Combined application of zinc oxide and iron nanoparticles enhanced Red Sails lettuce growth and antioxidants enzymes activities while reducing the chromium uptake by plants grown in a Cr-contaminated soil.

Soil contamination with chromium (Cr) is becoming a primary ecological and health concern, specifically in the Kasur and Sialkot regions of Pakistan. The main objective of the current study was to evaluate the impact of foliar application of zinc oxide nanoparticles (ZnO NPs) (0, 25, 50, 100 mg L-1) and Fe NPs (0, 5, 10, 20 mg L-1) in red sails lettuce plants grown in Cr-contaminated soil. Our results showed that both ZnO and Fe NPs improved plant growth, and photosynthetic attributes by minimizing oxidative stress in lettuce plants through the stimulation of antioxidant enzyme activities. At ZnO NPs (100 mgL-1), dry weights of shoots and roots and fresh weights of shoots and roots were improved by 53%, 58%, 34%, and 45%, respectively, as compared to the respective control plants. The Fe NPs treatment (20 mgL-1) increased the dry weight of shoots and the roots and fresh weights of shoots and roots by 53%, 76%, 42%, and 70%, respectively. Application of both NPs reduced the oxidative stress caused by Cr, as evident by the findings of the current study, i.e., at the ZnO NPs (100 mgL-1) and Fe NPs (20 mgL-1), the EL declined by 32% and 44%, respectively, in comparison with respective control plants. Moreover, Fe and ZnO NPs enhanced the Fe and Zn contents in red sails lettuce plants. Application of ZnO NPs at 100 mg L-1 and Fe NPs at 20 mg L-1, improved the Zn and Fe contents in plant leaves by 86%, and 68%, respectively, as compared to the control plants. This showed that the exogenous application of these NPs helped in Zn and Fe fortification in plants. At similar of concenteration ZnO NPs, CAT and APX activities were improved by 52% and 53%, respectively. Similarly, the POD contents were improved by 17% and 45% at 5 and 10 mg/L of Fe NPs. Furthermore, ZnO and Fe NPs limited the Cr uptake by plants, and the concentration of Cr in the leaves of lettuce was under the threshold limit. The exogenous application of ZnO NPs (100 mg L-1) and Fe NPs (20 mg L-1) reduced the Cr uptake in the leaves of red sails lettuce by 57% and 51%, respectively. In conclusion, ZnO and Fe NPs could be used for the improvement of plant growth and biomass as well as nutrient fortification in stressed environments. These findings not only underscore the efficacy of nanoparticle-assisted phytoremediation but also highlight its broader implications for sustainable agriculture and environmental health. However, future studies on other crops with molecular-level investigations are recommended for the validation of the results.

ZnO and Fe NPs improved the growth and photosynthesis of red sails lettuce plantsBoth NPs enhanced antioxidants enzymes activities in stressed plantsNPs mediated response reduced the oxidative stress and Cr uptake in red sails lettuceZnO and Fe NPs resulted in Zn and Fe fortification, respectively, in red sails lettuce.

Decolorization of Blue CL-BR dye by AOPs using bleach wastewater as source of H2O2.

This research was focused on the investigation of the efficacy of advanced oxidation processes (Fenton, ozonation and UV/H2O2) for decolorization of reactive azo dye (Blue CL-BR) using bleach wastewater as possible source of H202. All the experiments were performed on the laboratory scale set-up. The results showed that colour removal efficiencies by UV or bleach (H2O2) alone were not so efficient. Fenton process with bleach wastewater was found to be the most effective at process conditions such as pH of 3 and H2O2/Fe2+ ratio of 24:1, resulting in 64% colour removal. Almost complete colour removal, i.e., 99% and 95% were achieved by UV/H2O2 and UV/bleach wastewater in 30 and 60 min, respectively. Ozonation proved an efficient method for decolorization of Blue CL-BR dye at alkaline pH. It was possible to achieve 98% colour removal with 30 min of ozonation at pH 9. The colour removal of dye was found to follow first order kinetics.

Sludge granulation and efficiency of phase separator in UASB reactor treating combined industrial effluent.

Sludge granulation and the effect of gas-liquid-solid separator (GLSS) design on the efficiency of upflow anaerobic sludge blanket (UASB) and upflow anaerobic sludge filter (UASF) reactors, operating at HRTs ranging from 3 to 12 h were investigated. VSS/TS ratio gradually increased in both the reactors with increasing sludge age (from 0.5 to more than 0.7 for UASB reactor and 0.012 to 0.043 for UASF reactor). X-Ray diffraction analysis of the UASF sludge showed the presence of expanding clays revealing its additional absorption capability. Fuoraphyllite and albite precipitation related to excellular polymers of the microbial shell structure, showed the extended growth of microorganisms during sludge granulation. A gradual decrease (82%-69%) in COD removal with decreasing HRT was apparent in UASF reactor. In case of UASB reactor, this decrease was marginal because addition of GLSS device significantly improved (14%-20%) the overall efficiency of the UASB reactor. GLSS enhanced the efficiency of the UASB reactor by increasing the settleability of suspended particles and accelerating the coagulation of colloidal particles due to the velocity gradient.