Comparison of four methods for quantification of biofilms in biphasic cultures

Three methods for determining the total biofilm amount in biphasic cultures have been compared: dry weight by filtration after solvent treatment, optical density with a biomass probe and protein content. The activity of the biofilm was estimated through mineral nitrogen consumption. Calculation of the coefficients of variation shows that these parameters could be used to characterise such a biofilm. The optical density by biomass probe was the most reliable one (repeatability <0.5%) to quantify total biofilm and a linear relation was verified against dry weight

Commercial Applications of Microalgae

The first use of microalgae by humans dates back 2000 years to the Chinese, who used Nostoc to survive during famine. However, microalgal biotechnology only really began to develop in the middle of the last century. Nowadays, there are numerous commercial applications of microalgae. For example, (1) microalgae can be used to enhance the nutritional value of food and animal feed owing to their chemical composition, (2) they play a crucial role in aquaculture and (3) they can be incorporated into cosmetics. Moreover, they are cultivated as a source of highly valuable molecules. For example, polyunsaturated fatty acid oils are added to infant formulas and nutritional supplements and pigments are important as natural dyes. Stable isotope biochemicals help in structural determination and metabolic studies. Future research should focus on the improvement of production systems and the genetic modification of strains. Microalgal products would in that way become even more diversified and economically competitive

Optimisation of pressurized liquid extraction using a multivariate chemometric approach for the determination of anticancer drugs in sludge by ultra high performance liquid chromatography–tandem mass spectrometry

The present paper describes an analytical method for the determination of 2 widely administered anticancer drugs, ifosfamide and cyclophosphamide, contained in sewage sludge. The method relies on the extraction from the solid matrix by pressurized liquid extraction, sample purification by solid-phase extraction and analysis by ultra high performance liquid chromatography coupled with tandem mass spectrometry. The different parameters affecting the extraction efficiency were optimized using an experimental design. Solvent nature was the most decisive factor for the extraction but interactions between some parameters also appeared very influent. The method was applied to seven different types of sludge for validation. The performances of the analytical method displayed high variability between sludges with limits of detection spanning more than one order of magnitude and confirming the relevance of multi-sample validation. Matrix effect has been determined as the most limiting analytical step for quantification with different extent depending on analyte and sludge nature. For each analyte, the use of deuterated standard spiked at the very beginning ensured the complete compensation of losses regardless of the sample nature. The suitability of the method between freshly spiked and aged samples has also been verified. The optimized method was applied to different sludge samples to determine the environmental levels of anticancer drugs. The compounds were detected in some samples reaching 42.5 μg/kgDM in ifosfamide for the most contaminated sample

Intensification de la brique fermentation alcoolique de substrats betteraviers (et autres substrats) pour la production d'éthanol

L'éthanol est un composé à usages très variés allant de la chimie à l'agroalimentaire. Cependant, la croissance actuelle du marché se fait essentiellement autour de l'utilisation de l'éthanol en tant que carburant. L'objectif de ce projet est d'intensifier la production d'éthanol à partir du sirop basse pureté, produit de la seconde cristallisation des jus d'extraction de betterave, afin de diminuer les consommations en énergie et en eau pour la production d'éthanol. Pour ce faire, en partenariat avec l'UNGDA et l'ADEME, nous avons mené des travaux de recherche sur les fermentations à haute densité afin d'obtenir des vins à teneur plus élevée en éthanol. A l'issu d'un état de l'art et de quatre visites dans des ateliers de production, une stratégie de recherche en trois points a été établie. Le premier point a consisté en la recherche d'une composition de milieu de fermentation permettant d'augmenter la concentration finale en éthanol. Le second point a eu pour but de déterminer si les besoins en nutriments se limitaient uniquement à la phase de croissance ou au contraire si l'apport de ces nutriments était bénéfique tout au long de la fermentation. Le dernier point a quant à lui utilisé l'ensemble des résultats obtenus pour définir une conduite de procédé, permettant d'obtenir la concentration finale en éthanol la plus élevée possible. Ces résultats montrent qu'il est possible de réaliser des fermentations haute densité à partir de sirop basse pureté et d'obtenir 15,2 % (v/v) d'éthanol en fin de fermentation. L'application de ces travaux dans les ateliers de production permettrait d'économiser par litre d'éthanol pur, entre 20 et 30 % d'énergie pour la distillation, entre 35 et 49 % d'eau pour la réalisation des milieux de fermentation à partir de SBP et de diminuer de 23 à 38 % le volume de déchet produit après distillation.Ethanol is a compound with a wide usage range from chemistry to food. However, the current market growth mainly concerns the use of ethanol as fuel. The objective of this project was to intensify ethanol production from low purity syrup 2, which is a substrate from sugar beet, in order to reduce the consumptions of energy and water for its production. To do this, in partnership with UNGDA and ADEME, we have conducted research on high-gravity fermentations in order to increase the ethanol concentration at the end of the fermentation. With the coming of a state of the art and four visits in production facilities, a three points research strategy has been established. The first point consisted of fermentation medium composition finding in order to increase the final ethanol concentration at the end of the fermentation. The second point was to determine if the nutrients requirements were limited only during the growth phase or, on the contrary, if nutriments were beneficial throughout the fermentation. The latter point was to use the overall results to define a fermentation process, to obtain a final ethanol concentration as high as possible. These results show that it is possible to achieve high gravity fermentation from low purity syrup and reach a final ethanol concentration of 15.2 % (v/v). The application of this work in production facilities could save per liter of pure ethanol between 20 and 30% energy for distillation, between 35 and 49 % water for the production of fermentation media from SBP and decrease from 23 to 38 % of the volume of waste produced after distillation.TOULOUSE-INP (315552154) / SudocSudocFranceF

