The basic feature of the UASB reactor is that it can form granular sludge with good sedimentation performance without adsorbing a carrier, and maintain a high concentration of micro-objects in the reactor, so it can withstand a high COD load (up to 30 ~ 50kgCOD / (m3. d) above), COD removal rate can reach more than 90%. In aerobic biological treatment, the best aerobic pure biological fluidized bed. The COD load of deep well aeration and other processes is only about 10kgCOD / (m3.d), and the COD removal rate is 70% ~ 80%. Compared with other anaerobic bioreactors, the characteristics of UASB are as follows.
1. Simple and clever structure:
The sedimentation zone is set at the top of the reactor. The wastewater enters from the bottom of the reactor and flows upward through the sludge bed area to contact a large number of anaerobic bacteria. Organic matter in the wastewater is decomposed into biogas by anaerobic bacteria (the main components are CH4 and CO2). During the upwelling process, the wastewater was entrained with biogas and anaerobic solids. Biogas is solid-liquid separated in the gas chamber area. The treated purified water is drained from the top of the reactor, and the wastewater completes the entire process of treatment. Most of the sludge in the sedimentation zone can be returned to the sludge bed zone, which can keep sufficient biomass in the reactor. It can be seen that the entire first half of the time integrates biological reaction and sedimentation. There is no mechanical stirring and no filler in the reactor, the structure is simple, and the operation and management are convenient.
2. Anaerobic granular sludge can be cultivated in the reactor:
When the UASB reactor treats most organic wastewater, as long as the operation method is correct, anaerobic granular sludge can generally be cultivated in the reactor. The characteristics of the anaerobic granular sludge are high activity for removing organic matter, and density is higher than flocculant. The sludge is large and has good sedimentation performance, and the high biomass can be maintained in the reactor.
3. Separation of sludge age (SRT) from hydraulic retention time (HRT):
Because the reactor can maintain a high biomass, the sludge age is very long, the HRT of the wastewater in the reactor is short, and the SRT is greater than the HRT, so the reactor has a high volume loading rate and good operation Stability, which is the biggest difference between modern anaerobic reactors and traditional anaerobic reactors.
4. The UASB reactor has great adaptability to various types of wastewater:
The UASB reactor can not only produce high-concentration organic wastewater such as alcohol, molasses, citric acid and other production wastewater, but also medium-concentration organic wastewater, such as beer, slaughter, soft drinks and other production wastewater, and it can produce low-concentration organic wastewater, such as domestic wastewater. , Urban sewage, etc. The UASB reactor can be operated at high temperature (55 degrees Celsius) and medium temperature (about 35 degrees Celsius), and can be stably operated at low temperatures (about 20 degrees Celsius). In addition to the organic wastewater containing toxic and harmful substances, the UASB reactor can adapt to almost all types of organic wastewater discharged from different industries.
5. Low energy consumption and less mud production:
Because the UASB reactor does not require oxygen, does not require stirring, does not require heating, while achieving high energy efficiency, it achieves low energy consumption and can provide a large amount of bioenergy biogas. Therefore, the UASB reactor is a productive type Wastewater treatment equipment. Because the SRT is very long, not only the sludge produced is stable, but also the sludge production is small, thereby reducing the sludge treatment costs.
6, can not remove nitrogen and phosphorus in wastewater:
The UASB reactor, like other anaerobic treatment equipment, has the disadvantage that it cannot remove nitrogen and phosphorus from wastewater. This is determined by the nature of the anaerobic biochemical reaction. In the treatment of high and medium concentration wastewater, an anaerobic-aerobic tandem process is adopted, that is, a UASB reactor is used to remove most of the carbon-containing organic matter in the wastewater as a pretreatment, and aerobic treatment equipment is used to remove the remaining carbon-containing organic matter and nitrogen, Phosphorous and other substances, which are the best choice of wastewater treatment process, have great energy saving significance, and can greatly save infrastructure investment and reduce operating costs. Therefore, it has very good economic and environmental benefits.