In this paper, we compared the costs and benefits of reducing premature mortality caused by exposure to surface ozone and particulate matter with an aerodynamic diameter <2.5 μm (PM₂.₅) in East Asia in 2020. The cost of ozone and PM₂.₅emission reduction is estimated using the Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS)-China model. The benefit of reducing premature mortality caused by exposure to corresponding ozone and PM₂.₅emission is valued by the value of statistical life (VSL). The costs and benefits are evaluated for two emission reduction policies in 2020 with varying stringency in China: Case FS (the strict policy implementation case in China) and Case FR (the less strict policy implementation case in China). For ozone, the emission reduction cost and the benefit of life saving are 33,000 and 8200, 36,600–99,700 and 22,200–60,700 (million int. $, 2005), for Case FS and Case FR, respectively. The corresponding cost and benefit for PM₂.₅are 3580 and 523, 292,000–797,000 and 194,000–530,000 (million int. $, 2005), respectively. In total (ozone and PM₂.₅), the respective values are 36,400 and 8720, 329,000–897,000 and 217,000–591,000 (million int. $, 2005). Owing to these large benefits and also relatively low PM control costs, the benefits of controlling PM₂.₅surpass control costs significantly. The benefit/cost ratio is especially high for PM₂.₅for both policies and highlight the priority of controlling aerosol emissions in East Asia.

A novel alginate–montmorillonite biopolymer-clay composite bead formulation for water defluoridation was developed in this study. Montmorillonite was dispersed alginate solution, and the mixture was cross-linked in an aqueous solution of aluminum(III). The resulting cross-linked beads were characterized using FTIR, SEM, and mechanical measurements. In order to reveal the defluoridation capacity of the beads, batch adsorption experiments were carried out. Optimum conditions and effect of competing ions were investigated. Experimental data were modeled using several isothermal, kinetic, and thermodynamic models. Maximum Langmuir adsorption capacity was reached as 31.0 mg g⁻¹at 25 °C. It is also found that the adsorption is physical in nature and follows the Elovich kinetic model, and the fluoride removal efficiency is not affected by the presence of most competing anions. The results show that aluminum alginate–montmorillonite composite beads can be used as effective and natural sorbents for fluoride removal from water.

We have conducted an interlaboratory comparison study for total mercury and methylmercury analysis in natural (unspiked) water samples annually for the past 4 years. The samples were primarily freshwater, with the exception of one coastal seawater sample in 2014. The study provided participants with an opportunity to assess the quality of their measurements and the intercomparability of their data with their peers. Data on analytical methods used were collected and used to determine whether any methods yield biased results and should be discontinued. The majority of participants received performance scores of 3 or higher, indicating satisfactory performance and results close to the consensus means. However, the coefficients of variation between labs were greater than 20 % in most cases, which may not be sufficiently precise for multilaboratory environmental research, where the processes being studied may vary by 20 % or less. Total mercury analysis methods that do not use gold amalgamation were shown to be underperforming relative to those that do. No significant correlation was observed between sample storage time or temperature and total mercury recovery. Methylmercury analysis methods that do not use distillation performed poorly relative to those that use distillation.

Calcium alginate beads entrapping a mixture of Fe(0) and nanosized magnetite (NMT) were prepared and evaluated for their capability to reduce nitrate in groundwater. Microscopic and spectroscopic analyses of the beads revealed that clusters of Fe(0)/NMT were entirely embedded in alginate polymer matrix containing a large number of carboxylic and hydroxyl functional groups. The extent of nitrate reduction increased with increasing content of Fe(0) and NMT in the beads, but there was a critical NMT mass limit relative to Fe(0) mass where no further increase in nitrate reduction occurred. The beads showed slower nitrate reduction kinetics than bare Fe(0)/NMT but had comparable capacity in overall nitrate removal. Nitrate reduction increased proportionally with an increase in bead dosage to give a maximum removal of 94.5 % at 37.5 g L⁻¹ in 48 h. Nitrate reduction with 50 g L⁻¹ beads achieved completion of two reduction cycles in 72 h to reduce 2.19 mM nitrate to less than 0.71 mM (10 mg-N L⁻¹) in each cycle. The overall results demonstrated that the beads developed in this study have a potential utility in remediation of nitrate in groundwater.

