Ballast seawater is considered globally as a major vector for invasions of non-indigenous organisms. Several technologies have been tested for their ability to remove organisms from ballast water. In the present study, we constructed a novel pulsed high-voltage discharge (PHVD) system that could operate in either high current mode with several hundred amperes or shockwave generating mode with relatively lower current in seawater. In laboratory-scale experiments, the PHVD system with shockwave-generating mode was found to be more effective in killing zooplankton (1.9- to 4.0-fold) and phytoplankton (3.3-fold) than high current mode at discharge with 300-500 pulses at 7.1 kV. Further experiments were carried out at different voltages and pulse-numbers to examine effects of the shockwave-generating PHVD system on viabilities of one zooplankton larva, two phytoplankton species, and an indicator bacterium suspended in seawater in a static chamber. For zooplankton, live cells were not detected at discharge with 400 pulses at 13 kV. For phytoplankton, the initial live cells of a dinoflagellate was decreased by 77 ± 0.5%, and the initial chl a concentration of a diatom was decreased by 76 ± 6% at discharge with 700 pulses at 13 kV. For an indicator bacterium Escherichia coli, live cells were not detected at discharges with 200 or 700 pulses at 13 kV. Measurements of ATP content of organisms showed congruent results with those obtained by the above methods, suggesting it may be a rapid method for evaluating treatment efficiency. Though further scale-up studies are necessary, these results suggest that the PHVD system have a high potential for applying to ballast seawater treatment.

Water retention and transport in soils is dependent upon the surface tension of the aqueous phase. Surfactants present in aqueous solution reduce the surface tension of aqueous phase. In soil-water systems, this can result in water drainage and reductions in field capacity and hydraulic conductivity. In this investigation, the surface tension of surfactant solutions mixed with soil—in a constant fixed ratio—was measured as a function of surfactant concentration. Two anionic surfactants were used: sodium dodecyl sulphate and sodium bis (2-ethylhexyl) sulfosuccinate. Two soils were also used—a clay soil and a sandy soil. The key observation made by this investigation was that the addition of soil to the surfactant solution provided a further component of surface tension reduction. Neither soil sample reduced the surface tension of water when surfactant was absent from the aqueous phase, though both soils released soil organic matter at low surfactant concentrations as shown by measurement of the chemical oxygen demand of the supernatant solutions. Furthermore, both surfactants were shown to be weakly adsorbed by soil as shown by the use of a methylene blue assay. It is therefore proposed that the additional reduction in surface tension arises from synergistic interactions between the surfactants and dissolved soil organic matter.

Fly ash generated from medical waste incinerator and wastewater produced from electroplating plants contains various hazardous contaminants such as heavy metals and chlorinated organic compounds. The primary goal of this research was to investigate the feasibility of removing heavy metals from wastewater using medical waste incinerator fly ash as the treatment reagent with addition of small amount of sodium carbonate (Na₂CO₃) in a hydrothermal process. Copper (Cu) was used as the model heavy metal contaminant in the process. The results revealed that medical waste incinerator fly ash could effectively stabilize Cu(II) ion from wastewater, the crystal phase and simple substance formed during the treatment played a significant role in the fixation of heavy metals in wastewater and fly ash. The heavy metal leachability of treated ash was also measured after removal process. The co-disposal of Cu-containing wastewater and heavy metals-bearing medical waste incinerator fly ash by hydrothermal treatment with addition of a small amount of Na₂SO₃ was found promising as an effective way of removing Cu from wastewater. The reutilization feasibility of fly ash and the formation mechanism of copper-containing substances were also discussed in this paper.

Highway detention ponds can fill with sediments from runoff water loaded with traffic-related materials. Sediment disposal is problematic and various protocols are currently studied, including phytoremediation. Here we present a preliminary study on four highway detention ponds in southern France to identify key sediment characteristics. Our objectives were to characterize metal content and physicochemical properties of the sediments and to evaluate the role of charophytes, which grow spontaneously in ponds, on metal lability. Vegetated and non-vegetated areas were compared. The lability of Mn, Cu, Zn, and Pb complexes was greater in the presence of charophytes. No variation in grain size composition was observed between non-vegetated and vegetated areas. These results may be useful to implement a phytoremediation strategy using those spontaneous charophytes. Our results suggest that local factors may impact sediment characteristics: for instance, strong gusts of wind, typical of southern France climate, may blow particles (some of them not related to traffic) in and out of detention ponds.

For more than a decade, Lakeland, FL, has invested in restoring its urban Lake Hollingsworth from a hypereutrophic state to its natural eutrophic state. The lake bottom was dredged of nearly 2 million m3 of accumulated organic sediments, and treatment wetlands, storm water curb inlet strainers, and a storm water baffle box were installed within the lake’s catchment area to reduce the loading of dirt, leaves, and trash to the lake. After dredging ceased, the lake was dosed one time with alum to improve water clarity and reduce phosphorus recycling from its sediments. Water quality surrogates for algal biomass— Secchi disk transparency and water column total nitrogen, total phosphorus, and chlorophyll-α concentrations— were reviewed to assess Lakeland’s progress towards its goal. In the years since dredging has stopped, algal biomass concentration in Lake Hollingsworth has significantly declined. Even with these improvements, however, the lake still remains hypereutrophic.

