Geochemical fractionation of iron in paper industry and municipal landfill soils: Ecological and health risks insights.

Industrial processes and municipal wastes largely contribute to the fluctuations in iron (Fe) content in soils. Fe, when present in unfavorable amount, causes harmful effects on human, flora, and fauna. The present study is an attempt to evaluate the composition of Fe in surface soils from paper mill and municipal landfill sites and assess their potential ecological and human health risks. Geochemical fractionation was conducted to explore the chemical bonding of Fe across different fractions, i.e., water-soluble (F1) to residual (F6). Different contamination factors and pollution indices were evaluated to comprehend Fe contamination extent across the study area. Results indicated the preference for less mobile forms in the paper mill and landfill, with 26.66% and 43.46% of Fe associated with the Fe-Mn oxide bound fraction (F4), and 57.22% and 24.78% in the residual fraction (F6). Maximum mobility factor (MF) of 30.65% was observed in the paper mill, and 80.37% in the landfill. The enrichment factor (EF) varied within the range of 20 < EF < 40, signifying a high level of enrichment in the soil. The individual contamination factor (ICF) ranged from 0 to >6, highlighting low to high contamination. Adults were found to be more vulnerable towards Fe associated health risks compared to children. The Hazard Quotient (HQ) index showed the highest risk potential pathways as dermal contact > ingestion > inhalation. The study offers insights into potential Fe contamination risks in comparable environments, underscoring the crucial role of thorough soil assessments in shaping land use and waste management policies.

Biosequestration of lignin in municipal landfill leachate by tailored cationic lipoprotein biosurfactant through Bacillus tropicus valorized tannery solid waste.

Bioremediation of municipal landfill leachate (MLL) is often intricate due to presence of refractory lignin. In the present study, it was attempted to tailor the histidine rich protein moiety of cationic lipoprotein biosurfactant (CLB) to sequester the lignin from MLL. Animal fleshing (AF), the solid waste generated in tanning industry was utilized for the production of histidine rich CLB by de novo substrate dependent synthesis pathway involving Bacillus tropicus. The optimum conditions for the maximum production of CLB were determined using response surface methodology. At the optimized conditions, the maximum yield of CLB was 217.4 mg/g AF (on dry basis). The produced histidine rich CLB was purified using Immobilized metal affinity chromatography at the optimum binding and elution conditions. The histidine residues were more pronounced in the CLB, as determined by HPLC analysis. The CLB was further characterized by SDS-PAGE, Zeta potential, XRD, FT-IR, Raman, NMR, GC-MS and TG analyses. The CLB was immobilized onto functionalized nanoporous activated bio carbon (FNABC) and the optimum immobilization capacity was found to be 211.6 mg/g FNABC. The immobilization of CLB onto FNABC was confirmed using SEM, FT-IR, XRD and TG analyses. The isotherm models, kinetic and thermodynamics studies of CLB immobilization onto FNABC were performed to evaluate its field level application. Subsequently, the CLB-FNABC was then applied for the sequestration of lignin in MLL. The maximum lignin sequestration was achieved by 92.5 mg/g CLB-FNABC at the optimized sequestration time, 180 min; pH, 5; temperature, 45 °C and mass of CLB-FNABC, 1.0 g. The sequestration of lignin by CLB- FNABC was confirmed by SEM, FT-IR and UV-Vis analyses. Further, the mechanistic study revealed the anchoring of CLB onto the surface of lignin through electrostatic interaction.

Thermal heterogeneity in the proximity of municipal solid waste landfills on forest and agricultural lands.

