Sand and activated carbon filtration in removing microorganisms from wastewater

This work aimed to test the efficiency of associating two natural, local, abundant and eco-friendly granular media; sand provided from South Algeria and granular activated carbon (GAC) manufactured by Algerian Company as a tertiary treatment for urban wastewater in Algeria. The effective diameter was 0.5 and 1.2 mm for sand and GAC respectively. The pilot consisted of two circular columns; one filled with sand and the other with GAC. The raw water used was brought from the secondary treatment (activated sludge) from the Ain El Houtz wastewater treatment plant. The sand filter column was fed 5 h/d with a constant filtration rate of 3.8 m/h, then 5 L of filtered water fed the granular activated carbon filter with a filtration rate of 0.8 m/h. After 16 weeks of operation, total germs, total coliforms, fecal coliforms, E. coli and fecal streptococcus had been reduced in a range of 82%–90% by filtration on the sand and 92%–96% by activated carbon. Clostridium has been reduced by 97% and 99% by sand filtration and activated carbon respectively and Salmonella by 66% and 94% on the sand and activated carbon respectively. This process is promising as a tertiary treatment in terms of cost and sustainable development since only natural, local and eco-friendly materials are used.