Wastewater land application is a cost-effective method to treat and dispose wastewater; however, it may cause soil salinization. Salt mass balance and the potential soil salinization caused by the wastewater land application were investigated in the crop root zone in a wastewater land application system at the City of Littlefield, TX, USA from October 7, 2005 to September 28, 2007 using a lysimeter system. This study showed that, after 2 years of wastewater land application, the ranges of soil salinity were still lower than the threshold (8,500 μS/cm) for Bermuda grass assuming a 10% yield reduction. The leached salt mass showed large spatial and temporal variation. The average values of electrical conductivity of the saturated paste extract of the soil samples increased from 1,433 μS/cm in June 2006 to 1,840 μS/cm in June 2007. The average values of the soil sodium adsorption ratio between June 2006 and June 2007 increased from 11 to 14 resulting in a potential risk of soil dispersion and decreasing the soil infiltration rate. Although the measured leaching fractions in nearly all sampling periods, except one, were higher than the leaching requirement, salt accumulations in the root zone were still found with only two exceptions. Since the time required for reaching equilibrium between cumulative salt mass input and cumulative salt mass output varies from 1 year to a few years, or even longer, the long-term investigation is recommended for the study of salt mass balance in the root zone of this wastewater land application system.

The number of chemical compounds in sewage and consequently their release into the environment is increasing. Some of them are toxic and many of them are considered endocrine disrupters. Here, the capacity of three wastewater treatment plants (WWTPs) to remove caffeine, hormones and bisphenol-A was investigated. Bisphenol-A and caffeine are highly water-soluble compounds, as opposed to hormones (estradiol, estriol, and ethynilestradiol) which are hydrophobic compounds. In the Sewage Treatment Plant (SWT)1 the sewage is treated by activated sludge process, in the second plant, SWT2, sewage is treated by upflow anaerobic sludge blanket reactors followed by dissolved air flotation, and in the third, SWT3 sewage is treated by stabilization lagoons. The first lagoon is 3.5 m deep, thus facultative and polishment processes occur. It was speculated that there was a difference in efficiency between the three plants in removing micropollutants. Small differences were found in the amounts removed, probably accounted for by retention time. The caffeine and bisphenol-A were almost completely removed, higher than 90% for both compounds (bisphenol-A and caffeine) in all WWTPs. The hormones, however, had a smaller rate of removal, between 70% and 87%. It is suspected that retention time is essential for removal efficiency, together with type of treatment. In fact, the hormones, caffeine, and bisphenol-A found in the environment definitely come from untreated sewage.

The polluted site object of our study was located on an island nourished using different materials, including industrial by-products, inside the area of Porto Marghera (Venice Lagoon, Italy). Until the 1970s, this area was one of the most important chemical districts in Italy and was largely subjected to heavy metals and metalloids pollution. In the year 2004, some Populus and Salix spp. had been planted in this polluted site in order to investigate both the hydrological control and the phytoremediation capability of these trees. In the present work, polluted soil was analyzed at different depths for both metals content and culturable microbial communities with the aim to evaluate the establishment of previously planted poplar and willow plants. Bacteria were characterized on the basis of the r/K-strategists distribution since r-strategists (fast-growing bacteria) and K-strategists (slow-growing bacteria) are characteristic for unstable and stable environments, respectively. A better characterization of bacterial communities composition was obtained from colony development and eco-physiological indices. Results appeared to confirm a good establishment of poplar and willow plants in the heavy metal contaminated site.

The analysis of gamma emitters natural radionuclides, i.e., 226Ra, 232Th, and 40K, has been carried out in soil, vegetation, vegetable, and water samples collected from some Northern area of Pakistan, using gamma-ray spectrometry. The γ-ray spectrometry was carried out using high-purity Germanium detector coupled with a computer-based high-resolution multi-channel analyzer. The activity concentrations in soil ranges from 24.7 to 78.5 Bq kg−1, 21.7 to 75.3 Bq kg−1, and 298.5 to 570.8 Bq kg−1 for 226Ra, 232Th, and 40K with the mean value of 42.1, 43.3, 9.5, and 418.3 Bq kg−1, respectively. In the present analysis, 40K was the major radionuclide present in soil, vegetation, fruit, and vegetable samples. The concentration of 40K in vegetation sample varied from 646.6 to 869.6 Bq kg−1 on dry weight basis. However, the concentration of 40K in fruit and vegetable samples varied from 34.0 to 123.3 Bq kg−1 on fresh weight basis. In vegetation samples, along with 40K, 226Ra, and 232Th were also present in small amount. The transfer factors of these radionuclides from soil to vegetation, fruit, and vegetable were also studied. The transfer factors were found in the order: 40K > 232Th ≈ 226Ra. The analysis of water samples showed activity concentrations values for all radionuclides below detection limit. The internal and external hazard indices were measured and found less than the safe limit of unity. The mean value of outdoor and indoor absorbed dose rate in air was found 64.61 and 77.54 nGy h−1, respectively. The activity concentrations of radionuclides found in all samples during the current investigation were nominal. Therefore, they are not associated with any potential source of health hazard to the general public.

