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Papers by A. Gomes

Macromol

Active packaging with biobased polymers aim to extend the shelf life of food and to improve the e... more Active packaging with biobased polymers aim to extend the shelf life of food and to improve the environmental sustainability of the food industry. This new concept was tested with samples of fresh poultry meat wrapped with chitosan reinforced with 2.5% of commercial nanocellulose (NC) incorporating 1% of essential oils (EO) from Aloysia citrodora (ACEO) and Cymbopogon citratus (CCEO). The performance of the bionanocomposites containing EOs was assessed and compared with unwrapped meat samples and samples wrapped with chitosan/NC, during a 13 day period of refrigerated storage for several physicochemical parameters related to food deterioration and microbial growth. Wrapping the meat with the chitosan/NC polymer helped to increase the shelf life of the meat. The incorporation of EOs added extra activity to the biocomposites, further delaying the meat deterioration process, by halting the lipid oxidation and the Enterobactereaceae growth until the 9th day. The composition of both EOs ...

Journal of Biotechnology, 2005

Mixed anaerobic bacterial consortia have been show to reduce azo dyes and batch decolourisation t... more Mixed anaerobic bacterial consortia have been show to reduce azo dyes and batch decolourisation tests have also demonstrated that predominantly methanogenic cultures also perform azo bond cleavage. The anaerobic treatment of wool dyeing effluents, which contain acetic acid, could thus be improved with a better knowledge of methanogenic dye degradation. Therefore, the decolourisation of two azo textile dyes, a monoazo dye (Acid Orange 7, AO7) and a diazo dye (Direct Red 254, DR254), was investigated in a methanogenic laboratory-scale Upflow Anaerobic Sludge Blanket (UASB), fed with acetate as primary carbon source. As dye concentration was increased a decrease in total COD removal was observed, but the acetate load removal (90%) remained almost constant. A colour removal level higher than 88% was achieved for both dyes at a HRT of 24 h. The identification by HPLC analysis of sulfanilic acid, a dye reduction metabolite, in the treated effluent, confirmed that the decolourisation process was due mainly to azo bond reduction. Although, HPLC chromatograms showed that 1-amino-2-naphthol, the other AO7 cleavage metabolite, was removed, aeration batch assays demonstrated that this could be due to auto-oxidation and not biological mineralization. At a HRT of 8 h, a more extensive reductive biotransformation was observed for DR254 (82%) than for AO7 (56%). In order to explain this behaviour, the influence of the dye aggregation process and chemical structure of the dye molecules are discussed in the present work.

Journal of Membrane Science, 2005

The influence of osmotic pressure and solute adsorption on permeate flux during nanofiltration (N... more The influence of osmotic pressure and solute adsorption on permeate flux during nanofiltration (NF) of a wool textile dye solution was investigated. Solutions of C.I. Acid Orange 7 with concentrations ranging from 2 to 2000 mg/l were subjected to nanofiltration with a NF 45 membrane. An increase of flux decline with dye concentration was observed. The resistance-in-series model gives evidence that the main factor causing this flux decline is the solute adsorption. This is reinforced by the increase in the apparent rejection with dye concentration. Although osmotic pressure was taken into account, its contribution to a decrease of the driving force seems not to be significant. Adsorption resistance was calculated from a correlation between the pure water fluxes, measured before and after the essays, and feed dye concentration. A Langmuir isotherm type curve agreed well with experimental data. From the solution-diffusion model, the intrinsic rejection coefficient can be predicted as function of feed dye concentration.

