The treatment of the organic fraction of municipal solid waste (OFMSW) as a possible source of micro- and nano-plastics and bioplastics in agroecosystems: a review

Plastics fragmentation into smaller debris, namely, micro- and nano-plastics (MPs and NPs), is a matter of global concern because of their wide distribution in terrestrial and marine environments. The latest research has focused mainly on aquatic ecosystems, and fragmentation of bioplastics into micro- and nano-particles (MBPs and NBPs) is not considered. The distribution, concentration, fate and major source of MPs, NPS, MBPs and NBPs in agroecosystems still need to be understood. The use of composts and sewage sludge from the organic fraction of municipal solid waste (OFMSW) treatment plants as soil amendments is likely to represent a major input of these debris. The present review provides insights into the current evidence of pollution from micro- and nano-particles of both fossil- and bio-origin in the OFMSW treatment, and aims at evaluating if the recycling of organic waste and its application as a soil fertilizer outweigh the risk of pollution in terrestrial environments. Huge unpredictability exists due to the limited numbers of data on their quantification in each source of possible solution. Indeed, the major hurdles arise from the difficult to quantify the micro-, especially the nano-, particles and subsequently assess the concentrations in the environments, as well as bioaccumulation risks, and toxic effects on organisms. Graphical Abstract

Soil Colour and Plant-Wax Markers: Application in Forensic Investigations under Urban Subtropical Environments

Most cases involving soil in criminal investigations in Brazil have focused on the chemical and mineralogical analyses of soil fractions without including the organic matter. The organic fraction contains plant-wax markers which may be useful to “fingerprint” forensic soils due to their chemical diversity, relative longevity and resistant nature. The aim of this study was to test the long- (kilometre), medium- (metre) and short- (centimetre) scale variability of plant-wax biomarkers in a forensic context in anthropised urban soils and soils developed under subtropical conditions. Two areas from the Curitiba municipality and two areas from the Colombo municipality, Paraná State, South Brazil, were selected. Soil colour analysis was carried out to obtain reflectance data over the 360–740 nm wavelength range. Furthermore, plant-wax marker compounds (n-alkanes and fatty-alcohols) were assessed by extraction and separation into different classes and an analysis of the compounds by gas chromatography (GC/MS). The compositions of the wax-marker profiles were different in samples collected side-by-side, showing sensitivity to local variations under subtropical conditions and in areas under intense human urban disturbance. Under these conditions, biomarkers may be used in real crime scenes, even on a micrometric scale of variation.

Anaerobic Digestion of the Organic Fraction of Municipal Solid Waste in Plug-Flow Reactors: Focus on Bacterial Community Metabolic Pathways

The aim of this study is to investigate the performance of a pilot-scale plug-flow reactor (PFR) as a biorefinery system to recover chemicals (i.e., volatile fatty acids (VFAs)), and biogas during the dry thermophilic anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW). The effects of the hydraulic retention time (HRT) on both outputs were studied, reducing the parameter from 22 to 16 days. In addition, VFA variation along the PFR was also evaluated to identify a section for a further valorization of VFA-rich digestate stream. A particular focus was dedicated for characterizing the community responsible for the production of VFAs during hydrolysis and acidogenesis. The VFA concentration reached 4421.8 mg/L in a section located before the end of the PFR when the HRT was set to 16 days. Meanwhile, biogas production achieved 145 NLbiogas/d, increasing 2.7 times when compared to the lowest HRT tested. Defluviitoga sp. was the most abundant bacterial genus, contributing to 72.7% of the overall bacterial population. The genus is responsible for the hydrolysis of complex polysaccharides at the inlet and outlet sections since a bimodal distribution of the genus was found. The central zone of the reactor was distinctly characterized by protein degradation, following the same trend of propionate production.

The Current Status and Future Potential of Biogas Production from Canada’s Organic Fraction Municipal Solid Waste

With the implementation of new policies supporting renewable natural gas production from organic wastes, Canada began replacing traditional disposal methods with highly integrated biogas production strategies. Herein, data from published papers, Canadian Biogas Association, Canada’s national statistical agency, and energy companies’ websites were gathered to gain insight into the current status of anaerobic digestion plants in recovering energy and resource from organic wastes. The availability of materials prepared for recycling by companies and local waste management organizations and existing infrastructures for municipal solid waste management were examined. Governmental incentives and discouragements in Canada and world anaerobic digestion leaders regarding organic fraction municipal solid waste management were comprehensively reviewed to identify the opportunities for developing large-scale anaerobic digestion in Canada. A range of anaerobic digestion facilities, including water resource recovery facilities, standalone digesters, and on-farm digesters throughout Ontario, were compared in terms of digestion type, digester volume, feedstock (s), and electricity capacity to better understand the current role of biogas plants in this province. Finally, technology perspectives, solutions, and roadmaps were discussed to shape the future in terms of organic fraction municipal solid waste management. The findings suggested that the biogas industry growth in Canada relies on provincial energy and waste management policies, advanced technologies for diverting organic waste from landfills, improving biogas yield using existing pretreatment methods, and educating farmers regarding digester operations.

Biorefinery Based on Waste Biomass

In a broad sense, all materials with a biological origin can be called biomass, which includes those materials that have been obtained from the direct conversion of solar energy, such as plants and crops, their residues, the materials obtained from their industrial transformation as well as subproducts and residues and the organic fraction of the municipal solid wastes [...]