The potential of ferrihydrite-modified diatomite as a phosphorus co-precipitant was investigated at a laboratory scale. Ferrihydrite-modified diatomite was demonstrated to effectively remove phosphorus from lake water as well as strongly bind phosphorus in sediment under anoxic conditions. Phosphorus removal from the lake water proceeded primarily through phosphorus adsorption onto ferrihydrite-modified diatomite and further phosphorus consumption by stimulated diatom growth. A total phosphorus removal efficiency of 85% was achieved when lake water was dosed with 250 mg/L ferrihydrite-modified diatomite; the residual total phosphorus concentration was 17.0 µg/L, which falls within the range for oligotrophic phosphorus levels. During a 30-day anoxic incubation period, total phosphorus concentrations in lake water treated with 400, 500, or 600 mg/L of ferrihydrite-modified diatomite slightly decreased and maximum total phosphorus concentrations remained below 15 µg/L. Addition of ferrihydrite-modified diatomite resulted in a marked increase in the iron-bound phosphorus fraction, a pronounced decrease in labile phosphorus and organic-bound phosphorus fractions, and stable aluminum-bound phosphorus, calcium-bound phosphorus, and residual phosphorus fractions in the anoxic sediments. Comparable iron-bound phosphorus concentration in the sediment treated by 400 mg/L of ferrihydrite-modified diatomite relative to that of the sediment treated by the combination of 400 mg/L of ferrihydrite-modified diatomite and alum solution at the concentration less than 532 mg/L indicated that ferrihydrite-modified diatomite exhibited a stable phosphorus-binding capacity when dosed at a similar amount. Ferrihydrite-modified diatomite had the potential to be used as an effective phosphorus co-precipitant.

This paper explores the regulation of water quality protection downstream from the Ranger Uranium Project in the Alligator Rivers Region, an area of high conservation value which is both World Heritage- and Ramsar-listed. Available historical monitoring data for surface water quality in Magela Creek downstream of Ranger have been compiled and analysed with respect to hydrologic data and the Australian and New Zealand Environment and Conservation Council–Agricultural and Resource Management Council of Australia and New Zealand (ANZECC–ARMCANZ) regulatory guidelines, introduced in late 2000. The paper focuses on the underlying scientific basis for the current approach and examines the complex inter-relationships of minesite water management, hydrology, climate, monitoring design, implementation and interpretation which are used to differentiate between natural variability and potential mine-derived solutes. The research found that the application of the ANZECC–ARMCANZ guidelines has clearly improved the regulation of water quality protection downstream from the Ranger Uranium Project. The scientific basis is more coherent than the previous regulatory regime; however, for U (a key parameter of indigenous Mirarr-Gundjeihmi and public concern), higher downstream concentrations are permitted than those observed through natural variability, leaving open the potential for an influence of mine-derived U loads while still being within regulatory limits. Another improvement that could be made to the current regulatory regime, to provide enhanced protection of the water quality in Magela Creek downstream of Ranger, would be to explicitly link the water quality monitoring regime with hydrologic flow conditions. The paper makes a valuable case study for the application of water quality guidelines, especially for controversial projects such as uranium mining surrounded by a World Heritage- and Ramsar-listed region on indigenous land—a context of clear relevance for many places around the world.

