Appraisal of the tire derived rubber (TDR) medium for wastewater treatment under aerobic and anaerobic conditions

BACKGROUND The present study evaluated the effectiveness and durability of tire derived rubber (TDR) for biofilm development and related long term use in fixed biofilm reactors for wastewater treatment. RESULTS TDR incubated (30 +/- 2 degrees C) with activated sludge showed comparatively higher biofilm development (0.51 g) under aerobic than under anaerobic (0. 42 g) conditions after 7 weeks. During biofilm succession, a significant shift in bacterial community was observed from pathogenic to autotrophic after 4 weeks. The decreasing bacterial count (MPN index) (approximate to 80%) (Escheria coli and feacal coliforms) and chemical oxygen demand (COD), and biological oxygen demand (BOD) (70% approx.) depicted diminishing organic load in sludge. Changes in pH and nutrients like NO2-, NO3-, PO43- and SO32- indicated presence of other key bacterial species with efficient nutrient consuming abilities in biofilm. Scanning electron microscopy showed few aberration and rich bacterial growth on treated TDR. Furthermore, detailed analysis through Fourier transform infrared (FTIR) spectroscopy confirmed minor transformation in TDR under anaerobic conditions. CONCLUSION TDR proved to be a durable and cost effective support material that can be used in aerobic fixed biofilm reactors for wastewater treatment. However, operational conditions of the reactor should be optimized to keep the biofilm structure intact and to achieve the desired wastewater treatment efficiency. (c) 2013 Society of Chemical Industry