Water Quality of Aroeira River for Use in Irrigation of Vegetable Crops in the Northern Region of the State of Espirito Santo,Brazil

The aim of this study was to evaluate the physical, chemical and microbiological quality of the water of the Aroeira River in the city of Silo Mateus, northern region of Espirito Santo State, Brazil, from April 2012 to March 2013, for use in irrigation of vegetable crops. Five points were selected along the river for analysis of pH, chloride （mg/L C1-）, total hardness （mg/L CaCO3）, dissolved oxygen （mg/L O2）, ammoniacal nitrogen （mg/L N-NH3）, total iron （mg/L Fe）, phosphate/orthophosphate （mg/L PO43-）, turbidity （NTU）, acidity （mg/L CO2）, temperature （℃）, electrical conductivity （dS/m）, as well as microbiological and parasitological analyses. Only point l, located upstream of the points of domestic sewage discharges, is the closest to be considered suitable for use in irrigation of vegetable crop, demonstrating the possible risks to the health of populations who use water with sewage discharges in urban communities for irrigation of vegetable crops.     

Remediation Actions by a Risk Assessment Approach: A Case Study of Mercury Contamination

The risk assessment procedure for identifying the remediation actions which may be adopted at a mercury contaminated site, when the plants are upgraded in the future, is proposed. The potentially active exposure/migration pathways in the future arrangement of the area will be due to Hg contaminated subsoil as a primary source (vapor inhalation and groundwater leaching) and to groundwater as a possible secondary source (transport to the point of compliance). The data of mercury concentration in the soil were acquired through environmental monitoring campaigns, and were processed to establish the three-dimensional distribution of contamination in subsoil, to locate sources and to define their geometrical and chemical characteristics. Speciation tests of mercury in the soil indicated that the most abundant species present were poorly leachable under the site-specific environmental conditions, confirming the coefficient distribution value obtained by the leaching tests. Analytical and numerical fate and transport modeling tools were used to locate digging zones in the contaminated subsoil, so as to reduce the possible groundwater contaminant loading and to avoid the down-gradient exceeding the concentration limit according to regulations. Remediation actions additional to civil works were required, which consists of soil digging within one contamination source, for about 22,200 m³ of soil. In order to evaluate the Hazard Index (HI) for human receptors due to Hg vapor inhalation, the air concentration of volatile mercury at the exposure point was estimated, based on direct measurements carried out at the site. Simulation gave HI values below 1 for all tested scenarios, suggesting that public health is protected without any additional actions to the already scheduled plant upgrading and digging for groundwater protection.     

Influence of environmental factors on the biological treatment of organic compounds in contaminated lagoon sediments

Background and Scope  Many technologies available to remediate soils are not cost-effective when applied to marine and lagoon sediments, due to the physico-chemical characteristics of these matrices (high percentages of small particle size material, high moisture and organic matter content, many different types of inorganic and organic contamination). For these types of waste, slurry phase bioreactors can provide versatile processes, with very high removal efficiencies of recalcitrant organic compounds. The biodegradation of these contaminants strictly depends on the specific structure of the molecules and on environmental factors, such as the dissolved oxygen concentration, salinity, pH, and macronutrient availability. This paper presents the results of lab-scale tests performed to investigate the effect of the above-mentioned factors on the removal efficiency of saturated hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs) in slurry phase biological treatment of lagoon sediments. Methods  Sediments were contaminated by saturated hydrocarbons (958 mg/kg d.w.), polyaromatic hydrocarbons (PAHs) (29 mg/kg d.w.) and polychlorobiphenyls (PCBs) (236 μg/kg d.w.). Carbon to nitrogen to phosphorous ratios in the matrix were not properly balanced for biological treatment. High concentrations of metals were also present (Cu: 200 mg/kg d.w.; Zn: 1710 mg/kg d.w.; As: 33 mg/kg d.w.; Cd: 13 mg/kg d.w.; Pb: 244 mg/kg d.w.). Biodegradation studies were carried out at 21 ± 1°C, in completely mixed slurry phase aerobic, anaerobic and sequential anaerobic/aerobic batch systems (3.5 1), with a solid to liquid ratio of 10% w/w. Where required, anaerobic conditions occurred naturally within three days of not aerated treatment. The aerated reactors were also equipped with traps for the waste vapors. Twelve tests were performed, over a period between ten and twenty-two days, mixing water, sediments and different amounts of various additives (macronutrients to balance C:N:P to 100:10:1 w/w, sodium chloride from 0 to 20 g/1, pH buffer solution) in the reactors, depending on the test being performed. Results and Discussion  No significant differences among the removal efficiencies of saturated hydrocarbons in tests could be observed. Abatements between 63% and 93% were obtained. The dissolved oxygen concentration was the most critical factor affecting the treatment of PAHs. Removal efficiencies below 20% were obtained for two and three-ring PAHs in the non-aerated tests. Higher values, between 45% and 61%, were obtained for these compounds in the aerated treatments; however, large (16% to 21%) abiotic losses (volatilization) were observed in these cases. Four-ring PAH removal efficiency was below 5% in all the non-aerated treatments, except for test performed without additions (30%); in the aerobic processes, removal efficiencies between 40% and 50% were obtained, except for test performed with nutrient addition and 10 g NaCl/1 (16%). Abatements of five and six-ring PAHs were between 43% and 69% in the aerated tests, and between 17% and 51% in the non-aerated treatments. Concerning PCBs, tests evidenced that reductive dehalogenation mechanisms have occurred in the anaerobic reactors with the most stable pH values, resulting in an increase of 2,4,4′-CB and 2,2′,5,5′-CB concentrations; the aerobic treatments did not modify the PCB mixture. In both types of systems, no variation of the total PCB concentration could be observed. Conclusions  This study showed that saturated hydrocarbon removal efficiency was nearly insensitive to the environmental factors investigated. The molecule structure and the dissolved oxygen concentration were the most affecting factors the removal efficiency of PAHs. PCB degradation under anaerobic conditions could be related to the pH values measured during the tests. Evaluation of results suggested that the abatement of pollutants investigated was not limited by a high salinity. High concentrations of dissolved metals and macronutrient addition did not influence the removal efficiency. Recommendations and Outlook. The slurry phase biological treatment of contaminated sediments could be applied whenever moderate removal efficiencies were required for remediation from saturated hydrocarbons and PAHs within a few days; further studies should be performed to improve the PCB abatement. Aerobic conditions should be maintained for the biodegradation of polyaromatic compounds; seawater or lagoon water could be used in the system.     

