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 wastewater in 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 21460 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 (Æ) of van’t Hoff- Arrhenius law was 0.958, which explained and showed typical characteristics in the low sludge yield of an ATAT process.

Evaluation of specific biological heat potential of oily wastewater in an autothermal thermophilic aerobic treatment system.

This study focuses on the specific biological heat potential (h(b)) of oil and grease wastewaterin an autothermal thermophilic aerobic treatment (ATAT) system. A novel experimental device was applied to evaluate h(b) by using heat balance model under steady state. In the study the treatment system was daily fed with realistic and artificial wastewater at 11250 and 17420 mg COD l(-1), respectively. The wastewater was rich in oil and grease at 1220 and 600 mg l(-1), respectively. The sludge retention time (SRT) was controlled at 5 days. The results showed that the average values of h(b) were 3.7 and 3.1 kcal g(-1) COD removed and the true growth yield (Y0) were 0.10 and 0.13 mg MLSS mg(-1) COD for realistic and artificial wastewater respectively. These two systems could maintain reactoroperating temperatures at 43 degrees C and 48 degrees C, respectively. The COD removal efficiency was as high as 90 to 97%. The oil and grease reduction was 68 to 72%. The high organic matter removal capacity and low sludge yield of ATAT process have been demonstrated.

Using respirometer in biodegradation phenomenon of natural organic matters.

This study conducted in monitoring respirometer oxygen consumption of aerobic microorganism during biodegradation processes of ozonated organic matters, which can estimate both biodegraded efficiency and coefficient of natural organic matters (NOMs) in water source. It can be proposed that different ozone dosage might change biodegradation characteristics of organic matters. The result reveals that higher ozone dosage may cause higher biomass yield coefficient of microorganism, and cultured microorganism may easily utilize biodegradation organic matters (BOMs) produced by ozonation, finally increasing overall removal efficiency. Therefore, using respirometer to evaluate the production of BOMs by ozonation before the biological treatment is effective for controling ozone dosage and enhancement of NOMs removal by biological processes.

Characterization of natural organic matters effect on the biodegradation in the slow sand filter.

This study focuses on the differences in biodegradation of the natural organic matters (NOMs) of p-hydroxy-benzoic acid (PHBA) and 4-hydroxy-3-methoxy-benzoic acid (VA) with slow sand filter (SSF). The PHBA and VA were biologically transformed into another organic matter in the slow sand filtration (SSF) at the start-up period. The dissolved organic carbon (DOC) of PHBA and VA were stabilized at 2 mg/l after 5th day. The SUVA value of PHBA run decreased with higher sand depth and flow rate, and VA run's increased with higher sand depth, but smaller than PHBA run. Therefore, the PHBA promoted the DBPFP (formation potential of disinfection by products), the VA brought higher biodegradation and lower DBPFP.