This study was aimed to examine the efficiency of a novel bacterial consortium on the reduction of toxic hexavalent chromium [Cr(VI)] to non-toxic trivalent Cr [Cr(III)]. Six Cr(VI)-resistant bacteria (IS1-IS6) were isolated from a tannery waste disposal site at Mount Barker, South Australia, of which three viz., IS1, IS2 and IS3 were selected based on Cr(VI) reduction ability in minimal salt medium. The isolates were identified as Bacillus endophyticus (IS1), Microbacterium paraoxydans (IS2) and Bacillus simplex (IS3) by 16S rRNA gene sequencing. All three isolates were able to tolerate chromium (Cr(VI), 300–400 mg L ⁻¹), arsenic (As(V), 1,000 mg L ⁻¹), copper (Cu(II), 300–400 mg L ⁻¹) and lead (Pb(II), 1,000 mg L ⁻¹). The isolates were evaluated both as an individual and as a consortia for Cr(VI) reduction in minimal salt medium and storm water, both spiked with 100 mg Cr(VI) L ⁻¹. In both cases, the rate of Cr(VI) reduction was found to be significantly higher in the bacterial consortium inoculation ( t_½ = 8.45 for minimal salt medium; 6.02 h for storm water), compared to inoculation with individual isolates ( t_½ = 53.3–115.5 h for minimal salt medium; 8.77–9.76 h for storm water). The rate of Cr(VI) reduction in both minimal salt medium and storm water was found to be higher in bacterial consortium inoculation (IS1 + IS2 + IS3) than in individual isolate inoculation. This experiment demonstrated that bacterial consortium prepared by using B. endophyticus, M. paraoxydans and B. simplex was more effective in Cr(VI) detoxification than application of individual bacterium. This experiment also proved that a bacterial consortium was more effective in Cr(VI) detoxification than the application of individual bacterial strain.

Petroleum hydrocarbon contamination of soil is an emerging environmental threat on the Earth due to possible toxic impact on different ecological receptors. The present study was mainly carried out to evaluate the phytotoxicity of long-term total petroleum hydrocarbon-contaminated soils by the toxicity end points obtained from three plant species Zea mays, Lactuca sativa L., and Cucumis sativus. The tested soil exerted phytotoxicity for all the evaluated end points of plants with dose-dependent relationship. The determined IC₅₀ indicates inhibition in root elongation as the most sensitive toxicity end point for L. sativa L., while inhibition in cross-section area of meristematic zone as the most susceptible and inhibition in seed germination as the least susceptible end points for both Z. mays and C. sativus. The tested root morphometric parameters confirm their applicability as novel toxicity end points. In addition, microcalorimetric analysis confirmed the applicability of inhibition in metabolic heat emission rate as a toxicity end point. Microcalorimetry can be applied to determine the exerted phytotoxic effect on seedlings. The present combined approach concludes that the phytotoxicity of the tested soil is species-specific and varies as follows: Z. mays < C. sativus < L. sativa L. The findings of this study may have implications in planning comprehensive phytotoxicity assessment for hydrocarbon-contaminated soils or screening plant species for phytoremediation program.

Stormwater is a potential and readily available alternative source for potable water in urban areas. However, its direct use is severely constrained by the presence of toxic pollutants, such as heavy metals (HMs). The presence of HMs in stormwater is of concern because of their chronic toxicity and persistent nature. In addition to human health impacts, metals can contribute to adverse ecosystem health impact on receiving waters. Therefore, the ability to predict the levels of HMs in stormwater is crucial for monitoring stormwater quality and for the design of effective treatment systems. Unfortunately, the current laboratory methods for determining HM concentrations are resource intensive and time consuming. In this paper, applications of multivariate data analysis techniques are presented to identify potential surrogate parameters which can be used to determine HM concentrations in stormwater. Accordingly, partial least squares was applied to identify a suite of physicochemical parameters which can serve as indicators of HMs. Datasets having varied characteristics, such as land use and particle size distribution of solids, were analyzed to validate the efficacy of the influencing parameters. Iron, manganese, total organic carbon, and inorganic carbon were identified as the predominant parameters that correlate with the HM concentrations. The practical extension of the study outcomes to urban stormwater management is also discussed.

