The Use of Apple Pomace in Removing Heavy Metals from Water and Sewage

The release of toxic substances in the environment continues to be a problem despite increased efforts to reduce this. The commonly used methods of removing heavy metal ions from water and wastewater have many disadvantages, including a low efficiency and high cost. Heavy metals and dyes are the most problematic pollutants due to their toxicity and stability in the environment. For this reason, in recent years, remediation technologies such as the sorption on materials of natural origin, have been developed. However, these technologies are still rarely used at an industrial level. Recently, scientists have attempted to apply the promising properties of nanotechnology to this field, conducting research on the possibility of using biosorbents in the nanoscale in wastewater treatment. Much attention is currently paid to the preparation of cost-effective, efficient, and environmentally friendly adsorbents, as well as their chemical modifications, to increase the metal removal efficiency from water and wastewater. The waste materials from the agricultural industry are cheap adsorbents that require little treatment. This kind of biosorbent is not able to remove specific metal ions, but by chemical modifications its adsorption capacity and specificity can be increased. The data from the literature are reported for various types of bio-adsorbent materials, e.g., fruit or vegetable pomace and nut shells. One of the most promising raw materials is apple pomace. It was estimated that, in recent years, global apple production reached approximately 75 million tons, equating to 5–7 million tons of apple pomace per year. The management of such waste is a serious challenge. The rational management of exhausting resources requires looking at waste in terms of its use as a reusable raw material. The aim of this paper was to collect information and compare the parameters (pH, dose of adsorbent, and kinetics, etc.) of heavy metal sorption on apple pomace in order to demonstrate the potential of this adsorbent application.