Márcia Dezotti

Fármacos no meio ambiente

Pharmaceutical drugs have been detected in sewage treatment plants, surface waters, underground waters and potable waters. Some investigations have been conducted in several countries such as Germany, Brazil, Canada, United States, The Netherlands, England and Italy. Patients and animals excrete part of pharmaceuticals used for human and veterinary medicine after administration in domestic sewage or on the soil. Drugs residues which have not been completely removed during passage through a sewage treatment plant (STP) enter the aquatic environment. The effects of such residual drugs in terrestrial and aquatic organisms are scarcely known.

Desreguladores endócrinos no meio ambiente: efeitos e conseqüências

There is an increasing interest in micropollutants in the environment that can interfere with the endocrine system, affecting health, growth and reproduction of animals and humans. These substances are known as Endocrine Disrupting Chemicals (EDCs) and can be found in domestic sewage, domestic wastewater treatment plant effluents, and in natural and potable waters. There are numerous chemicals classified as EDCs, such as pesticides, chemicals used and produced by chemical industries and natural and synthetic estrogens. EDCs can be related to the increase of the incidence of anomalies in the reproductive system of animals, cancer in humans and reduction of the masculine fertility.

Effects of ozone pre-treatment on diclofenac: intermediates, biodegradability and toxicity assessment.

Diclofenac (DCF), a common analgesic, anti-arthritic and anti-rheumatic drug, is one of the most frequently detected compounds in water. This study deals with the degradation of diclofenac in aqueous solution by ozonation. Biodegradability (BOD(5)/COD ratio and Zahn-Wellens test), acute ecotoxicity and inhibition of activated sludge activity were determined in ozonated and non-ozonated samples. Liquid chromatography coupled with time-of-flight mass spectrometry (LC/TOF-MS) was used to identify the intermediates formed in 1 h of ozonation. Eighteen intermediates were identified by these techniques and a tentative degradation pathway for DCF ozonation is proposed. Experimental results show that ozone is efficient at removing DCF: >99% removal (starting from an initial concentration of 0.68 mmol L(-1)) was achieved after 30 min of ozonation (corresponding to an absorbed ozone dose of 0.22 g L(-1), which is 4.58 mmol L(-1)). However, only 24% of the substrate was mineralized after 1 h of ozonation. The biodegradability, respiration inhibition in activated sludge and acute toxicity tests demonstrate that ozonation promotes a more biocompatible effluent of waters containing DCF.

Effect of different operational conditions on biofilm development, nitrification, and nitrifying microbial population in moving-bed biofilm reactors.

In this study, the effect of different operational conditions on biofilm development and nitrification in three moving-bed biofilm reactors (MBBRs) was investigated: two reactors were operated in a continuously fed regime and one in sequencing-batch mode. The presence of organic carbon reduced the time required to form stable nitrifying biofilms. Subsequent stepwise reduction of influent COD caused a decrease in total polysaccharide and protein content, which was accompanied by a fragmentation of the biofilm, as shown by scanning electron microscopy, and by an enrichment of the biofilm for nitrifiers, as observed by fluorescent in situ hybridization (FISH) analysis. Polysaccharide and protein concentrations proved to be good indicators of biomass development and detachment in MBBR systems. Ammonium- and nitrite-oxidizing bacteria activities were affected when a pulse feeding of 4 g of NH(4)-N/(m(2)·day) was applied. Free nitrous acid and free ammonia were likely the inhibitors for ammonium- and nitrite-oxidizing bacteria.

Degradation and estrogenic activity removal of 17β-estradiol and 17α-ethinylestradiol by ozonation and O3/H2O2

This work investigated the degradation of a natural (17beta-estradiol) and a synthetic (17alpha-ethinylestradiol) estrogens (pure or in the mixture) and the removal of estrogenic activity by the ozonation and O3/H2O2 process in three different pHs (3, 7 and 11). The effect of oxidation via OH radical was evaluated adding a radical scavenger (t-butanol) in the medium. Estrogenic activity was performed using the YES assay. 17beta-estradiol and 17alpha-ethinylestradiol presented similar estrogenic potential and the association of these estrogens resulted in an addictive effect for estrogenic activity. Ozonation and O3/H2O2 processes were effective in removing the estrogens in aqueous solution. In the mixture at pH 11, removals were higher than 98% and 96% for 17beta-estradiol and 17alpha-ethinylestradiol, respectively. In pH 3, 17beta-estradiol and 17alpha-ethinylestradiol removals were 100% and 99.7%, respectively. When estrogens were treated separately, the removals in pH 11 were superior to 99.7 and 98.8%, while in pH 3 were 100% and 99.5% for 17beta-estradiol and 17alpha-ethinylestradiol, respectively. 17alpha-ethinylestradiol has been always removed at lower rates (pure or in the mixture) for all applied conditions. Estrogenic activity was completely removed in pH 3 for ozonation or O3/H2O2. The samples oxidized in pH 11 presented higher estrogenic activity than those in pH 7. Estrogens removal was lower at pHs 7 and 11, when the scavenger was added to the media. The higher estrogen residual concentrations found in ozonation in presence of tert-butanol are contributing for higher estrogenic activity observed in pHs 7 and 11. By-products with estrogenic activity were formed by oxidation via OH radical. Only a few compounds could be identified in pHs 7 and 11 and they have a phenolic ring, which, probably is contributing to the estrogenic activity observed.

