Two-phase high solid anaerobic digestion with dewatered sludge: Improved volatile solid degradation and specific...

Area of Science:

• Environmental Engineering
• Biotechnology
• Waste Management

Background:

• Anaerobic digestion is a key process for treating high-solid municipal dewatered sludge.
• Temperature and pH are critical parameters influencing the efficiency of volatile solid (VS) degradation and methane (CH4) production.

Purpose of the Study:

• To investigate the impact of different temperature regimes and pH levels on anaerobic digestion of high-solid sludge.
• To optimize VS degradation and CH4 generation by manipulating operational conditions.

Main Methods:

• Comparison of single-phase reactors (35°C and 55°C) with two-phase reactors (varying acidification and digestion temperatures).
• Implementation of adjusted initial pH (10.0) in a two-phase system (Group 3) based on Group 2 conditions.
• Monitoring of VS degradation ratio and CH4 generation ratio across different experimental groups.

Main Results:

• Two-phase systems (G2 and G3) demonstrated higher VS degradation and CH4 generation ratios compared to single-phase systems (G1).
• Extreme thermophilic/thermophilic-mesophilic systems within G2 showed superior VS degradation and CH4 generation.
• Initial pH adjustment to 10.0 in G3 enhanced VS degradation and CH4 generation specifically in the acidification phase, but not for the overall system.

Conclusions:

• Two-stage anaerobic digestion, particularly with specific thermophilic and mesophilic combinations, is more effective for high-solid sludge treatment.
• While initial pH adjustment can benefit the acidification stage, its overall impact on the entire two-stage system's efficiency needs further investigation.