Water Science & Technology, 68(10), 2214-2219, Oct 2013

Biodegradability enhancement and detoxification of cork boiling wastewater (CBW) are required for... more Biodegradability enhancement and detoxification of cork boiling wastewater (CBW) are required for the successful implementation of biological treatment options. We studied the possibility of achieving these goals through ozonation pre-treatment by experimenting on the effect of ozone dose and pH. The CBW used had a pH of 5.81, a chemical oxygen demand (COD) of 1,865 mg L
1, a biochemical oxygen demand (BOD5) of 498 mg L
1 and total phenol (TP) and tannin compounds concentrations of 523 and 399 mg L
1, respectively. The ozone doses ranged from 0.27 to 2.63 for the O3(applied)/COD0 ratios with samples at natural pH and set to 3.33 and 9.96. Ozonation allowed the BOD20/COD ratio (biodegradability index) to increase from 0.37 to 0.63 and a toxicity reduction from 3.08 to 1.24 TU (Microtox). The corresponding removals obtained were 15.2–62.0%, 38.4–83.2% and 56.7–92.1% for COD, TP and colour, respectively. The best outcome of ozonation pre-treatment requires O3(applied)/COD0 ratios over 1.5 and an acid pH. The increase of TP removals with ozone dose at acid pH led to biodegradability enhancement and CBW detoxification. However, for similar conditions the highest COD removals were obtained at alkaline pH due to the hydroxyl radicals’ high oxidation ability but lack of selectivity.

Bioresource Technology, 147, 143-151, Sep 2013

Cork boiling wastewater pollutants were fractionated by sequential use of four ultrafiltration me... more Cork boiling wastewater pollutants were fractionated by sequential use of four ultrafiltration membranes and five fractions were obtained: four retentates (>100, 50–100, 20–50 and 10–20 kDa) and one permeate (<10 kDa); which were used to study the correlation of molecular size with biodegradability and toxicity before and after ozonation. The results show that molecular size is correlated with organic load and restrains biodegradability. The fraction with >100 kDa corresponds to 56% of the organic load and the one with <10 kDa only 8%. The biodegradability of fractions increased 182% with fractions molecular size reduction from >100 to < 10 kDa and the chemical oxygen demand (COD) was from 3436 to 386 mg L−1. For biodegradability enhancement the best outcome of ozonation was obtained with compounds having molecular size >20 kDa and range from 5% up to 175% for applied ozone doses to COD ratios between 0.15 and 0.38.

The performance of two constructed wetlands (CWs) with horizontal subsurface flow (HSSF) configur... more The performance of two constructed wetlands (CWs) with horizontal subsurface flow (HSSF) configuration was investigated during a three phases treatment of cork boiling wastewater (CBW). The two CWs were filled with LECA. One was planted (CWP) with common reeds (Phragmites australis) and the other was kept unplanted as a control unit (CWC). The feeding CBW was sequentially diluted to 500, 600 and 750 mg/L COD and pH was set to 6.5-7.5. Other features of the feed solution were the intense dark colour, total phenols (TPh) concentration ranging from 36 to 62 mg/L and low biodegradability. Both CW units showed similar COD (44.7 and 56.6%, respectively) and TPh (40 and 65%, respectively) removal rates for a working period of 4 months. First results indicate that the presence of plants improved the system performance only in terms of total phosphorus (TP) removal (33% and 9% in the CWL and CWC unit, respectively). After phase 1 (500 mg/L influent COD) the major drawback was the absence of ...

Book Chapters by A. Gomes

Constructed Wetlands for Industrial Wastewater Treatment, 2018

Management of cork boiling wastewater (CBW) raises environmental, social and economic concerns in... more Management of cork boiling wastewater (CBW) raises environmental, social and economic concerns in Portugal and Spain, the world-leading producers and exporters. The feasibility of conventional biological treatment processes is very limited due to CBW main characteristics, such as high toxicity, low biodegradability and bioavailability of the organics. Constructed Wetlands systems (CWs) can provide an alternative treatment option with the economic, environmentally friendly and sustainable standards required by the cork manufacture industry since a combination of physical and biological processes can contribute to the effective treatment. This study investigated the performance of horizontal subsurface flow (HSF) CWs in the treatment of CBW. Two microcosm-scale units were loaded, after a careful and extended acclimatization process, with CBW; one bed was planted with common reeds (Phragmites australis) and the other was kept unplanted as a control bed. The mass removal efficiencies of the planted bed exceed those of the control and the mean values were up to 58 and 62% for total phenols and COD with operation loads of 0.6 and 16.5 g/m2/d, respectively Overall results showed the improved performance of the planted bed, indicating the positive contribution of the plants in the treatment process.

