Shortcut biological nitrogen removal (SBNR) in microbial fuel cells (MFCs)

Microbial Fuel Cells (MFCs) represent nowadays a promising technology for the treatment of industrial wastewater. In this work the Shortcut Nitritation/Denitritation process in H-type MFC was investigated. The cell was fed by sodium acetate and fumaric acid, as organic carbon source, and ammonium sulphate, sodium nitrite and sodium nitrate as nitrogen source. Anaerobic digestion supernatant (digestate) was used as bacterial source. Batch tests were performed at a TOC/N ratio of 0.35, and Total Organic Carbon (TOC), pH and Open Circuit Voltage (OCV) were daily monitored. High organic carbon removal (up to 85%) in short time (within 6 days) were achieved. The nitritation proved to be independent of organic carbon amount and composition: an ammonium content reduction of about 45% was observed. Regarding the denitritation step, an almost quantitative removal of nitrite and nitrate was observed when fumaric acid was used as a carbon source

Photolysis of in-situ electrogenerated hydrogen peroxide for the degradation of emerging pollutants

This study investigates the degradation of paracetamol, an emerging contaminant widely used as pain and fever reliever, by means of hydrogen peroxide either alone or in combination with UV-C photolysis. In particular, we provide a comparison between the performance of both commercial and electrogenerated H2O2 whose production has been achieved by galvanostatic electrolysis in undivided reactor with a gas diffusion cathode. The performance of the treatments has been assessed in terms of both pollutant decay and mineralization. The influence of the H2O2 to paracetamol molar ratio is discussed. The results show that the electrogenerated hydrogen peroxide, when activated by UV-C irradiation, results in faster degradation and mineralization of paracetamol. However, under the conditions adopted, complete depletion of the total organic carbon (TOC) has never been attained

Shortcut Biological Nitrogen Removal (SBNR) in an MFC anode chamber under microaerobic conditions. The effect of C/N ratio and kinetic study

In this work, the feasibility of the Shortcut Biological Nitrogen Removal (SBNR) in the anodic chamber of a Microbial Fuel Cell (MFC) was investigated. Thirty day experiments were carried out using synthetic wastewaters with a Total Organic Carbon vs. nitrogen ratio (TOC/N) ranging from 0.1 to 1. Ammonium, nitrite, nitrate, pH, and TOC were daily monitored. Results showed that microaerobic conditions in the anodic chamber favored the development of nitritation reaction, due to oxygen transfer from the cathodic chamber through the membrane. Nitritation was found to depend on TOC/N ratio: at TOC/N equal to 0.1 an ammonium removal efficiency of up to 76% was observed. Once the oxygen supply to the cathodic chamber was stopped, denitritation occurred, favored by an increase of the TOC/N ratio: a nitrite removal of 80.3% was achieved at TOC/N equal to 0.75. The presence of nitrogen species strongly affected the potential of the electrochemical system: in the nitritation step, the Open Circuit Voltage (OCV) decreased from 180 mV to 21 mV with the decrease of the TOC/N ratio in the investigated range. Lower OCV values were observed in the denitritation steps since the organic carbon acted as the energy source for the conversion of nitrite to nitrogen gas. A kinetic analysis was also performed. Monod and Blackman models described the ammonium and the organic carbon removal processes well during the nitritation step, respectively, while Blackman-Blackman fitted experimental results of the denitritation step better

Investigation of the synergistic effect of hydrogen peroxide and ultrasound on the photocatalytic treatment under visible light of dyes wastewater

A photocatalytic process under visible light irradiation (LED lamp 13 W) assisted by ultrasound and hydrogen peroxide was investigated, aiming at enhancing the hydroxyl radical production compared to simple photocatalysis. Several parameters, including ultrasound power and H2O2 concentration, were investigated in the degradation of Rhodamine B. Fe doped TiO2 synthesized by the solid-state method was used as the photocatalyst. The synergistic effects between photocatalysis, ultrasound, and H2O2 were studied, and the absence of synergy between photocatalysis and ultrasound was demonstrated. Instead, a synergistic effect was observed between photocatalysis and hydrogen peroxide addition, in fact, the combination of photocatalysis with H2O2 was demonstrated to totally remove the Rhodamine B (5 ppm) in 2 h, as contaminant removal was greater (by 50 %) when the two treatments were used simultaneously than the removal observed in the individual treatments, attributable to the Fenton reaction that promoted the hydroxyl radicals production

Cadmium Removal from Acqueous Solution by Adsorption on Spent Coffee Grounds

Cadmium is a highly toxic element and can cause serious damages to the health of human beings. It is on the seventh position on the Agency for Toxic Substances and Disease Registry (ATSDR, 2015) list for dangerous elements. The Environmental Protection Agency (EPA) and the International Agency for Research on Cancer (IARC) have also recognized cadmium as a carcinogen. For all these reasons, in the recent years stringent limits have been set for this element both in industrial and drinking water. In this paper the potential of spent coffee grounds (SCG) for the removal of cadmium from contaminated water was investigated. Batch experiments were performed at different temperatures, i.e. 10, 25 and 40°C on untreated SCG. The size range of the SCG particles studied was ≤ 500 μm. The results obtained showed that the equilibrium of cadmium on SCG was reached after 3 hours. The Langmuir isotherm provided the best correlation for the adsorption process, with a maximum adsorption capacity of 4.48 mg g–1at 10 °C. Thermodynamic analysis confirmed the exothermicity and spontaneity of the phenomenon. Kinetic studies have revealed that the cadmium adsorption onto SCG followed a pseudo-second order kinetic model and the activation energy value calculated was of 14.5 kJ mol-1, which have evidenced the physical nature of the process. Overall, this study strongly supports the use of SCG as an effective and economical adsorbent for the removal of cadmium from both industrial and drinking water.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Ciencias Aplicadas (CINDECA

