① For alcoholic organic wastewater with high pollutant concentration and high SS, it has high impact resistance and strong tolerance, which can completely meet the requirements of wastewater treatment with high concentration of suspended solids.
② In the case of high concentration suspension, although granular sludge cannot or is difficult to form, high-efficiency anaerobic device can cultivate sludge with good settling performance and high activity, which is the key to ensure COD removal rate.
(3) Under the condition of high concentration suspension, the volume load is much higher than that of the common full slag reflection tank, so the gas production is large and good economic benefits can be produced. Upflow anaerobic sludge reactor (UASB) technology has developed into one of the mainstream technologies for anaerobic treatment at home and abroad. In UASB, there is no carrier, sewage enters uniformly from the bottom and flows upward, and granular sludge (sludge floc) is suspended under the action of rising water flow and bubbles. The lower part of the reactor is a high-concentration sludge bed, and the upper part is a low-concentration suspended sludge layer, where organic matter is converted into methane and carbon dioxide gas. There is a three-phase separator in the upper part of the reactor, which can degas and make the sludge precipitate back to the reactor. The COD load of UASB is high, and the sludge concentration in the reactor is as high as100-150g/L, so the COD removal efficiency is three times higher than that of ordinary anaerobic reactor, which can reach 80% ~ 95%.
The anoxic tank has dual functions: first, the wastewater is pretreated biologically to improve its biodegradability, and some organic substances are adsorbed and degraded; The second is the sludge in the digestive system. It can form an A/O mode with subsequent contact oxidation, and has the function of simultaneous nitrogen and phosphorus removal, in which the main function of anaerobic stage is to remove organic pollutants and release phosphorus, and the main function of anoxic stage is to remove nitrogen. Because of its simultaneous removal of organic pollutants, nitrogen and phosphorus, this process is widely used in sewage treatment schemes that need to remove nitrogen and phosphorus.
Biological contact oxidation is a kind of biofilm process, which belongs to aerobic biochemical treatment process. The whole system consists of tank, filler and aeration equipment. Aerobic biochemical method is the growth and reproduction of bacteria, fungi, microorganisms, metazoa and other microorganisms on the filler carrier. Microorganisms absorb the organic matter in sewage as nutrients, adsorb and decompose the organic matter in sewage, and the microorganisms constantly metabolize and maintain their activity, thus purifying sewage. When dissolved oxygen and food are sufficient, microorganisms multiply very quickly and the biofilm gradually thickens. Dissolved oxygen and organic matter in sewage are utilized by microorganisms through diffusion. When the biofilm reaches a certain thickness, oxygen can't diffuse into the biofilm, and aerobic bacteria die, but facultative bacteria and anaerobic bacteria begin to multiply and form anaerobic layer. Using dead aerobic bacteria as substrate, anaerobic bacteria keep multiplying, and after a period of time, the number begins to decrease. With the escape of metabolic gases, the biofilm falls off in large pieces. On the surface of the fallen biofilm, a new biofilm is formed again. In the contact oxidation tank, due to the large surface area of filler, biofilm exists in every stage of development, which makes the ability of removing organic matter stable at a level. The main advantages of contact oxidation method are as follows:
(1) has high volume load, short treatment time and floor space saving. The maximum volume load of biological contact oxidation method can reach 3 ~ 6 kg BOD (m3 d), and the shortest residence time of sewage in the pond is only 0.5 ~1.5h. With the same volume of equipment, the treatment capacity of biological contact oxidation is several times higher, the treatment efficiency is high, and the occupied area is saved.
② High biological activity. Because the aeration system is arranged below the filler, it not only provides enough oxygen but also disturbs the biofilm, which accelerates the renewal of the biofilm and greatly improves the activity of the biofilm. Turbulence generated by aeration makes the biofilm contact with the organic matter in the sewage continuously, so as to avoid the formation of dead corners. After our detection in similar projects, the aerobic rate of filamentous biofilm with the same wet weight is 65438 0.8 times higher than that of activated sludge process.