Optimization of very high gravity fermentation process for ethanol production from industrial sugar beet syrup

In order to reduce production costs and environmental impact of bioethanol from sugar beet low purity syrup 2, an intensification of the industrial alcoholic fermentation carried out by Saccharomyces cerevisiae is necessary. Two fermentation processes were tested: multi-stage batch and fed-batch fermentations with different operating conditions. It was established that the fed-batch process was the most efficient to reach the highest ethanol concentration. This process allowed to minimize both growth and ethanol production inhibitions by high sugar concentrations or ethanol. Thus, a good management of the operating conditions (initial volume and feeding rate) could produce 15.2% (v/v) ethanol in 53 h without residual sucrose and with an ethanol productivity of 2.3 g L h−1

Elimination of an anticancer drug (cyclophosphamide) by a membrane bioreactor: comprehensive study of mechanisms

The mechanisms of elimination of an anticancer drug (cyclophosphamide) by a membrane bioreactor were investigated. The membrane bioreactor was run for 153 days with a sludge retention time (SRT) of 20 days. A removal efficiency of 60% was observed despite some variations in the influent. This removal was higher than reported in most of the studies in the literature. Biodegradation was the predominant removal mechanism and sorption onto sludge could be neglected

Micropollutants removal in tertiary moving bed biofilm reactors (MBBRs): Contribution of the biofilm and suspended biomass

The performance of tertiary moving bed biofilm reactors (MBBRs) was evaluated in terms of micropollutants (MPs) removal from secondary-treated municipal wastewater. After stepwise establishment of a mature biofilm, monitored by scanning electron and confocal microscopies, abiotic and biotic removals of MPs were deeply studied. Since no MPs reduction was observed by the both photodegradation and volatilization, abiotic removal of MPs was ascribed to the sorption onto the biomass. Target MPs i.e. Naproxen, Diclofenac, 17ß-Estradiol and 4n-Nonylphenol, arranged in the ascending order of hydrophobicity, abiotically declined up to 2.8%, 4%, 9.5% and 15%, respectively. MPs sorption onto the suspended biomass was found around two times more than the biofilm, in line with MPs’ higher sorption kinetic constants (ksor) found for the suspended biomass. When comparing abiotic and biotic aspects, we found that biotic removal outperformed its counterpart for all compounds as Diclofenac, Naproxen, 17ß-Estradiol and 4n-Nonylphenol were biodegraded by 72.8, 80.6, 84.7 and 84.4%, respectively. The effect of the changes in organic loading rates (OLRs) was investigated on the pseudo-first order degradation constants (kbiol), revealing the dominant biodegradation mechanism of co-metabolism for the removal of Diclofenac, Naproxen, and 4n-Nonylphenol., while 17ß-Estradiol obeyed the biodegradation mechanism of competitive inhibition. Biotic removals and kbiol values of all MPs were also seen higher in the biofilm as compared to the suspended biomass. To draw a conclusion, a quite high removal of recalcitrant MPs is achievable in tertiary MBBRs, making them a promising technology that supports both pathways of co-metabolism and competitive inhibition, next to the abiotic attenuation of MPs

Micropollutants removal from secondary-treated municipal wastewater using weak polyelectrolyte multilayer based nanofiltration membranes.

