EFFECT OF LOW-TEMPERATURE THERMAL-ALKALINE PRETREATMENT WITH ALKYL POLYGLUCOSIDES (APGS) FOR LOW-ORGANIC-CONTENT SLUDGE ON ANAEROBIC DIGESTION.

Low-temperature thermo-alkaline pretreatment with alkyl polyglucosides (APGs) was employed for improving the utilization of low-organic-content sludge in anaerobic digestion (AD). An orthogonal experiment (L₉ (3⁴)) was designed to estimate the influence of four factors on pretreatment, and the order determined by significance level was: pH > temperature > APG dosage > time. Under the conditions of pH 11, 60 °C, and 60 min, the content of organic matter dissolved from sludge increased as the APG dosage increased to 18 g/L. When fermenting at a dosage above its critical micelle concentration (CMC), however, APG inhibited aerogenesis due to the adverse impact on methanogen activity. Thus, the optimal APG dosage was fixed at 3.0 g/L. After 35 days of mesophilic AD, the biogas volume, the methane volume fraction, and the organics utilization rate reached their respective peaks. The methane volume fraction (45.8%) was lower than normal biogas (at least 53%), so further evaluation is needed. [ABSTRACT FROM AUTHOR]