. The mixture of 90% RPME wastewater and 10% anaerobic sludge was used as substrate. The morphologies of anaerobic microorganism involved in anaerobic digestion of RPME in MAHB reactor was observed using Scanning Electron Microscopy (SEM) and Fluorescence Microscope. Only small amount of protozoa and fungi were observed in the MAHB reactor system. It was found that bacteria responsible in biodegradation of biomass inside the MAHB reactor were dominant. It was also demonstrated that fast growing bacteria which were capable to growth under high substrate levels and reduced pH was dominant at the front compartments (acidification zone). Towards the end of the reactor, a slower growing scavenging bacteria that grow better at higher pH was found. In addition, the population of Methanococcus, Methanosaeta and Methanosarcina were higher compare to other species of methane former bacteria.