Effect of Elevated Salt Concentrations on the Aerobic Granular Sludge Process: Linking Microbial Activity with Microbial Community Structure

ABSTRACT The long- and short-term effects of salt on biological nitrogen and phosphorus removal processes were studied in an aerobic granular sludge reactor. The microbial community structure was investigated by PCR-denaturing gradient gel electrophoresis (DGGE) on 16S rRNA and amoA genes. PCR products obtained from genomic DNA and from rRNA after reverse transcription were compared to determine the presence of bacteria as well as the metabolically active fraction of bacteria. Fluorescence in situ hybridization (FISH) was used to validate the PCR-based results and to quantify the dominant bacterial populations. The results demonstrated that ammonium removal efficiency was not affected by salt concentrations up to 33 g/liter NaCl. Conversely, a high accumulation of nitrite was observed above 22 g/liter NaCl, which coincided with the disappearance of Nitrospira sp. Phosphorus removal was severely affected by gradual salt increase. No P release or uptake was observed at steady-state operation at 33 g/liter NaCl, exactly when the polyphosphate-accumulating organisms (PAOs), “Candidatus Accumulibacter phosphatis” bacteria, were no longer detected by PCR-DGGE or FISH. Batch experiments confirmed that P removal still could occur at 30 g/liter NaCl, but the long exposure of the biomass to this salinity level was detrimental for PAOs, which were outcompeted by glycogen-accumulating organisms (GAOs) in the bioreactor. GAOs became the dominant microorganisms at increasing salt concentrations, especially at 33 g/liter NaCl. In the comparative analysis of the diversity (DNA-derived pattern) and the activity (cDNA-derived pattern) of the microbial population, the highly metabolically active microorganisms were observed to be those related to ammonia (Nitrosomonas sp.) and phosphate removal (“Candidatus Accumulibacter”).

Nitrification of industrial and domestic saline wastewaters in moving bed biofilm reactor and sequencing batch reactor

Nitrification of saline wastewaters was investigated in bench-scale moving-bed biofilm reactors (MBBR). Wastewater from a chemical industry and domestic sewage, both treated by the activated sludge process, were fed to moving-bed reactors. The industrial wastewater contained 8000 mg Cl(-)/L and the salinity of the treated sewage was gradually increased until that level. Residual substances present in the treated industrial wastewater had a strong inhibitory effect on the nitrification process. Assays to determine inhibitory effects were performed with the industrial wastewater, which was submitted to ozonation and carbon adsorption pretreatments. The latter treatment was effective for dissolved organic carbon (DOC) removal and improved nitrification efficiency. Nitrification percentage of the treated domestic sewage was higher than 90% for all tested chloride concentrations up to 8000 mg/L. Results obtained in a sequencing batch reactor (SBR) were consistent with those attained in the MBBR systems, allowing tertiary nitrification and providing adequate conditions for adaptation of nitrifying microorganisms even under stressing and inhibitory conditions.

Photocatalytic/H2O2 treatment of oil field produced waters

Gas chromatography/mass spectroscopy (GC/MS) was used to evaluate the efficiency of the photocatalytic degradation of pollutants present in the oil field produced waters from Campos Basin, Rio de Janeiro, Brazil over TiO2 (anatase), in terms of organic loading reduction and acute toxicity removal observed in a previous publication. The effect of adding hydrogen peroxide has been investigated through an experimental design and found to be an adverse one. Two types of photocatalyst (Aldrich and Degussa P25) were used, and afterwards, their surfaces were investigated using scanning electron microscopy (SEM). The former showed an intense initial coverage by organic compounds and a severe corrosion with the use of hydrogen peroxide. The latter presented almost no initial coverage and was not corroded for small periods of photocatalytic treatment, also in the presence of the peroxide.

Ozonation of azo dyes (Orange II and Acid Red 27) in saline media.

Ozonation of two azo dyes was investigated in a monitored bench scale bubble column reactor (8.5-L), varying liquid media salt content (0, 1, 40 and 100 g L(-1), NaCl). In experiments with Orange II pH was varied (5, 7.5 and 9) but ozonation of Acid Red 27 was performed at pH 7.5. Ozone self-decomposition rate-constant increased with salt concentration. Color removal was very effective and fast achieved under all experimental conditions. For the two azo dyes tested, more than 98% of color intensity was removed in 30-min ozonation assays. However, only partial mineralization of azo dyes (45%-Orange II; 20%-Acid Red 27) was attained in such experiments. The degree of mineralization (TOC removal) was negatively affected by salt concentration. Biodegradation assays conducted by respirometry revealed the inhibitory effect of dye degradation products formed during ozonation.

Photocatalysis as a tertiary treatment for petroleum refinery wastewaters

Photocatalysis has been used as tertiary treatment for petroleum refinery wastewaters to comply with the regulatory discharge limits and to oxidize persistent compounds that had not been oxidized in the biological treatment. The wastewater is generated by the refinery and directly discharged into the Guanabara Bay (Rio de Janeiro). Although BOD removal is high, a residual and persistent COD, besides a somewhat high phenol content remains. Three photocatalysts were tested - TiO2 (Aldrich), ZnO (Aldrich), and TiO2 (P25, Degussa) - the third being the most active. The optimized conditions obtained with an experimental design were 3.0 g L-1 TiO2 and pH 6.3. The use of hydrogen peroxide (H2O2) showed no beneficial effect. Removal of 93% of phenols, 63% of dissolved organic carbon (DOC), and more than 50% of oil and grease (OG) were achieved in the photocatalytic process, improving the quality of the treated wastewater.