Biodegradation by bioaugmentation of dairy wastewater by fungal consortium on a bioreactor lab-scale and on a pilot-scale

International audienceA fungal consortium including Aspergillus niger, Mucor hiemalis and Galactomyces geotrichum was tested for the treatment of dairy wastewater. The bio-augmentation method was tested at lab-scale (4 L), at pilot scale (110 L) and at an industrial scale in Wastewater Treatment Plants (WWTP). The positive impact of fungal addition was confirmed when fungi was beforehand accelerated by pre-culture on whey (5 g/L lactose) or on the dairy effluent. Indeed, chemical oxygen demand (COD) removal yields increased from 55% to 75% for model medium, diluted milk. While after inoculation of an industrial biological tank from a dairy factory with the fungal consortium accelerated by pre-cultivation in a 1000 L pilot plant, the outlet COD values decreased from values above the standard one (100 mg/L) to values in the range of 50-70 mg/L. In addition, there was a clear impact of fungal addition on the 'hard' or non-biodegradable COD owing to the significant reduction of the increase of the COD on BOD5 ratio between the inlet and the outlet of the biological tank of WWTP. It was in the range of 451%-1111% before adding fungal consortium, and in the range of 257%-153% after bio-augmentation with fungi. An inoculated bioreactor with fungal consortium was developed at lab-scale and demonstrated successfully at pilot scale in WWTP

Residue of dates from the food industry as a new cheap feedstock for ethanol production

International audienceSyrup resulting from date by-products constitutes a favorable medium for yeast development, owing to its sugar composition; it was hence tested for ethanol production. Three yeasts, Saccharomyces cerevisiae, Zygosaccharomyces rouxii and Candida pelliculosa, were selected for ethanol production on dates syrup. In batch fermentation, the ethanol concentration depended on the initial sugar concentration and the yeast strain. For an initial sugar concentration of 174.0 ± 0.2 kg m−3, maximum ethanol concentration was 63.0 ± 0.1 kg m−3 during S. cerevisiae growth, namely higher than the amounts achieved during Z. rouxii and C. pelliculosa growth, 33.0 ± 2.0 kg m−3 and 41.0 ± 0.3 kg m−3 respectively. Contrarily, only Z. rouxii was able to grow on 358.0 ± 1.0 kg m−3 initial sugar amount, resulting in 55.0 ± 1.0 kg m−3 ethanol produced

The use HPTLC and Direct Analysis in Real Time-Of-Flight Mass Spectrometry DART-TOF-MS for rapid analysis of degradation by oxidation and sonication of an azo dye

International audienceAdvanced oxidation processes are efficient for the removal of recalcitrant compounds, like azo-dyes. However, the intermediates produced during their degradation can be more toxic than the parent compounds. Improving the knowledge concerning the degradation pathways may be therefore helpful to optimize the process. In this aim, HPTLC and Direct Analysis in Real Time-Of-Flight Mass Spectrometry DART-TOF-MS were considered and applied to analyze the sono-oxidation of an azo dye, methyl red sodium salt (MRSS) as a model compound. Initial and final UV-Vis spectra showed a clear disappearance of the maximum absorption peak, but shows limit since it cannot allow by-products identification. MRSS degradation was confirmed by HPTLC, which also confirmed that MRSS degradation was mainly due to oxidation, while in the considered experimental conditions the sonication effect appeared negligible. Three major peaks were observed by DART-TOF-MS after MRSS oxidation, m/z=139.002, m/z=223.073 and m/z=279.137, Relative abundance of m/z=139.002, which was much higher after oxidation, tends to prove that a large proportion of initial oxydized MRSS was fragmented. The MRSS m/z = 270.078. The coupling of HPTLC and DART-TOF-MS may be subsequently considered to identify the oxidation reaction products

Electro-Fenton pretreatment for the improvement of tylosin biodegradability

International audienceThe feasibility of an electro-Fenton process to treat tylosin (TYL), a non-biodegradable antibiotic, was examined in a discontinuous electrochemical cell with divided cathodic and anodic compartments. Only 15 min electrolysis was needed for total tylosin degradation using a carbon felt cathode and a platinum anode; while 6 h electrolysis was needed to achieve high oxidation and mineralization yields, 96 and 88 % respectively. Biodegradability improvement was shown since BOD5/COD increased from 0 initially to 0.6 after 6 h electrolysis (for 100 mg L−1 initial TYL). With the aim of combining electro-Fenton with a biological treatment, an oxidation time in the range 2 to 4 h has been however considered. Results of AOS (average oxidation state) and COD/TOC suggested that the pretreatment could be stopped after 2 h rather than 4 h; while in the same time, the increase of biodegradability between 2 and 4 h suggested that this latter duration seemed more appropriate. In order to conclude, biological cultures have been therefore carried out for various electrolysis times. TYL solutions electrolyzed during 2 and 4 h were then treated with activated sludge during 25 days, showing 57 and 67 % total organic carbon (TOC) removal, respectively, namely 77 and 88 % overall TOC removal if both processes were considered. Activated sludge cultures appeared, therefore, in agreement with the assessment made from the analysis of physico-chemical parameters (AOS and COD/TOC), since the gain in terms of mineralization expected from increasing electrolysis duration appeared too low to balance the additional energy consumption

