Performance of microaeration hydrolytic acidification process in the pretreatment of 2-butenal manufacture wastewater.

The performance of the microaeration hydrolytic acidification (MAHA) process and microbial community were investigated under different organic loading rates (OLRs) for the pretreatment of 2-butenal manufacture wastewater (2-BMW). Results indicated that OLRs had different impact on the performance of MAHA process. More than 23.7 ± 2.3% of the chemical oxygen demand (COD) removal and the highest acidification degree (20.9 ± 3.1%) were obtained when OLRs were less than 4.0 ± 0.1 kgCOD/m d. However, further increasing OLRs to 6.1 ± 0.1 kgCOD/m d subsequently led to the significant reductions of COD removal and acidification degree. In addition, it could be preliminarily inferred that 2H-pyran-2-one tetrahydro-4-(2-methyl-1-propen-3-yl), 5-formyl-6-methyl-4,5-dihydropyran and ethyl sorbate were the main refractory and toxic organics for microorganisms in the wastewater. The soluble microbial product (SMP) and extracellular polymeric substance (EPS) contents (protein, polysaccharide, nucleic acid) had obvious changes under different OLRs. With parallel factor (PARAFAC) model, four fluorescent components were identified. The F of protein-like substances in SMP significantly decreased with increasing OLRs to 6.1 ± 0.1 kgCOD/m d, which might attribute to fluorescence quenching. Illumina MiSeq sequencing revealed that Pseudomonas, Longilinea, T78, Clostridium, WCHB1-05, Acinetobacter, SHD-231 and Oscillospira were dominant genera at different OLRs.