Phenolic Compounds Removal in Woodwaste Leachate by a Trickling Biofilter

Woodwaste produces large volumes of leachate, which often contains high concentrations of phenolic compounds. These compounds necessitate appropriate management. Biological methods are efficient, innovative, and economic. In particular, biofiltration process has various advantages compared to CAS and MBR technologies. Two pilot filters, with and without biological activity, were designed for continuous mechanisms to follow. This study supposes that the three mechanisms of volatilization, sorption, and biodegradation are present, confirm these assumptions, and determine the contribution of each mechanism. Good efficiency was obtained in the biofilter and 97–98.2% of COD and BOD removal were observed, respectively. Excellent performances were achieved and reached 99.9% of initial concentrations removal for all the phenolic compounds

Biofiltration of bitumen vapours - Operational aspects

[Abstract] This study was carried out in response to odour problems around a bitumen mixing and storage plant. The general objective of this study was to determine the potential of biofiltration for the treatment of air containing bitumen vapours. Two pilot-scale biofilters, a single-stage system and a two-stage system, were operated using a synthetic gas for a period of 106 days. Results demonstrated that a period of about 50 days was necessary to reach a steady state. The two biofilters performed very well in regards to H2S, while VOC treatment was much less efficient. Maximum elimination capacities of 25 g·m-3·h-1 for H2S and 5.3 g·m-3·h-1 for VOCs were obtained with the two-stage system. It was possible to establish certain operating conditions necessary for proper operation and to determine that a two-stage system is more efficient for the simultaneous treatment of H2S and VOCs

Low cost semi-continuous bioprocess and online monitoring of hydrogen production from crude glycerol.

High process costs arising from expensive media components, hydrogen partial pressure buildup in the head-space of the reactor, sharp decrease in medium pH due to accumulation of organic acids, substrate inhibition, as well as loss of biomass due to short hydraulic retention times are the major bottlenecks of fermentative hydrogen production. Therefore, the purpose of the present investigation was to develop a process to deal with all these problems at a time. The proposed approach demonstrates enhanced hydrogen production by a low cost process involving crude glycerol (CG), the waste from the biodiesel production process, as the only feedstock. This semi-continuous type of fermentation carried out in a 7.5 L bioreactor helped to eliminate substrate inhibition with no compromise in cumulative hydrogen production. By controlling product inhibition and the negative effect of by-product accumulation, as well as by preventing the loss of active biomass, a production of 5.18 L-H₂ per L-medium has been achieved. This amount is higher than the 2.02 to 2.68 L-H₂ per L-medium previously reported for CG bioconversion. Reduction of feed CG concentration from 120 g L⁻¹ to 60 g L⁻¹ was found to improve the glycerol utilization from 65% to 91%

Exploration of Free Energy Surface and Thermal Effects on Relative Population and Infrared Spectrum of the Be6B11− Fluxional Cluster

The starting point to understanding cluster properties is the putative global minimum and all the nearby local energy minima; however, locating them is computationally expensive and difficult. The relative populations and spectroscopic properties that are a function of temperature can be approximately computed by employing statistical thermodynamics. Here, we investigate entropy-driven isomers distribution on Be6B11− clusters and the effect of temperature on their infrared spectroscopy and relative populations. We identify the vibration modes possessed by the cluster that significantly contribute to the zero-point energy. A couple of steps are considered for computing the temperature-dependent relative population: First, using a genetic algorithm coupled to density functional theory, we performed an extensive and systematic exploration of the potential/free energy surface of Be6B11− clusters to locate the putative global minimum and elucidate the low-energy structures. Second, the relative populations’ temperature effects are determined by considering the thermodynamic properties and Boltzmann factors. The temperature-dependent relative populations show that the entropies and temperature are essential for determining the global minimum. We compute the temperature-dependent total infrared spectra employing the Boltzmann factor weighted sums of each isomer’s infrared spectrum and find that at finite temperature, the total infrared spectrum is composed of an admixture of infrared spectra that corresponds to the lowest energy structure and its isomers located at high energies. The methodology and results describe the thermal effects in the relative population and the infrared spectra

Utilisation des procédés électrochimiques et leurs combinaisons avec les procédés biologiques pour le traitement des lixiviats de sites d’enfouissement sanitaires - revue de littérature

