The land application of biowastes, including biosolids and compost, is a significant source of microplastics (MP) to terrestrial environments, yet global data on contamination levels are limited. We determined the concentrations of microplastics in biowastes destined for land application in Aotearoa New Zealand. Microplastics were extracted from biosolids, vermicompost, bulk compost, and bagged compost via wet peroxide oxidation digestion and density separations using a modified sediment-microplastics isolation (SMI) unit. The polymer type of each suspected microplastic was confirmed by micro-Fourier-transform infrared (µ-FTIR) spectroscopy, with a minimum detection size of 18 µm. Microplastic concentrations > 0.48 MP/g were identified in every sample, with the highest average abundances in biosolids (2.71 MP/g) and vermicompost (2.69 MP/g), followed by bulk compost (1.94 MP/g) and bagged compost (1.1 MP/g). Fragments (62.7%) were the most frequently detected microplastic morphotype, followed by films (24.7%), fibers (12.2%), and beads (0.4%). Common polymers detected were polypropylene (37.9%), polyethylene (28.6%), and polymethyl methacrylate (PMMA) (11.7%). Identifiable morphotypes included polyurethane foam sponge fragments, polyethylene terephthalate glitter, and PMMA multicolored films. Biodegradable polymers were identified, and their presence in mature compost suggests that compost facilities were unable to provide optimal conditions to support the complete biodegradation of polymers. Annual microplastic contamination in soils from the application of biowaste amendments is projected to be between 1.10 × 10⁷ to 2.71 × 10⁷ MP/ha. The product origin of most microplastics could not be identified, highlighting the ubiquity of microplastics and the urgent need to reduce plastic at the source to reduce instances of pollution in valuable biowastes.

Rapid and cost-effective tests for the evaluation of industrial and municipal effluents are urgently needed for environmental monitoring. In this context, peroxidase (PER) activity has been proposed as an early-warning biosensor for assessing the water quality of various wastewater discharges and leachates. The peroxidase-toxicity (Perotox) assay includes 0.1 µg/mL PER, albumin, DNA (for the DNA protection index), 0.001% monounsaturated Tween-80, and the substrates luminol and H₂O₂. The results revealed that an initial burst of luminescence was followed by a steady decrease in luminescence within the first minute, accompanied by periodic (cyclic) changes in the intermediate compound III (CIII) of PER. When urban effluents were added, PER activity was inhibited, with a concomitant increase in lipid peroxidation, indicating oxidative damage. The reduction in PER activity was also associated with the collapse in the periodic formation of CIII, alongside a steady increase in CIII over time. The addition of DNA to the reaction mixture helped mitigate the inhibition of PER by certain effluents, enabling the calculation of a DNA protection index. The levels of polystyrene (PS) in the organic fraction of the effluents were higher in the primary aeration lagoon (36 µg/L) compared to secondary lagoons and membrane filtration (< 16 µg/L). Data analysis revealed that PER activity was negatively correlated with population size (r = -0.34) and the levels of PS materials (r = -0.56). In conclusion, the Perotox assay is proposed as a rapid screening tool for identifying potentially toxic environmental complex mixtures, such as municipal effluents.

Rapid population growth, industrialization, and urbanization have contributed to the generation of large volumes of waste, causing disposal challenges. This present study examined the impact of dumping sites on air, soil, and water pollution in five Southern African countries. The five selected Southern African countries have unique situations concerning landfill pollution caused by a mix of environmental, social and health issues. These countries encounter significant water, air and soil pollution due to inadequate waste management techniques. The study adopted a literature survey approach, reviewing published papers and reports on chemical pollutants. A total of 151 downloaded papers, obtained through systematic keyword searches across multiple databases, were analyzed. The chemical pollutants investigated include heavy metals, polybrominated diphenyl ethers (PBDEs), per- and polyfluoroalkyl substances (PFAS), polycyclic aromatic hydrocarbon (PAH) substances in water resources, and polychlorinated biphenyls (PCBs). The reported levels of heavy metals (lead), PBDE, PFAS, PAHs, and PCBs ranged from 23,000 to 14,600,000 µg/kg, 127-3,702 pg·L^-1, 310-1,089 ng·L^-1, 45-95 mg/kg, and 0.2-5.3 mg/kg, respectively. The results indicate that landfills, as well as open dumping sites, are major threats to surface and underground water resources. The study suggests that policies to regulate and monitor landfills should be implemented to mitigate the environmental impact of landfills.

