Capers as a natural coagulant: a sustainable approach to wastewater treatment and sludge valorization via...

This research investigates the potential of capers as a natural coagulant for removing metal contaminants and turbidity from wastewater. The physicochemical properties of caper powder were analyzed using several advanced techniques: Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy combined with energy dispersive X-ray analysis, zeta potential measurements, and X-ray fluorescence spectrometry. A Box-Behnken experimental design was used to assess the impact of caper powder dosage, granulation, and initial pH on pollutant removal, with optimal conditions determined by response surface methodology. Caper powder demonstrated remarkable efficiency in pollutant removal, reaching maximum removal efficiencies of 90.05% for zinc, 99.90% for copper, and 98.12% for turbidity under optimized conditions, which exceed many previously studied natural coagulants, which typically achieve 60-80% metal removal efficiency. The proposed mechanism involves complexation, electrostatic interactions, surface adsorption, and van der Waals forces. In addition, durability tests indicated the sustained effectiveness of caper powder over successive applications. This study also explores using the metal-rich waste material produced during the treatment process to make glass. The successful synthesis of sodium borate glass has been achieved, and the study has examined how the generated sludge influences its thermal behavior, density, morphology, structure, optical properties, and dielectric characteristics. This research demonstrates that caper powder is an effective natural material for water treatment and highlights the importance of reusing waste materials from the treatment process, turning them into valuable products.