Decontamination of produced water containing petroleum hydrocarbons by electrochemical methods: a minireview

Produced water (PW) is the largest waste stream generated in oil and gas industries. The drilling and extraction operations that are aimed to maximize the production of oil may be counterbalanced by the huge production of contaminated water (called PW) with pollutants, such as heavy metals, dissolved/suspended solids, and organic compounds. PW is conventionally treated through different physical, chemical, and biological methods. In offshore platforms, because of space constraints, compact physical and chemical systems are used. However, major research efforts are being developed with innovative technologies for treating PW in order to comply with reuse and discharge limits. Among them, electrochemical technologies have been proposed as a promising alternative for the treatment of this kind of wastewaters. Then, this paper presents a minireview of efficient electrochemical technologies used until now for treating PW generated by petrochemical industry.     

Climate change impacts in the Middle East and Northern Africa (MENA) region and their implications for vulnerable population groups

Regional Environmental Change - The Middle East and North Africa (MENA) region emerges as one of the hot spots for worsening extreme heat, drought and aridity conditions under climate change. A...     

Marine sponges with contrasting life histories can be complementary biomonitors of heavy metal pollution in coastal ecosystems

In this study, we compared the usefulness of a long-living sponge (Hymeniacidon heliophila, Class Demospongiae) and a short-living one (Paraleucilla magna, Class Calcarea) as biomonitors of metallic pollution. The concentrations of 16 heavy metals were analyzed in both species along a gradient of decreasing pollution from the heavily polluted Guanabara Bay to the less impacted coastal islands in Rio de Janeiro, SE Brazil (SW Atlantic). The levels of most elements analyzed were higher in H. heliophila (Al, Co, Cr, Cu, Fe, Mn, Ni, Hg, Ni, and Sn) and P. magna (Ni, Cu, Mn, Al, Ti, Fe, Pb, Co, Cr, Zn, and V) collected from the heavily polluted bay when compared with the cleanest sites. Hymeniacidon heliophila accumulates 11 elements more efficiently than P. magna. This difference may be related to their skeleton composition, histological organization, symbiont bacteria and especially to their life cycle. Both species can be used as a biomonitors of metallic pollution, but while Hymeniacidon heliophila was more effective in concentrating most metals, Paraleucilla magna is more indicated to detect recent pollutant discharges due to its shorter life cycle. We suggest that the complementary use of species with contrasting life histories can be an effective monitoring strategy of heavy metals in coastal environments.     

Determination of plate waste in primary school lunches by weighing and visual estimation methods: A validation study

The aim of this study was to validate the visual estimation method for aggregated plate waste of main dish at Portuguese primary school canteens. For this purpose plate waste at school lunch was measured for 505 individual servings, using weighing individual servings and plate waste and visual estimation method by a 6-point scale, as developed by Comstock et al. (1981). A high variability of initial serving weights was found with serving sizes ranging from 88.9 to 283.3 g and with a coefficient of variation ranging from 5.5% to 24.7%. Mean plate waste was 27.5% according to the weighing method. There was a significant bias in the conversion of the visual waste estimations to actual waste, being overestimated by an average of 8.0 g (ranging from ?12.9 g to 41.4 g). According to Bland and Altman plot, the mean difference between methods was of 8.0 g and the amplitude interval was 102.6 g. The study showed that the visual estimation method is not as accurate as the weighing method in assessing nonselective aggregated plate waste at primary school canteens. Our findings are thus very important on considering plate waste assessment, since the wide variation on initial servings introduces a relevant bias when considering standard portions or a random sample of initial servings. Although, greater convenience, time-saving and the possibility to monitor plate waste of large groups, make the visual estimation method an important method to assess plate waste at school canteens, these results highlighted the need of portions standardization and control of initial servings to allow for its use.     

