The amount of sludge that can be inoculated in an anaerobic reactor is directly related to the type and size of the reactor. Taking the widely used third-generation anaerobic internal circulation reactor IC as an example, the maximum inoculation amount of anaerobic sludge is about 50-55% of the effective volume of the IC reactor, while the sludge inoculation amount of other types of anaerobic reactors is relatively small, and the maximum organic load that can be processed is also lower.
When an anaerobic reactor needs to undergo biological start-up, if the organic load to be processed is less than the maximum processing load of the reactor, the corresponding anaerobic sludge inoculation amount can be calculated based on the total amount of organic matter to be processed, without the need for full inoculation, thereby reducing the procurement cost of anaerobic sludge.
So how much anaerobic sludge should be inoculated? This requires understanding the basic concept of sludge load: sludge load refers to the amount of organic matter applied per unit mass of effective anaerobic sludge per day, measured in kilograms of SCOD, calculated using the following formula:
Among them, Q is the daily processing capacity of the anaerobic reactor
SCOD is the concentration of SCOD in wastewater
VS is the total volatile solids of anaerobic sludge in anaerobic reactors
Taking the IC reactor as an example, for anaerobic sludge with normal methane production activity, the optimal range of sludge load is usually 0.2-0.4 kgSCOD/kgVS. d, and the maximum sludge load should not exceed 0.55 kgSCOD/kgVS. d. Of course, the optimal and maximum load ranges may vary depending on different industries and water quality.
If the required amount of wastewater to be treated and the corresponding SCOD concentration of wastewater can be determined before the biological start-up of the anaerobic reactor, and the concept of sludge load mentioned above can be understood, then the appropriate sludge load can be selected through the above calculation formula and the required amount of anaerobic sludge to be inoculated can be calculated.
Additionally, it should be noted that if anaerobic granular sludge inoculation is used, a small amount of granular sludge will be crushed after pumping inoculation, and will be lost from the anaerobic reactor during subsequent biological start-up. Based on experience, the amount lost is about 5% of the inoculation amount. When calculating the inoculation amount of anaerobic sludge, it is necessary to take into account this loss.