Information on the spatial extent of potential impact areas near disposal sites is vital to the development of a sustainable natural resource management policy. Eight Canadian landfills of various sizes and shapes in different climatic conditions are studied to quantify the spatial extent of their bio-thermal zone. Land surface temperature (LST) and normalized difference vegetation index (NDVI) are examined with respect to different Land Use Land Cover (LULC) classes. Within 1500 m of the sites, LST ranged from 18.3 °C to 29.5 °C and 21.3 °C-29.7 °C for forest land and agricultural land, respectively. Linear regression shows a decreasing LST trend in forest land for five out of seven landfills. A similar trend, however, is not observed for agricultural land. Both the magnitude and the variability of LST are higher in agricultural land. The size of the bio-thermal zone is sensitive to the respective LULC class. The approximate bio-thermal zones for forest class and agricultural classes are about 170 ± 90 m and 180 ± 90 m from the landfill perimeter, respectively. For the forest class, NDVI was negatively correlated with LST at six out of seven Canadian landfills, and stronger relationships are observed in the agricultural class. NDVI data has a considerably larger spread and is less consistent than LST. LST data appears more appropriate for identifying landfill bio-thermal zones. A subtle difference in LST is observed among six LULC classes, averaging from 23.9 °C to 27.4 °C. Geometric shape makes no observable difference in LST in this study; however, larger landfill footprint appears to have higher LST.

Spatiotemporal and seasonal dynamics in the microbial communities of a landfill-leachate contaminated aquifer.

The microbiome of an aquifer contaminated by landfill leachate and undergoing intrinsic remediation was characterised using 16S rRNA metabarcoding. The archaeal/bacterial V3-V4 hypervariable region of the 16S rRNA gene was sequenced using Illumina MiSeq, and multivariate statistics were applied to make inferences. Results indicate that the aquifer recharge and aquifer sediment samples harbour different microbial communities compared to the groundwater samples. While Proteobacteria dominated both the recharge and groundwater samples, Acidobacteria dominated the aquifer sediment. The most abundant genera detected from the contaminated aquifer were Polynucleobacter, Rhodoferax, Pedobacter, Brevundimonas, Pseudomonas, Undibacterium, Sulfurifustis, Janthinobacterium, Rhodanobacter, Methylobacter and Aquabacterium. The result also shows that the microbial communities of the groundwater varied spatially, seasonally and interannually, although the interannual variation was significant for only one of the wells. Variation partitioning analysis indicates that water chemistry and well distance are intercorrelated and they jointly accounted for most of the variation in microbial composition. This implies that the species composition and water chemistry characteristics have a similar spatial structuring, presumably caused by the landfill leachate plume. The study improves our understanding of the dynamics in subsurface microbial communities in space and time.

Waste disposal characteristics and data variability in a mid-sized Canadian city during COVID-19.

COVID-19, declared a global pandemic by the World Health Organization, has caused governments to react swiftly with a variety of measures to quell the spread of the virus. This study investigates changes in waste disposal characteristics and the relationship between the mass of biomedical waste disposed and new COVID-19 tests performed in Regina, Canada. Results suggest that between May and September 2020, significant differences in the median amount of waste disposed exist. The amount of monthly waste disposed was slightly lower to about 450-550 tonnes/month. Monthly waste data variability, however, was significantly lower. Seasonal effects on total waste disposal is observed, but is less obvious than pre-COVID time. Furthermore, the distribution of different waste fractions varies, probably due to operational and industrial characteristics. A non-linear relationship exists between the number of COVID-19 tests performed and the mass of biomedical waste disposed, perhaps due to a lagged relationship between biomedical waste generation and disposal.

Analysis of multiclass organic pollutant in municipal landfill leachate by dispersive liquid-liquid microextraction and comprehensive two-dimensional gas chromatography coupled with mass spectrometry.

We propose a simple, fast, and inexpensive method for the analyses of 72 organic compounds in municipal landfill leachate, based on dispersive liquid-liquid microextraction and comprehensive two-dimensional gas chromatography coupled with mass spectrometry. Forty-one organic compounds belonging to several classes including hydrocarbons, mono- and polyaromatic hydrocarbons, carbonyl compounds, terpenes, terpenoids, phenols, amines, and phthalates, covering a wide range of physicochemical properties and linked to municipal landfill leachate, were quantitatively determined. Another 31 organic compounds such as indoles, pyrroles, glycols, organophosphate flame retardants, aromatic amines and amides, pharmaceuticals, and bisphenol A have been identified based on their mass spectra. The developed method provides good performances in terms of extraction recovery (63.8-127%), intra-day and inter-day precisions (< 7.7 and < 13.9 respectively), linearity (R2 between 0.9669 and 0.9999), detection limit (1.01-69.30 µg L-1), quantification limit (1.87-138.6 µg L-1), and enrichment factor (69.6-138.5). Detailed information on the organic pollutants contained in municipal landfill leachate could be obtained with this method during a 40-min analysis of a 4-mL leachate sample, using only 75 µL of extraction solvent.