Macromol

Active packaging with biobased polymers aim to extend the shelf life of food and to improve the e... more Active packaging with biobased polymers aim to extend the shelf life of food and to improve the environmental sustainability of the food industry. This new concept was tested with samples of fresh poultry meat wrapped with chitosan reinforced with 2.5% of commercial nanocellulose (NC) incorporating 1% of essential oils (EO) from Aloysia citrodora (ACEO) and Cymbopogon citratus (CCEO). The performance of the bionanocomposites containing EOs was assessed and compared with unwrapped meat samples and samples wrapped with chitosan/NC, during a 13 day period of refrigerated storage for several physicochemical parameters related to food deterioration and microbial growth. Wrapping the meat with the chitosan/NC polymer helped to increase the shelf life of the meat. The incorporation of EOs added extra activity to the biocomposites, further delaying the meat deterioration process, by halting the lipid oxidation and the Enterobactereaceae growth until the 9th day. The composition of both EOs ...

Journal of Biotechnology, 2005

Mixed anaerobic bacterial consortia have been show to reduce azo dyes and batch decolourisation t... more Mixed anaerobic bacterial consortia have been show to reduce azo dyes and batch decolourisation tests have also demonstrated that predominantly methanogenic cultures also perform azo bond cleavage. The anaerobic treatment of wool dyeing effluents, which contain acetic acid, could thus be improved with a better knowledge of methanogenic dye degradation. Therefore, the decolourisation of two azo textile dyes, a monoazo dye (Acid Orange 7, AO7) and a diazo dye (Direct Red 254, DR254), was investigated in a methanogenic laboratory-scale Upflow Anaerobic Sludge Blanket (UASB), fed with acetate as primary carbon source. As dye concentration was increased a decrease in total COD removal was observed, but the acetate load removal (90%) remained almost constant. A colour removal level higher than 88% was achieved for both dyes at a HRT of 24 h. The identification by HPLC analysis of sulfanilic acid, a dye reduction metabolite, in the treated effluent, confirmed that the decolourisation process was due mainly to azo bond reduction. Although, HPLC chromatograms showed that 1-amino-2-naphthol, the other AO7 cleavage metabolite, was removed, aeration batch assays demonstrated that this could be due to auto-oxidation and not biological mineralization. At a HRT of 8 h, a more extensive reductive biotransformation was observed for DR254 (82%) than for AO7 (56%). In order to explain this behaviour, the influence of the dye aggregation process and chemical structure of the dye molecules are discussed in the present work.

Journal of Membrane Science, 2005

The influence of osmotic pressure and solute adsorption on permeate flux during nanofiltration (N... more The influence of osmotic pressure and solute adsorption on permeate flux during nanofiltration (NF) of a wool textile dye solution was investigated. Solutions of C.I. Acid Orange 7 with concentrations ranging from 2 to 2000 mg/l were subjected to nanofiltration with a NF 45 membrane. An increase of flux decline with dye concentration was observed. The resistance-in-series model gives evidence that the main factor causing this flux decline is the solute adsorption. This is reinforced by the increase in the apparent rejection with dye concentration. Although osmotic pressure was taken into account, its contribution to a decrease of the driving force seems not to be significant. Adsorption resistance was calculated from a correlation between the pure water fluxes, measured before and after the essays, and feed dye concentration. A Langmuir isotherm type curve agreed well with experimental data. From the solution-diffusion model, the intrinsic rejection coefficient can be predicted as function of feed dye concentration.

