The effluent from an anaerobic digester (10 L in size) has a COD concentration of 5,560 mg/L, among which 50% is soluble. The gas analysis shows that a total of 0.072 kg of CH4 is produced at the end of the process. Assuming that methanogens can convert 70% of the insoluble COD in the influent into soluble COD and use soluble COD to produce CH4 gas, what is the total COD level in the influent that contains 30% of soluble COD?