A study on ozonation and ozone based advanced oxidation processes for the removal of naphthenic acids from water: kinetic studies modelling and optimal control

Industrial wastewater is one of the largest environmental challenges of this century. Most of these wastewaters contain non-biodegradable pollutants which need special treatment methods. Advanced oxidation processes (AOP’s), such as, ozonation, catalytic ozonation and ozone/ hydrogen peroxide have proved their effectiveness on the degradation of bio-recalcitrant pollutants. The main drawback in these processes is the high operating cost. The objective of this study was to develop innovative continuous ozonation and ozone based processes that can effectively degrade industrial non-biodegradable pollutants. Naphthenic acids (NAs) was used as the model pollutant in this study due to its importance as a major pollutant in oil and oil sands industries. The target was to convert bio-recalcitrant NAs into biodegradable substances with minimum consumption of ozone gas (operating cost). These processes can be followed by the biodegradation process to fully remove the rest of the pollutants. This research passed through several stages including screening of operating parameters, kinetic studies, and modeling, followed by optimal control of these processes. It was found that ozone concentration had the most significant effect on the NAs degradation compared to other parameters. The kinetics of direct and indirect (radical) ozonation of NAs were investigated and rate constants and activation energies of these reactions were determined. Catalytic ozonation of NAs was explored using alumina supported metal oxides and unsupported catalysts. Activated carbon was found to be the most effective catalyst. The addition of hydrogen peroxide into the ozonation systems significantly improved the removal of NAs compared with the ozonation only process. Models based on mass balance for the ozonation and ozone/ hydrogen peroxide processes were developed to predict the concentration profiles of reacting species. Optimal control policies of ozone/oxygen gas flow rate versus time were developed and validated to minimize NAs concentration in the liquid outlet stream from the continuous ozonation and ozone/ hydrogen peroxide processes. The experimental results demonstrated that the optimal control policies successfully minimized NAs concentration in the outlet stream. At the same time, ozone gas consumption was reduced to its minimum, i.e., just enough to minimize the concentration of NAs in the outlet stream.

A study on ozonation and ozone based advanced oxidation processes for the removal of naphthenic acids from water: kinetic studies modelling and optimal control

Industrial wastewater is one of the largest environmental challenges of this century. Most of these wastewaters contain non-biodegradable pollutants which need special treatment methods. Advanced oxidation processes (AOP’s), such as, ozonation, catalytic ozonation and ozone/ hydrogen peroxide have proved their effectiveness on the degradation of bio-recalcitrant pollutants. The main drawback in these processes is the high operating cost. The objective of this study was to develop innovative continuous ozonation and ozone based processes that can effectively degrade industrial non-biodegradable pollutants. Naphthenic acids (NAs) was used as the model pollutant in this study due to its importance as a major pollutant in oil and oil sands industries. The target was to convert bio-recalcitrant NAs into biodegradable substances with minimum consumption of ozone gas (operating cost). These processes can be followed by the biodegradation process to fully remove the rest of the pollutants. This research passed through several stages including screening of operating parameters, kinetic studies, and modeling, followed by optimal control of these processes. It was found that ozone concentration had the most significant effect on the NAs degradation compared to other parameters. The kinetics of direct and indirect (radical) ozonation of NAs were investigated and rate constants and activation energies of these reactions were determined. Catalytic ozonation of NAs was explored using alumina supported metal oxides and unsupported catalysts. Activated carbon was found to be the most effective catalyst. The addition of hydrogen peroxide into the ozonation systems significantly improved the removal of NAs compared with the ozonation only process. Models based on mass balance for the ozonation and ozone/ hydrogen peroxide processes were developed to predict the concentration profiles of reacting species. Optimal control policies of ozone/oxygen gas flow rate versus time were developed and validated to minimize NAs concentration in the liquid outlet stream from the continuous ozonation and ozone/ hydrogen peroxide processes. The experimental results demonstrated that the optimal control policies successfully minimized NAs concentration in the outlet stream. At the same time, ozone gas consumption was reduced to its minimum, i.e., just enough to minimize the concentration of NAs in the outlet stream.