This study assessed the effect of ambient air pollution on leaf characteristics of white willow, northern red oak, and Scots pine. Willow, oak, and pine saplings were planted at sixteen locations in Belgium, where nitrogen dioxide (NO2), ozone (O3), sulfur dioxide (SO 2), and particulate matter (PM10) concentrations were continuously measured. The trees were exposed to ambient air during 6 months (April-September 2010), and, thereafter, specific leaf area (SLA), stomatal resistance (R s), leaf fluctuating asymmetry (FA), drop contact angle (CA), relative chlorophyll content, and chlorophyll fluorescence (F v/F m) were measured. Leaf characteristics of willow, oak, and pine were differently related to the ambient air pollution, indicating a species-dependent response. Willow and pine had a higher SLA at measuring stations with higher NO2 and lower O3 concentrations. Willow had a higher R s and pine had a higher F v/F m at measuring stations with a higher NO2 and lower O 3 concentrations, while oak had a higher F v/F m and a lower FA at measuring stations with a higher NO2 and lower O3 concentrations. FA and R s of willow, oak, and pine, SLA of oak, and CA of willow were rather an indicator for local adaptation to the micro-environment than an indicator for the ambient air pollution. © 2013 Springer Science+Business Media Dordrecht.

The in-depth knowledge on management and reducing annual acidic pollution is important for improving the sustainable livelihood of people living in areas with acid sulphate soils (ASS). This study involved a long-term (2001–2006), large-scale canal water quality monitoring network (87 locations) and a field experiment at nine sites to quantify the dynamic variability of acidic pollution and its source in a coastal area with ASS in the Mekong River Delta of Vietnam. Widespread acidic pollution (pH <5) of surface water occurred at the beginning of the rainy season, while pH of the canal water remained high (7–8) at the end of the rainy season and during the dry season. The study identified canal embankment deposits, made of ASS spoils from canal dredging/excavation, as the main source of acidic pollution in the surrounding canal network. The findings suggested that there was a linkage between the amount of acidic loads into canal networks and the age of the embankment deposits. The most acute pollution (pH ~ 3) occurred in canals with sluggish tidal water flow, at 1–2 years after the deposition of excavated spoils onto the embankments in ASS. The amount of acidic loads transferred to the canal networks could be quantified from environmental parameters, including cumulative rainfall, soil type and age of embankment deposits. The study implied that dredging/excavation of canals in ASS areas must be carried out judiciously as these activities may increase the source of acidic pollution to the surrounding water bodies.

Four room temperature ionic liquids, [BMIM][PF₆], [BMIM][NTf₂], [PEGMIM][PF₆], and Aliquat, were investigated regarding their use in a two-phase partition bioreactor dedicated to remove two hydrophobic VOC, dimethyldisulfide and toluene. Aliquat and [PEGMIM][PF₆] cannot be further considered, owing to the toxicity of the former shown during glucose uptake inhibition tests and the water solubility of the latter. The partition coefficients of [BMIM][PF₆] and [BMIM][NTf₂] were found comparable to those recorded for typical liquid solvents used in multiphase bioreactors. They were also non-biodegradable, showed during long-term biodegradability tests. After 1 day of lag time, similar glucose biodegradation rates were recorded in the presence of 5 % [BMIM][PF₆] or [BMIM][NTf₂], if compared to controls deprived of ionic liquid. However, a clear inhibitory effect of the ionic liquids was observed during VOC biodegradation experiments. This phenomenon was significantly minimized after acclimation of activated sludge to VOC, since nearly similar consumption rates of toluene were recorded in the control deprived of IL and in the presence of 5 % bmimPF₆, 0.49 and 0.48 g m⁻³ h⁻¹, respectively. These promising results showed that more complex acclimation strategies, including microbial acclimation to both ionic liquids and VOC, will have to be considered.

