Identification and Quantification of Polycyclic Aromatic Hydrocarbons in Polyhydroxyalkanoates Produced from Mixed Microbial Cultures and Municipal Organic Wastes at Pilot Scale

Abstract

Polyhydroxyalkanoates (PHAs) are well-known biodegradable plastics produced by various bacterial strains, whose major drawback is constituted by the high cost of their synthesis. Producing PHAs from mixed microbial cultures and employing organic wastes as a carbon source allows us to both reduce cost and valorize available renewable resources, such as food waste and sewage sludge. However, different types of pollutants, originally contained in organic matrices, could persist into the final product, thus compromising their safety. In this work, the exploitation of municipal wastes for PHA production is evaluated from the environmental and health safety aspect by determining the presence of polycyclic aromatic hydrocarbons (PAHs) in both commercial and waste-based PHA samples. Quantification of PAHs by gas chromatography-mass spectrometry on 24 PHA samples obtained in different conditions showed very low contamination levels, in the range of ppb to a few ppm. Moreover, the contaminant content seems to be dependent on the type of PHA stabilization and extraction, but independent from the type of feedstock. Commercial PHA derived from crops, selected for comparison, showed PAH content comparable to that detected in PHAs derived from organic fraction of municipal solid waste. Although there is no specific regulation on PAH maximum levels in PHAs, detected concentrations were consistently lower than threshold limit values set by regulation and guidelines for similar materials and/or applications. This suggests that the use of organic waste as substrate for PHA production is safe for both the human health and the environment.

From Organic Wastes and Hydrocarbons Pollutants to Polyhydroxyalkanoates: Bioconversion by Terrestrial and Marine Bacteria

“…These substances can migrate through the technology chain into the final product. Different PHA samples produced using the pilot-scale platform described in Moretto et al [49] were analyzed to quantify relevant contaminants, such as polycyclic aromatic hydrocarbons [175], polychlorinated biphenyls (PCB) [176] and heavy metals [177]. In these PHA samples derived from urban organic waste, the total contents of the three categories of substances complied with the present guidelines and regulations.…”

Creating Value from Acidogenic Biohydrogen Fermentation Effluents: An Innovative Approach for a Circular Bioeconomy That Is Acquired via a Microbial Biorefinery-Based Framework

“…Secondly, it has been shown that the fermented effluents need some pretreatments (filtration) to ensure that the inhibitory compounds, such as ammonia and excess growth factors, are removed before being used in PHA production [71]. A broad range of microbes (as pure cultures or mixed-microbial cultures) have been used for PHA production [72].…”

Combined Strategies to Prompt the Biological Reduction of Chlorinated Aliphatic Hydrocarbons: New Sustainable Options for Bioremediation Application

“…The results suggest that it can be used directly as a sustainable and effective carbon source with remarkable economic and environmental benefits ( Figure 3 ). Furthermore, the whole set of materials was also analyzed for the determination of relevant contaminants, such as heavy metals [ 46 ], polycyclic aromatic hydrocarbons (PAH) [ 47 ], and polychlorinated biphenyls (PCB) [ 48 ]. The studies demonstrated that all the MMC-PHAs met regulatory standards required for traditional plastic materials.…”