Biodegradation of naphthalene sulfonate polymers by Pleurotus ostreatus in packed-bed bioreactor

The ability of white rot fungus Pleurotus ostreatus to biodegrade 2-naphtalene sulfonic acid polymers (NSAP) contained in petrochemical wastewater was evaluated. The biodegradation experiment was conducted in a packed-bed bioreactor with a bed made of straw, which acted as both support and co-substrate for the fungi. The reactor worked at a Hydraulic Retention Time (HRT) of 3d and showed a stable NSAP degradation (35 ± 5%). Respirometric tests conducted on the effluent from the packed-bed bioreactor showed that the fungal treatment was also able to significantly increase the bCOD/COD ratio, which rose from 9% (raw wastewater) to 40% (treated wastewater). It was observed that the fungal degradation of the straw in the bed releases non-biodegradable by-products. Taking into account this contribution, the combined treatment of fungi and activated sludge was able to reduce the initial COD by up to 73%.