High-rate anaerobic reactor

* Working principle Basic configuration of anaerobic reactor is similar to series connection of two layers of UASB reactor. High-rate reactor is composed by five areas with different function, as mixing area, No.1 anaerobic reaction area, No.2 anaerobic reaction area, settling area and gas-liquid separating zone. Mixing area: Influent, partial sludge and returning mixture coming from gas-liquid separating zone will be mixed in this area. * No.1. Anaerobic area: The mixture coming from mixing area enters this area where most of organic matter transfers to gas. Sludge inside this area expands and be fluidized under strong agitation of up-flow of mixing liquid and gas, so that increase the surface contact of sludge and liquid and improve sludge activity. A few of sludge- liquid mixture will be raised to gas-liquid separating zone by increasing gas. * Gas-liquid separating zone: Gas is discharged out of system after separation from mixture in this zone. The separator of liquid will return to bottom mixing area through recirculation tube and repeat above process. * No.2 Anaerobic area: Effluent from No. anaerobic area enters No.2 Anaerobic area through three-phase separator. Being a lower sludge concentration area and the majority of organisms in wastewater in an anaerobic zone has been degraded, thus the amount of methane produced less. Gas through the gas pipe enters into gas-liquid separating zone and creases less of agitation in No. 2 anaerobic area, which provided favorable conditions for the sludge remained. * Settling area: Mixture of No.2 Anaerobic area is carried out solid-liquid separation in the settling areas, the supernatant is drained away by outlet pipe, sedimentation of granular sludge returns to sludge bed of No.2 Anaerobic area. * From working principle of anaerobic reactor can be seen that High-rate reactor achieves the SRT> HRT through the two-layer three-phase separator and obtain a high sludge concentration; to full access to the mud and get a good Mass Effect through a large number of gas and severe disturbance of the inner loop. * Technical feature of process: - High volume load: organic load of influent of High-rate reactor is 3 times that of other general UASB reactor as it has high sludge concentration, large number of microorganisms and inner loop. - Low investment and small land requested: High-rate reaction size is about 1/4-1/3 of the size of general UASB reactor that much reduce the investment of foundation for reactor. Furthermore, ratio of height and diameter is large (usual about 4-8), thus it saves much land. High-rate reactor is suitable for industrial and mining enterprises. - Strong ability against impact load: Flow quantity of inner loop could be 2-3 times of input water quantity when the wastewater concentration is low about COD=2000¡«3000mg/L; Flow quantity of inner loop could be 10-20 times of input water quantity when the wastewater concentration is high about COD=10000¡«15000mg/L. - Strong ability against low temperature: High-rate reactor contains a large number of microorganisms that reduces the impact of temperature for anaerobic digestion. Usual, High-rate reactor can carried out the anaerobic digestion under room temperature about 20-25¡æ, thus resolve difficulty of thermal insulation and save energy. - Balance pH: Flow quantity of inner loop equals to recirculation flow quantity. It takes the use of Alkali transferred from COD to balance pH. Thus reduce the alkali dosage for input water. - Internal auto-cycle, without external power: the return of normal anaerobic reactor is achieved through external pressure, while the high-rate anaerobic reactor to produce biogas as to enhance their own power to achieve the mixture inside the circle, thus it does not need the pump to enforce the circulation, saves power consumption. - Output stability is good. It takes use of class 2 anaerobic treatment of series connection of UASB that reduce the bad interference of high concentration of Ks produced anaerobic process. - Start-up period is short: high-rate anaerobic reactor contains sludge with high activity, makes biological proliferation fast that quicken the reactor startup speed. Startup period of High-rate anaerobic reactor is generally 1 to 2 months; while the period of ordinary UASB startup is 4 to 6 months.