Lab-scale feasibility tests for sediment treatment using different physico-chemical techniques

Purpose  

The fairly high amounts of sediments dredged in coastal or internal water bodies for navigational and/or environmental purposes claims for the identification of appropriate management strategies. Dredged sediments are frequently affected by organic and inorganic contamination, so that their reuse, as an alternative to final landfill disposal, could need remediation. In this framework, a two-year joint research project was carried out to assess the feasibility of different remediation technologies for the treatment of polluted sediments.     

Polycyclic Aromatic Hydrocarbons (PAHs) Slurry Phase Bioremediation of a Manufacturing Gas Plant (MGP) Site Aged Soil

Bench scale tests have been carried out in order to investigatebioremediation feasibility of a Manufacturing Gas Plant site(Bovisa Gasometri – MI – I) aged soil, highly contaminated bypolyaromatic hydrocarbons (PAHs) and mineral oils. Biodegradationstudies were carried out at 22 °C in a slurry system reactor, with a solid to liquid ratio of 10% w/w. Three testswere performed, over a period of 23, 24 and 91 days respectively.In the first test, only soil and water were put into the system.In the second test, microbial activity was inhibited to evaluatethe amount of abiotic losses. In the third test, macronutrientswere added to the reactor; bioaugmentation was also carried outby an inoculum of autochthonous PAH-degrading microorganisms. Saturated hydrocarbons, PAHs, transformation products, heterotropic and PAH-degrading bacteria and fungi were monitored.Tests showed that high removal efficiency could be obtained following 23 days of treatment for all PAHs, including high molecular weight compounds. Abiotic losses were an importantprocess contributing to concentration abatement in soil, especially in the first phase of the treatment. Lag time lackfor all polyaromatic hydrocarbons revealed that autochthonousmicroorganisms were well adapted to these contaminants; bioaugmentation did not seem to speed up the process. The higherremoval rate and efficiency for high molecular weight PAHs obtained in the third test suggested that nutrient addition could play an important role in the biodegradation process ofthese compounds, whereas it did not significantly modify total(abiotic + biotic) removal of light compounds.     

Sequential solidification/stabilization and thermal process under vacuum for the treatment of mercury in sediments

Purpose  

Millions of cubic meters of sediments are dredged every year in the world. About 10–20% on weight basis of this material is contaminated by organic and/or inorganic pollutants. This work presents the laboratory tests performed to study a system for the remediation and reuse of mercury-contaminated sediments. The treatment is based on a cement-based granulation step (solidification/stabilization (S/S)), followed by a thermal process under vacuum during which volatile and semi-volatile compounds are removed. The experiments focused on: (1) cement hydration reactions; (2) pollutant removal efficiencies; and (3) leaching behavior, in relation to temperature and duration of the thermal process. Mercury speciation was also investigated.     

Partitioning of glutenin flour of special wheat using aqueous two-phase systems

The partitioning behavior of the glutenin proteins was evaluated in aqueous two-phase systems (ATPSs) formed by sulfate salts (lithium or sodium) and poly(ethylene glycol) (PEG) with average molar mass of 1500 g mol⁻¹ or 4000 g mol⁻¹. The partition coefficients for the glutenin proteins in each ATPS were investigated as a function of the temperature (278.2 K–318.2 K), tie line length (TLL) and electrolyte nature. In all ATPS, the majority of glutenin proteins spontaneously concentrate in the polymer-rich phase (K_p > 1). The partition coefficient is very dependent on the salt nature and the ATPS formed by PEG + lithium sulfate presents higher K_p values as compared with the ATPS formed PEG + sodium sulfate. An increase of molar mass of polymer promotes a decrease of K_p. Thermodynamic parameters of transfer (Δ_trG, Δ_trH and Δ_trS) were obtained by the application of the Van’t Hoff equation (VHE). The values obtained by VHE indicate that the transfer of glutenin proteins to the polymer-rich phase has an enthalpic origin.     

Micronutrients in the fruits and leaves of irrigated and non-irrigated coffee plants

The growing requirement for micronutrients by increasingly more productive Robusta coffee genotypes and for the expansion of coffee plantations into low fertility soils has led to the need for better understanding of the micronutrient dynamics in Robusta coffee plants. The aim of the present study was to investigate micronutrient concentrations and their accumulation from flowering to fruit ripening, as well as micronutrient leaf concentrations throughout the year, in irrigated and non-irrigated Coffea canephora plants. Three-year-old Robusta coffee plants of genotype 02 were used. The fruit micronutrient accumulation curves for irrigated and non-irrigated Robusta coffee plants were best fitted by sigmoid functions. Irrigation resulted in higher micronutrient accumulation in fruits. Iron and boron were the micronutrients found in the highest amounts in fruits and leaves.