Efficiency of a cleanup technology to remove mercury from natural waters by means of rice husk biowaste: ecotoxicological and chemical approach

In the present work, the efficiency of rice husk to remove Hg(II) from river waters spiked with realistic environmental concentrations of this metal (μg L^?1 range) was evaluated. The residual levels of Hg(II) obtained after the remediation process were compared with the guideline values for effluents discharges and water for human consumption, and the ecotoxicological effects using organisms of different trophic levels were assessed. The rice husk sorbent proved to be useful in decreasing Hg(II) contamination in river waters, by reducing the levels of Hg(II) to values of ca. 8.0 and 34 μg L^?1, for an Hg(II) initial concentration of 50 and 500 μg L^?1, respectively. The remediation process with rice husk biowaste was extremely efficient in river waters spiked with lower levels of Hg(II), being able to eliminate the toxicity to the exposed organisms algae Pseudokirchneriella subcapitata and rotifer Brachionus calyciflorus and ensure the total survival of Daphnia magna species. For concentrations of Hg(II) tenfold higher (500 μg L^?1), the remediation process was not adequate in the detoxification process, still, the rice husk material was able to reduce considerably the toxicity to the bacteria Vibrio fischeri, algae P. subcapitata and rotifer B. calyciflorus, whose responses where fully inhibited during its exposure to the non-remediated river water. The use of a battery of bioassays with organisms from different trophic levels and whose sensitivity revealed to be different and dependent on the levels of Hg(II) contamination proved to be much more accurate in predicting the ecotoxicological hazard assessment of the detoxification process by means of rice husk biowaste.     

The water-soluble fraction of potentially toxic elements in contaminated soils: relationships between ecotoxicity, solubility and geochemical reactivity

To better understand the impacts posed by soil contamination to aquatic ecosystems it is crucial to characterise the links between ecotoxicity, chemical availability and geochemical reactivity of potentially toxic elements (PTE’s) in soils. We evaluated the adverse effects of water extracts obtained from soils contaminated by chemical industry and mining, using a test battery including organisms from different trophic levels (bacteria, algae and daphnids). These tests provided a quick assessment of the ecotoxicity of soils with respect to possible adverse effects on aquatic organisms although the ecotoxicological responses could be related to the solubility of PTE’s only to a limited extent.The analysis of results of bioassays together with the chemical characterisation of water extracts provided additional relevant insight into the role of conductivity, pH, Al, Fe, and Mn of soil extracts on toxicity to organisms. Furthermore, an important conclusion of this study was that the toxicity of extracts to the aquatic organisms could also be related to the soil properties (pH, Org C and Fe_ox) and to the reactivity of PTE’s in soils which in fact control the soluble fraction of the contaminants.The combined assessment of ecotoxicity in water fractions, solubility and geochemical reactivity of PTE’s in soils provided a more comprehensive understanding of the bioavailability of inorganic contaminants than ecotoxicological or chemical studies alone and can therefore be most useful for environmental risks assessment of contaminated soils.     

A Study of How Experts and Non-Experts Make Decisions on Releasing Genetically Modified Plants

The introduction of genetically modified plants into the environment has been marked by different positions, either in favor of or against their release. However, the problem goes well beyond such contradictory positions; it is necessary to take into account the legislation, ethics, biosafety, and the environment in the considerations related to the release of genetically modified organisms (GMOs). To this end, the Brazilian Committee of Biosafety (CTNBio), a consultative and deliberative multidisciplinary collegiate, provides technical and advisory support to the Brazilian Federal Government. This committee consists of scientists and non-scientists who participate in evaluating the dossiers of companies that are requesting approval by the Brazilian Government; consequently, the aim of this study was to investigate whether commercial approvals of GMOs were associated with the profile of the CTNBio members. Research was based on the minutes taken at CTNBio meetings carried out from 2006 up to 2009, considering law 11.105/2005 and the Constitution of 1988 as legal frameworks, to determine the number of voters in favor of or against releasing genetically modified Bt-maize, Bt-cotton, and herbicide resistant soybeans to be used in Brazilian agriculture. Via the internet, we had access to the curriculum vitae of the CTNBio members through the Plataforma Lattes database of the National Council for Scientific and Technological Development (CNPq), where we found their area of expertise. CTNBio members were divided into expert-for, expert-against, non-expert-for, and non-expert-against. Results showed that CTNBio decisions could be based on technical criteria as well as on the policy of the institution that expert-members were representing.     

Effects of activated sludge and UV disinfection processes on the bacterial community and antibiotic resistance profile in a municipal wastewater treatment plant

Environmental Science and Pollution Research - Wastewater tertiary treatment has been pointed out as an effective alternative for reducing the concentration of antibiotic resistant bacteria and...     

Sunlight-driven environmental photodegradation of 2-chlorobiphenyl (PCB-1) in surface waters: kinetic study and mathematical simulations

Environmental Science and Pollution Research - Polychlorinated biphenyls (PCBs) are a family of highly toxic, resistant, and persistent organic pollutants, among which 2-chlorobiphenyl (PCB-1) is...