Nanofiltration (NF) is seen as a very promising technology to remove micropollutants (MPs) from wastewater. Unfortunately this process tends to produce a highly saline concentrate stream, as commercial NF membranes retain both the MPs and most of the ions. The high salinity makes subsequent degradation of the MPs in a bioreactor very difficult. The main goal of this study is to prepare and study a NF membrane that combines a low salt rejection with a high MPs rejection for the treatment of secondary-treated municipal wastewater. This membrane was prepared using layer by layer (LbL) deposition of the weak polycation poly(allylamine hydrochloride) (PAH), and the weak polyanion poly(acrylic acid) (PAA), on the surface of a hollow fiber dense ultrafiltration (UF) membrane. The ionic strength of the coating solutions was varied and properties of the formed polyelectrolyte multilayers (PEMs), such as hydration, hydrophilicity, hydraulic resistance and ions retention were studied. Subsequently we tested the apparent and steady state rejection of MPs from synthetic wastewater under cross-flow conditions. The synthetic wastewater contained the MPs Diclofenac, Naproxen, Ibuprofen and 4n-Nonylphenol, all under relevant concentrations (0.5–40 μg/L, depending on the MP). PEMs prepared at lower ionic strength showed a lower hydration and consequently a better retention of MPs than PEMs prepared at higher ionic strengths. A strong relationship between the apparent rejection of MPs and their hydrophobicity was observed, likely due to adsorption of the more hydrophobic MPs to the membrane surface. Once saturated (steady state), the molecular size of the MPs showed the best correlation with their rejection, indicating rejection on the basis of size exclusion. In contrast to available commercial NF membranes with both high salt and MP rejection, we have prepared an unique membrane with a very low NaCl retention (around 17%) combined with a very promising removal of MPs, with Diclofenac, Naproxen, Ibuprofen and 4n-Nonylphenol being removed up to 77%, 56%, 44% and 70% respectively. This membrane would allow the treatment of secondary treated municipal wastewater, strongly reducing the load of MPs, without producing a highly saline concentrate stream

Binding of Zearalenone, Aflatoxin B1, and Ochratoxin A by Yeast-Based Products: A Method for Quantification of Adsorption Performance

A methodology was developed to quantify the efficiency of yeast-based pro ducts for adsorption of three mycotoxins: zearalenone (ZEA), aflatoxin B 1 (AFB 1 ), and ochratoxin A (OTA). Eight products were tested (yeast cell wall or in activated yeast). The described experimental protocol based on in vitro tests provi ded reliable isotherms for each mycotoxin. The most suitable models were the Hill model for ZEA, the Langmuir model for AFB 1 , and the Freundlich model for OTA. From these models, original mathematical affinity criteria were defined to quantif y the product adsorption performances for each mycotoxin. The best yeast product, a yeast cell wall from baker’s yeast, can adsorb up t o68 % of ZEA, 29 % of AFB 1 , and 62 % of OTA, depending on the mycotoxin concentrations. The adsorption capacity larg ely depended both on yeast composition and mycotoxin, but no direct correlation between yeast composition and adsor ption capacity was found, confirming that adsorption of mycotoxin on yeast-based products involves complex phenomena. The resul ts of this study are useful for comparing the adsorption efficiency of various yeast products and understanding the me chanisms involved in adsorption

Improvement of the growth of Arthrospira (Spirulina) platensis from Toliara (Madagascar): Effect of agitation, salinity and CO2 addition

Arthrospira (Spirulina) platensis Toliara isolated from alkaline and salt lakes in the south-western area of Madagascar is a potential source of proteins that could efficiently fight against food deficiency in developing countries like Madagascar. Up to now, productivity in this country has been low, so a better understanding of the growth conditions of this species is needed to improve its production. Growth experiments were undertaken in bubble columns at laboratory scale. The influence of agitation of the culture, medium salinity (ranging from 13 to 35gL−1) and CO2 addition (ranging from 0 to 2%, v/v) on growth and protein content was examined. Because Arthrospira cells are fragile, a bubble column without additional mixing gave the best growth. Arthrospira (Spirulina) platensis showed higher specific growth rate (μmax) and protein content for lower salinity. Addition of 1% of CO2 improved the productivity by near 60%. The feasability of semi-continuous culture was demonstrated and optimal culture conditions led to a mean productivity of 0.22±0.03gL−1d−1, a mean specific growth rate of 0.015±0.002h−1 and a protein content of 53±2% of total dry weight