Bacterial aerosols in a municipal landfill environment.

Landfills collecting substantial amounts of municipal waste support multiplication of different bacteria mainly due to organic matter contained in the deposited materials. With time, they may become active emission sources of these microorganisms. Taking into account both occupational and public health and safety, there is an indisputable necessity to monitor the level of air contamination caused by both bacterial cells and their components (e.g., endotoxins). In this study, the concentrations of total viable bacteria (TVB), and Gram-negative bacteria (GNB), as well as their particle size distributions and concentrations of GNB endotoxins were assessed at various locations within the landfill area. The concentrations of TVB and GNB in the air samples changed depending on the season, location (i.e. active sector versus surroundings) and landfill activity level (i.e. exploitation or standstill periods). Higher abundances of endotoxins were found during the standstill period, and they were significantly correlated with organic dust concentrations. The microbial particle size distribution was associated with the landfill operational state, being predominated by fine below 4.7 µm and coarse fractions above 7.0 µm within the active sector during exploitation and standstill periods, respectively. These results supported by a spatial distribution of bacterial aerosol indicate a clear impact of operated landfill on microbiological air quality within the occupied location and nearby areas. Considering health and safety of landfill workers and neighboring residents, who can be exposed to airborne microbial pollutants, repeated bioaerosol monitoring need to be established. It should facilitate both a special planning within the landfill area and undertaking preventive actions in its near and distant surroundings.

Effects of groundwater metal contaminant spatial distribution on overlaying kriged maps.

Groundwater is a major source of drinking water for many Canadians, and contamination by heavy metals poses a significant risk to people and the environment. In this study, three water quality indices are studied in the vicinity of an unlined landfill in a semiarid climate. The study investigates indices using geostatistical analysis and ordinary kriging. This study employs a novel coupling technique in order to compare the index-based maps to a groundwater quality map from overlapping heavy metal kriged maps. A total of 11 heavy metals were evaluated in preliminary analysis, but only four (Mn, As, Fe, and U) had higher concentrations than allowable limits in some or all of the monitoring wells at the site. Results from mean-based classification of indices suggest the aquifer in proximity to the landfill has been impacted by metal contaminants. Kriged maps show that the spatial variations of Mn and U are similar, while results of Fe and As are also similar. However, the two sets of maps have distinctly different patterns. Maps for indices show an elevated plateau extending from the unlined landfill to the southeast corner, implying that the landfill may have negatively impacted groundwater quality. A groundwater quality map is developed by overlaying the heavy metal maps. The resulting map shows that the north and west parts of the study have lower groundwater pollution with respect to metal contaminants. The groundwater quality map may be more applicable for practitioners who need comprehensive water quality measurement.

Treatment of refractory contaminants by sludge-derived biochar/persulfate system via both adsorption and advanced oxidation process.

A novel strategy for the removal of refractory organic contaminants was realized through sludge-derived biochar (SDBC)/persulfate (PS) system via both adsorption and advanced oxidation process under ambient conditions. SDBC was prepared by one single step of slow pyrolysis of municipal sewage sludge, appeared a porous structure, and contained abundant oxygen-containing functional groups as well as amorphous Fe species. Large surface area and porous structure of SDBC benefitted the adsorption and enrichment of contaminants, while oxygen-containing functional groups and Fe species on the surface were considered as reactive components for the activation of PS. Under conditions of [PS]0 = 1.85 mM, [4-chlorophenol]0 = 0.039 mM, [SDBC]0 = 1 g L-1, pH0 = 6.30 and temperature = 25 °C, the removal of model compound of 4-chlorophenol achieved 92.3%, and this significant performance of SDBC/PS system was consistent in a broad pH window. Radical scavengers and electron paramagnetic resonance (EPR) studies suggested that SDBC successfully activated PS to produce various oxidative radicals. Meanwhile, recycle experiments and Fe3+ leaching tests further demonstrated the stability of SDBC during the activation of PS. Municipal landfill leachate effluent through a membrane bio-reactor was testified as the refractory real wastewater, in which both the removal of total organic carbon and ammonia was significant. Thus, SDBC showed certain advantages in PS activation such as feasible preparation method, remarkable efficiency and stability. These advantages proved SDBC/PS system as an effective strategy of controlling waste by waste, and implicated its potential application in full-scale for the treatment of refractory organic contaminants.

