Utilizing incinerated sewage sludge ash for antibacterial alkali-activated materials

Doping binders with heavy metal ions is an effective strategy for combating microbial-induced corrosion in sewerage systems. In this study, we utilized incinerated sewage sludge ash (ISSA), which contains trace amounts of heavy metals, to provide a biocidal effect within an alkali-activated material (AAM) prepared with GGBS and waste glass powder. The resulting mixture was then exposed to a real sewage environment for 24 months. The results show significant reductions in the total abundance of corrosive bacteria, as indicated by 16S rRNA gene and dsrB concentrations, along with decreased diversity in the microbial communities in the biofilm adhered to the ISSA-incorporated binder. Notably, the number of sulfur-reducing bacteria (SRB) and sulfur-oxidizing bacteria (SOB), such as Starkeya novella and Halothiobacillus neapolitanus (known neutrophilic SOB), were also reduced in this binder. This observation confirmed the bacteriostatic effect of ISSA, which was further supported by the release of Zn/Cu ions from this binder measured by leaching tests. Furthermore, the ISSA-incorporated binder exhibited approximately six times less corrosion depth than the control, due to its lower proportion of capillary pores and Ca content in AAM gels, in conjunction with ISSA's bacteriostatic effect.