TESTING BIOLOGICALLY-ACTIVE FILTERS FOR REMOVING ALDEHYDES FORMED DURING OZONATION

This pilot-plant study was initiated to evaluate biological filtration for the removal of aldehydes formed during ozonation. An additional o bjective of this testing was to demonstrate that aldehyde measurements could be used as a surrogate for analysis of assimilable organic carb on (AOC). The use of granular activated carbon (GAC) as an alternative to anthracite coal as the filter medium was also investigated, and it was observed that GAC filters developed biological activity sooner an d showed longer-term stability. Although biological activity was estab lished sooner on slow-rate filters, the high-rate filters in time achi eved a comparable capability. Data for formaldehyde and glyoxal provid e information on removal of readily biodegradable and more recalcitran t ozone by-products, respectively, and demonstrate trends similar to t hose for the removal of AOC.