Two tannin-based coagulants have been tested on anthraquinonic dye elimination from aqueous solutions. Acquapol S5T, derived from Acacia mearnsii de Wild, and Silvafloc, derived from Schinopsis balansae, were found to be excellent agents in the destabilization of Alizarin Violet 3R dye and its elimination through coagulation from textile effluents. Both coagulants showed that high affinity to the dye molecule in a wide pH range and q values reaches significant levels (up to 0.5 mg mg − 1) with reasonable low coagulant doses. Dye–coagulant system presented a consistent behavior if studied under the statistical perspective of a design of experiments, where initial dye concentration and coagulant dose were the operating variables. Finally, both coagulants seemed to follow a predictable theoretical model under the Langmuir hypothesis with an accurate adjusted r 2 coefficient above 0.9.

In the last 20 years, a new generation of materials was developed: the biodegradable plastics. They reduce the accumulation of plastic in the environment and the cost of waste management because they can be fed in composting plants or, if used in agriculture (mulch films), they are applied to the soil and left there. Ten monomers were chosen among the most used in the synthesis of biodegradable polymers (1,2-ethanediol, 1,4-butanediol, 1,6-hexanediol, adipic acid, azelaic acid, sebacic acid, terephthalic acid, glucose, lactic acid, and succinic acid) and tested according to ASTM 5988-96 (a standard test method for determining aerobic biodegradation in soil of plastic materials measuring the carbon dioxide evolution). Two sandy loam soils, collected in two different sites in Italy, were used to evaluate the mineralization rate of the monomers. Four tests (two replicates each) were carried out for 27–39 days. Experimental data show no relevant differences in the respirations of the two soils and in the carbon dioxide productions of the tested monomers. The final mineralization percent was 42–45% for glucose, succinic, and lactic acid and 50–56% for the other monomers.

The biofilter system containing tire-derived rubber particle (TDRP) filter media was utilized to treat the odorous gas contaminant, hydrogen sulfide, in consideration of the economic advantage of reusing discarded tire materials and the high potential of TDRP media for biofilm attachment. The pilot-scale system having 0.38 m3 of bed volume operated with synthetic hydrogen sulfide gas on continuous basis from a range of 0.34 to 1.15 m3/min. This bioreactor system achieved over 94% removal efficiency at 20–90 ppm of inlet H2S concentration while operating in 20–67 s of empty bed retention time, indicating that overall effective operation was performed at mass loading rates of H2S ranging from 19.6 to 28.5 g H2S/(m3 h). It was apparent by the effectiveness of the system’s performance that this system had the capability to effectively remove hydrogen sulfide with high efficiency over a range of concentrations. A maximum elimination capacity was not found for the biofilter during this study, which tested loading rates between 0 and 30 g H2S/(m3 h).

The wide-ranging impacts of globally increasing carbon dioxide (CO2) concentration and rising metal-contaminated soils are serious problems in terrestrial ecosystems. In this study, we investigated the effects of elevated CO2 on the lead (Pb) uptake of pine seedlings and the microbial activity in Pb-contaminated soil. Three-year-old pine seedlings were exposed to ambient, as well as elevated levels of CO2 (380 and 760 ppmv, respectively) in 500 mg/kg Pb-contaminated soil. Growth rates, C/N ratios and Pb uptake of the pine seedlings were determined. Dissolved organic carbon (DOC) content and microbial activity were also measured in the rhizosphere soil. Elevated CO2 significantly increased the total biomass and accumulation of Pb in roots and shoots. In addition, the accumulation of Pb in the roots under elevated CO2 concentration was four times higher than those in the roots under ambient CO2 concentration. Elevated CO2 levels also affected C/N ratios in the pine seedlings and soil enzyme activities. Decline in the overall nitrogen content and increases in the C/N ratios of pine needles were observed. Soil enzyme activity increased in the rhizosphere soils, including those of β-glucosidases, N-acetylglucosaminidases, and phosphatases. Quality of the DOC was affected by elevated CO2, while the quantity of DOC was affected by Pb additions under elevated CO2 conditions. Two major conclusions can be drawn from this study: (1) elevated CO2 significantly increased biomass and metal uptake of pine seedlings and (2) chemical metabolism on pine tissue and processes of organic decomposition were more affected by elevated CO2 levels than by Pb contamination.

The toxicities of three synthetic surfactants to the marine macroalga, Ulva lactuca, have been examined by monitoring chlorophyll a fluorescence quenching. The anionic surfactant, sodium dodecyl sulphate (SDS), exerted no measurable toxicity over the concentration range 0–10 mg L−1, while presence of the non-ionic surfactant, Triton X-100 (TX), elicited a small reduction in photochemical efficiency that was independent of concentration. The cationic surfactant, hexadecyltrimethylammonium bromide (HDTMA), incurred a dose-dependent response to ∼3 mg L−1 (EC50 = 2.4 mg L−1), but a reduction in toxicity thereafter. Presence of TX had little effect on the toxicity of HDTMA but an equimolar concentration of SDS directly offset the impact of HDTMA on photochemical efficiency. Relative toxicities of the surfactants are attributed to differences in affinity for the algal surface and tendencies to disrupt cell membranes and interact with intracellular macromolecules. Non-linear dose responses and antagonistic effects are attributed to non-specific interactions between molecules of the same surfactant and electrostatic interactions between molecules of different amphiphilic character.

