The design method of UASB process system is discussed. The anaerobic treatment of pulse water distributor has been successfully applied to all kinds of high and medium concentration industrial wastewater treatment. Although the medium and high concentration of wastewater to a considerable extent was resolved, but when the contaminated water containing inhibitory substances, such as sulfate containing monosodium glutamate wastewater treatment is still a certain degree of difficulty. In the field of anaerobic treatment is the most widely used UASB reactor, so this paper focuses on the design method of UASB reactor. However, it has some common points with other anaerobic treatment processes, for example, the fluidized bed and UASB have three-phase separator. And UASB and anaerobic filter bed for water distribution requirements are consistent, so the results can also be used as a reference for other reactor design.
Contains the water treatment process of anaerobic treatment unit includes pretreatment, anaerobic treatment (including processing and utilization of biogas Collection) and aerobic postprocessing and sludge treatment, can be used as shown in Figure 1 represents the process.
Two, UASB system design
1, pretreatment facilities in general pretreatment system including coarse grid, fine grid or hydraulic sieve, grit chamber, regulation (acidification) pool, nutrient salt and pH control system. The purpose of the grid and grit chamber is to remove coarse solids and inorganic solids, which are necessary to protect the water distribution pipes of various types of anaerobic reactors. When the sewage containing gravel, for example with sweet potato as raw material of brewing wastewater, cannot be overemphasized the importance of grit removal. Non biodegradable solid, the accumulation of anaerobic reactor will occupy a large number of tank capacity, reactor, the continuous reduction of the reactor will eventually lead to a complete failure of the system. Because the anaerobic reaction is sensitive to water quality, water quantity and impact load, the regulation of the proper size of industrial waste water, the regulation of water quality and quantity is the guarantee of the stable operation of anaerobic reactor. The role of regulation pool is homogeneous and mean, generally also can consider both precipitation, mixing, dosing, neutralization and acidification pretreatment etc.. The sedimentation tank is arranged in the regulation pool, the volume to deduct settling zone volume; according to the granulation and pH regulatory requirements, when the water alkalinity and nutrients is not need to add alkalinity and nutrients (N, P); automatically adding acid, alkali and drug use metering pump, by adjusting water or force mechanical stirring of neutralization.
At the same time, acidification pool or two-phase system is to remove and change, improve the biological reaction conditions and the main means of biochemical and anaerobic pretreatment material, inhibition of anaerobic process, anaerobic pretreatment is one of the purposes of. It is generally not considered the acidification effect only when the solution is considered. For complex wastewater, it is necessary to make a certain degree of acidification in the regulation pool, but it is not necessary to complete acidification. Because completely after acidification of wastewater pH will decrease, by adjusting the pH value of administration. In addition, there is evidence that complete acidification has a detrimental effect on the particle process of the UASB reactor. It may be advantageous to consider acidification or phase separation in the following circumstances:
1) when the pre acidification can be used to remove or change the structure of toxic or inhibitory compounds on the methane bacteria;
2) when the wastewater has a high Ca2+, the partial acidification can avoid the CaCO3 scaling on the surface of the granular sludge;
3) when the treatment of high - containing suspended solids and / or the use of high - load, the removal of non - soluble components of limited time;
4) the effect of partial acidification can be achieved by adjusting the reasonable design of the cell. For example, up to the flow of water in the reactor at the bottom of the formation of sludge layer (1.0m). At the bottom of the water hole design is 5 ~ 10m2 / hole.
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