Biological heat potential and temperature effect of an autothermal thermophilic aerobic treatment (ATAT) system

This study focused on the evaluation of the specific biological heat potential (hb) of a food-processing artificial wastewaterin the autothermal thermophilic aerobic treatment (ATAT) system. A novel experimental method was developed to evaluate the hb value by using the heat balance model under the steady state. This system was daily fed with oily and artificial wastewater at 21,460 mg l(-1) COD. The sludge retention time (SRT) was controlled at 15 days. The results showed that the average values of hb were 3.25 to 3.63 kcal g(-1)-COD-removed for the artificial wastewater. The values of true growth yield (Y0) were 0.08 to 0.19 mg-MLSS mg(-1)-COD for the food-processing wastewater at different temperatures. The COD removal efficiency was 77 to 91%, and it was decreased as temperature increased. But, the oil and grease (O and G) removal efficiency was 50 to 69%, and increased as temperature increased. These results might indicate that oil and grease become more soluble and accessible to microorganisms at high temperatures. The study indicated the temperature effect constant (Ø) of van't Hoff-Arrhenius law was 0.958, which explained and showed typical characteristics in the low sludge yield of an ATAT process.