Oxidative Photodegradation of Pyrene and Fluoranthene by Fe-Based and Zn-Based Fenton Reagents

Increased industrialization has introduced a lot of hazardous materials into ecosystems. Polycyclic aromatic hydrocarbons (PAHs) are among the most toxic and persistent organic pollutants emanating from petrochemical industrial areas. Remediation of PAHs-contaminated soil has been a particularly big challenge. Photochemical oxidation–reduction processes have gained attention because of their high efficiency and robustness for PAH removal from contaminated soils. In this study, the efficacy of Fe-based and Zn-based Fenton reagents for remediating soil contaminated with pyrene (Pyr) and fluoranthene (Flr) is evaluated. UV treatment (2-h exposure) at 254 nm resulted in 21.6 and 28.5% degradations of Pyr and Flr, respectively. The Zn-based Fenton reagent performed better than the Fe-based reagent by degrading 99.9% of Pyr. The Fe-based Fenton reagent (under UV light) resulted in 97.1–99.7% and 95.1–98.9% Pyr and Flr degradations, respectively, in 0.5–2 h. Notably, the temperature increase during UV irradiation facilitated the enhanced degradation of Pyr and Flr, as observed from negative correlations (r = (−)0.902–0.961 and p = 0.039–0.098) between the temperature and PAH concentrations. The newly tested Zn-based Fenton reagent was equally effective as the Fe-based Fenton reagent in degrading Pyr and Flr in soil. Hence, it can be used as a new alternative reagent to remediate PAH-polluted soils

Comparative evaluation of different carrier-based multi-strain bacterial formulations to mitigate the salt stress in wheat

The application of liquid bacterial consortia to soil under natural conditions may fail due to various environmental constraints. In this study, the suitability and efficiency of compost, biogas slurry, crushed corn cob, and zeolite as carriers to support the survival of plant growth-promoting rhizobacteria (PGPR) and improve the performance of multi-strain bacterial consortia to mitigate the effects of salinity stress on wheat under pot conditions were evaluated. The survival of strains of Pseudomonas putida, Serratia ficaria, and Pseudomonas fluorescens labelled with gusA was evaluated for up to 90 days. Seeds coated with different carrier-based formulations of multi-strain consortia were sown in pots at three different salinity levels (1.53, 10, and 15 dS m−1). Results showed that salinity stress significantly reduced wheat growth, yield, gas exchange, and ionic and biochemical parameter values, but the 1-aminocyclopropane-1-carboxylate (ACC) deaminase-containing multi-strain consortium used mitigated the inhibitory effects of salinity on plant growth and yield parameters. However, carrier-based inoculation further improved the efficacy of multi-strain consortium inoculation and significantly (P < 0.05) increased the growth, yield, and physiological parameters value of wheat at all salinity levels. On the basis of the observed trends in survival and the outcomes of the pot trials, the inoculation of multi-strain consortia in compost and biogas slurry carriers resulted in more successful wheat growth under salinity stress compared to that in the rest of the treatments tested