José Santos Oliveira

The behaviour of ashes and heavy metals during the co-combustion of sewage sludges in a fluidised bed.

Co-combustion tests of dry sewage sludges with coal were performed in a pilot bubbling FBC aiming at the characterization of ashes and determining the behaviour of heavy metals in the process. The tests showed compliance with the regulatory levels as far as heavy metal emissions were concerned. The bottom ashes, which accounted for about 70% of the total ash production, were obtained in a granular form, with diameters ranging from 0.5 to 4 mm. The heavy metals were distributed in ashes obtained from different locations of the installation and their concentrations were found to vary depending on the location of capture. The increase in heavy metals content in bottom ashes was not found to lead to higher leachability and ecotoxicity compared to sewage sludges, suggesting that there could be opportunities for their further use. Mercury suffered vaporisation inside the reactor, thus leaving bottom ashes free of contamination by it. However, there was observed a strong retention of mercury in cyclone ashes due to the presence of unburned carbon which probably acted as an adsorbent. The effluent mercury was also found to be mostly associated with the particulate fraction, being less than 20% emitted in gaseous forms. The results suggested that the combustion of the sewage sludge could successfully be carried out and the amount of unburned carbon leaving the combustor but captured in cyclone was large enough to ensure substantial retention of mercury at low temperatures, hence could contribute to an improvement of the mercury release which still remains an issue of great concern to resolve during combustion of waste materials.

IMPAIRMENT OF HUMAN CYP1A2-MEDIATED XENOBIOTIC METABOLISM BY ANTLEY-BIXLER SYNDROME VARIANTS OF CYTOCHROME P450 OXIDOREDUCTASE

Y459H and V492E mutations of cytochrome P450 reductase (CYPOR) cause Antley-Bixler syndrome due to diminished binding of the FAD cofactor. To address whether these mutations impaired the interaction with drug-metabolizing CYPs, a bacterial model of human liver expression of CYP1A2 and CYPOR was implemented. Four models were generated: POR(null), POR(wt), POR(YH), and POR(VE), for which equivalent CYP1A2 and CYPOR levels were confirmed, except for POR(null), not containing any CYPOR. The mutant CYPORs were unable to catalyze cytochrome c and MTT reduction, and were unable to support EROD and MROD activities. Activity was restored by the addition of FAD, with V492E having a higher apparent FAD affinity than Y459H. The CYP1A2-activated procarcinogens, 2-aminoanthracene, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, and 2-amino-3-methylimidazo(4,5-f)quinoline, were significantly less mutagenic in POR(YH) and POR(VE) models than in POR(wt), indicating that CYP1A2, and likely other drug-metabolizing CYPs, are impaired by ABS-related POR mutations as observed in the steroidogenic CYPs.

Genotoxicity of instant coffee: possible involvement of phenolic compounds.

Instant coffee exhibits direct genotoxic activity in the tester strains TA 98, 100, 102, 104 and YG 1024. In the Ames tester strain TA 100, the presence of S9 mix, S100 mix, S9 mix without cofactors led to a significant decrease of the genotoxicity observed. The decrease observed in the presence of S9 mix seems to be highly correlated with the catalase content of S9 mix. The genotoxicity of instant coffee detected in strain TA 100 was dependent on the pH, with higher genotoxic effects at pH values above neutrality. Also, dependent on the pH was the ability of some phenolic molecules present in coffee promoting the degradation of deoxyribose in the presence of Fe3+/EDTA. These results suggest that apart from other molecules present in instant coffee responsible for their genotoxicity in several short term assays, phenolic molecules could also be implicated in the genotoxicity of coffee, via reactive oxygen species arising from its auto-oxidation.

Sanitary quality of sands from beaches of azores islands

An evaluation of the sanitary quality of the sand beaches of Azores archipelago was undertaken May-October 1994 and 1995. The samples were analysed for total and faecal coliforms, faecal enterococci, Clostridium, Pseudomonas aeruginosa and fungi (keratinolytic, yeasts, potential pathogenic and allergic and/or environmental saprophytes). The results were evaluated according to a “ Proposal Guideline for the Microbiological Quality of Sand ”. The data showed good or satisfactory sanitary quality of the sand beaches. The results indicated that the faecal enterococci can be a better indicator organism than the total and faecal coliforms. The fungi could be used as indicator organisms. The application of the “Proposal” should complete the criteria used in the “Blue Flag” distinction for high environmental quality beaches.

Genotoxicity of instant coffee and of some phenolic compounds present in coffee upon nitrosation.

Instant coffee exhibits genotoxic activity upon nitrosation at acidic pH values in the Ames tester strain TA100. Using adsorption chromatography (Amberlit XAD-2) it was observed that the major fraction of molecules responsible for the genotoxic activity upon nitrosation was not retained on this resin, suggesting that the polar molecules present in instant coffee could be responsible for the genotoxicity observed upon nitrosation. Some phenolic molecules present in instant coffee (catechol, caffeic acid, and chlorogenic acid) were also genotoxic upon nitrosation under the same experimental conditions. The concentrations of nitrosatable phenolic compounds in the studied coffee were determined by HPLC and their contributions to the total genotoxicity observed were studied. The results obtained suggest that besides phenolic compounds other molecules were also involved in the genotoxicity of this beverage upon nitrosation. Teratogenesis Carcinog. Mutagen. 20:241-249, 2000.

