Robert Hausler

Advances in principal factors influencing carbon dioxide adsorption on zeolites

Abstract We report the advances in the principal structural and experimental factors that might influence the carbon dioxide (CO2) adsorption on natural and synthetic zeolites. The CO2 adsorption is principally govern by the inclusion of exchangeable cations (countercations) within the cavities of zeolites, which induce basicity and an electric field, two key parameters for CO2 adsorption. More specifically, these two parameters vary with diverse factors including the nature, distribution and number of exchangeable cations. The structure of framework also determines CO2 adsorption on zeolites by influencing the basicity and electric field in their cavities. In fact, the basicity and electric field usually vary inversely with the Si/Al ratio. Furthermore, the CO2 adsorption might be limited by the size of pores within zeolites and by the carbonates formation during the CO2 chemisorption. The polarity of molecules adsorbed on zeolites represents a very important factor that influences their interaction with the electric field. The adsorbates that have the most great quadrupole moment such as the CO2, might interact strongly with the electric field of zeolites and this favors their adsorption. The pressure, temperature and presence of water seem to be the most important experimental conditions that influence the adsorption of CO2. The CO2 adsorption increases with the gas phase pressure and decreases with the rise of temperature. The presence of water significantly decreases adsorption capacity of cationic zeolites by decreasing strength and heterogeneity of the electric field and by favoring the formation of bicarbonates. The optimization of the zeolites structural characteristics and the experimental conditions might enhance substantially their CO2 adsorption capacity and thereby might give rise to the excellent adsorbents that may be used to capturing the industrial emissions of CO2.

Removal of metals in leachate from sewage sludge using electrochemical technology

Abstract Heavy metals in acidic leachates from sewage sludge are usually removed by chemical precipitation, which often requires high concentration of chemicals and induces high metallic sludge production. Electrochemical technique has been explored as an alternative method in a laboratory pilot scale reactor for heavy metals (Cu and Zn) removal from sludge leachate. Three electrolytic cell arrangements using different electrodes materials were tested: mild steel or aluminium bipolar electrode (EC cell), Graphite/stainless steel monopolar electrodes (ER cell) and iron‐monopolar electrodes (EC‐ER cell). Results showed that the best performances of metal removal were obtained with EC and EC‐ER cells using mild steel electrodes operated respectively at current intensities of 0.8 and 2.0A through 30 and 60 min of treatment. The yields of Cu and Zn removal from leachate varied respectively from 92.4 to 98.9% and from 69.8 to 76.6%. The amounts of 55 and 44 kg tds‐1 of metallic sludge were respectively produced using EC and EC‐ER cells. EC and EC‐ER systems involved respectively a total cost of 21.2 and 13.1 CAN

Degradation of Selected Acidic and Neutral Pharmaceutical Products in a Primary-Treated Wastewater by Disinfection Processes

per ton of dry sludge treated including only energy consumption and metallic sludge disposal. The treatment using EC‐ER system was found to be effective and more economical than the traditional metal precipitation using either Ca(OH)2 and/or NaOH.

Effectiveness of soil washing, nanofiltration and electrochemical treatment for the recovery of metal ions coming from a contaminated soil.

Anti-inflammatory and anti-convulsive drugs are being detected in measurable quantities in municipal wastewaters. Some of these emerging substances undergo major transformation at the sewage treatment plant after biological and chemical treatments. The degradation of pharmaceutical products from high-quality treated wastewaters by disinfection processes is well documented. However, the effect of disinfection processes on these products in physicochemical primary-treated municipal effluents remains to be investigated. Pilot projects using ozone, performic acid and UV-radiation disinfection processes were carried out at the Montreal wastewater treatment plant. Residues of pharmaceutical products like salicylic acid, clofibric acid, ibuprofen, naproxen, triclosan, carbamazepine, diclofenac, and 2-hydroxy-ibuprofen were found in the treated wastewaters before disinfection at concentrations ranging from 42 to 2556 ng/L. Most of these substances were eliminated at a rate greater than 50% at an ozone dose of 10 mg/L. Higher removal rates (as high as 70%) were observed when 20 mg/L of ozone was used. Removal rates for UV radiation, on the other hand, were often below 10% among the substances studied. Limited removal rate was observed after UV radiation for diclofenac and triclosan (25 and 40% efficiency, respectively). The irradiation used here (25 mJ/cm2) for bacterial treatment appeared, as previously reported, to be too low to cause the significant breakdown of many of the pharmaceutical substances contained in these wastewaters. Poor reduction efficiencies (< 8%) were observed with the performic acid treatment. Further investigations on analytical methodologies are therefore needed to assess the potential impact of degradation by-products on the environment and on human health.