The anaerobic biodegradability of combined microwave-ultrasonic pretreated thickened excess activated sludge (PTEAS) mixed with raw primary sludge (PS) was investigated in this study. The pretreatment resulted in the enhancement of mesophilic anaerobic digester performance which in turn improved biogas production capacity and quality, total and volatile solid reduction, dewaterability, protein solubilisation and significant reduction of pathogens to produce class A biosolid. This study presented the results of two continuously stirred mesophilic anaerobic digesters charged with various proportions of a mixture of PTEAS and PS similar to the large-scale industrial practice. Digester 1 was charged with 75 % PTEAS and 25 % PS, while digester 2 was fed with 25 % PTEAS and 75 % PS. The methane production was 122 mL CH₄/g total chemical oxygen demand for digester 2 after 20 days of anaerobic digestion. This amount further increased for both digesters with digestion time. The biogas quality in terms of methane to carbondioxide ratio (CH₄/CO₂) was significantly improved for digester 1 compared with digester 2 after 20 days of digestion. Volatile solid reduction of 76 and 57 % was achieved for digester 1 and digester 2 respectively after the same 20 days of digestion. The CH₄/CO₂ ratio reached 2.2:1 and 1.1:1 after 20 days of digestion for digester 1 and digester 2, respectively. Higher percentage of PTEAS increases the digestion kinetics, the methane production capacity and the biogas quality. Furthermore, total coliform reduction of 84 and 44 % was achieved for digester 1 and digester 2 respectively after 22 days of digestion. Hydrolysis rate and biochemical methane production were improved for both digesters based on the results of Gompertz kinetic model and the hydrolysis rate constants as determined by model fitting of the experimental data.

After alkaline hydrothermal conversion of volcanic tephra to zeolite (VT-Z) particles, calcium ion cross-linked alginate-zeolite composites (VT-Z/CA) were subsequently fabricated as sorbents for enhancing removal of Cu(II) ions from aqueous solution. The naturally occurring VT minerals were used as silica and alumina sources for zeolite crystallization. The conversion conditions were optimized by altering the alkaline concentration, conversion time, temperature and addition of ethanol. After the synthesized VT-Z particles were entrapped into CA biopolymer template, the developed VT-Z/CA composites not only make full use of the excellent adsorption capabilities of zeolites but also prevent the major problems of mobility/agglomeration for zeolite particles in aqueous media. The VT-Z/CA composites were characterized and studied for aqueous removal of Cu(II) ions in a batch mode. Solution pH 5.5 was found to be the best choice. The kinetic data were evaluated by the pseudo-first, pseudo-second order, and Elovich model. The adsorption kinetics followed the pseudo-first model. Langmuir isotherm best described the adsorption behavior with the maximum adsorption capacity for Cu(II) at 121.1 mg g⁻¹ (45 °C). The composites were successfully explored for treatment of Cu(II)-bearing livestock farm wastewater in China. The VT-Z/CA composites offer a highly attractive alternative for remediating heavy metal contaminated water with advantages of being easy to operate, cost-effective, biodegradable, and environmentally benign.

This study aims to investigate the effect of freeze-thaw on the sensitivity of two different strains of Escherichia coli bacteria, O157:H7 strain 961019 and E. coli ATCC 25922 strain, to UV irradiation. The O157:H7 strain was a toxin-producing E. coli, and the ATCC 25922 strain is an opportunistic pathogen that can cause urinary tract infection. Cells of the two E. coli strains were frozen at −7, −15, and −30 °C with one, three, and five freeze-thaw cycles prior to UV irradiation. The UV inactivation levels of the freezing-treated E. coli cells were compared with those without freezing (the controls). Freezing affected the sensitivity of the test microbes to UV light, and the effect was strain dependent. A significant increase in resistance to UV light was observed in the freezing-treated cells as compared to the control samples. The ATCC 25922 strain showed more resistance to UV irradiation than the O157:H7 strain 961019 in most cases. The O157:H7 strain 961019, on the other hand, became more resistant to UV with increased freeze-thaw cycles.

