污水處理入面A2/O PROCESS的 HYDRAULIC RETENTION TIME

要解答你這個問題，首先你要了解 AEROBIC ZONE 和 ANOXIC ZONE的分別：

Aerobic Zone

Definition: In this zone of exercise intensity, the body uses both stored fat and carbohydrates for energy. At 70-80% of your maximum heart rate, 50% of your calories burned in this zone are fats, 1% are proteins and 50% are carbohydrates. This intensity zone is excellent for increasing the number and size of blood vessels, increasing vital capacity and respiratory rate and achieving increases in pulmonary ventilation, as well as increases in arterial venous oxygen.
The aerobic phase of your workout should be of 50 minutes or less to prevent build-up of lactic acid. Always warm up with 5-10 minutes of easy pace and after the aerobic phase, cool down with 5-10 minutes at an easy pace.

這個 forum 有AEROBIC ZONE 和 ANOXIC ZONE的分別：

http://www.wef.org/technicaldiscussions/Topic2527-9-1.aspx