UV-VIS and FTIR spectroscopic analyses of inclusion complexes of nonylphenol and nonylphenol ethoxylate with β-cyclodextrin.

This research was conducted to integrate soil washing, nanofiltration (NF) membranes and electrochemical treatment as feasible methods for the remediation of contaminated soils. For this investigation, two acidic leachates (pH=2) were prepared using HCl and H(2)SO(4)-NaCl as soil-washing agents. The results of the soil washing indicated that HCl and the combined H(2)SO(4)-NaCl were effective for the extraction of ions resulting from a contaminated soil. It was observed that both leachates presented similar chemical compositions. Following this procedure, the leachate solutions were pre-filtered by microfiltration, followed by NF using the Desal-5 (DK) membrane. The experiment results showed that NF membranes presented a high ion-retention rate for the two leachates. In general, better retentions were observed with the leachate prepared with HCl than H(2)SO(4)-NaCl. In order to treat the concentrate resulting from the NF treatment, it underwent an electrochemical procedure (electrochemical deposition) as an alternative method for safe disposal. The results showed a high reduction of toxic ions, such as Pb and Cu, from the solution. These three processes applied in conjunction not only indicated that the treatment of solutions heavily contaminated with inorganic pollutants resulting from contaminated soils were feasible but also suggested the possibility of treating different types of heavy industrial effluents.

Evidence of neuroendocrine disruption in freshwater mussels exposed to municipal wastewaters.

A study of inclusion complexation of liquid non-ionic surfactants, nonylphenol (NP) and nonylphenol 9 mole ethoxylate (NP9EO), with beta-cyclodextrin (beta-CD), was carried out by mass spectrometry, surface tension, and ultraviolet-visible (UV-VIS) and Fourier transform infrared (FTIR) spectroscopies. The inclusion complexation was effectuated by heating at 80 degrees C and filtration of aqueous NP+beta-CD and NP9EO+beta-CD suspensions. The mass spectrometry and surface tension measurements revealed that NP and NP9EO form inclusion complexes with beta-CD and beta-CD possesses a higher affinity for NP. These results are supported by the data from UV-VIS spectroscopic analyses that have indicated that a three times greater amount of NP is entrapped into beta-CD than NP9EO. This phenomenon has been associated with the smaller size and a higher degree of hydrophobicity of NP that favours its entrapment into beta-CD as compared to that of NP9EO. At the structural level, the data from FTIR spectroscopic study have indicated that alkyl chains of NP and NP9EO can form van der Waals interactions with the cavity of beta-CD. Moreover, NP and NP9EO seem to cause a reorganization of the intramolecular hydrogen bonds and change of the hydration of beta-CD, but did not appear to strongly interact with C-C, C-O-C, and OH groups of beta-CD. Together these results suggest that the formation of inclusion complexes by NP and NP9EO with beta-CD molecules could constitute an effective and advantageous technique to remove liquid non-ionic surfactants from wastewater due to the non-toxic character of beta-CD to humans and the environment.

Effects of ozone, ultraviolet and peracetic acid disinfection of a primary-treated municipal effluent on the Immune system of rainbow trout (Oncorhynchus mykiss)

The purpose of this study was to test the hypothesis that exposure to municipal effluents can disrupt the neuroendocrine system in Elliptio complanata freshwater mussels. The capacity of ozonation to mitigate these effects was also examined. Mussels were exposed for 14 days to a continuous flow of increasing concentrations of the effluent before and after ozonation. Neuroendocrinal effects were examined by tracking changes in acetylcholinesterase, glutamate, gamma-aminobutyrate, serotonin, dopamine and their respective adenylcyclase activities in synapse membranes, monoamine oxidase and vitellogenin-like proteins. Oxidative stress and damage were examined by superoxide dismutase and lipid peroxidation, respectively, in the visceral tissues. The results revealed that the exposure of freshwater mussels increased the levels of vitellogenin-like proteins in both the primary-treated and ozonated effluents, dopamine and glutamate, and decreased the turnover of the neurostimulant acetylcholine. Moreover, these endpoints were significantly correlated with oxidative stress and damage. A canonical analysis of the responses revealed that dopamine and the neuroexcitatory neuromediators--acetylcholesterase and glutamate--were the endpoints more strongly related with oxidative stress and damage. Mussel morphology and estrogenic biomarkers (vitellogenin-like proteins, gonad lipid stores) were also significantly related, albeit to a lesser extent, to oxidative stress and damage. In general, ozone treatment was not sufficient to mitigate the observed neuroendocrinal effects in freshwater mussels. We conclude that the continuous exposure of freshwater mussels to municipal wastewater effluents leads to neuroendrocinal alterations and to oxidative stress.

