Thermal pre-treatment of aerobic granular sludge: Impact on anaerobic biodegradability

• Published in: Water research (Oxford) 2011-11, Vol.45 (18), p.6011-6020
• Main Authors: Val del Río, A., Morales, N., Isanta, E., Mosquera-Corral, A., Campos, J.L., Steyer, J.P., Carrère, H.
• Format: Article
• Language: English
• Subjects: Activated sludge; Aerobic granules; Aerobiosis; Anaerobic digestion; Anaerobiosis; Applied sciences; Batch Cell Culture Techniques; Biochemical methane potential (BMP); Biodegradability; Biodegradation, Environmental; Biological Oxygen Demand Analysis; Biomass; Environmental Sciences; Exact sciences and technology; Hydrogen-Ion Concentration; Life Sciences; Lipids - analysis; Methane; Methane - analysis; methane production; pig manure; Pollution; pretreatment; Proteins - analysis; Reactors; Sequencing batch reactor (SBR); Sewage - chemistry; Sewage - microbiology; Sludge; Solubility; Temperature; Thermal pre-treatment; Volatilization; Waste water; wastewater; wastewater treatment; Water treatment and pollution
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2011.08.050

The aerobic granular systems are a good alternative to the conventional activated sludge (AS) ones to reduce the production of sludge generated in wastewater treatment plants (WWTP). Although the quantity of produced sludge is low its post-treatment is still necessary. In the present work the application of the anaerobic digestion combined with a thermal pre-treatment was studied to treat two different aerobic granular biomasses: one from a reactor fed with pig manure (G1) and another from a reactor fed with a synthetic medium to simulate an urban wastewater (G2). The results obtained with the untreated aerobic granular biomasses showed that their anaerobic biodegradability (BD) (33% for G1 and 49% for G2) was similar to that obtained for an activated sludge (30–50%) and demonstrate the feasibility of their anaerobic digestion. The thermal pre-treatment before the anaerobic digestion was proposed as a good option to enhance the BD when this was initially low (33% G1) with an enhancement between 20% at 60 °C and 88% at 170 °C with respect to the untreated sludge. However when the initial BD was higher (49% G2) the thermal pre-treatment produced a slight improvement in the methane production (14% and 18%) and at high temperatures (190 and 210 °C) which did not justify the application of such a treatment. [Display omitted] ► Thermal pre-treatment and anaerobic digestion of aerobic granular sludge was tested. ► The granules from a reactor treating pig manure had a biodegradability of 33%. ► Their thermal pre-treatment at 170 °C led to a biodegradability enhancement of 88%. ► The granules from a reactor treating synthetic media had a biodegradability of 49%. ► Their thermal pre-treatment enhanced only 18% the methane production at 210 °C.