Methane Generation Performance and Kinetic Analysis of Food Waste and Excess Sludge Treatruant by Anaerobic Co-Digestion Technology

Abstract:

The study compared the performance and kinetics for the generation of methane by different ratios of food waste to excess sludge at 1∶0，0∶1，1∶1. Results showed that the co-digestion not only shortened the time of methane generation when compared to food waste alone treatment，but also improved the production efficiency with a yield of 233.394 mL/gVS，which was 17.4% higher than the calculated value of 198.939 mL/gVS according to food waste and excess sludge alone groups. The correlation coefficient R2 was greater than 0.989 by the first order kinetics fitting. The G∞ of food waste，excess sludge and co-digestion groups was 276.5，113.955 mL/gVS and 248.81 mL/gVS，respectively. They were similar to the actual measured values of 285.24，112.238 mL/gVS and 233.94 mL/gVS，respectively. Also，the comparative study of pH，VFAs，ammonia-nitrogen，SCOD and dehydrogenase enzyme was carried out and showed that the co-digestion balanced nutrients and decreased the system acidification，which resulted in a better buffer capacity and the system stability for the mixed substrates. It increased the amount of easily degradable organic matters and improved the methane producing efficiency as compared to the excess sludge only group. The dehydrogenase activity of co-digestion group was higher than that of kitchen waste only digestion group during the whole digestion process，with a maximal value of 657.2 TFμg/（mL·h）.