Wastewater nitrification using ceramic industry waste

The presence of nitrogen in wastewater can cause eutrophication as well as health problems. Recent, more restrictive, legislation in Europe means that wastewater treatment systems should now be able to remove nitrogen; in many cases older plants, which were originally built without this objective, are currently being modified to include it. This paper presents the results obtained from a study using a pilot plant consisting of a biological aerated filter. The main goal of this experiment was to achieve nitrification, the most critical phase of the nitrification-denitrification process. The pilot plant was full-scale height with a pilot-scale cross-sectional area. The material used as biofilm support was a waste product from the ceramic industry. The influent was the primary effluent of a conventional sewage treatment plant. The flow was counter-current flow. The optimum amount of oxygen that needed to be supplied was studied. When only the biochemical oxygen demand (BOD5) and suspended solids (SS) requirements of the European Union Directive 91/271 CEE (European Economic Community) were fulfilled, NH4+ and NO3- effluent concentrations of 24 mg NH4+/l and 36 mg NO3-/l were obtained. However, in order to achieve effluent concentrations of 10 mg NH4+/l and 91 mg NO3-/l, the volumetric size requirements of the biological filter were increased by 4.2:1, equivalent to a maximum admissible BOD5 volumetric load decrease from 6.33 to 1.51 kg BOD5/m(3) per day.