Reforms to improve the treatment efficiency of UASB
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In the UASB process for wastewater treatment, wastewater recirculation is not taken into account in the design. In actual operation, this recirculated wastewater enters the anaerobic zone, thereby increasing the load on the anaerobic treatment significantly. The load caused by wastewater recirculation is roughly equal to the load of the wastewater entering the anaerobic zone; for example, if the COD of the recirculated wastewater is 3000 while the COD of the water in the monitoring tank is 100, then the actual load on the anaerobic system is equal to the load of the water exiting the regulation tank plus the load from this recirculated wastewater. The wastewater recirculation mechanism serves to regulate the anaerobic upward flow rate, maintain the alkalinity within the UASB tank, and extend the residence time. The physical and chemical properties of this recirculated wastewater are essentially the same as those of the water in the monitoring tank, but the COD levels differ significantly. In my opinion, using the water from the monitoring tank, or at least a large portion of it, for UASB wastewater recirculation can improve the efficiency of anaerobic treatment and save considerable costs associated with aerobic processing – around 30 million yuan per year. After such modifications, it is possible to increase the design load of the anaerobic treatment system. I believe this is the reason why the UASB system often fails to reach its designed processing capacity
If the cost of agents used to adjust alkalinity is not high, there is no need to supplement alkalinity
I’m not quite clear; what kind of water is the wastewater return? Aerobic reflux or UASB itself reflux? What specific renovation measures are there? The removal rates achieved using UASB in my experiences have been relatively low, around 20-40%. If there are any effective improvement methods, could you share them?
What is recycled is the effluent from the anaerobic sedimentation tank; the main purpose of this recycling is to replenish alkalinity, adjust the retention time, and dilute the incoming water in order to prevent shock loads. The removal efficiency of UASB is highly dependent on the characteristics of the sludge. In anaerobic systems, granular sludge is primarily used. In the past, our company added aerobically dewatered sludge to the anaerobic system, but the results were not satisfactory; it might be worth giving it a try
Sure, UASB design involves backflow; adding aerobic sludge to the UASB is a measure taken when the sludge concentration is insufficient during the early stages of UASB tuning, right? The aeration sludge showed poor inoculation efficiency, with large amounts of dead sludge floating on the surface of the tank.
If the effluent from the monitoring tank is used as the return flow for the UASB, it will **increase the load on the aerobic biological treatment system, thereby raising the costs associated with its operation.