The Effect of Ni-Modified LSFCO Promoting Layer on the Gas Produced through Co-Electrolysis of CO2 and H2O at Intermediate Temperatures

The co-electrolysis of CO2 and H2O at an intermediate temperature is a viable approach for the power-to-gas conversion that deserves further investigation, considering the need for green energy storage. The commercial solid oxide electrolyser is a promising device, but it is still facing issues concerning the high operating temperatures and the improvement of gas value. In this paper we reported the recent findings of a simple approach that we have suggested for solid oxide cells, consisting of the addition of a functional layer coated to the fuel electrode of commercial electrochemical cells. This approach simplifies the transition to the next generation of cells manufactured with the most promising materials currently developed, and improves the gas value in the outlet stream of the cell. Here, the material in use as a coating layer consists of a Ni-modified La0.6Sr0.4Fe0.8Co0.2O3, which was developed and demonstrated as a promising fuel electrode for solid oxide fuel cells. The results discussed in this paper prove the positive role of Ni-modified perovskite as a coating layer for the cathode, since an improvement of about twofold was obtained as regards the quality of gas produced.

The Effect of Ni-Modified LSFCO Promoting Layer on the Gas Produced Through Co-Electrolysis of CO2 and H2O at Intermediate Temperatures

The co-electrolysis of CO2 and H2O at intermediate temperature is a viable approach for the power-to-gas conversion that deserves for further investigation, considering the need for green energy storage. The commercial solid oxide electrolyser is a promising device, but it is still facing to solve issues concerning the high operating temperatures and the improvement of gas value. In this paper we reported the recent findings of a simple approach that we have amply suggested for solid oxide cells consisting in the addition of a functional layer coated to the fuel electrode of commercial electrochemical cells. This approach simplifies the transition to the next generation of cells manufactured with the most promising materials currently developed and improves the gas value in the outlet stream of cell. Here, the material in use as a coating layer consisted of a Ni-modified La0.6Sr0.4Fe0.8Co0.2O3 which was developed and demonstrated as promising fuel electrode for solid oxide fuel cells. The results discussed in this paper proved the positive role of Ni-modified perovskite as a coating layer for the cathode, since an improvement of about twice was obtained about the quality of gas produced.

Simulating Trambouze reaction for a series reactor

Simulating the existing data on Trambouze reaction is compiled in this article. The objective of the work is to present the change of volumetric flow rate and the inlet concentration of key reactant A in a series continuous stirred tank reactor-plug flow reactor (CSTR-PFR) configurations. The volumetric flow rate does not affect selectivity and conversion for a constant volumetric flow rate operating condition, entering CSTR and PFR, at a specific concentration of reactant. The CSTR-PFR series reactor configuration is proposed for the aim of maximizing the selectivity of the desired product B in comparison to the undesired products X and Y. CSTR as the first reactor is capable to achieve the maximum conversion at the highest selectivity of A. PFR is then proposed after CSTR in a configuration of CSTR-PFR, to allow higher conversion value to be achieved for the resulted outlet stream conditions coming out of the first reactor, CSTR. Both reactors commonly encounter a decrease in the initial concentration of A and an increase to the formation of other products. The CSTR entering volumetric flow rate influence the volume sizes needed in achieving the maximum selectivity and conversion

PREFACE: 14th International Symposium on Aquatic Oligochaeta

This volume is the proceedings for the 14th International Symposium on Aquatic Oligochaeta (ISAO), held in Hirosaki, Aomori Prefecture, Honshu, Japan, from 9 through 14 September 2018, organized by the Department of Natural Science, Faculty of Education, Hirosaki University, Hirosaki. The symposium was attended by 43 participants from 16 countries who presented 30 oral and 6 poster contributions. The scientific sessions were convened at the Iwaki Conference Hall in the 50th Anniversary Auditorium, Hirosaki University. In addition to the scientific sessions, there was a one-day excursion to visit a traditional playhouse Kouraku-Kan, lunch along the edge of Lake Towada – an oligotrophic caldera lake, and hiking along the lake’s outlet stream, Oirase-Keiryu, flowing through a cool temperate forest typical of northern Honshu. The symposium organizing committee consisted of Akifumi Ohtaka, Kimio Hirabayashi, Katsutoshi Ito, Mana Ito, Takaaki Torii, Naoya Kimura, Stuart R. Gelder, and Mark J. Wetzel, with invaluable support from students from Hirosaki University.