Application of vadose-zone monitoring system for real-time characterization of leachate percolation in and under a municipal landfill.

Leachates from solid-waste landfills are considered a severe threat to groundwater quality. The fate of pollutants in the waste and underlying unsaturated zone is crucial for evaluating environmental risks and selecting a restoration strategy. In this study, a vadose-zone monitoring system (VMS) installed in a municipal landfill was used, for the first time, to continuously track leachates percolation dynamics and assess their chemical transformation across the entire thickness of the waste body (15m) and underlying unsaturated zone (16m) to the water table. Winter rains were found to quickly infiltrate through the waste and underlying vadose zone despite a clay cover that was implemented as part of a restoration and leachate-prevention strategy. Within the waste body, the flow pattern was controlled by preferential flow paths, which changed frequently. It is hypothesized that ongoing decomposition of the waste creates dynamic variations in the waste's physical structure and flow pattern. Water samples collected from the waste layer indicated the formation of highly polluted leachates. The chemical composition in the waste body showed extreme variability between sampling points with respect to DOC (407-31,464mg/L), BOD/COD ratios (0.07-0.55), Fe2+ (6.8-1154mg/L), ammonium (68-2924mg/L) and heavy metal concentrations. Environmental hot spots creating concentrated, aggressive, "acid-phase" leachates still exist in the waste more than 13years after closing the landfill. However, continuous changes in the flow pattern and moisture distribution affected the creation and decay of such environments. In the underlying sandy vadose zone, some sections repeatedly exhibited stronger and faster flow characteristics than others. These local fluxes of concentrated leachates rapidly transported heavy contaminant loads toward the groundwater. However results showed evidence of continual attenuation processes in the deep vadose zone, with the anaerobic digestion of organic matter, as well as the significant retention of heavy metals.

Methanogen communities in a municipal landfill complex in China.

Landfills are significant global sources of atmospheric methane, but little is known about the ecology and community structure of methanogens in these sites. Here, we investigated the methanogen community based on methyl coenzyme M reductase A gene amplicons in the vertical profiles of three different sites at a municipal landfill complex in China. Links between methanogen communities and refuse properties were explored using multivariate analysis. Clone library results showed that most clones (92%) were related to the hydrogenotrophic methanogens, Methanomicrobiales. Almost all of the Methanomicrobiales clones retrieved in this study are members of the genus Methanoculleus Eight clones were affiliated with the genus Methanofollis The remaining clones were clustered within the genus Methanosarcina Terminal restriction fragment length polymorphism profiles showed that the landfill was predominated by 22 taxa, making up 69%-96% of the community. Of these, a single taxon comprised 36%-65% of the communities across all sites and depths. Principal components analysis separated the methanogen community into three groups, irrespective of site or depth. Redundancy analysis suggested that total phosphorus and pH play roles in structuring methanogen communities in landfills.

Occurrence and ecological potential of pharmaceuticals and personal care products in groundwater and reservoirs in the vicinity of municipal landfills in China.

Pharmaceutical and personal care products (PPCPs), including antibiotics, azole anti-fungals, non-steroid anti-inflammatory drugs, lipid regulators, parabens, antiseptics, and bisphenol A, were investigated in groundwater and reservoirs in the vicinity of two municipal landfills in the metropolis of Guangzhou, South China. Dehydroerythromycin, sulfamethoxazole, fluconazole, salicylic acid, methylparaben, triclosan, and bisphenol A were the mostly frequently detected PPCPs in the groundwater at low ng L(-1) levels. In the reservoirs, the PPCPs were widely detected at higher frequencies and concentrations, especially sulfamethoxazole, propiconazole, and ibuprofen, with maximal concentrations above 1 µg L(-1). The PPCPs in the groundwater did not show significant seasonal differences or spatial trends. However, in the reservoirs, higher PPCP concentrations were observed in spring than in other seasons. The anti-bacterials in the groundwater posed medium risks to algae. In the reservoirs, the sulfonamides and macrolides posed low to high risks, while ibuprofen, salicylic acid, and clofibric acid presented low to medium risks to aquatic organisms. Overall, the results showed that the PPCP contaminants and subsequent ecological risks in the groundwater and surface water in the vicinity of the landfills may be of serious concern. More research is needed to better correlate the landfill leachates and PPCP contamination in the nearby aquatic environments.