Changes in dissolved organic matter (DOM) characteristics were investigated during a storm event in the Kyungan River using UV-visible, fluorescence spectroscopy, resin fractionation, and size exclusion chromatography (SEC). Water samples were collected at nine sampling times to reflect a variation of the river water level. A dramatic increase was observed for chemical oxygen demand (COD) versus biochemical oxygen demand, suggesting that non-biodegradable organic components may be more contained in the organic matters driven by the storm. Specific UV absorbance values increased from 2.15 to 3.16 L/mgC-m, reaching the maximum level at the highest water level. The storm runoff resulted in the reduction of protein-like fluorescence (PLF), the increase of fulvic-like and humic-like fluorescence for the synchronous fluorescence spectra of DOM. Weight-average molecular weight (MWw) values increased from 1,100 to 1,510 Da due to the increment of high MW fractions in the SEC chromatograms. Overall changes in DOM composition may be explained by the inflow of soil-derived DOM from the upstream basins brought by the storm. The humification index (HIX) exhibited a positive correlation with MWw values, suggesting that HIX may be suggested to a prediction descriptor for DOM MW during the storm event. PLF presented a negative correlation with DOM MW, suggesting that protein-like fluorescent compounds are associated with low MW components in the river. More input of humic substances by the storm runoff appears to shift DOM into a higher MW value as revealed by a positive correlation between MWw and hydrophobic fraction.

There is evidence in the literature that the ratio of mass of sorbent (M) to volume of solution (V) affects the results of batch tests with soils and sediments. This restricts the use of such data to conditions with the same M/V ratio they were derived with, unless its influence is corrected. To find a correction, we conducted batch tests with soil and zinc solution using four M/V ratios. For each ratio, the experiments produced a different relationship between the mass of zinc sorbed per unit mass of soil (a s) and the zinc concentration in the solution after shaking and removal of the solid phase (C det), which is usually taken as the equilibrium concentration (C eq). A theoretical analysis revealed that the M/V effect can be accounted for by dividing C det by the M/V ratio, if it is caused by the presence of a “third phase”. The relationship between a s and C det×V/M is the same for all ratios then.

Column experiments were conducted using ideal natural sands and stainless-steel beads to examine the complete dissolution behavior of an organic immiscible liquid. Trichloroethene was used as the representative organic liquid. The elution curves exhibited multi-step behavior, with multiple extended periods of relatively constant contaminant flux. These secondary steady-state stages occurred at concentrations several orders-of-magnitude below aqueous solubility for the well-sorted sands. In contrast, the secondary steady-state stages occurred within 1 log of aqueous solubility for the poorly sorted sand. The non-ideal behavior is hypothesized to result from constraints to hydraulic accessibility of the organic liquid to flowing water, which may be expected to be mediated by the pore-scale configuration of the flow field and the fluid phases.

The Nandong Underground River System (NURS) is located in Southeast Yunnan Province, China. Groundwater in NURS plays a critical role in socio-economical development of the region. However, with the rapid increase of population in recent years, groundwater quality has degraded greatly. In this study, the analysis of 36 groundwater samples collected from springs in both rain and dry seasons shows significant spatial disparities and slight seasonal variations of major element concentrations in the groundwater. In addition, results from factor analysis indicate that NO ₃ ⁻ , Cl⁻, SO ₄ ²⁻ , Na⁺, K⁺, and EC in the groundwater are mainly from the sources related to human activities while Ca²⁺, Mg²⁺, HCO ₃ ⁻ , and pH are primarily controlled by water-rock interactions in karst system with Ca²⁺ and HCO ₃ ⁻ somewhat from anthropogenic inputs. With the increased anthropogenic contaminations, the groundwater chemistry changes widely from Ca-HCO₃ or Ca (Mg)-HCO₃ type to Ca-Cl (+NO₃) or Ca (Mg)-Cl (+NO₃), and Ca-Cl (+NO₃+SO₄) or Ca (Mg)-Cl (+NO₃+SO₄) type. Concentrations of NO ₃ ⁻ , Cl⁻, SO ₄ ²⁻ , Na⁺, and K⁺ generally show an indistinct grouping with respect to land use types, with very high concentrations observed in the groundwater from residential and agricultural areas. This suggests that those ions are mainly derived from sewage effluents and fertilizers. No specific land use control on the Mg²⁺ ion distribution is observed, suggesting Mg²⁺ is originated from natural dissolution of carbonate rocks. The distribution of Ca²⁺ and HCO ₃ ⁻ does not show any distinct land use control either, except for the samples from residential zones, suggesting the Ca²⁺ and HCO ₃ ⁻ mainly come from both natural dissolution of carbonate rocks and sewage effluents.

Sorption equilibrium of phenol and aniline onto the granular activated carbon and hyperreticulated un-functionalized polymeric resin (MN200) was investigated in single and binary component aqueous systems. Higher loading was obtained for aniline than phenol onto both sorbents, which is probably due to hydrophobic difference between both solutes and the greater electronic density of the aromatic ring of the aniline. Granular activated carbon reported larger uptake than resin MN200 for both solutes, which may be attributed to the better physical properties of the granular activated carbon, for instance, larger surface area. The experimental sorption could be properly described by the Langmuir and Freundlich isotherms. Five models for predicting the binary equilibrium sorption isotherm were compared in order to determine the best fit model to correlate binary experimental data: the extended Langmuir isotherm with and without a constant interaction factor, a simplified model based on the single equilibrium factors, the empirical extended Freundlich isotherm and the modified extended Langmuir equation, which considers the synergistic interactions between sorbate-sorbate and not only the competition between them defined by the extended Langmuir model. The modified extended Langmuir model provides the best agreement between predicted and experimental data indicating that the synergistic interactions between solutes play an important role in the binary phenol/aniline sorption system.