Dairy wastewater valorization enhances white rot fungi performance in recycled paper effluent treatment

Wastewaters produced by the recycled paper and cardboard sector (RPCE) pose significant environmental risks due to high levels of chemical oxygen demand (COD) and a lack of essential nutrients required for effective biological degradation. In response, this investigation introduces a novel and cost-effective valorization approach: employing nutrient-laden dairy wastewater (DWW) as an eco-friendly source of nitrogen and phosphorus to enhance the bioremediation performance of a fungal consortium comprising Bjerkandera adusta and Phanerochaete chrysosporium. A primary aim of the study was to optimize the RPCE concentration to achieve a balance between contaminant reduction and industrial feasibility. Results showed that although a 25% RPCE concentration achieved the peak decolorization rate, a 50% concentration emerged as the optimal operational condition for industrial scale-up. This strategy enables the processing of larger effluent volumes while maintaining high treatment quality. Under these optimized conditions, the system attained removal rates of 93.7% for COD and 35.5% for color. Moreover, the toxicity of the treated effluent was substantially reduced, evidenced by a 55.4% drop in the phytotoxicity index (PI). The proven effectiveness of this fungal co-treatment method in non-sterile settings underscores its robustness and suitability for straightforward, cost-effective implementation in large-scale industrial systems, thus advancing circular economy principles.