This review examines the physicochemical mechanisms governing pharmaceutical persistence, the formation of transformation products (TPs), and the effectiveness and limitations of conventional and advanced treatment technologies for water reuse, focusing on carbamazepine, diclofenac, iodinated contrast media, metformin, and selected antibiotics, which persist through wastewater treatment. The review follows one chain of reasoning: persistence drivers determine which TPs form, which compartments and exposure pathways are reached, and which treatment barriers can act. Conventional activated sludge often provides incomplete removal, whereas integrated trains combining biological processes, adsorption, ozonation, UV/H2O2, membranes, and other advanced oxidation technologies can improve control, although energy demand, membrane fouling, residuals, and TP formation remain constraints. Pilot- and full-scale studies report average abatement of about 80% or more with ozonation or activated carbon, but behavior differs among compounds, and evidence for complete multi-barrier trains is limited. Unlike reviews addressing occurrence, individual technologies, or TPs separately, this review links the drivers of persistence to the selection and sequencing of treatment barriers, and extends the assessment to groundwater migration, soil–plant and food-chain transfer, and antimicrobial-resistance pathways within a common water-reuse framework. This supports adaptive treatment design targeting parent compounds, TPs, and cross-compartment risks. HRMS, non-target screening, and AI/ML-assisted optimization support adaptive monitoring and control. However, identifying a TP does not demonstrate risk, so effect-based methods are needed, and AI/ML applications are mainly predictive and validated on small datasets. Safe and sustainable water reuse likely requires multi-barrier treatment, source control, continuous monitoring, TP assessment, and integrated risk management.
Portland cement production is a major contributor to global CO2 emissions, while large volumes of mine tailings remain stockpiled as long-term environmental liabilities. This study investigates valorisation of copper mine tailings (CMT) as a supplementary cementitious material within a resource recovery framework. Intrinsic reactivity was quantified using the R3 test and linked to hydration behaviour through isothermal calorimetry, X-ray diffraction, FTIR and scanning electron microscopy, alongside compressive strength evaluation. The CMT exhibited an R3 heat release of 156 J/g, confirming its intrinsic pozzolanic reactivity. Isothermal calorimetry showed that a 10% clinker replacement reduced cumulative heat release by only 2.67%, indicating partial compensation of clinker dilution through filler and pozzolanic effects. A cradle-to-gate life cycle assessment employing system expansion quantified environmental benefits from clinker displacement and avoided tailings storage burdens. Climate change impacts decreased from 0.935 to 0.583 kg CO2-eq with increasing CMT replacement, despite an 1800 km transport distance. Impact reductions were predominantly driven by clinker substitution, with additional gains from mitigating waste accumulation. These findings demonstrate a technically viable pathway for integrating CMT into lower-carbon blended cement.
Airborne microplastics (MPs) have emerged as environmental pollutants that can co-occur with hazardous contaminants; however, evidence of heavy-metal associations with atmospheric MPs remains limited. This study investigated the abundance, characteristics, metal loadings, and health risks of airborne MPs in Metro Manila, Philippines. Air samples were collected from classroom, laboratory, dining room, office, living room, and store environments, followed by polymer identification via μFTIR and metal quantification using ICP–MS. MP concentrations ranged from 0.074 to 0.595 MP/m3 indoors (mean: 0.297 ± 0.20 MP/m3) and from 0.057 to 0.262 MP/m3 outdoors (mean: 0.173 ± 0.07 MP/m3), with no statistically significant difference. Fibers dominated the MP assemblage (52.38%), followed by fragments and films. PP, PET, and PE were the most prevalent polymers. Heavy metal concentrations ranged from 0.35 to 27521.66 mg/kg indoors and from 0.11 to 30556 mg/kg outdoors, with notable contributions from Zn, Cu, Ba, Pb, and Ag. These showed site-specific variations associated with room function and anthropogenic activity, with elevated Cu and Zn in high-activity indoor spaces. Pollution indices (PLI, MPI) indicated moderate pollution levels, while the ecological risk index indicated moderate ecological risk. Spearman analysis showed strong positive correlations between MPI-HM and As, Fe, and Zn (r = 0.70, p < 0.05), while PCA and HCA differentiated sampling sites by metal- and MP-related profiles. Inhalation risk assessment indicated low-to-moderate non-carcinogenic risk; however, the co-occurrence of toxic metals with respirable MPs highlights the occurrence of hazardous substances within the recovered airborne MP fraction. This study provides one of the first assessments of heavy metals associated with airborne MPs in indoor–outdoor urban environments.
Per- and polyfluoroalkyl substances (PFAS) are emerging contaminants known for their persistence and potential health risks. Stormwater runoff serves as a major pathway for contaminant transport into aquatic ecosystems, yet data on the occurrence, distribution, and transport of PFAS via stormwater runoff remain limited. This study revealed PFAS in stormwater runoff from high- and low-traffic areas in Trenton and Glassboro, NJ, during precipitation events from February to August 2024, and explored the removal of PFAS by drinking water treatment residuals (WTRs). Results showed that perfluorooctanesulfonic acid (PFOS), perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), and perfluoropentanoic acid (PFPeA) were the most prevalent PFAS compounds in the stormwater runoff in both locations. PFAS concentrations were significantly higher in high-traffic than low-traffic areas in both cities, with Trenton showing higher levels than Glassboro, reaching 444 ng/L and 233 ng/L, respectively. PFAS levels were highest at rainfall onset and gradually declined as precipitation continued. Adsorption studies using Al-WTR for representative legacy and emerging PFAS showed a maximum adsorption capacity of 121 μg/g for PFOS, followed by PFNA (101.5 μg/g), PFOA (96.3 μg/g), HFPO-DA (76 μg/g), PFBS (67 μg/g), and PFHxS (66.7 μg/g). These findings provide critical insights into PFAS distribution, transport, and removal in urban stormwater runoff, emphasizing the roles of traffic and stormwater dynamics in PFAS dispersal.
Antibiotic pollution in water systems is a critical global challenge that worsens the global water scarcity crisis by contaminating vital freshwater reserves and creating dangerous antimicrobial resistance. Photocatalysis uses solar energy to power green catalytic treatments that clean antibiotic-contaminated water by breaking down persistent pharmaceuticals without using any harsh chemicals. Bismuth-based heterojunction photocatalysts leverage heterojunction engineering that drastically improves charge carrier separation and minimizes electron-hole recombination while enhancing redox potential for the destruction of environmental pollutants. In this article, we reviewed the removal of levofloxacin (LEV) and ciprofloxacin (CIP), the two most detected antibiotics in wastewater and aquatic environments globally, by various bismuth-based heterojunctions. Their photodegradation performance has been compiled and compared, and possible degradation routes, photodegradation mechanisms, and ecotoxicity of the degraded products are discussed. A true comparison of the degradation performance of CIP and LEV by various heterojunctions is difficult because various light sources, radiation intensity, pollutant concentration, and catalyst dose were used in various published studies. Of the heterojunctions so far developed, Fe3O4/Bi2WO6 and Bi2O3/(BiO)2CO3 showed excellent CIP removal, and their photodegradation rate constants were 0.5571 and 0.476 min−1, respectively. Conversely, for the removal of LEV, Bi2WO6/CuS and BiOCl/Bi2Fe4O9 provided excellent photodegradation, and the rate constants were 0.2639 and 0.0934 min−1, respectively. Toxicity analyses show that many degradation intermediates of CIP and LEV are toxic and mutagenic if the photodegradation is incomplete. The development of low-cost photocatalytic drug removal technology based on bismuth-based heterojunctions holds significant potential to make drinking water safer for human and animal consumption.
