Multi-batch treatment of swine slaughterhouse wastewater by microalgal-fungal consortium system: Stability and...

Swine slaughterhouse wastewater (SSW) is highly hazardous due to its extreme organic pollution load. In this study, an efficient and stable microalgal-fungal consortium system (MFCS) was constructed with Chlorella sp. DT025 and Penicillium sp. AHP141 for the multi-batch treatment of SSW. The MFCS was employed to treat five consecutive batches of SSW, demonstrating its efficient and stable removal of organic pollutants. Specifically, the removal ratio of COD, TN, TP, NO₃^--N, and NO₂^--N reached 68.16%, 76.47%, 61.47%, 57.55%, and 33.30%, respectively. Moreover, the MFCS achieved a high lipid production of 1.54 g/L after five batches of SSW treatment. In the MFCS, the relative expression levels of Nr, Nrt, rbcL, fbp, and glgA in Chlorella sp. DT025 increased by 8.05, 2.01, 3.26, 2.05, and 2.83 folds, respectively. Furthermore, dissolved organic matter (DOM) in SSW was efficiently removed by the MFCS. The removal ratio of tyrosine-like, tryptophan-like, fulvic-like, soluble microbial by-product-like, and humic acid-like components reached 75.79%, 66.02%, 66.09%, 71.90%, and 69.50%, respectively. The fluorescence index (1.33), biological index (1.38), and humification index (0.33) of SSW treated by the MFCS all remained within normal ranges, indicating no secondary pollution to the water body. Finally, tyrosine-like compounds were found to play an important role in the wastewater treatment process by correlation analysis. These results indicated that the MFCS enables continuous and stably treatment of SSW, effectively removing DOM from the wastewater without generating secondary environmental risks.