Characterization of latex aerobic granules

Abstract

Aerobic granules are compact, dense and regular-shaped granular sludge with good settling properties which were successfully cultivated in sequencing batch reactors (SBR), a hybrid system of the activated sludge process for the treatment of wastewater. This study investigates the physical and chemical characteristics of latex aerobic granules cultivated from rubber (latex) industrial wastewater. The physical characteristics were determined using field emission scanning electron microscope (FESEM) and analytical methods while the chemical characteristics of the granules were investigated using X-ray fluorescent (XRF) analysis, X-ray diffraction (XRD) analysis and Fourier transform infrared spectroscopy (FTIR) analysis. The results revealed that latex granules exhibit a loose and irregular structure dominated by coccal-shaped bacteria with an average size of 4.0-5.0 mm and a settling velocity of 35-53 mph. The element analysis using XRF discovered that the latex granules contained Zn, Al, S, Ti, Ca, Si, P, K, V, Cr, Fe, Cu, Br and Pd whereby zinc showed a very high concentration in the granules. XRD analysis further suggested the presence of zincowoodwardite, berlinite, rutile and quartz. FTIR analysis discovered the presence of aliphatic hydrocarbons, alkene, alkyne and tertiary amine which were mainly contributed by isoprene, the monomer of latex, and nutrient constituents. In addition, the physical and chemical characteristics of latex granules were also compared with domestic aerobic granular sludge using results obtained by previous studies.