The study of sand filtration performance for turkey processing wastewater (containing high concentration of oil and
grease) treatment was conducted by Young (2004). The result shows an excellent performance, where BOD5 removal
remained more than 97% at the end of sand filter operation (81 days) in low rate sand filters. But with the high and
medium loading rate, the BOD5 removal efficiencies declined and fluctuated after appearance of black layers on the
top of sand filtration. The research also found that treatment efficiencies of two layer sand filter averaged 95% of
TOC and 97% of BOD5 removal for 35 days while, three layer sand filter averaged 97% of TOC and 99% of BOD5
removal for 49 days in turkey wastewater using pea gravel for pre-treatment. This study initiated that multiple layer
sand filters had better performances of BOD5 and COD removal than single layer filter where three layer sand filters
had highest COD removal capacity due to longer filter runs.