Reduced Inhibition and Increased Nitrification Efficiency of Refinery Wastewater with the Introduction of Lignocellulosic Bio-Media (kenaf)

Complex mixtures of hydrocarbons commonly found in petroleum refinery wastewater which may include ammonia, heavy metals, anions and cations are often found to be inhibitory to activated sludge systems. Therefore, operation of nitrifying activated sludge processes are typically problematic and are operated at high sludge recycle ratios to achieve high biomass concentrations within the reactor to limit toxic inhibition of nitrifiers. These long sludge ages often result in bio-accumulation of inhibitory compounds that further limit organic biodegradation, nitrification, and flocculation. Addition of Kenaf as a bio-media, when added to a suspended growth process can improve settling and biomass retention, allowing additional solids recycle and longer solids retention which can reduce overall biological sludge production. Additionally, the absorptive nature of the Kenaf also limits organic shock loads, and the likelihood of process upsets. Improved nitrification performance is attributed to additional retention of nitrifying bacteria and reduced inhibitor availability by the Kenaf. Unlike competitive plastic technologies, the Kenaf can easily and economically be wasted from the activated sludge system at the end of its life-cycle and be replaced with minimal effect on operations.