Analyzing the impact of PAC on water quality characteristics,
the properties of AS, and the microbial community characteristics
during the long-term operation, we observed that the mechanism
in which PAC enhances the effect of the AS system mainly included
the following several aspects:
1. PAC has a strong adsorption capacity for hydrophobic substances.
The removal of hydrophobic refractory organic
compounds is enhanced after the addition of PAC to the AS system.
Acidic substances will accumulate in the system during
microbial metabolism. The adsorption of PAC on acid can remove
this part of organic matter and eliminate the adverse effects of
metabolites on the system environment.
2. In the PAC–AS system, in addition to the adsorption effect, PAC
also plays a role in the reinforcement of biodegradation. The
addition of PAC does not change the structure of the microbial
community and the metabolic pathway of microbial degradation,
but can improve the biomass, the metabolic activity, and
the settleability performance of AS.
In summary, a synergistic effect is observed between the adsorption
of PAC and biodegradation. The interaction enables a more
effective treatment of comprehensive chemical wastewater in the
PAC–AS system compared with the AS system.