What is the difference between anaerobic and hypoxic?

It seems to be related to the oxygen content; I’ve forgotten the exact figure.

It is classified based on the degree of need for poplar by the corresponding items :)

There is a significant difference: anaerobic treatment is a biochemical process involving anaerobic bacteria, which do not require oxygen; in fact, oxygen is toxic to them. Therefore, it is necessary for the dissolved oxygen level in the system to be zero, and this is its most prominent feature. Additionally, anaerobic reactions require high and stable temperatures, with mesophilic reactions taking place at temperatures between 31 and 33 degrees Celsius. Anaerobic reactions require a strict pH. The anoxic reaction is a biochemical process involving facultative bacteria, which are capable of carrying out reactions both in aerobic and anaerobic conditions. The dissolved oxygen level in such systems needs to be below 0.5 mg/L. The requirements regarding temperature and pH are not as strict as those for anaerobic reactions; generally, levels below 0.2 mg/L are considered the anaerobic zone, while levels between 0.2 mg/L and 0.5 mg/L are considered the anoxic zone. Phosphorus release in the anaerobic stage, denitrification for nitrogen removal in the anoxic stage. The dissolved oxygen levels in the anaerobic and anoxic zones are indeed not as easy to control as those in the aerobic zone, after all, there are no devices for consuming oxygen; therefore, it is difficult to deal with situations where the dissolved oxygen level is too high. (The lack of oxygen, with dissolved oxygen levels below 0.2, does not affect denitrification); however, actions can be taken from the following aspects. 1. For inflowing water, sewage generally has very low dissolved oxygen levels. However, if there is aeration in the grit chamber or if the water is allowed to fall before entering, it is necessary to consider controlling the amount of air supplied or reducing the height of the drop, in order to minimize oxygenation. II. Recirculated sludge: It is sufficient as long as there is enough dissolved oxygen in the water entering the sedimentation tank; as long as denitrification does not occur in the sedimentation tank. Excessive dissolved oxygen can result in too high a level of dissolved oxygen in the recirculated sludge. III. Internal recirculation: Both AO and AAO systems are equipped with internal recirculation mechanisms. By controlling aeration near the recirculation pump, it is possible to make the air volume in that section of the aeration tank lower than that in other sections; as a result, less dissolved oxygen will be carried back by the internal recirculation flow.

This post was last edited by cdpulin on 2010-9-7 14:31. “There is gold in books, and there are beautiful women in books.” Why does the original poster ask such a question? Is it for research?

You can think of it that way: if you’re good enough, you can refute their claims!

The 4th floor and the 7th floor made it very clear; how is it unclear upstairs? Simply put, it can be determined by measuring the dissolved oxygen level; in anaerobic conditions, the dissolved oxygen level is 0–0.2 mg/L ； The dissolved oxygen level in hypoxic conditions is 0.1–0.5 mg/L ； The dissolved oxygen level for aerobic conditions is 1–3 mg/L

Let’s see the impact of oxygen on the process

There is no molecular oxygen or combined oxygen in the anaerobic tank; the electron acceptor for the degradation of organic matter is the organic matter itself (the intermediate products of anaerobic oxidation or fermentation). In contrast, in the anoxic tank, the electron acceptors are NO3- or NO2-, which means that combined oxygen is allowed to be present in the anoxic tank. If molecular oxygen is introduced into anaerobic or anoxic tanks, it will inhibit the metabolic activity of anaerobic microorganisms or denitrifying bacteria, as the electrons released from organic matter are directly transferred to molecular oxygen. The main purpose of anaerobic treatment is to degrade organic matter, while anoxic tanks utilize anoxic denitrification to remove nitrate nitrogen (thereby reducing total nitrogen; often, the nitrified liquid is recycled back to the anoxic tank to control total nitrogen levels). In some nitrogen and phosphorus removal processes, in order to reduce the interference of NO3- on the anaerobic phosphorus release by polyphosphate-accumulating bacteria, the recycled liquid is first subjected to anoxic denitrification. During this anoxic process, NO3- and NO2- serve as electron acceptors (rather than molecular oxygen or organic matter).

“\"Anaerobic,\" as the name implies, means \"hating the presence of oxygen,\" and this refers to anaerobic bacteria. Since the function of anaerobic bacteria depends on the absence of oxygen, and oxygen inhibits their activity, it is theoretically true that the less oxygen there is, the better – ideally, zero oxygen at all. “\"Hypoxia,\" as the name implies, means \"a lack of oxygen.\" This indicates that there is still some oxygen present, only in smaller amounts; it is in a state of deficiency. This is determined by the characteristics of the specific bacterial strain. Incidentally, “aerobic” means “preferring oxygen”; of course, the higher the oxygen concentration, the better, as aerobic bacteria can only perform their functions when there is an adequate supply of oxygen. In short, in terms of oxygen content, it is “aerobic” > “hypoxic” > “anaerobic””