Lanthanum/aluminum-modified zeolite adsorbent (La/Al-ZA) was prepared and investigated for their ability to remove phosphorus from wastewater. Various batch adsorption conditions, e.g., pH, ionic strength, temperature, contact time, initial phosphorus concentration, and the dosage of adsorbent were tested. The results showed that the adsorption amount increased with the increase of temperature, contact time, and initial phosphorus concentration and decreased with the increase of adsorbent dosage and initial anion concentration. The adsorption amount first increased with increasing pH from 2.0 to 4.0 and reached a plateau over the pH range from 4.0 to 8.0, then significantly decreased from 8.0 to 12.0, and the suitable adsorption was achieved with the pH range 4–9. The phosphorus removal efficiency decreased slightly from 95.86 to 93.39 and 92.53 %, respectively, in the presence of Cl⁻ and SO₄²⁻ at the lower concentration of 0.1 mmol/L, while they decreased significantly from 95.86 % to the ranges of 85.02–88.80 % and 83.77–87.45 %, respectively, in the presence of Cl⁻ and SO₄²⁻ at higher concentrations ranging from 0.5 to 2.0 mmol/L, and the effects on adsorption of La/Al-ZA follow the order: Cl⁻ > SO₄²⁻. Phosphorus adsorption matched with both Langmuir and Freundlich isotherms. The results presented here supported the potential use of the new La/Al-ZA as a material for the treatment of phosphorus in wastewater.

Robust and cheap, biofiltration is one of the most used methods for the biological treatment of industrial gaseous odours and VOCs emissions. The chemical, physical and microbial properties, as well as the economical impact of 11 organic and inorganic packing materials potentially suitable for biofiltration, have been investigated in order to select the most relevant for the treatment of rendering gaseous emissions. Fibrous materials such as peat and coconut fibres are predisposed to compaction. Moreover, according to their low expected running period, their implementation remains expensive, such as activated carbon which induce overweening costs (>100,000€ an -1 for the treatment of 40,000 m3 h-1 with a 60-s empty bed gas residence time). Considering economical aspects, physico-chemical and biological properties, pines barks, composted wood mulch and expanded schist seem fit for this application. The performance of these materials was therefore investigated in a pilot-scale study conducted on a rendering site. According to its appropriate pH (8.62) and water-holding capacity (1.41 g g-1) and its highest nutrients content and colonization at the biofilter start-up (93 g of ATP m-3, 29.10 13 CFU m-3), composted would mulch show the best odour removal efficiency during the 134 days of operation. Performances ranged between 75 and 93 % for the treatment of odourous inlet load between 1.16 and 10.10·106 ouE m-3 h-1 with an empty bed gas residence time of 47 s. However, the pressure drop of the compost bed decreased, suggesting structural changes which may impact the performances in the long term. © 2013 Springer Science+Business Media Dordrecht.

A post-harvest experiment was conducted further to our previous greenhouse pot study on upland kangkong (Ipomoea aquatica Forsk.) and Alfred stonecrop (Sedum alfredii Hance) intercropping system in Cd-contaminated soil inoculated with arbuscular mycorrhizal (AM) fungi. Previously, four treatments were established in the intercropping experiment, including monoculture of kangkong (control), intercropping with stonecrop (IS), and IS plus inoculation with Glomus caledonium (IS+Gc) or Glomus versiforme (IS+Gv). Both kangkong and stonecrop plants were harvested after growing for 8 weeks. Then, the tested soils were reclaimed for growing post-harvest kangkong for 6 weeks. In the post-harvest experiment, there were no significant differences between the IS and control treatments, except for a significantly decreased (p<0.05) soil available P concentration with IS treatment. Compared with IS, both IS+Gc and IS+Gv significantly decreased (p<0.05) soil DTPA-extractable (phytoavailable) Cd concentrations, but not total Cd, by elevating soil pH, causing significantly lower (p<0.05) Cd concentrations in both the root and shoot of kangkong. In addition, both Gc and Gv significantly increased (p<0.05) soil acid phosphatase activities and available P concentrations and hence resulted in significantly higher (p<0.05) plant P acquisitions. However, only Gv significantly increased (p<0.05) kangkong yield, while Gc only significantly elevated (p<0.05) the shoot P concentration. It suggested that AM fungi have played key roles in Cd stabilization and P mobilization in the intercropping system, and such positive responses seemed to be sustainable and valuable in post-harvest soils.