The majority of the existing water bodies around the world are increasingly polluted with oily wastewater. The aim of this study was to investigate the role of single protozoan isolates (Aspidisca, Trachelophyllum and Peranema) and of a consortium of these three protozoan isolates in the biodegradation of fats and oils present in polluted domestic wastewater. The biomass of protozoan isolates, chemical oxygen demand (COD), dissolved oxygen (DO) and concentrations of fats and oils were determined in triplicate before and after the inoculation of isolates in oily wastewaters, using standard methods. Results revealed optimum growth of protozoan cell densities under favourable conditions of 30 °C, pH 6 and 8 (from 1.00 to 4.00, 3.96, 3.80 and 4.20 × 10²cells/ml for Aspidisca, Trachelophyllum, Peranema and a consortium of the three isolates, respectively). The average percentage uptake of DO by Aspidisca, Trachelophyllum, Peranema and their consortium was 95, 96, 96 and 100 %, respectively, for both 30 and 25 °C and at pH levels of (4, 6, 8 and 10), respectively. The results revealed that the COD removal rates of the isolates at various pH levels were ≥20 and ≤90 %, respectively, for 30 and 25 °C. At a temperature of 30 °C, the biodegradation capabilities of the isolates ranged from 3.0 to 8.0, 3.0 to 6.0, 7.0 to 11.0 and 8.0 to 22.0 %, while at 25 °C, the biodegradation rates were 3.0 to 6.0, 4.0 to 7.0, 3.0 to 8.0 and 4.0 to 15.0 % for Aspidisca, Trachelophyllum, Peranema and the consortium of these three isolates, respectively.

Understanding the biogeochemistry of metal-contaminated peatlands is important for predicting the impact of mining and industrial activities on peatlands and downstream surface waters and for predicting recovery of previously impacted sites. The objective of this work was to characterize the factors controlling spatial and temporal variability in surface peat (0–15 cm) and pore water chemistry of 18 regionally representative peatlands in Sudbury, Ontario, Canada. The pollution gradient is clearly evident as Cu and Ni concentrations in surface peat are elevated close to the main Copper Cliff smelter. Surface peat also differs greatly in acidity (pH) and organic matter content among sites, and dissolved organic carbon (DOC) concentrations in pore water are positively correlated with peat carbon content. In addition, sites having surface peat that is more decomposed also have pore water DOC that is more humified. Pore water chemistry varies seasonally; samples taken in late summer and fall were characterized by higher SO₄, and lower pH and higher concentrations of base cations and metals such as Ni, Co, and Mn compared with those in late spring that had higher DOC, higher pH, and higher concentrations of metals such as Cu and Fe. Despite the large spatial and temporal variability in pore water chemistry, soil-solution partitioning (K d) of some metals (Ni, Co, and Mn) can be explained by pH alone. Modeling soil-solution partitioning for these metals and Cu, Al, and Fe is significantly improved with the addition of SO₄; dissolved organic matter quality and quantity and/or the δ¹⁸O signature of the pore water in regression models indicating several factors other than acidity has an influence on pore water chemistry.

Nitrogen inputs to coastal watersheds have been linked to eutrophication. However, the role that domestic sources of wastewater play in contributing nitrogen to coastal watersheds is not well known in the southeastern USA. In a yearlong study (2011–2012), nitrogen concentrations were compared in watersheds served by septic systems and a centralized sewer system in the Coastal Plain of North Carolina. Surface and groundwater samples from septic systems and sewer watersheds were analyzed for total dissolved nitrogen (TDN), total nitrogen, and nitrogen and oxygen isotopes in nitrate. Groundwater beneath the drainfield and adjacent to streams had median concentrations of TDN at 5.9 and 4.4 mg/L, respectively. Additionally, median groundwater-transported loads of TDN to the stream from septic systems sites (0.6 kg-TDN/year) were significantly greater than sites in sewer watersheds (0.2 kg-TDN/year). Isotopic analyses revealed that effluent from septic systems was the primary source of nitrate in watersheds served by septic systems, while fertilizer and/or soil organic matter were dominant sources of nitrate in sewer watersheds. Nitrogen exported from septic systems contributed to elevated nitrogen concentrations in groundwater and streams throughout the watershed, whereas nitrogen exports from sewers were focused at a single point source and affected surface water concentrations. Based on watershed TDN exports from septic systems minus TDN exports from sewers watersheds, it was estimated that septic systems contributed 1.6 kg TDN/ha/year to watershed exports of TDN. Overall, septic systems and sewers contributed to elevated nitrogen loading and should be considered in nutrient-sensitive watershed management.