A column with a surface area of 790 cm2 and effective height of 105 cm was used for the study. The column was filled with stabilized refuse (which had been studied for two consecutive years regarding leachate recycling) compacted to an average density of 500 kg/m3. High strength brewery wastewater, with a COD of 6000 mg/l, was homogeneously trickled over the top of the refuse at daily flow rates of 8, 16, 24, and 36 liters/day. Each flow rate was maintained for more than three weeks to achieve steady performance. After six months of intensive study, it was demonstrated that the stabilized refuse had a very good ability to treat the brewery wastewater. The COD was reduced to as low as 60 mg/l, which was equivalent to a removal efficiency of 99%, after the wastewater had trickled through the 90 cm refuse layer. The COD reduction achieved in the stabilized refuse layer perfectly fitted the following equation:
formula

The variations of major parameters such as pH, alkalinity, and volatile fatty acids, strongly indicated that acidogenesis occurred quickly in the first 15 cm. As the flow rate increased, acidogenesis occurred deeper in the column and its recovery became slower. The oxidation reduction potential (ORP) dropped to as low as −290 mV in the refuse column, indicating the anaerobic conditions of the system.

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