In recent years, elevated arsenic concentrations in groundwater used for drinking water supplies have been recognised in the Madrid Tertiary detrital aquifer. Although only natural causes have been suggested as the source of arsenic, this study aims to highlight that the anthropogenic contribution cannot be disregarded. During the sub-catchment's areas sampling, we found many geographical sites where natural arsenopyrite [FeAsS] originally encapsulated in pegmatite bodies and quartz veins, was artificially outcropped and dumped out, since mining wastes were scattered and exposed to weathering. Several mineral and ground specimens were collected to analyse its mineralogical and chemical composition by X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) spectrometry and by Environmental Scanning Electron Microscope (ESEM). Both, the abundant existence of secondary phases, such as scorodite [FeAsO₄⋅2H₂O] and jarosite [KFe₃(SO₄)₂(OH)₆], much more soluble than arsenopyrite, and the lixiviation experiments of arsenopyrite in acidic media to simulate acid mine drainage (AMD) conditions, usually found in old mining districts, point to a potential risk of arsenic contamination of surface water bodies, which operate as recharged waters of the aquifer in the studied area. The elemental determination of heavy metals present in ground samples by XRF analyses, reaching up to 1,173 mg kg⁻¹ of copper, 347 mg kg⁻¹ of lead and 113,702 mg kg⁻¹ of arsenic; and the physicochemical and arsenic fractionation studies of soil samples, led us to classify the soil as Spolic Technosol (Toxic). The contamination of the area due to old mining activities could release arsenic to Madrid water supplies; accordingly, additional decontamination studies should be performed.

The objective of this research was the evaluation of the effects of exogenous added surfactants on hydrocarbon biodegradation and on cell surface properties. Crude oil hydrocarbons are often difficult to remove from the environment because of their insolubility in water. The addition of surfactants enhances the removal of hydrocarbons by raising the solubility of these compounds. These surfactants cause them to become more vulnerable to degradation, thereby facilitating transportation across the cell membrane. The obtained results showed that the microorganism consortia of bacteria are useful biological agents within environmental bioremediation. The most effective amongst all, as regards biodegradation, were the consortia of Pseudomonas spp. and Bacillus spp. strains. The results indicated that the natural surfactants (rhamnolipides and saponins) are more effective surfactants in hydrocarbon biodegradation as compared to Triton X-100. The addition of natural surfactants enhanced the removal of hydrocarbon and diesel oil from the environment. Very promising was the use of saponins as a surfactant in hydrocarbon biodegradation. This surfactant significantly increases the organic compound biodegradation. In the case of those surfactants that could be easily adsorbed on cells of strains (e.g., rhamnolipides), a change of hydrophobicity to ca. 30-40% was noted. As the final result, an increase in hydrocarbon biodegradation was observed.

In this study, the efficiency of chitin and chitosan toward the removal of ethylbenzene from aqueous solutions was investigated. Batch adsorption experiments of ethylbenzene-contaminated waters (5–200 mg/L) were carried out to evaluate the removal performance. Ethylbenzene uptake was determined from the changes in concentration, as the residual concentration was measured by gas chromatography with mass spectroscopy. The results indicated that the adsorption of ethylbenzene by chitin and chitosan were in agreement with the Langmuir isotherm, for two parameters model, and Redlich–Peterson isotherm, for three parameters model. A maximum removal percentage of 65% of ethylbenzene can be achieved using chitosan as adsorbent material. The adsorption capacity of ethylbenzene followed the order chitosan > chitin. The pseudo-second order rate model described best the adsorption kinetics of ethylbenzene for the two selected adsorbents. The kinetic studies also revealed that the pore diffusion is not the only rate controlling step in the removal of ethylbenzene. Overall, the study demonstrated that chitosan is a potential adsorbent for the removal of ethylbenzene at concentrations as high as 200 mg/L.

In this study, Gonium sp. was investigated for possible usage in dye-containing wastewater treatment. Trials were performed in media including triacontanol hormone, Reactive Orange 14, Reactive Red 120, Reactive Black 5, Remazol Brilliant Blue R (RBBR), and also hormone against the controls. Algae could remove RBBR with the highest dye removal percentage (56%) among the tested dyes. The optimum pH was 9 in removing 50 mg L−1 RBBR at a dye removal percentage of 47.1%. The role of laccase activity of Gonium sp. was also investigated. This first attempt in the literature showed the involvement of the enzyme in the algal growth and bioremoval process. In the presence of the plant growth hormone in the culture, the activity showed a steady and significant increase up to nearly sixfold between 5th and 14th days of incubation.