Implementation of natural zeolite for filtration of secondary municipal effluents

Abstract

A three column filtration system was designed and operated for the investigation of ammonium and suspended solids removal from wastewater by using natural zeolite. The zeolite is a clinoptilolite from the Bigadic district of Turkey. The process consisted of three parallel columns that operated on a down flow mode; the influent to the system was collected from the effluent of a municipal wastewater treatment plant. Laboratory studies consisted of batch tests for determining the capacity of clinoptilolite and column tests for the assessment of kinetics during contaminants removal from wastewater. During batch tests, samples containing 20 mg/L of ammonium were treated by zeolitic particles with a diameter of 0.5-1 mm at pH 7.3 and resulted to an effluent with about 10.4 mg/g of ammonium. The effect of zeolitic particle diameters on the removal capacity was investigated during column tests by the utilization of particles with the following diameters: (i) 0.5-1 mm, (ii) 1-2 mm, and (iii) 2-4 mm under the same filtration rate and column diameter. Ammonium and suspended solids removal rates were measured and compared for all columns. The optimum results were obtained for the filter in which 0.5-1 mm diameter clinoptilolite particles were used, with 100% ammonium removal and 38% suspended solids removal rates, respectively, for an operation period of 78 h. As a result, the addition of clinoptilolite to sand filters in existing plants may be an efficient alternative for upgrading the performance of a municipal wastewater treatment plant, used as a tertiary treatment step for polishing ammonium content.