Removal of Cr and Organic Matter from Real Tannery Wastewater via Fenton-like Process Using Commercial Nano-Scale Zero-Valent Iron

Abstract

The tannery wastewater from the tanning stage (TWT) comprises organic and Cr pollutants, which can adversely affect aquatic life and have carcinogenic effects. In this study, we investigated the performance of a Fenton-like process using commercial Nano-scale zero-valent iron (nZVI) for the simultaneous removal of Cr and organic matter from real TWT. We used an experimental design to select the principal operating parameters. A Plackett–Burman design identified variables for Cr-total and COD removal, followed by a central composite design (CC-D) to determine optimal variable levels. Finally, the response surface methodology (RSM) was used to find the optimum concentration of individual variables influencing Cr-total removal. Additionally, the effect of the leather-related, co-existing substances that influenced the efficiency of the process and the possibility of recycling nZVI were explored. The inclusion of nZVI was significantly more effective at removing both Cr-total and COD (97.3% ± 5.7% and 73.9% ± 9.1%, respectively), whereas the traditional Fenton process achieved lower removal rates (55.6% ± 10.0% for Cr-total and 34.8% ± 10.9% for COD). The optimal conditions for the Fenton-like process were nZVI/H2O2 = 1.05 w/w, and pH = 2.93. We obtained the best results during the first 5 min of the reaction, which increased after 48 h of agitation and subsequent neutralization. According to the results of four consecutive cycles, nZVI exhibited high reusability (97%) without compromising its adsorption potency. XPS analysis confirmed Cr removal through the adsorption mechanism on the nZVI surface. Hence, a Fenton-like process based on nZVI can be used as a promising alternative for treating organic and Cr wastewater.

Unlocking the Potential: Algal Biomass Cultivation and Growth Kinetics Using Tanning Process Water

“…Specialized treatment technologies exist for tannery wastewater. However, they have drawbacks like ineffective metal removal at low concentrations and high chemical consumption. − Biotechnological approaches show promise, utilizing microorganisms for heavy metal remediation. − Microalgae, particularly Spirulina , are gaining attention for their pollutant abatement capabilities. − Spirulina’s integration into cleaner production and sustainability practices has gained traction, with studies highlighting its potential in wastewater treatment, carbon sequestration, and biofuel production. ,− Its rapid growth and high nutrient uptake efficiency make it effective for bioremediation. ,− Spirulina cultivation offers sustainable food and feed production, requiring minimal resources compared with conventional crops. Additionally, Spirulina -derived products contribute to a circular economy, promoting resource efficiency and waste valorization. − The literature reports the kinetic model of Spirulina based on the ability to remove metal ions, nutrients, and specific growth rates. − As per our knowledge, there is limited information on the growth model, which incorporates nutrient adsorption, light absorption, photosynthetic efficiency, respiration, and biosynthesis efficiency during synthetic or real wastewater cultivation.…”