Summary of Debugging Experience with UASB Anaerobic Treatment Technology
Startup of UASB Anaerobic Reactor: Summary of Experience
The startup of a UASB (Upflow Anaerobic Sludge Blanket) anaerobic reactor can be divided into two types: primary startup and secondary startup.
Primary Startup refers to the process of starting up a UASB reactor using sludge other than granular sludge as the inoculum.
Secondary Startup refers to the process of starting up a UASB reactor using granular sludge as the inoculum.
Currently, our company uses the secondary startup method. The following issues should be noted:
Influent Load: The load during secondary startup can be relatively high. In general, the initial influent concentration can reach 3000 mg/l to 5000 mg/l. After a period of time, when the COD removal rate reaches more than 80%, the influent concentration should be appropriately increased. The corresponding flow rate should not be too high. We advocate for low flow rates and low loads during the initial startup of anaerobic reactors. This method has been successfully implemented in the two sets of anaerobic reactors at our company.
Suspended Solids in Influent: The concentration of suspended solids in the influent should not be too high, as this will severely affect the formation of anaerobic granular sludge. If the accumulation of suspended solids exceeds the growth rate of microorganisms, it will ultimately lead to a significant reduction in the activity of anaerobic sludge. This is because the entire anaerobic reaction system has a limited capacity.
Control of Influent Type: The influent to the anaerobic reactor needs to be strictly controlled. Through acclimatization, we can treat some difficult-to-process wastewater, such as column washing water. However, during the startup of the entire anaerobic reaction system, such water should not be introduced, as it will significantly prolong the startup time. During the startup process, we should also regularly monitor the production conditions and make appropriate decisions regarding the influent during the startup phase. Units needing wastewater treatment can consult enterprises with similar wastewater treatment experience on the Sewage Treasure Project Service Platform.
Observation of Granular Sludge: During the startup, regular samples should be taken from the granular sludge sampling ports to observe the growth of the granular sludge. By combining the COD values of the influent and effluent, we can assess the startup progress of the anaerobic reactor.
Effluent pH: The pH of the effluent should be regularly recorded. If the pH value falls below 6.8, appropriate remedial measures should be taken in a timely manner (adjusting the influent load, or adding soda ash if necessary) to ensure a successful startup.
Biogas Production and Sludge Washing: Regular communication with the hot air furnace operator is essential to understand biogas production levels. If the gas production is low, an analysis should be conducted from three aspects: influent load, temperature, and granular sludge formation, to find solutions.
Influent Temperature: The temperature inside the anaerobic reactor should be controlled between 34°C and 38°C. The temperature difference within 24 hours should not exceed 2°C. This can be controlled by adjusting the influent temperature.
