Anaerobic co-digestion of glycerol and wastewater derived from biodiesel manufacturing
2010
Siles, J.A. | Martín, M.A. | Chica, A.F. | Martin, A.
The anaerobic co-digestion of glycerol and wastewater derived from biodiesel manufacturing, in which COD was found to be 1054 and 428g/L, respectively, was studied in batch laboratory-scale reactors at mesophilic temperature (35°C). Glycerol was acidified with H₃PO₄ in order to recover the alkaline catalyst employed in the transesterification reaction (KOH) as agricultural fertiliser (potassium phosphates). Wastewater was subjected to an electrocoagulation process in order to reduce its oil content. After mixing, the anaerobic revalorisation of the wastewater was studied employing inoculum-substrate ratios ranging from 5.02 to 1.48gVSS/gCOD and organic loading rates of 0.27-0.36gCOD/gVSSd. Biodegradability was found to be around 100%, while the methane yield coefficient was 310mLCH₄/gCOD removed (1atm, 25°C). At the equilibrium time, the proportionality between [formula removed] and the load was constant, showing 1.55mLCH₄/(gVSSgCODh). The results showed that anaerobic co-digestion reduces the clean water and nutrient requirement, with the consequent economical and environmental benefit.
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