Evaluation and techno-economic analysis of packed bed scrubber for ammonia recovery from drying fumes produced during the thermal drying of sewage sludge

This study investigates the recovery of ammonia from drying fumes during thermal drying of sewage sludge with packed bed acid scrubbers to recover ammonia and to produce ammonium sulfate. The process is modelled for two concentrations, 75 and 100 ppm, and 1000m3/h inlet flowrate of drying fumes containing air and ammonia gas. It results in finding optimal parameters for scale-up of drying fumes during thermal drying of 7700t/a sewage sludge of Lappeenranta city. It is found that a single scrubber, with a 24000 m3/h of inlet gas and an ammonia concentration of 75 ppm, liquid to gas ratio of 1.5, temperature and pH of liquid acid as 100°C and 3 respectively, gives the efficiency of more than 99%, and reduces ammonia concentration in the outlet stream to 0.2 ppm. The capital cost is 290 k€, operating cost is 113k€/a, removal cost with and without revenue of ammonium sulfate is 20 €/t and 18 €/t of sludge. The packed bed acid scrubber would be suitable to remove ammonia in the drying fumes to recover ammonia from the drying fumes, but the initial economic analysis highlights that the production of commercial grade ammonium sulfate fertilizer would be an expensive option.

Coupled Plasma-Catalytic System with Rang 19pr Catalyst for Conversion of Tar

A coupled plasma-catalytic system (CPCS) for the conversion of toluene was investigated and compared to the homogeneous system of gliding discharge plasma. Toluene was used as a model compound, which is present in tars. The study was carried out at atmospheric pressure, in a gas composition similar to the one obtained during pyrolysis of biomass. The effect of the initial toluene concentration, energy supplied to gliding discharge (GD) and the presence of a catalyst on the conversion of toluene was studied. Both the composition of outlet gas and its calorific value were monitored. Based on the obtained results it can be concluded that the conversion of toluene increases with the increase of gliding discharge power. The highest toluene conversion (89%) was received in the coupled plasma-catalytic system (catalyst: RANG-19PR) under the following conditions: CO (0.13 mol. fr.), CO2 (0.12 mol. fr.), H2 (0.25 mol. fr.), N2 (0.50 mol. fr.) and 4400 ppm of toluene with a gas flow rate of 1000 Nl/h. The composition of the outlet gas in the homogeneous system and in the CPCS changed in the range of a few percents. Toluene levels were reduced tenfold. Benzene, C3 and C4 hydrocarbons, as well as acetylene, ethylene and ethane, were detected in the outlet stream in trace amounts. Carbon deposits were present in the reactor. The products of methanation of carbon oxides were detected in the both studied systems. A mechanism of toluene decomposition in the CPCS was proposed. The application of the catalyst brought about an increase in the calorific value of the outlet gas. It was above the minimal level demanded by engines and turbines.

Inversion of a glacier hydrology model

ABSTRACTThe subglacial hydrologic system exerts strong controls on the dynamics of the overlying ice, yet the parameters that govern the evolution of this system are not widely known or observable. To gain a better understanding of these parameters, we invert a spatially averaged model of subglacial hydrology from observations of ice surface velocity and outlet stream discharge at Kennicott Glacier, Wrangell Mountains, AK, USA. To identify independent parameters, we formally non-dimensionalize the forward model. After specifying suitable prior distributions, we use a Markov-chain Monte Carlo algorithm to sample from the distribution of parameter values conditioned on the available data. This procedure gives us not only the most probable parameter values, but also a rigorous estimate of their covariance structure. We find that the opening of cavities due to sliding over basal topography and turbulent melting are of a similar magnitude during periods of large input flux, though turbulent melting also exhibits the greatest uncertainty. We also find that both the storage of water in the englacial system and the exchange of water between englacial and subglacial systems are necessary in order to explain both surface velocity observations and the relative attenuation in the amplitude of diurnal signals between input and output flux observations.