Fungal treatment of an effluent from sewage sludge digestion to remove recalcitrant organic matter

In this study, Phanerochaete chrysosporium was tested for first time to treat the liquid effluent from a sewage sludge digestion. This anaerobic digestion liquor (ADL) has a COD concentration of around 7500 mg/L, a very low biodegradability (BOD5/COD = 0.02) and deep colour, being impossible their effective treatment by conventional biological methods. Assays inoculating the fungi were carried out at 26 degrees C during 10 days in a batch reactor, following the evolution of colour, COD and BOD5. The effect of adding different concentrations of glucose was evaluated, resulting to be a key factor for increasing the efficacy of the treatment. Based on batch results, a continuous fungal water-jacketed bioreactor was successfully started up. COD removals above 65 % were achieved both in batch and continuous operations. These results show the possibilities of this sustainable and economic approach to remove refractory COD in the low-biodegradable effluents derived from anaerobic digestion of sludge or other complex wastes.