EVALUATION OF ODOR REMOVAL BY PILOT-SCALE BIOLOGICAL TREATMENT PROCESS TRAINS DURING SPRING RUNOFF IN AN ICE-COVERED RIVER

Biological water treatment has been shown to effectively remove biodeg radable organic matter, chlorinated by-products and ozonation by-produ cts from drinking water during a large pilot-scale study for the Ameri can Water Works Association Research Foundation using the North Saskat chewan River, at Edmonton. In addition to studying total organic carbo n, assimilable organic carbon, chlorine demand, haloacetic acid format ion potential, trihalomethane formation potential, adsorbable organic halide formation potential, chloral hydrate and aldehydes, this study used a flavour profile panel to follow the removal of odour through di fferent process trains involving biological treatment during the annua l spring runoff which has historically caused odour incidents in the w ater supply. Over the 5-week period of the study, the raw water was fo und to develop from a very mild grassy odour to a strong odour, variou sly characterized as septic, manure, musty, earthy and hay-like. The o dour persisted and changed character to varying degrees through the va rious process trains under study. The results verified the futility of relying on a strictly oxidative treatment like ozone for odour remova l as well as showing that biological treatment using granular activate d carbon could produce an essentially odour-free effluent during a tra nsient raw-water odour event.