Microplastics (MPs) increase global awareness due to their ubiquity, high concentration levels, and devastating effects on the aquatic environment. Wastewater treatment plants (WWTPs) are recognized as a significant source of microplastics in aquatic and terrestrial environments, particularly for plastics used in personal care products and textile fibers from the clothing industry. The focus of the present study was the determination of MP in wastewater and sewage sludge samples of WWTP of Ioannina city, according to their shape, size, concentration, and polymer type. A wet peroxide oxidation (WPO) method using 30% H₂O₂ and 0.05 M ferrous (II) solution was applied to the water effluent, while an enzymatic digestion method combined with WPO was employed to eliminate the organic matter and extract MPs from sludge samples. Micro-Raman spectroscopy coupled with appropriate software was applied to detect and quantify the microplastic particles. The outcomes from this study showed that the most representative shape of MP in effluent wastewater and sludge was fragments (66.7% and 75%, respectively), followed by fibers, spheres, and films. Polyamide (PA), p-acrylic acid (PAA), and p-acrylamide-co-p-acrylic acid (PAM-co-PAA) were the most abundant polymers (100% frequency of detection), followed by p-vinyl chloride (PVC), p-butyl methacrylate (PBMA), p-ethylene (PE), p-styrene (PS), p-propylene (PP), p-vinyl alcohol (PVA), and p-vinyl butyral (PVB) (20%-80% frequency of detection). The mean concentration of MPs in five sampling campaigns was 5.8 ± 0.6 particles/L in secondary WWTP effluents and 33.3 ± 8 particles/g in sludge. This study focused on monitoring campaign, in order to better understand the occurrence, impact, and risks associated with MPs on WWTPs.

Pharmaceuticals in water bodies are a significant threat to aquatic life and human health, often persisting due to incomplete degradation in conventional wastewater treatment plants (WWTPs). Heterogeneous photocatalysis is a promising method for efficiently treating wastewater (WW). TiO₂ P-25, a well-known photocatalyst, has been widely used to remove persistent organic pollutants (POPs) from aquatic media, primarily on a laboratory scale. In this study, the photocatalytic removal of Paroxetine (PXT), an antidepressant drug, is investigated at the lab scale and pilot scale using a compound parabolic collector (CPC) reactor (85 L) working in batch recirculating mode and secondary treated hospital wastewater (HWW) as the substrate using different catalyst concentrations (200, 300, and 500 mg/L). The lab experiments achieved the fastest PXT degradation with 500 mg/L, while the pilot tests found 200 mg/L to be optimal. Thirteen transformation products (TPs) were identified using liquid chromatography-high-resolution mass spectrometry (LC-HR-MS-Orbitrap), and their ecotoxicity was assessed with ECOSAR software, indicating they were less toxic than PXT. The T.E.S.T. software showed most TPs were not mutagenic but displayed developmental toxicity. Toxicity assessments from the pilot scale using the Microtox bioassay demonstrated that toxicity was eliminated by the end of the photocatalytic treatment. In conclusion, the study provides an integrative approach to photocatalytic degradation of PXT, integrating lab-scale and pilot-scale experiments, pure water and real WW matrices, environmentally relevant concentrations, TPs’ identification along with toxicity assessment of both in-silico and in-vitro, which is not followed in most previous studies dealing with the photocatalytic degradation of pollutants.

Contaminants of emerging concern (CEC) continue to plague wastewater treatment facilities in their battle to recover water resources and circumvent environmental contamination. Of particular challenge are legacy pollutants - pollutants that are no longer in use but continue to enter wastewater treatment facilities due to their historic uses. Among these pollutants are polybrominated diphenyl ethers (PBDEs), a flame retardant used in many consumer products. PBDEs have been detected in waterways worldwide and were documented to impact juvenile Chinook salmon in the waterways of Puget Sound in Washington State, USA. This has both economic impacts in the region where salmon is a major commercial export, and societal implications where native tribes have deep cultural heritage connections with salmon. PBDEs are primarily removed from wastewater by sorption to wastewater sludge. However, this process can result in long-term impacts when PBDEs re-emerge in landfill leachates after sorptive material disposal. In this perspective, we explore what is currently understood about engineered solutions for the removal of PBDEs from wastewater, and we present an approach for the permanent destruction of PBDEs, which combines anaerobic bioprocesses for initial debromination, followed by aerobic treatments for the final degradation of the PBDEs. Through this perspective, we hope to inspire global research efforts to develop sustainable biological treatment solutions for CEC destruction during wastewater treatment.

Electrochemical wastewater treatment technologies, such as electrodeposition, electroflocculation, and electrocatalytic electrosorption, are effective and environmentally friendly but have challenges in large-scale applications due to low efficiency, poor stability, and high electrode material costs. Density functional theory (DFT) and artificial intelligence (AI) offer strong support for the design of new electrode materials. These technologies enable efficient material screening and deeply investigate electrochemical mechanisms. However, current models struggle to simulate complex reactions, causing a gap between theory and practice. While new materials exhibit good performance in the lab, their long-term stability and high cost limit industrial use. Future efforts should focus on improving electrode material stability and efficiency, using DFT for more accurate predictions and AI for faster material discovery and optimization. Additionally, integrating educational innovation research in electrochemical techniques into these efforts will help train skilled professional students and encourage them to develop cutting-edge thinking. Reducing material costs and enhancing reaction efficiency are also key to achieving industrial-scale applications.