③ The concentration of microorganisms is high, and the sludge concentration of the general activated sludge process is 2 ~ 3g/L, and the microorganisms are suspended in the tank; However, most microorganisms in the contact oxidation tank are attached to the filler, and the concentration of microorganisms in water and filler per unit volume can reach10 ~ 20g/L. Because of the high concentration of microorganisms in the biological contact oxidation process, it is beneficial to increase the volume load and reduce the occupied area.
④ Low sludge yield.
⑤ The effluent quality is good and stable. When the influent changes for a short time, the effluent quality is less affected and the biofilm activity recovers quickly, which is suitable for short-term intermittent operation.
⑥ Convenient operation and management.
The process flow is shown in the right figure: EGSB is very similar to UASB, but the difference is that EGSB adopts an upward flow rate as high as 2.5 ~ 6m/h, which makes the granular sludge in the reactor partially or completely expand. The distance between sludge particles increases, thus increasing the volume of sludge bed. Under the action of Shangsheng Gao velocity and gas production, the organic matter in wastewater contacts the sludge bed more fully. Therefore, wastewater can be allowed to have a short residence time in the reactor, so that EGSB can be used to treat wastewater with lower concentration. Compared with UASB, the water distribution is easier and more uniform, the mass transfer effect is better and the organic matter removal rate is higher. It can adapt to high-concentration organic wastewater and low-concentration organic wastewater, with high volume load and high COD removal rate.
Advantages of EGSB:
1, wide application range, no need for pre-acidification, and simple process;
2. The influent temperature and pH value are not high, and the influent COD can reach ~ 30,000 mg/L;
3. Self-expansion can be realized by water inflow and gas production, and the expansion degree of the bed will automatically change according to the change of load, so there is no need to increase a circulating pump to ensure expansion, so the power consumption is small;
4. The expansion degree of the bed in the reactor gradually increases from bottom to top, which belongs to variable-speed expansion bed, with strong impact load resistance and high organic matter removal rate (generally above 75%~95%); 5. Three-phase separator: the patented design of three-phase separator can effectively separate gas, solid and liquid, and ensure the effective residence time of sludge;
6. There is no internal circulation in the reactor, so the rising flow rate is slow and the separation will not be affected when the load is high;
7. Easy to operate and maintain, easy to manage.
SBR process integrates water, aeration and sedimentation in one tank. Generally, it consists of multiple ponds, and the working state of each pond changes and runs in turn. The single tank is decanted with a decanter, and the water is discharged intermittently, so it is also called sequencing batch activated sludge process.
This process changes the traditional distribution of aeration tank and sedimentation tank from spatial distribution to time distribution, forming an integrated intensive structure, which is conducive to the realization of compact module layout and the greatest advantage is to save land. In addition, the backflow of sludge can be reduced,
It has energy-saving effect. In the typical SBR process, the water is stopped during precipitation, and static precipitation can obtain higher precipitation efficiency and better water quality. With the development of automation technology and the popularization of PLC control system, the engineering application of SBR process has entered a new era.
The process flow is shown in the right: IC reactor, namely expanded granular sludge bed reactor, is the third generation anaerobic bioreactor developed on the basis of UASB reactor. Through the backflow and recycling of effluent, it greatly improves the rising velocity of sewage, and the granular sludge in the reactor is always in an expanding state, which strengthens the contact and mass transfer between sewage and microorganisms and obtains higher removal efficiency. The height of the reactor is as high as 16-25m. From the appearance, the IC reactor consists of a first anaerobic reaction chamber and a second anaerobic reaction chamber, and the top of each anaerobic reactor is provided with a gas-solid-liquid three-phase separator. Like two UASB reactors in series.
Characteristics of integrated circuits:
(1) has high volumetric load rate and short hydraulic retention time.