Anaerobic digestion and gasification coupling for wastewater sludge treatment and recovery

Municipal sewage effluents are complex mixtures that are known to compromise the health condition of aquatic organisms. The aim of this study was to evaluate the impacts of various wastewater disinfection processes on the immune system of juvenile rainbow trout (Oncorhynchus mykiss). The trout were exposed to a primary-treated effluent for 28 days before and after one of each of the following treatments: ultraviolet (UV) radiation, ozonation and peracetic acid. Immune function was characterized in leucocytes from the anterior head kidney by the following three parameters: phagocytosis activity, natural cytotoxic cells (NCC) function and lymphocyte (B and T) proliferation assays. The results show that the fish mass to length ratio was significantly decreased for the primary-treated and all three disinfection processes. Exposure to the primary-treated effluent led to a significant increase in macrophage-related phagocytosis; the addition of a disinfection step was effective in removing this effect. Both unstimulated and mitogen-stimulated T lymphocyte proliferation in fish decreased dramatically in fish exposed to the ozonated effluent compared to fish exposed to either the primary-treated effluent or to aquarium water. Stimulation of T lymphocytes proliferation was observed with the peracetic acid treatment group. In conclusion, the disinfection strategy used can modify the immune system in fish at the level of T lymphocyte proliferation but was effective to remove the effects on phagocytosis activity.

Adsorption and recovery of nonylphenol ethoxylate on a crosslinked beta-cyclodextrin-carboxymethylcellulose polymer

Sewage sludge management is an energy intensive process. Anaerobic digestion contributes to energy efficiency improvement but is limited by the biological process. A review has been conducted prior to experimentation in order to evaluate the mass and energy balances on anaerobic digestion followed by gasification of digested sludge. The purpose was to improve energy recovery and reuse. Calculations were based on design parameters and tests that are conducted with the anaerobic digester of a local wastewater treatment plant and a small commercial gasification system. Results showed a very significant potential of energy recovery. More than 90% of the energy content from sludge was extracted. Also, approximately the same amount of energy would be transferred in both directions between the digester (biogas) and the gasifier (thermal energy). This extraction resulted in the same use of biogas as the reference scenario but final product was a totally dry biochar, which represented a fraction of the initial mass. Phosphorus was concentrated and significantly preserved. This analysis suggests that anaerobic digestion followed by dehydration, drying and gasification could be a promising and viable option for energy and nutrient recovery from municipal sludge in replacement of conventional paths.

Alterations in DNA metabolism in Elliptio complanata mussels after exposure to municipal effluents

A study of adsorption/recovery of nonylphenol 9 mole ethoxylate (NP9EO) on a crosslinked beta-cyclodextrin-carboxymethylcellulose (beta-CD-CMC) polymer was carried out by ultraviolet-visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopies. The adsorption was performed in mixtures containing 500 mg of the beta-CD-CMC polymer and aqueous NP9EO solutions at concentrations 12-82 mg/L, whereas the recovery of NP9EO was effectuated by shaking the beta-CD-CMC polymer loaded with methanol. The assays were made at 25 degrees C and atmospheric pressure under agitation. The results have shown that the adsorption is a rapid process and the beta-CD-CMC polymer exhibits a high NP9EO adsorption capacity of 83-92 w% (1.1-6.8 mg NP9EO/g beta-CD-CMC polymer) dependent of the initial NP9EO concentration in liquid phase. This adsorption may involve the formation of an inclusion complex beta-CD-NP9EO and a physical adsorption in the polymer network. The adsorption equilibrium measurements, which were analyzed using the Langmuir isotherm, have indicated a monolayer coverage and the homogeneous distribution of active sites at the surface of the beta-CD-CMC polymer. Moreover, the negative value obtained for the free energy change (-13.2 kJ/mol) has indicated that the adsorption process is spontaneous. In parallel, the beta-CD-CMC polymer exhibited a high NP9EO recovery efficiency of 97 w% that may occur through a decrease of binding strength between beta-CD-CMC polymer and NP9EO. Together, these results suggest that the beta-CD-CMC polymer could constitute a good adsorbent for removing nonylphenol ethoxylates from wastewater due to its high adsorption capacity and non-toxic character of beta-CD and CMC to environment.