Perspectives in nanotechnology based innovative applications for the environment

In this perspective paper, the actual trends in nanotechnology based innovative applications for the environment are analyzed and possible future trends were studied. On the basis of the relevant topics of the NINE congress held in Rome, 2016, a bibliographical search was performed on papers fitting in one or more categories within the last 5 years, that is: 1. Nanosensors and bionanosensors for environmental characterization and monitoring 2. Technologies for the production of Nanomaterials for the environment 3. Nanostructured materials for advanced remediation processes 4. Nano-based water and wastewater treatment processes 5. Membrane processes for the environment 6. Health and safety issues concerning Nanomaterials 7. Education on Environmental Engineering and Nanotechnology. A yearly count of contributions was performed and taken as an indicator of interest of the specific topic within the wide broad scientific community. In a second step, the resulting data was analyzed by regression techniques to estimate the trend in the next future and to evaluate the next challenges within the international research framework

The influence of heavy metals and organic matter on hexavalent chromium reduction by nano zero valent iron in soil

During the last decades great attention has been payed at evaluating the feasibility of Cr(VI) reduction in soil by nano zero valent iron (nZVI). An inhibitory effect on the Cr(VI) reduction by Fe-0 nanoparticles is generally shown in the presence of high level of heavy metals and natural organic matter in soil. Heavy metals in the environment can react with nZVI by redox reactions, precipitation/dissolution reactions, and adsorption/desorption phenomena. As a result of the presence of metals as Ni, Pb, a decrease in the rate of Cr(VI) reduction was observed. Hence, in the present study, experimental tests of Cr(VI) reduction by nZVI in the presence of selected heavy metals, such as nickel and lead, and in the presence of high level of organic matter, are presented and discussed. Results showed a decrease in the rate of Cr(VI) reduction in soil by nZVI (at a x25 stoichiometric excess) from 91% to 78%, 71% and 74% in the presence of Ni, Pb and both metals respectively. As regards the results of Cr(VI) reduction in the presence of organic matter, by using a reducing solution of nZVI (x25 stoichiometric excess) a decrease of Cr(VI) reduction yield from 91% to 12% was observed after 2 hours of treatment in a soil containing 35.71 g/kg of organic matter. Such low efficiency was attributed to the adsorption of organic matter onto Fe-0 nanoparticles surface, thus saturating the active reaction sites of Fe-0 nanoparticles. In addition, a significant reduction of the organic carbon in the treated soil was observed (up to 77.5%) caused by the degradation of organic matter and its dissolution in the liquid phase. A slight decrease of the total metal concentration in treated soil was also observed. Finally, kinetic tests show that Cr(VI) reduction using nZVI in the presence of a high concentration of organic compound obeyed a pseudo-zero-order kinetic model

Cadmium Removal from Acqueous Solution by Adsorption on Spent Coffee Grounds

Cadmium is a highly toxic element and can cause serious damages to the health of human beings. It is on the seventh position on the Agency for Toxic Substances and Disease Registry (ATSDR, 2015) list for dangerous elements. The Environmental Protection Agency (EPA) and the International Agency for Research on Cancer (IARC) have also recognized cadmium as a carcinogen. For all these reasons, in the recent years stringent limits have been set for this element both in industrial and drinking water. In this paper the potential of spent coffee grounds (SCG) for the removal of cadmium from contaminated water was investigated. Batch experiments were performed at different temperatures, i.e. 10, 25 and 40°C on untreated SCG. The size range of the SCG particles studied was ≤ 500 μm. The results obtained showed that the equilibrium of cadmium on SCG was reached after 3 hours. The Langmuir isotherm provided the best correlation for the adsorption process, with a maximum adsorption capacity of 4.48 mg g–1at 10 °C. Thermodynamic analysis confirmed the exothermicity and spontaneity of the phenomenon. Kinetic studies have revealed that the cadmium adsorption onto SCG followed a pseudo-second order kinetic model and the activation energy value calculated was of 14.5 kJ mol-1, which have evidenced the physical nature of the process. Overall, this study strongly supports the use of SCG as an effective and economical adsorbent for the removal of cadmium from both industrial and drinking water.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Ciencias Aplicadas (CINDECA

Soil Biocementation via Enzyme Induced Carbonate Precipitation (eicp) Method Employing Soybeans as a Source of Cheap Enzyme

In this work, the soil improvement technique via Enzyme Induced Carbonate Precipitation (EICP) was investigated by employing, as an alternative to expensive pure enzymes, enzymes extracted from agro-food wastes (tomato, apple, and soybean) such that the process is economically viable and fully embraces the concept of the circular economy. The feasibility of the process was evaluated by monitoring calcium carbonate precipitation in a sand sample. The effect of selected operative parameters was investigated during the injection into different grain size sand samples. The optimal operating conditions in terms of sand grain size, temperature, Urea/Calcium concentration were found. Results demonstrated the effectiveness of this alternative solution for EICP method in term of acquired material strength and the possibility to operate sand consolidation through an economically sustainable process