An Overview of the Valorization of Aquatic Plants in Effluent Depuration through Phytoremediation Processes

International audienceEnvironmental biotechnologies are a popular choice for using efficient, low-cost, low-waste, and environmentally friendly methods to clean up and restore polluted sites. In these technologies, plants (terrestrial and aquatic) and their associated micro-organisms are used to eliminate pollutants that threaten the health of humans and animals. They have emerged as alternative methods to conventional techniques that have become increasingly aggressive to the environment. Currently, all actors of the environment, whether governors, industrialists, or citizen associations are more interested in the application and development of these technologies. The present overview provides available information about recent developments in phytoremediation processes using specifically aquatic plants. The main goal is to highlight the key role of this technology in combating the drastic organic and inorganic pollution that threatens our planet daily. Furthermore, this study presents the valorization of aquatic plant after phytoremediation process in energy. In particular, this article tries to identify gaps that are necessary to propose future developments and prospects that could guarantee sustainable development aspired by all generations

Biochar: A Key Player in Carbon Credits and Climate Mitigation

The creation of the carbon market came forth as a tool for managing, controlling, and reducing greenhouse gas emissions, combining environmental responsibility with financial incentives. Biochar has gained recognition as one of potential carbon offset solution. The practical and cost-effective establishment of biochar carbon credit standards is crucial for the integration of biochar into carbon trading systems, thus encouraging investments in the biochar industry while promoting sustainable carbon dioxide sequestration practices on a global scale. This communication focuses on the potential of biochar in carbon sequestration. Additionally, it spotlights case studies that highlight how biochar effectively generates carbon credits, as well as discussing the evolving carbon removal marketplace. Furthermore, we address knowledge gaps, areas of concern, and research priorities regarding biochar implementation in carbon credits, with the aim of enhancing our understanding of its role in climate change mitigation. This review positions biochar as a versatile and scalable technology with the potential to contribute significantly to carbon credits, aligning with sustainable development goals. It calls for continued research, transparency, and international cooperation to explore the full potential of biochar in climate change mitigation efforts

Biostimulation to improve the dye biodegradation of organic dyes by activated sludge

In this work, biodegradation of organic pollutants by activated sludge (AS) in the presence of glucose (2 g/L) as an additional carbon source was studied. The AS (without pre-acclimation) was freely suspended under aerobic conditions. Three organic dyes representative of the Algerian textile industry were selected: Cibanon Navy (CN), Solophenyl Scarlet (SS) and Cibacron Green (CG). The results showed that after 10 days of incubation, AS displayed good biodegradation capabilities achieving removal percentages ranging from 50.3% to 89.4% and reduction in COD ranging from 93.1% to 98.3%. Particularly, the textile dye CN was removed up to 89% with high reduction in COD (94.7%). The microbial development stimulated by glucose achieved therefore efficiently the discoloration of contaminated solutions and pollutant degradation. Although it is assumed that dyes can be degraded only under anaerobic conditions, the wastewater treatment using AS appears therefore suitable to the removal of different types of textile dyes before final discharge

Impact of an osmotic stress on the intracellular volume of Hansenula anomala.

International audienceThe effect of an osmotic stress resulting from high glucose or NaCl concentrations on the morphology and intracellular volume of Hansenula anomala was examined by scanning electronic microscopy and changes in the intracellular volume accessible to tritiated water, respectively. No noticeable change in the cell morphology was observed, with the cells remaining ellipsoidal. An increase in the contribution of compatible solutes, such as arabitol, glycerol and trehalose, to the cell volume, was not sufficient to counterbalance the decrease in the volume accessible to tritiated water for increasing water stress, leading to a decrease in cell volume. For a given morphology, a decrease in the cell volume allowed the cell to maximize the surface to ratio volume for a better distribution of the external osmotic pressure. It also allowed maximization of the compatible solute concentration (for a given amount of accumulated compounds), leading to an increase in the internal osmotic potential to counterbalance the osmotic potential of the surrounding medium. However, the accumulation of compatible solutes in the cell did not allow any adjustment of the osmotic potential of cells in high-osmolarity medium, especially in the case of NaCl as the osmoticum, thereby confirming the higher stress effect of salt relative to glucose