Efficacy of coconut coir composite filters for oil and grease removal: A qualitative ATR-FTIR pilot study

Wastewater from restaurants and workshops containing high concentrations of oil and grease (O&G) poses a significant environmental challenge, necessitating effective and accessible treatment methods. This qualitative, proof-of-concept pilot study investigated the efficacy of low-cost, locally sourced filter materials—coconut coir, recycled beach sand, activated charcoal, and inactivated charcoal—in various combinations for removing O&G. Filtration prototypes were developed and tested on real wastewater samples. Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy was employed to characterise the chemical changes pre- and post-filtration. Results indicated that a combination of coconut coir, recycled beach sand, and activated charcoal (M3) was identified as the most effective for oil removal from restaurant wastewater, evidenced by the disappearance of the ester carbonyl peak (1744 cm⁻¹) and other oil-related aliphatic C–H stretches. For grease removal from workshop wastewater, a combination of coconut coir, recycled beach sand, and inactivated charcoal (G4) demonstrated superior performance, marked by the absence of key aliphatic C–H stretches (2922 cm⁻¹, 2853 cm⁻¹) characteristic of grease. In both optimal filter combinations, an increased intensity of hydroxyl (O–H) group signals in the filtrate was observed, correlating with effective O&G removal. This research highlights the potential of these sustainable filter systems for decentralized wastewater treatment, contributing to responsible resource utilisation (SDG 12). The findings offer a practical framework for designing pollutant-specific, low-cost filtration systems for small-scale enterprises.