Based on the fact that streamwater quality reflects landscape conditions, the objectives of this study were: to investigate nitrogen (N), carbon (C), and major ion concentrations in six streams crossing minimally disturbed Atlantic Forest areas, with similar geomorphological characteristics; to determine N and C fluxes in one of these pristine streams (Indaiá); and assess the impact of human activity on the biogeochemistry of two other streams in the same region, crossing urbanized areas. The distribution pattern of carbon and inorganic nitrogen dissolved forms, as well as the major ion and biogenic gas concentrations in the streamwater, was similar in pristine streams, indicating that the C and N dynamics were determined by influence of some factors, such as climate, atmospheric deposition, geology, soil type, and land covering, which were analogous in the forested watersheds. The urban streams were significantly different from the pristine streams, showing low dissolved oxygen concentrations, high respiration rates, and high concentrations of carbon dioxide, dissolved inorganic nitrogen, dissolved inorganic carbon, and major ion. These differences were attributed to anthropogenic impact on water quality, especially domestic sewage discharge. Additionally, in the Indaiá stream, it was possible to observe the importance of rainfall over temporal dynamics of dissolved carbon forms, and also, the obtained specific flux of dissolved inorganic nitrogen was relatively elevated (approximately 11 kg ha⁻¹ year⁻¹). These results reveal the influence of human activity over the biogeochemistry of coastal streams and also indicate the importance N export of Atlantic Forest to the ocean.

We investigated the potential of soil moisture and nutrient amendments to enhance the biodegradation of oil in the soils from an ecologically unique semi-arid island. This was achieved using a series of controlled laboratory incubations where moisture or nutrient levels were experimentally manipulated. Respired CO2 increased sharply with moisture amendment reflecting the severe moisture limitation of these porous and semi-arid soils. The greatest levels of CO2 respiration were generally obtained with a soil pore water saturation of 50–70%. Biodegradation in these nutrient poor soils was also promoted by the moderate addition of a nitrogen fertiliser. Increased biodegradation was greater at the lowest amendment rate (100 mg N kg−1 soil) than the higher levels (500 or 1,000 mg N kg−1 soil), suggesting the higher application rates may introduce N toxicity. Addition of phosphorous alone had little effect, but a combined 500 mg N and 200 mg P kg−1 soil amendment led to a synergistic increase in CO2 respiration (3.0×), suggesting P can limit the biodegradation of hydrocarbons following exogenous N amendment.

The influence of the operational variables on the Anammox process has been generally researched considering each variable separately. However, the optimization of the process also requires the identification of the more significant variables and their possible interactions. Response surface models were successfully applied to evaluate the performance of the Anammox process in a deammonification system (i.e., one-stage biofilm Anammox process) taking into account the combined effects caused by two sets of three variables. Specific Anammox activity was measured by a manometric method and used as the response variable. The obtained models pointed out that the significant variables were the temperature, the value of pH, and the ratio between the unionized species of the substrates (free ammonia and free nitrous acid (FA/FNA)). There were interactions among them caused by chemical equilibriums. Total nitrogen concentration and ammonium concentration were found to be not significant in the tested range. According to the models, the optimum values of temperature, pH, and free ammonia to free nitrous acid ratio within the test ranges were, respectively, 30°C, 7.0, and 0.3. Further research at higher temperatures and lower values of pH and FA/FNA ratios would be necessary in order to find the absolute optimum conditions for the process. The obtained model can be also useful in order to develop control strategies that take into account the significant variables and their optimum ranges. A strategy to control deammonification reactors has been proposed, according to the results of the modeling.

The goal of this project was to develop a method to measure the total gaseous mercury (TGM) concentrations in unsaturated soils. Existing methods did not allow for easy replication, were costly, and were more suited for other gases, such as CO2, that do not react with collection surfaces. To overcome these problems, we developed a method that simultaneously collects up to ten soil pore air samples. We used a single mass flow controller, one pump, and two banks of rotameters to draw soil air out of the ground at 25 smL min−1 onto gold-coated quartz traps. Analysis of the gold traps was performed with a Tekran 2500 CVAFS mercury detector. The system was field tested at the Piney Reservoir Ambient Air Monitoring Station in western Maryland. Our system was relatively precise and accurate. For example, replicate TGM concentrations differed by less than 25% and recovery of known amounts of mercury were greater than 95%. Field measurements showed that the maximum soil pore air TGM concentrations, between 3 and 4 ng m−3, occurred at the Oe–A soil horizon interface. At all other depths, the total mercury concentrations were lower than the ambient air concentrations of 1.8 ng m−3. We believe our new method can be used to precisely and accurately measure the TGM concentrations in unsaturated soils at multiple locations simultaneously.