RESUMO
The effectiveness of advanced technologies on eliminating antibiotic resistant bacteria (ARB) and resistance genes (ARGs) from wastewaters have been recently investigated. Solar photo-Fenton has been proven effective in combating ARB and ARGs from Municipal Wastewater Treatment Plant effluent (MWWTPE). However, most of these studies have relied solely on cultivable methods to assess ARB removal. This is the first study to investigate the effect of solar photo-Fenton upon ARB and ARGs in MWWTPE by high throughput metagenomic analysis (16S rDNA sequencing and Whole Genome Sequencing). Treatment efficiency upon priority pathogens and resistome profile were also investigated. Solar photo-Fenton (30â¯mgâ¯L-1 of Fe2+ intermittent additions and 50â¯mgâ¯L-1 of H2O2) reached 76-86% removal of main phyla present in MWWTPE. An increase in Proteobacteria abundance was observed after solar photo-Fenton and controls in which H2O2 was present as an oxidant (Fenton, H2O2 only, solar/H2O2). Hence, tolerance mechanisms presented by this group should be further assessed. Solar photo-Fenton achieved complete removal of high priority Staphylococcus and Enterococcus, as well as Klebsiella pneumoniae and Pseudomonas aeruginosa. Substantial reduction of intrinsically multi-drug resistant bacteria was detected. Solar photo-Fenton removed nearly 60% of ARGs associated with sulfonamides, macrolides, and tetracyclines, and complete removal of ARGs related to ß-lactams and fluoroquinolones. These results indicate the potential of using solar-enhanced photo-Fenton to limit the spread of antimicrobial resistance, especially in developing tropical countries.
Assuntos
Peróxido de Hidrogênio , Microbiota , Antagonistas de Receptores de Angiotensina , Inibidores da Enzima Conversora de Angiotensina , Antibacterianos/farmacologia , Resistência Microbiana a Medicamentos/genética , Concentração de Íons de Hidrogênio , Águas ResiduáriasRESUMO
This review aims to gather main achievements and limitations associated to the application of solar photocatalytic processes with regard to the removal of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) from municipal wastewater treatment plant effluent (MWWTPE). Solar photocatalytic processes were chosen considering the context of developing tropical countries. Among these processes, solar photo-Fenton has been proved effective for the elimination of ARB from MWWTPE at neutral pH in bench and pilot scale and also under continuous flow. Yet, ARG removal varies as according to the gene. Irradiation intensity and matrix composition play a key role on treatment efficiency for this purpose. The use of sulfate radical in modified solar photo-Fenton is still incipient for ARB and ARG removal. Also, investigations related to ARB resistance profile and horizontal gene transfer rates after solar photo-Fenton treatment must be further analyzed. Regarding solar heterogeneous photocatalysis, TiO2 and TiO2-composites applied in suspension are the most commonly investigated for the removal of ARB and ARGs. Irradiation intensity, temperature and catalyst dosage affect treatment efficiency. However, most studies were performed in synthetic solutions using reduced sample volumes. Extended exposition times and addition of H2O2 to the system (solar/TiO2/H2O2) are required to prevent bacteria regrowth and ensure ARG abatement. In addition, enhancement of TiO2 with graphene or (semi)metals improved ARB elimination. Differences concerning irradiation intensity, matrix composition, catalyst dosage, and model ARB and ARGs used in studies analyzed in this review hinder the comparison of photocatalysts synthesized by various research groups. Finally, future research should aim at evaluating the efficiency of solar photocatalytic processes in real matrices originated from sewage treatment systems applied in developing countries; determining indicators of antimicrobial resistance in MWWTPE; and investigating ARB mutation rate as well as the removal of cell-free ARGs present in suspension in MWWTPE.