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- Chemical oxidation of fish canning wastewater by Fenton’s reagentPublication . Cristovão, Raquel; Gonçalves, Cristiana; Botelho, Cidália; Martins, Ramiro; Boaventura, RuiThe fish canning industry generates large volume of wastewater for which the treatment is particularly difficult due to the high content of organic matter and salts and to the significant amount of oil and grease they present. In this work, a closed jacketed batch reactor was used to study the feasibility of applying a Fenton reaction step after an activated sludge biological treatment. For this purpose and in order to find optimal conditions, a 33 Box-Behnken full factorial design was used. The predicted optimum value (64% DOC degradation) was found for hydrogen peroxide concentration of 1520 mg/L, iron concentration of 338 mg/L and pH 3.2.
- Uptake and release of divalent zinc ions from aqueous solutions by aquatic moss Fontinalis antipyretica.Publication . Martins, Ramiro; Boaventura, RuiAquatic mosses are able to accumulate zinc and some other heavy metal ions from aqueous solutions and partially release them when exposed to metal-free water. They play an important role in the assessment of toxic elements in water. The advantage of mosses over direct water sampling is that the use of the former lessens spatial and temporal variations, enhances the level of contaminant identification by concentrating toxic elements, and provides information relative to the bioavailable species. However, to make the concentration of metals that can be measured in mosses a reliable indicator of the concentration of toxic elements in the water, we need to model the bioaccumulation phenomenon. Laboratory experiments were conducted to determine zinc uptake and release kinetics by the aquatic moss Fontinalis antipyretica, as this species is widely spread in Portuguese rivers and the majority of the European countries. Zinc was chosen for this study because (i) it acts as micro-nutrient for plant growth in low concentration values; (ii) it is toxic when in excess inhibiting the growth and (iii) it is present in many industrial wastewaters and mine drainage waters discharged into rivers and lakes.
- Biogas production by anaerobic codigestion using kiwi waste and wine sludgePublication . Giacon, Mariana Ferrari; Zschaach, L.G.; Afonso, Maria João A.P.S.; Kreutz, Cristiane; Martins, RamiroConsidering a large generation of wastes, the anaerobic codigestion (AcoD) is an alternative to transform two or more types of organic waste in energy and biofertilizer. To test the biogas production potential using kiwi waste and wine sludge, two AD assays with each substrate isolated and AcoD with four different substrate proportion was realized, using as inoculum sludge from a septic tank. The experimental was realized during 19 days in batch reactor (250 mL). Among digestion results, kiwi waste had de best result, being 27.0 mLN gVS-1 of biogas. The most satisfactory value in AcoD was 40.5 mLN g VS-1 of biogas, from treatment with 0.5 g kiwi and 3.3 g wine sludge. The AcoD test produced 16 mLN gVS-1 of biogas more than AD
- Multistage treatment for olive mill wastewater: Assessing legal compliance and operational costsPublication . Vuppala, Srikanth; Paulista, Larissa Oliveira; Morais, Daniela F.S.; Pinho, Inês L.; Martins, Ramiro; Gomes, Ana I.; Moreira, Francisca C.; Vilar, Vítor J.P.A treatment train for the remediation of a raw olive mill wastewater (OMW) was investigated, aiming to comply with the emission limit values (ELVs) for direct discharge into water bodies. The following stages were proposed: (i) pre-treatment (filtration and sedimentation), (ii) coagulation, (iii) biological oxidation, and (iv) advanced oxidation process (AOP). Under the best-operating conditions for coagulation (0.8 g L- 1 of Al2(SO4)3, pH = 4.5), high removal of total suspended solids (TSS) (97%), turbidity (98%), and phenols (57%) was achieved, along with a decrease in the inhibition of the biological activity. A subsequent biological oxidation stage provided a high removal of organic matter (chemical oxygen demand (COD) removal of 73%). For the third stage, three AOPs were applied and compared – photo-Fenton with UVA radiation (PF-UVA), anodic oxidation (AO), and ozonation (O3). After 3 h of treatment, the PF-UVA process (pH = 2.8, [H2O2] = 400–500 mg L- 1, [Total dissolved iron]0 = 100 mg L- 1) allowed to meet the ELV for COD, but the other parameters exceeded the threshold, while O3 process (inlet concentration = 100 mg O3 Ndm- 3, gas flow = 0.2 Ndm3 min- 1) allowed to comply with phenols, TSS, and sulfate limits. The AO process (current density up to 200 mA cm- 2) was the least efficient AOP for all studied parameters. The operational costs for the coagulation and biological oxidation stages were estimated at 1.20 € m- 3. Regarding the most effective AOPs, ozonation presented an estimated cost 2.3-fold higher than PF-UVA (11.9 € m- 3 vs. 5.2 € m- 3).