Water Science & Technology, 68(10), 2214-2219, Oct 2013

Biodegradability enhancement and detoxification of cork boiling wastewater (CBW) are required for... more Biodegradability enhancement and detoxification of cork boiling wastewater (CBW) are required for the successful implementation of biological treatment options. We studied the possibility of achieving these goals through ozonation pre-treatment by experimenting on the effect of ozone dose and pH. The CBW used had a pH of 5.81, a chemical oxygen demand (COD) of 1,865 mg L
1, a biochemical oxygen demand (BOD5) of 498 mg L
1 and total phenol (TP) and tannin compounds concentrations of 523 and 399 mg L
1, respectively. The ozone doses ranged from 0.27 to 2.63 for the O3(applied)/COD0 ratios with samples at natural pH and set to 3.33 and 9.96. Ozonation allowed the BOD20/COD ratio (biodegradability index) to increase from 0.37 to 0.63 and a toxicity reduction from 3.08 to 1.24 TU (Microtox). The corresponding removals obtained were 15.2–62.0%, 38.4–83.2% and 56.7–92.1% for COD, TP and colour, respectively. The best outcome of ozonation pre-treatment requires O3(applied)/COD0 ratios over 1.5 and an acid pH. The increase of TP removals with ozone dose at acid pH led to biodegradability enhancement and CBW detoxification. However, for similar conditions the highest COD removals were obtained at alkaline pH due to the hydroxyl radicals’ high oxidation ability but lack of selectivity.

Bioresource Technology, 147, 143-151, Sep 2013

Cork boiling wastewater pollutants were fractionated by sequential use of four ultrafiltration me... more Cork boiling wastewater pollutants were fractionated by sequential use of four ultrafiltration membranes and five fractions were obtained: four retentates (>100, 50–100, 20–50 and 10–20 kDa) and one permeate (<10 kDa); which were used to study the correlation of molecular size with biodegradability and toxicity before and after ozonation. The results show that molecular size is correlated with organic load and restrains biodegradability. The fraction with >100 kDa corresponds to 56% of the organic load and the one with <10 kDa only 8%. The biodegradability of fractions increased 182% with fractions molecular size reduction from >100 to < 10 kDa and the chemical oxygen demand (COD) was from 3436 to 386 mg L−1. For biodegradability enhancement the best outcome of ozonation was obtained with compounds having molecular size >20 kDa and range from 5% up to 175% for applied ozone doses to COD ratios between 0.15 and 0.38.

The performance of two constructed wetlands (CWs) with horizontal subsurface flow (HSSF) configur... more The performance of two constructed wetlands (CWs) with horizontal subsurface flow (HSSF) configuration was investigated during a three phases treatment of cork boiling wastewater (CBW). The two CWs were filled with LECA. One was planted (CWP) with common reeds (Phragmites australis) and the other was kept unplanted as a control unit (CWC). The feeding CBW was sequentially diluted to 500, 600 and 750 mg/L COD and pH was set to 6.5-7.5. Other features of the feed solution were the intense dark colour, total phenols (TPh) concentration ranging from 36 to 62 mg/L and low biodegradability. Both CW units showed similar COD (44.7 and 56.6%, respectively) and TPh (40 and 65%, respectively) removal rates for a working period of 4 months. First results indicate that the presence of plants improved the system performance only in terms of total phosphorus (TP) removal (33% and 9% in the CWL and CWC unit, respectively). After phase 1 (500 mg/L influent COD) the major drawback was the absence of ...

Constructed Wetlands for Industrial Wastewater Treatment, 2018

Management of cork boiling wastewater (CBW) raises environmental, social and economic concerns in... more Management of cork boiling wastewater (CBW) raises environmental, social and economic concerns in Portugal and Spain, the world-leading producers and exporters. The feasibility of conventional biological treatment processes is very limited due to CBW main characteristics, such as high toxicity, low biodegradability and bioavailability of the organics. Constructed Wetlands systems (CWs) can provide an alternative treatment option with the economic, environmentally friendly and sustainable standards required by the cork manufacture industry since a combination of physical and biological processes can contribute to the effective treatment. This study investigated the performance of horizontal subsurface flow (HSF) CWs in the treatment of CBW. Two microcosm-scale units were loaded, after a careful and extended acclimatization process, with CBW; one bed was planted with common reeds (Phragmites australis) and the other was kept unplanted as a control bed. The mass removal efficiencies of the planted bed exceed those of the control and the mean values were up to 58 and 62% for total phenols and COD with operation loads of 0.6 and 16.5 g/m2/d, respectively Overall results showed the improved performance of the planted bed, indicating the positive contribution of the plants in the treatment process.