Efficient treatment of leather wastewater using a combination of CEPT and SBR with a novel flocculant

The suspended solids in leather wastewater serve as carriers for many pollutants, and traditional treatment methods have certain limitations. Hence, this research integrated chemically enhanced primary treatment (CEPT) with sequential batch reactor (SBR) technologies by using ecologically friendly vermiculite flocculants instead of conventional ones. In the CEPT phase, with solely addition of the vermiculite flocculant, the removal rates for turbidity, chemical oxygen demand (COD), suspended solids (SS), and total phosphorus (TP) reached 97.9 %, 62.1 %, 94.5 %, and 88.6 %, respectively. Upon adding both the vermiculite flocculant and a coagulant aid, the removal ratios improved to 98.9 %, 75.1 %, 97.6 %, and 88.6 %. Processing after SBR biochemical treatment further enhanced the removal ratios to 99.9 %, 96.7 %, 99.9 %, and 95.5 % for turbidity, COD, SS, and TP, respectively. Additionally, the high-throughput sequencing revealed a dynamic change in the dominant microbial phyla throughout the treatment process, which is associated with the effectiveness of treating COD, TP, and TN. In summary, the use of the vermiculite flocculant combined with the CEPT+SBR approach demonstrates significant ecological and environmental advantages in treating leather wastewater, providing valuable insights for future treatment strategies.