IC reactor has large biomass (up to 60g/L) and long sludge age. Especially due to the existence of internal and external circulation, the mass transfer effect is good. When treating high concentration organic wastewater, the influent volumetric loading rate can reach15 ~ 25 kg cod/m3 d.
(2) Strong impact load
In IC reactor, when the COD load increases, the biogas output increases and the internal circulation gas stripping increases. When treating high-concentration wastewater, the circulating flow can reach 10 ~ 20 times of the influent flow. The high concentration and harmful substances in wastewater are fully diluted, which greatly reduces the harmful degree, thus improving the impact load resistance of the reactor; When the COD load is low, the biogas output is also low, thus forming a low internal circulation flow. Therefore, the internal circulation actually plays a role in automatically balancing the COD impact load on the reactor.
(3) the deposition of solids is avoided
Some wastewater contains a lot of suspended solids, which are easy to accumulate in reactors with slow flow rate, such as UASB, and gradually replace anaerobic sludge, which eventually deteriorates or even fails the operation effect of anaerobic reactors. However, in IC reactor, the Shangsheng Gao velocity of liquid and gas will impact the suspended matter outside the reactor.
(4) Less investment in infrastructure and small area.
Because the volume loading rate of IC reactor is 3 ~ 4 times higher than that of common UASB reactor, the volume of IC reactor is about 1/4 ~ 1/3 of that of common UASB reactor. Moreover, the height-diameter ratio is large, so it occupies a small area, which is very suitable for factories and mines with tight area. In addition, the capital investment of the reactor can be reduced.
(5) Improve the quality by biogas, realize internal circulation and reduce energy consumption.
The expansion and fluidization of anaerobic fluidized bed carrier are realized by pressurizing the feed pump. Conversely, some power must be consumed. During the normal operation of IC reactor, the biogas generated by itself is used as the driving force to realize the internal circulation of mixed liquid, and the forced circulation is realized without turning on the water pump, thus reducing the energy consumption.
(6) Reduce the dosage of chemicals and reduce the operation cost.
The amount of liquid circulating inside and outside is equivalent to the reflux of primary anaerobic effluent, which plays a buffering role in pH and keeps the pH in the reactor stable. It can reduce the amount of alkali in the feed water, thus saving the amount of chemical agents and reducing the operation cost.
(7) Good effluent stability.
Because the IC reactor has two UASB reactors running in series, the lower UASB reactor has a high organic loading rate and plays a role of "coarse" treatment, while the upper UASB reactor has a low load and plays a role of "fine" treatment. Generally speaking, multi-stage treatment process has better stability than single-stage treatment, and the effluent quality is stable.
(8)IC can operate at a higher temperature, which is very suitable for the high temperature of production wastewater and can save the operating cost of sewage steam heating.
A/O process is short for anoxic/aerobic (facultative/aerobic) process. It is a biological carbon and nitrogen removal technology developed on the basis of conventional secondary biochemical treatment, and it is a widely used treatment process to consider sewage nitrogen removal. Make full use of the characteristics of anoxic organisms and aerobic organisms to purify wastewater.
The typical A/O process is to advance the anoxic stage to the aerobic stage, and use the organic matter in raw water as the organic carbon source, so it is called pre-denitrification, which is converted into nitrate nitrogen. In anoxic stage, denitrifying bacteria in activated sludge utilize nitrate.
Denitrifying chemical ammonia and carbon-containing organic matter in wastewater, so that combined ammonia can be converted into molecular ammonia, achieving the effect of carbon and nitrogen removal, and at the same time having the biological selection function of preventing sludge bulking. Therefore, A/O process not only has stable denitrification function, but also has high removal rate of COD and BOD, deep treatment depth and less residual sludge.
The process flow chart is shown on the right: this process is especially suitable for cassava alcohol production enterprises built in the suburbs, and the oxidation pond wastewater is stopped.
The stay can be as long as several months. Because most of these enterprises are located in suburbs or towns, the annual production period is intermittent, so it is possible for this sewage treatment method with large area and long treatment time.