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A recent study published in Environmental Research explores a new approach to treating produced water (PW) from oil and gas operations. Researchers investigated using nickel-augmented biochar derived from eggshells and waste activated sludge (WAS) in granular cylindrical periodic discontinuous batch reactors (GC-PDBRs). This novel biochar is magnetized, enhancing its capability for carbon capture and treatment efficiency.

The study optimized the treatment process through a central composite design (CCD), achieving significant reductions in total phosphorus and chemical oxygen demand by 76-80% and 92-99%, respectively. The best results were observed at an 80% volumetric exchange ratio, with a 5-minute settling time and 3000 mg/L mixed liquor suspended solids (MLSS) concentration. Biokinetic modeling revealed that the Grau Second-order and Modified Stover-Kincannon models most accurately described pollutant removal in the reactors.

Microbiological analysis showed that higher volumetric exchange ratios promoted the growth of beneficial microorganisms, enhancing nitrogen removal and granule stability. The presence of bacteria such as Actinobacteriota spp., Bacteroidota spp., and Gammaproteobacteria was beneficial for granule formation.

This research highlights the effectiveness of combining intermittent aeration with magnetized biochar in treating PW. The findings suggest that this approach not only improves water quality but also contributes to carbon neutrality and sustainable development goals. By recycling waste materials like eggshells and WAS into valuable treatment agents, this method provides an eco-friendly and cost-effective solution for managing industrial wastewater.