- Treatment of Pomace Olive Oil Wastewater by Peroxy-Electrocoagulation with Aluminium SheetsPublication . Martins, Ramiro; Tesuka, Leticia Harumi; Grabowski, Thais Theomaris dos SantosThe extraction of olive pomace oil is a significant aspect of the edible oil industry in Mediterranean regions where olives are widely cultivated. The resulting wastewater generated from this industry is known to harbor pollutants, including residual solvents, oils, and chemicals from the refining process, that can have adverse effects on the environment and public health. Peroxy-electrocoagulation (PEC) is a method that can be used to treat wastewater from the olive pomace oil extraction industry. The purpose of the work was to reduce the concentration of pollutants in the effluent through the use of PEC with aluminum electrodes as a method of treatment. The Box-Behnken Design was used to study the relationship between hydrogen peroxide dosage (10, 20, and 30 g L-1), electric current density (5, 20 and 35 mA cm-2), and the initial pH (2.5, 3.5, and 4.5), in the PEC process, and the removal of chemical oxygen demand (COD) and total phenolic compounds (TPh). The highest removal was obtained with hydrogen peroxide dosage of 30 g L-1, and 20 mA cm-2, and with 29% of TPh removal at pH 2.5, and with 84% COD removal at pH 4.5. The procedure removed an average of 22% COD and 82% TPh. The concentration of hydrogen peroxide was one of the most significant factors in the process. Pre-treatment with other techniques is necessary to reduce harmful elements in the effluent before undergoing biological treatment.
- Treatment for the Olive Pomace Oil Extraction Industry by Appling Peroxy-ElectrooxidationPublication . Martins, Ramiro; Pinheiro, Luis Felipe do Nascimento; Grabowski, Thais Theomaris dos SantosThis study aimed to assess the effectiveness of peroxy-electrooxidation (PEO) for treating wastewater from the olive pomace oil extraction industry. The response surface methodology was utilized to optimize the efficiency of the PEO process under varying conditions of electrolysis time, current density, and hydrogen peroxide (H2O2) dosage. Appling graphite/aluminum sheets as cathode/anode in the treatment process showed that the concentration of H2O2 directly affected the efficiency of total phenolic compounds (TPh) removal. It was observed that at an H2O2 concentration of 15 g L-1, the removal efficiency was less than 80%. The removal of chemical oxygen demand (COD) is mainly influenced by the dosage of H2O2 and the reaction time. The experiments conducted on the PEO processes with graphite/iron sheets showed that the highest removal of TPh was achieved with an H2O2 dosage of 30 g L-1 and an intermediate reaction time of 30 minutes. Current density also had an impact on TPh removal. Regarding COD removal, the results showed that the highest removal rates were attained with increased H2O2 concentrations, but reaction time was a positive factor, with better results obtained with 30 and 50 minutes. The PEO is recommended as a pre-treatment for TPh removal but not for COD and other treatment processes should be evaluated.
- Caracterização das águas residuais da indústria de conservas de sardinhaPublication . Teixeira, Sônia; Martins, RamiroThe canned sardine industry has a set of different stages, from the washing of the sardines, head and viscera removal, boiling, cover and craving sauce addition, until the can sterilization. To obtain the final product, the industrial process produced high volumes of effluents. The effluent is pre-treated, but this is rarely effective and ends up in the county sewer. To implement a suitable treatment process, the first stage is to physically and chemically characterize the effluent. Since the polluting discharges are diversified, the characterization of the main unit flows allows to identify the most critical points and then establish the most suitable treatment. The study shows the results of the characterization of four (4) different flows of one canned sardines Industry unit. There were collected three samples (one per week) at four different points in the production process. The analysed parameters were: Total Suspended Solids (TSS); Volatile Suspended Solids (VSS); Chemical Oxygen Demand (COD); Biological Oxygen Demand (BOD); Total Phosphorus (P); Chloride (Cl-); Ammonia Nitrogen (N- NH3);Total Nitrogen Kjeldahl (Norg); Oil and Grease.
- Treatment of wastewater containing mineral oil by sorption onto granulated corkPublication . Ferreira, Catarina Isabel de Almeida; Pereira, J.; Pintor, Ariana; Correia, P.; Silva, J.; Vilar, Vítor J.P.; Botelho, Cidália; Martins, Ramiro; Orfão, J.; Boaventura, RuiThe aim of this work is the development of a new method to remove oils from wastewaters, namely hydrocarbons. These contaminants, when present in high concentrations, are efficiently removed by physical and chemical processes, such as gravity separators, flocculation and flotation processes; however for low concentrations, these methods are not applicable [1]. Moreover, advanced separation processes such as membrane separation [2] and activated carbon adsorption [3] are expensive options for the treatment of oil-containing wastewaters. This new technique is based on oil and hydrocarbons’ sorption on cork granules.