assessment of bio-trickling filter startup fortreatment of industrial wastewater

the aim of the present study was to assess the bio-trickling filter startup for the treatment ofwastewater produced by pegah dairy company at psychrophilic condition. the startup time of a bio-tricklingfilter is directly proportional to the concentration of microbial population. abio-trickling column with a height of150 cm was packed with lava rocks with the liquid recirculated through the packing. the startup flow rate for thepilot was 0.0035 l/min, with hydraulic retention time (hrt) of 10 days at 7-13ºc. results indicated that for hrtof 10 days, the efficiency of chemical oxygen demand (cod) removal was more than 85% for less than 100 gcod/m3/h. subsequently, dairy wastewater was added to the reminder of activated sludge with the hrt of 8days, and the nutrients were added to the pilot tank with a daily ratio of carbon/nitrogen/phosphorous: 100/5/1.for the subsequent 5 days, the pilot was maintained in a steady state. the results revealed that the pilot startupwas performed completely.