Ranking of ecotoxisity tests for underground water assessment using the Hasse diagram technique.

The present study deals with the novel application of the Hasse diagram technique (HDT) for the specific ranking of ecotoxicity tests capable of assessment of underground water quality. The area studied is a multi-municipal landfill in the northern Poland. The monitoring network of the landfill constitutes of 27 piezometers for underground water monitoring and two observation points at surface water courses. After sampling, chemical analysis of various water parameters was performed (pH, conductivity, temperature, turbidity (TURB), color, taste, smell and atmospheric conditions: temperature, precipitation and cloud cover, heavy metals content (Cu, Zn, Pb, Cd, Cr(6+), Hg), total organic carbon (TOC), sum of Polycyclic Aromatic Hydrocarbons (PAHs), Na, Mg, K, Ca, Mn, Fe, Ni, alkalinity (Alkal), general hardness, total suspended matter (SUSP), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), chlorides, fluorides, sulphides, sulphates, ammonium nitrogen, total nitrogen, nitrate and nitrite nitrogen, volatile phenols, ether extracts (ETHER), dry residues (DRY_RES), dissolved compounds). Parallel to the chemical parameters assessment six different ecotoxicity tests were applied (% root length(PG)/germination(PR) inhibition of Sorghum saccharatum (respectively PGSS/PRSS), Sinapis alba (respectively PGSA/PRSA), Lepidium sativum (respectively PGLS/PRLS), % bioluminescence inhibition of Vibrio fischeri (MT), % mortality of Daphnia magna (DM), % mortality of Thamnocephalus platyrus (TN)). In order to determine the applicability of the various ecotoxicity tests, a ranking of samples from different monitoring levels according to the test used (attributes) is done by using HDT. Further, the sensitivity of the biotests was determined and compared. From the sensitivity analysis of the both monitoring levels was evident that the choice of ecotoxicity tests could be optimized by the use of HDT strategy. Most reliable results could be expected by the application of root growth inhibition of Sorghum saccharatum (PGSS test). In order to clarify the relationship between the chemical parameters measured and each of the ecotoxicity tests a optimized similarity analysis between Hasse diagrams for the ecotoxicity tests for different levels of monitoring and Hasse diagrams obtained by the use of the chemical parameters was performed. Finally, it could be concluded that for reliable monitoring of underground waters passing a dump collector following chemical parameters are of significance: water hardness, dissolved matter, total nitrogen (ammonia and nitrate nitrogen), nickel, chlorides, alkalinity, total organic carbon and ether extract and the proper battery test could include PGSA, PGSS and PRSS.

Nitritation-denitritation in landfill leachate with glycerine as a carbon source.

The effects of limited oxygen concentration (0.7 mg O2/L) in the aeration phase of the SBR cycle and glycerine as an additional carbon source on the effectiveness of nitritation-denitritation and sludge production during municipal landfill leachate treatment were examined. As carbon sources, sodium acetate (Ac) and sodium acetate (Ac) with glycerine (Gly) in the proportions of 3:1 (v/v) and 1:1 (v/v) were added. Low dissolved oxygen concentration inhibited the second stage of nitrification and nitrites were the main final products. Nitritation effectiveness was ca. 98-99%. Denitritation efficiency was relatively low (61%) in the reactor fed with Ac, which may be linked with high sludge production (Yobs - 0.6 mgVSS/mg COD). Glycerine addition (Ac:Gly 1:1, v/v) caused an increase in process efficiency to 75.6% with a concurrent significant decrease in biomass production (Yobs - 0.46 mg VSS/mg COD).