Les lixiviats des sites d’enfouissement sanitaires contiennent divers types de composés organiques et inorganiques susceptibles de polluer les milieux aquatiques s’ils ne sont pas convenablement traités. Depuis quelques années, on note une utilisation croissante des techniques électrochimiques, avec des résultats satisfaisants, pour le traitement des lixiviats. Parmi les avantages liés à l’utilisation de ces procédés, on peut citer : une faible emprise au sol, un temps de traitement court, une utilisation limitée, voire inexistante, de réactifs chimiques et une facilité d’automatisation. La capacité à traiter les composés organiques bioréfractaires et à augmenter la biodégradabilité de l’effluent constitue un atout majeur lors du traitement de certains types de lixiviats. Dans cette revue de littérature, un accent particulier est porté sur les trois procédés électrochimiques les plus utilisés pour le traitement des lixiviats, à savoir : l’électro-oxydation (EO), l’électro-Fenton (EF) et l’électrocoagulation (EC). Pour chacun des procédés, les différents paramètres opératoires qui influencent l’efficacité du traitement sont élucidés. D’une façon globale, les procédés électrochimiques sont influencés entre autres par l’intensité du courant appliqué, le type d’électrode utilisé, la distance interélectrodes, le temps de traitement, le pH et la conductivité du milieu. Le couplage des procédés électrochimiques et biologiques pour le traitement des lixiviats a été investigué. L’intégration de ces deux procédés permet d’augmenter les performances épuratoires tout en réduisant les coûts et les temps de traitement. Toutefois, des études approfondies sont nécessaires afin d’optimiser ces couplages et d’éclaircir l’influence du traitement biologique sur le traitement électrochimique et vice-versa.Landfill leachates contain several types of organic and inorganic pollutants that can contaminate aquatic environments if they are not treated in an appropriate way. In recent years, there has been an increase in the use of electrochemical processes for the treatment of landfill leachates, with satisfactory results. Some advantages related to the use of electrochemical processes are: small space requirement, short treatment time, low requirements of chemical reagents and easy automation. The ability to remove biorefractory compounds and to increase the biodegradability of the effluent makes them interesting methods for the treatment of landfill leachates. In the present literature review, particular attention is paid to three electrochemical processes commonly used for the treatment of landfill leachates, namely Electro-Oxidation (EO), Electro-Fenton (EF) and Electro-Coagulation (EC). For each of them, we elucidate the different parameters that affect treatment efficiency. Generally, electrochemical processes are influenced by the applied current density, type of electrode, distance between electrodes, treatment time, pH and effluent conductivity. The combination of electrochemical processes with biological processes is also considered. The integration of these two processes improves the treatment efficiency for landfill leachates and reduces the cost and treatment time. However, further studies are required in order to optimize the combined method and to clarify the influence of biological treatment on the electrochemical treatment, and vice versa

Biofiltration on organic media, a new sustainable technology for wastewater treatment in small communities and industries

The large amounts of organic matter, nutrients, heavy metals and other chemical substances in water is one of the most troubling problems faced by all countries worldwide. Therefore, the priorities for sustainable development are the control, reduction and treatment of wastewater from urban, agricultural, agro-industrial and industrial discharges into water bodies. Unfortunately, the operational complexity and high investment and maintenance costs associated with conventional wastewater treatment systems have limited their usage in small municipalities, rural zones and small and medium industries. The biofiltration process on organic medium has recently been developed in Canada in order to solve the sanitation problems and meet its needs in these important sectors. This process is based on the capacity of certain organic media to act as natural resins, which are able to retain different types of pollutants through adsorption/absorption mechanisms and contribute to the settling of microorganisms capable of degrading the entrapped pollutants. Because this technology is decentralized and can resolve problems in many rural and semi-urban zones, it has recently been of interest in Mexico. It has been tested in the laboratory for treating urban and industrial wastewater using organic materials in the region and the first realscale system has been installed. Therefore, the objective of this research is to present the main results obtained for this technology at the real-scale and its impact on the urban sectors (small municipalities and rural zones) and agro-industry (pig and poultry farms) in Canada and Mexico

Liquid waste from bio-hydrogen production – A commercially attractive alternative for phosphate solubilizing bio-fertilizer

Organic acids produced by commercial phosphate solubilizing bio-fertilizer (PSB) can chelate the cations of insoluble phosphates (such as Ca3 (PO4)2) present in soil to solubilize the phosphate and make it available for plants. Meanwhile, during H2 production (dark fermentation) different organic acids are produced as unwanted by-products. Interestingly, the acid-rich liquid waste of the process has excellent phosphate solubilizing ability (36.12 folds increase) and it could be considered as a potential alternative for PSB. Studies have demonstrated that biodiesel manufacturing waste (crude glycerol) could be used as a substrate for hydrogen production and the secondary waste could be used as a phosphate solubilizing agent. Thus, this novel approach could: (i) offer a green fertilizer; (ii) improve economic sustainability of bio-hydrogen production and; (iii) could become a financial booster for biodiesel manufacturers by offering them a profitable waste management strategy