Systematic comparison of mechanical and thermal sludge disintegration technologies.
This study presents a systematic comparison and evaluation of sewage sludge pre-treatment by mechanical and thermal techniques. Waste activated sludge (WAS) was pre-treated by separate full scale Thermo-Pressure-Hydrolysis (TDH) and ball milling facilities. Then the sludge was processed in pilot-scale digestion experiments. The results indicated that a significant increase in soluble organic matter could be achieved. TDH and ball milling pre-treatment could offer a feasible treatment method to efficiently disintegrate sludge and enhance biogas yield of digestion. The TDH increased biogas production by ca. 75% whereas ball milling allowed for an approximately 41% increase. The mechanisms of pre-treatment were investigated by numerical modeling based on Anaerobic Digestion Model No. 1 (ADM1) in the MatLab/SIMBA environment. TDH process induced advanced COD-solubilisation (COD(soluble)/COD(total)=43%) and specifically complete destruction of cell mass which is hardly degradable in conventional digestion. While the ball mill technique achieved a lower solubilisation rate (COD(soluble)/COD(total)=28%) and only a partial destruction of microbial decay products. From a whole-plant prospective relevant release of ammonia and formation of soluble inerts have been observed especially from thermal hydrolysis.
Wett
B
B
Institute of Infrastructure, University of Innsbruck, Technikerstr. 13, 6020 Innsbruck, Austria. bernhard.wett@uibk.ac.at
Phothilangka
P
P
Eladawy
A
A
D000641:Ammonia / Q000032:analysis; D001673:Biodegradation, Environmental; D056804:Biofuels; D004787:Environmental Pollution / Q000517:prevention & control*; D006868:Hydrolysis; D011312:Pressure; D012722:Sewage; D013696:Temperature
D056804:Biofuels; D012722:Sewage; D000641:Ammonia