HPLC-FLD determination of 4-nonylphenol and 4-<Emphasis Type="Italic">tert</Emphasis>-octylphenol in surface water samples

A simple, sensitive and reliable HPLC-FLD method for the routine determination of 4-nonylphenol, 4-NP and 4-tert-octylphenol, 4-t-OP content in water samples was developed. The method consists in a liquid–liquid extraction of the target analytes with dichloromethane at pH  3.0–3.5 followed by the HPLC-FLD analysis of the organic extract using a Zorbax Eclipse XDB C8 column, isocratic elution with a mixed solvent acetonitrile/water 65:35, at a flow rate of 1.0 mL/min and applying a column temperature of 40°C. The method was validated and then applied with good results for the determination of 4-NP and 4-t-OP in Ialomi?a River water samples collected each month during 2006. The concentration levels of 4-NP and 4-t-OP vary between 0.08–0.17 μg/L with higher values of 0.24–0.37 μg/L in the summer months for 4-NP, and frequently <0.05 μg/L but also between 0.06–0.09 μg/L with higher values of 0.12–0.16 μg/L in July and August for 4-t-OP and were strongly influenced by sesonial and anthropic factors. The method was also applied on samples collected over 2 years 2007 and 2008 from urban wastewaters discharged into sewage or directly into the rivers by economic agents located in 30 Romanian towns. Good results were obtained when the method was used for analysis of effluents discharged into surface waters by 16 municipal wastewater treatment plants, during the year 2008.     

Biodegradation and bioconversion of cellulose wastes using bacterial and fungal cells immobilized in radiopolymerized hydrogels

Annually, great amounts of cellulose wastes, which could be measured in many billions of tons, are produced worldwide as residues from agricultural activities and industrial food processing. Consequently, the use of microorganisms in order to remove, reduce or ameliorate these potential polluting materials is a real environmental challenge, which could be solved by a focused research concerning efficient methods applied in biological degradation processes. In this respect, the scope of this chapter is to present the state of the art concerning the biodegradation of redundant cellulose wastes from agriculture and food processing by continuous enzymatic activities of immobilized bacterial and fungal cells as improved biotechnological tools and, also, to report on our recent research concerning cellulose wastes biocomposting to produce natural organic fertilizers and, respectively, cellulose bioconversion into useful products, such as: ‘single-cell protein’ (SCP) or ‘protein-rich feed’ (PRF). In addition, there are shown some new methods to immobilize microorganisms on polymeric hydrogels such as: poly-acrylamide (PAA), collagen-poly-acrylamide (CPAA), elastin-poly-acrylamide (EPAA), gelatin-poly-acrylamide (GPAA), and poly-hydroxy-ethyl-methacrylate (PHEMA), which were achieved by gamma polymerization techniques. Unlike many other biodegradation processes, these methods were performed to preserve the whole viability of fungal and bacterial cells during long term bioprocesses and their efficiency of metabolic activities. The immobilization methods of viable microorganisms were achieved by cellular adherence mechanisms inside hydrogels used as immobilization matrices which control cellular growth by: reticulation size, porosity degree, hydration rate in different colloidal solutions, organic and inorganic compounds, etc. The preparative procedures applied to immobilize bacterial and fungal viable cells in or on radiopolymerized hydrogels and, also, their use in cellulose wastes biodegradation are discussed in detail. In all such performed experiments were used pure cell cultures of the following cellulolytic microorganisms: Bacillus subtilis and Bacillus licheniformis from bacteria, and Pleurotus ostreatus, Pleurotus florida, and Trichoderma viride from fungi. These species of microorganisms were isolated from natural habitats, then purified by microbiological methods, and finally, tested for their cellulolytic potential. The cellulose biodegradation, induced especially by fungal cultures, used as immobilized cells in continuous systems, was investigated by enzymatic assays and the bioconversion into protein-rich biomass was determined by mycelial protein content, during such long time processes. The specific changes in cellular development of immobilized bacterial and fungal cells in PAA hydrogels emphasize the importance of physical structure and chemical properties of such polymeric matrices used for efficient preservation of their metabolic activity, especially to perform in situ environmental applications involving cellulose biodegradation by using immobilized microorganisms as long-term viable biocatalysts.     

Ecotoxicity assessment of lipid regulators in water and biologically treated wastewater using three aquatic organisms

Background, aim, and scope  

The high consumption of blood lipid regulators is leading to frequent reports of the occurrence of fibrates in natural streams and wastewater effluents. This paper describes a study undertaken to evaluate the acute toxicity of bezafibrate, clofibric acid, gemfibrozil, and fenofibric acid, a metabolite of fenofibrate whose ecotoxicity has not been previously reported.     

Do national advisories serve local consumers: an assessment of mercury in economically important North Carolina fish

Consumption of marine fish provides both benefits (lean protein, omega-3 fatty acids and essential nutrients) and risks (main source of mercury (Hg) exposure for humans). Mercury is a potent neurotoxin and the source of more fish advisories nationwide than any other toxicant. Despite the widespread nature of Hg, it is unknown whether local Hg contamination reflects national and regional levels often used as bases to inform consumers of potential fish consumption risk. Thus, the objectives of our study were to examine Hg levels of six commonly consumed marine species harvested locally off the North Carolina coast and to compare our results to published regional (Monterey Bay Aquarium's Seafood Watch List) and national (Environmental Protection Agency, EPA, and Food and Drug Administration, FDA) Hg averages, action levels, and guidelines. We found significant differences in Hg concentrations among collected species, and we identified correlations between Hg concentration and fish length and trophic levels. Collected mahi mahi and triggerfish were below the EPA fish tissue action level (0.3ppm). Wahoo and grouper exceeded the EPA action level but were below the FDA action level (1.0ppm). King mackerel had the highest Hg concentration among targeted species, exceeding both EPA and FDA action levels. Further, our local results were not always consistent with calculated averages from EPA and FDA databases for the same species, and although many of our findings were consistent with Monterey Bay Aquarium's Seafood Watch List (southeast region), recommendations based on Hg levels would conflict with recommendations they provide based on sustainability. We find regional and national averages are not always reflective of local Hg contamination and suggest local data may be needed to accurately assess consumer risk.     

Treatment of a wastewater from a pesticide manufacture by combined coagulation and Fenton oxidation

The treatment of a non-biodegradable agrochemical wastewater has been studied by coupling of preliminary coagulation—flocculation step and further Fenton oxidation. High percentages of chemical oxygen demand (COD) removal (up to 58 %) were achieved in a first step using polyferric chloride as coagulant. This reduced significantly the amount of H₂O₂ required in the further Fenton oxidation. Using the stoichiometric amount relative to COD around 80 % of the remaining organic load was mineralized. The combined treatment allowed achieving the regional discharge limits of ecotoxicity at a cost substantially lower than the solution used so far where these wastewaters are managed as hazardous wastes.