Conversion of Food Waste into Hydrochar Using Hydrothermal Carbonisation (HTC) and its application in co-combustion with coal and contaminant remediation

Abstract

Food waste is an organic waste which is generated from different sources like household, cafeteria and restaurants. About 1.3 billion tonnes of food waste is wasted every year and it is considered to be the largest portion of municipal solid waste dumped in landfill. There are different environmental issues related to food waste dumping in landfill such as air pollution, bad odour, methane generation and leaching. Recently, food waste has been accepted as a great source for energy generation. There have been different thermal technologies for the treatment of food waste from which hydrothermal carbonization (HTC) is the suitable treatment method. The food waste was treated under HTC process at three different temperatures (200, 250 and 300 °C) with retention time of 1 h. The potential of food waste for energy generation was studied in detail using co-combustion and Co-HTC process. Moreover, the effect of food waste as an adsorbent for the removal of pharmaceutical was also studied. Different characterization techniques used in this study were elementary and proximately analysis, High heating value (HHV), scanning electron microscopy (SEM), X-Ray diffraction (XRD), Brunauer Emmett Teller (BET), Fourier-transform infrared spectroscopy (FTIR), Thermal gravimetric analysis (TGA), and pelletization and tensile strength. The carbon content of hydrochar was significantly increased to 73% as compared to raw food waste. During co-combustion the percentage of hydrochar in a blend is responsible to improve the ignition and devolatization behaviour of coal. The HTC process also help to improve the HHV of the food waste as compared to raw feedstock. The Co-HTC process is very favourable to increase the mass yield, reduce ash content and increase the combustion behaviour of the blend. The addition of binder in coal and food waste blend can increase the strength of food waste pellets, which can be used for different energy generation processes. Lastly, chemical activation of food waste hydrochar can increase the surface area and can add new functional groups on the surface of hydrochar. This surface modification can increase the adsorption capacity of food waste hydrochar to remove carbamazepine and naproxen from aqueous solution.