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COMPARATIVE EVALUATION OF MESOPHILIC AND THERMOPHILIC DIGESTION - PHASE II. STEADY STATE STUDIES
Citation:
Kugelman, I. AND V. Guida. COMPARATIVE EVALUATION OF MESOPHILIC AND THERMOPHILIC DIGESTION - PHASE II. STEADY STATE STUDIES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/2-89/001b.
Description:
A study of the relative performance of anaerobic digestion systems under mesophilic and thermophilic conditions was conducted. Fifty liter laboratory scale digesters were fed primary sludge from the Allentown, PA Waste Water Treatment Plant. Long-term, steady-state performance data were obtained at 49.5oC and 35oC. Two hydraulic detention times, 25-days and 15 days, were used. Attempts to operate at temperatures above 5O C resulted in poor performance (propionic acid levels well above 1,000 mg/l). Operation of the mesophilic and thermophilic units was within parameter ranges normally considered satisfactory. Mesophilic operation was slightly superior to thermophilic operation as indicated by total and volatile solids breakdown and by gas production. Mesophilic breakdown of carbohydrate and oil and grease was superior. Thermophilic breakdown of organic nitrogen was superior. Dewaterability of sludge produced under mesophilic conditions was significantly better than sludge produced under thermophilic conditions.