Comparison Of Clinoptilolite With Gravel In A Recirculating Course Media Biofilter Treating Simulated Septic Tank Effluent

The main objective of the pilot scale study was to compare the performance of recirulating clinoptilolite biofilter with course gravel biofilter used to treat simulated septic tank effluent by simultaneous nitrification and denitrification. For better comparison of performance of total inorganic nitrogen removal and COD removal both the biofilter were chosen of identical size and identical operating conditions were maintained in the laboratory setup. Both the biofilters were operated at recycle ratio of 6 and surface hydraulic loading rate of 7.5 gal/ft2/day without recycle and 52.5 gal/ft2/day with recycle through out the duration of the duration of the research. Results of the composite sample analysis establish that better nitrification of the influent was achieved in the clinoptilolite biofilter. Average total inorganic nitrogen removal of 80.4 % was achieved in the clinoptilolite biofilter as compared to 73 % removal in gravel biofilter. Analysis of the results showed 77 % COD removal for the biofilters. The performance of the gravel biofilter was affected by excessive biomass generation in the biofilter leading to biological clogging. Clogging occurred in the clinoptilolite biofilter due to disintegration and breakage of clinoptilolite media affecting the performance of the biofilter.