Municipal solid waste sanitary and open landfills: Contrasting sources of microplastics and its fate in their respective treatment systems

Recently, research studies in identifying microplastics (MPs) from various environment has become a notable work, in the view of MPs as emerging pollutants as well as due to many undiscovered high-level impacts to both the environment and living beings. Out of many other sources, municipal solid waste land disposal methods, both controlled landfills and open dumping are observed to be one of the major sources of MPs origination as the predominant quantity of plastic wastes generated is being discarded in those methods. In this study, quantification, and characterization of MPs from the leachate generated from two different solid waste disposal methods and in their respective individual treatment systems were identified. From the studies, 20 different polymer types were spotted with the concentrations in the fresh leachate as 8.80 MPs/L and 9.93 MPs/L in the controlled landfill and open dumping, respectively. The fibers, films, and fragments are found to be the predominant polymer shapes in both the discarding process. Polypropylene and Polyethylene are the main prevailing polymer type in the controlled landfill, whereas polyethylene and polystyrene are in open dumping leachate samples. In addition, the analysis of the treatment system reveals that the ongoing units can remove the MPs from the leachate to some extent. For example, it removed ∼57.1% of MPs from landfill leachate using biological treatment combined with disinfection. Whereas ∼75.2% from the aerated lagoon and membrane treatment for leachate from the open dumping. More fibers with varying polymer types were identified from the effluent of membrane treatment, which is due to the membrane used. Finally, 37 MPs/g from dewatered sludge and ∼500 MPs/L of return sludge indicate the possibility of MPs that can reenter the biological system allowing an increase in the MPs abundance in the biological unit.