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The objective of this study was to evaluate a combined anaerobic-aerobic upflow fixed-bed reactor with liquid phase recirculation for the removal of nitrogen and organic matter from poultry slaughterhouse wastewater. The reactor performance was evaluated with a hydraulic retention time (HRT) of 11 h and three different recirculation rates (R=0.5; 1 and 2). The highest nitrogen removal efficiency value was obtained with an HRT of 11 h (6.8 h in the anaerobic zone and 4.2 h in the aerobic zone) and a recirculation rate of 2. In this condition, the total nitrogen removal efficiency was 69%, with effluent concentrations of 6 mg NH4+ L-1 and 12 mg NO3- L-1. For all tested conditions, there was good chemical oxygen demand (COD) removal, with efficiency above 95%. The effect of dilution and the favoring of mass transfer caused by the increase in the recirculation rate positively influenced reactor performance. Key words: Anaerobic degradation, nitrification, denitrification, combined reactor.

Wastewaters from olive mills and pulp and paper mill industries in Jordan have been characterized and treated using laboratory scale anaerobic and aerobic sequencing batch reactors, respectively. Nutrient requirements for these two industrial wastewaters were found to be less than what is usually reported in the literature for C:N:P ratio of 100:5:1 for aerobic treatment and 250:5:1 for anaerobic treatment. This was ascribed to the low biomass observed yield coefficients and relatively low removal efficiencies in these wastewaters. It was found that for anaerobic treatment of olive mills wastewater COD:N:P ratio of about 900:5:1.7 was able to achieve more than 80% COD removal. The observed biomass yield was about 0.06 kg VSS per kg of COD degraded. For extended aeration aerobic treatment of pulp and paper mill wastewater COD:N:P ratio of about 170:5:1.5 was able to achieve more than 75% COD removal. The observed biomass yield was about 0.31 kg VSS per kg of COD degraded. In both these wastewaters nutrients were not added. A simple formula is introduced to calculate nutrient requirements based on removal efficiency and observed biomass yield coefficient. Key Words: Olive mill wastewater; anaerobic treatment; aerobic treatment; sequencing batch reactor; biomass yield; nutrient requirement. African Journal of Biotechnology Vol. 3 (4), 2004: 236-238

Eighteen Erlenmeyer flask containing six different support media [pozzolan, polyvinyl chloride1 (PVC1), polyvinyl chloride2 (PVC2), foam, polyethylene terephthalate (PET) and polystyrene (PS)] were subject to identical volumetric organic loadings and hydraulic retention time in treating synthetic protein ± carbohydrate waste. The objective was to examine the influence of support media on performance of anaerobic denitrification and retention and their resulting impact on system performance and failure. According to the results relative to every control support media, it was noticed that the best support media were the ones in PVC1 and PVC2, with successive reduction rates of 68.33 and 61.93% for chemical oxygen demand (COD), and 55 and 49% for nitrate. On the other hand, in two submerged anaerobic biofilter reactor packed with the support media of PVC1 and PVC2, the reactor with PVC1 media exhibited 89.93% COD and 78.75% nitrate removal efficiency attributable to its higher production of EPSp and EPSc. Key words: Wastewater, anaerobic biofilm, extracellular polymeric substances (EPS), extraction, support media.