Leaching Behaviour of a Glass Produced from a MSWI Bottom Ash

This paper is mainly focused on the characterisation of a glass material (GM) obtained from the thermal treatment of a bottom ash (BA) produced at the Municipal Solid Waste (MSW) incineration plant of Valorsul. By melting the BA at 1400°C during 2 hours, and without using any chemical additives, a homogeneous black-coloured glass was obtained. The thermal and mechanical properties of this glass were characterised. The thermal expansion coefficient, measured by dilatometry, was 9-10 x 10-6 per °C and the modulus of rupture, determined by four-point bending test, was 75±6 MPa, which are similar values to those exhibited by commercial soda-lime-silica glasses used in structural applications. The chemical and the ecotoxicological leaching behaviour of the GM were also analysed. The GM was submitted to a leaching procedure composed of 15 sequential extraction cycles. A liquid/solid (L/S) ratio of 2 l/kg was applied in each cycle. The leachates were filtered through a membrane of PTFE (porosity: 0.45 8m). The filtered leachates were characterised for different chemical parameters and for an ecotoxicological indicator (bacterium Vibrio fischeri). The GM was also submitted to a microwave acidic digestion for the assessment of the total metal content. The crude BA was also submitted to the same experimental procedures. The GM showed levels of chemical emission and ecotoxicity for V. fischeri much lower than those determined for the crude BA. Similar characterisation studies will be pursued with the glass-ceramics produced by adequate thermal treatment of the glass, in order to investigate the effect of the crystallization on the final properties.

Miscanthus x Giganteus: Contribution to a Sustainable Agriculture of a Future/Present - Oriented Biomaterial

The main purpose of this work was to study the phytoremediation capacity of Miscanthus x giganteus to soils contaminated with heavy metals and also to evaluate the environmental risks due to its utilisation as a biomaterial. Indeed, the concentration of metals in the aerial part of the plant might represent a question of its future use. Four levels of contamination were studied: P0 = 0 t; P50 = 50 t; P100 = 100 t; P200 = 200 t domestic sludge.ha -1 . The results obtained permit to conclude that in terms of the productivity there are significant differences among the plants obtained with different levels of contamination. P50 and P100 presented significantly higher values. In relation to the ash, nitrogen and phosphorous contents, the results showed an increase in mineral matter and an accumulation in nitrogen and phosphorous, in the plants, with the increase of the level of contaminants. But this increase was not significant. No significant differences were observed in the plants among the different levels of sludge, for most of the metals studied. This fact leads to the conclusion that the utilisation of the biomass, obtained in those contaminated fields, is possible, as a biomaterial. Thus, contributing not only to increase its economical value but also to a sustainable agriculture.

Efficiency of removal in stabilization ponds II: statistical analysis of K values

The analytical values obtained from five WSP systems located in different ecoclimatic zones in the centre and South of Portugal, were subjected to a statistical analysis of K and K20 values (as used in the van Hoff-Arrhenius equation) utilizing an analysis of variance and a vectorial analysis of principal components. Significant differences between K and K20 values in facultative, maturation ponds and in the whole system were verified. The projection of the first principal components of eigenvectors made possible the classification of the stations, showing the existence of similarities and discrepancies in their removal BOD kinetics behaviour. The K20 value must be estimated and taken into account for the design of waste stabilization ponds.

CHARACTERIZATION OF SWEET, FIBRE AND BIOMASS SORGHUM POTENTIAL IN PORTUGAL AS AN INDUSTRIAL AND ENERGY FEEDSTOCK

The purpose of this work was to investigate the influence of crop management on the sorghum biomass quality and productivity, in Portugal, in order to access its potential as an industrial and energy feedstock. To do so, the effects of different fertilization levels, the sowing date and the harvest date in the biomass quality and productivity, were studied. Productivity was affected by the level of nitrogen and by the sowing date. Highest productivities were obtained in the most N-fertilised fields and in fields sowed between 251h March and 1’‘ May. Among subspecies, Sweet and Biomass Sorghum presented, globally, higher productivities than Fibre Sorghum. In all the experimental years, highest productivities, in all the fields, were achieved at 193 5 9 days after sowing, regardless of all the different sowing dates. Biomass quality was affected by the crop productivities. Fields with lowest productivities resulted in a biomass with a higher nitrogen and ash contents, namely the fields sowed at 2nd June and the fields without N-fertiliser. In the experimental conditions at Caparica, sweet sorghum crop showed a better potential as an industrial and energy feedstock, and to get better results, economically and environmentally, fields should he sowed between 25’h March and 1’‘ May, with a high nitrogen input (120 kg N/ha).

Environmental and Genotypical Influences on Triticale Grain Quality in Northeast of Portugal

The effect of environmental conditions on the nutritional values of six triticale genotypes was studied by testing at five stations located in the Vila Real and Braganca districts.