In situ continuous monitoring of dissolved gases (N2, O2, CO2, H2) prior to H2 injection in an aquifer (Catenoy, France) by on-site Raman and infrared spectroscopies: instrumental assessment and geochemical baseline establishment.

The establishment of a baseline of gases from an aquifer appears to be an essential prerequisite for monitoring and securing underground storage operations such as the storage of carbon dioxide (carbon capture and storage: CCS), methane or hydrogen. This study describes an innovative metrological technique dedicated to the in situ and continuous quantification of dissolved gases (CO2, O2, N2, CH4 and H2) in a shallow aquifer, on the site of Catenoy (Paris Basin) with a water table at a depth of 13 m. Monitoring was carried out from May 7, 2019 to November 19, 2019, before the simulation of H2 injection. Gases as vapors were collected from the aquifer through a nine-meter long, half-permeable polymer membrane positioned below a packer in a 25-meter deep well. Collected gases were analyzed simultaneously at the surface by fiber Raman (CO2, O2, N2, CH4 and H2) and infrared sensors (CO2). Gas concentrations were determined from Raman and infrared data, and then converted into dissolved concentrations using Henry's law. The dissolved gas concentrations were about constant over the 6 months period with average values of 31-40 mg L-1 (CO2), 8 mg L-1 (O2), 17 mg L-1 (N2), and 0 mg L-1 (H2, CH4) indicating a very low variability in the aquifer. This is believed to allow for rapid detection of any possible abnormal concentration variation, in particular linked to an accidental arrival of gases such as hydrogen. Such an online gas measurement system can be deployed as is on any site type of underground storage without any need for adaptation.

A combined approach for a better understanding of wastewater treatment plants operation: statistical analysis of monitoring database and sludge physico-chemical characterization.

Biological wastewater treatment plants (WWTP) are complex systems to assess. Many parameters are recorded daily in WWTP to monitor and control the treatment process, providing huge amounts of registered data. A combined approach of extracting information from the WWTP databases by statistical methods and from the sludge physico-chemical characterization was used here for a better understanding of the WWTP operation. The monitored parameters were analysed by multivariate statistical methods: Principal Components Analysis and multiple partial linear regression. The WWTP operational conditions determine the sludge characteristics. The bacterial activity of the sludge in terms of extra-cellular polymeric substances (EPS) production was assessed using size exclusion chromatography and the internal structure of sludge flocs was observed by confocal laser scanning microscopy. The diagnosis of three paper mill WWTP enabled the identification of an important EPS production, the presence of the nitrification process and the presence of PO(4)(3-) nutrient in WWTP-A. These three main characteristics of WWTP-A were related with a systematically good sludge settling. In WWTP-B and C with bad settling, the bacterial activity was weak.

The pitfalls of protein quantification in wastewater treatment studies.

Proteins, as one of the principal components of organic matter in wastewater, require adequate quantification to determine their concentration in the different stages of wastewater treatment process. Recent studies have used the corrected Lowry Method for protein quantification arguing that this method can differentiate proteins from interfering humic substances. In this study, the classic Lowry Method, the corrected Lowry Method and a commercial assay kit were assessed for the protein quantification in the presence of humic acid.

Effect of cytostatic drug presence on extracellular polymeric substances formation in municipal wastewater treated by membrane bioreactor.

The effect of the cyclophosphamide and its mean metabolites on extracellular polymeric substances (EPS) formation was investigated. Two lab-scale membrane bioreactors were followed in parallel (one with the cytostatic drugs, the second without). Chromatographic and spectroscopic studies (UV-Vis spectroscopy and IR spectroscopy) showed that the presence of CPs induced an increase in EPS concentration in the biological sludge, especially of soluble substances, mainly polysaccharides and proteins. Size exclusion chromatography analysis revealed that in the presence of CPs, macromolecular EPS were formed (polysaccharides corresponding to about 6 KDa and proteins to about 18 KDa). The formation of EPS seemed to be a protection mechanism. More important membrane fouling in reactor with CPs seemed to be related to the retention of an increased amount of soluble substances.

Exopolymeric production by bacterial strains isolated from activated sludge of paper industry.

The bacteria originated from the paper mill sludge were identified, isolated and cultured. Enterobacter (E) and Klebsiella (K) represented 70% of the culturable aerobic flora. Kinetics of EPS production in isolated culture and in arbitrary 1:1 mixture was investigated by high-pressure size exclusion chromatography (HPSEC). In isolated culture, Enterobacter produced regularly and gradually during 24 h of culture, while Klebsiella produced the total amount of EPS already after 4 h without any changes later. The chromatographic profiles of the EPS production of the 1:1 mixture after 4, 8 and 24 h of culture could be fitted as a linear combination of the profiles of exopolymers produced by pure Enterobacter and Klebsiella strains. After 24 h of culture, Enterobacter was predominant in term of population (82%) and produced about 77% EPS amount, in spite of competition phenomena observed during culture.

Separation of hydrocarbons and lipid from water using treated bark.

This paper explores the possibility of using treated bark to remove oily compounds from water. Bark was first biologically or chemically treated and saturated with transition metal ions (TMI) to avoid the release of soluble organic compounds from the bark in the treated effluents. Several experimental parameters affecting the oil removal efficiency (RE) were studied (initial oil concentration, temperature, time, etc.). Saturated bark was characterized using Fourier transform infrared (FTIR) spectroscopy and bark wetting index was determined. Results of the retention of lipids suggested that their removal could exceed 95% of initial oil concentration. The uptake of lipid by treated bark varied from 0.2 to 2.0 g of organic oil/g of dry sorbent. No significant chemical modifications of saturated bark were observed in infrared spectroscopy after the sorption of oleic acid on bark treated with transition metal ions. The structure of adsorbed tridimensional layer of oleic acid molecules seemed to take place through the double bond. The hydrocarbon RE exceeded 95% using oil-water mixture with a hydrocarbon/bark ratio of one. The sorption reaction of hydrocarbons and lipids was quasi-instantaneous and seemed to be influenced by the temperature. This indicated that the retention mechanism was related to the capillary action. Results of FTIR spectroscopy suggested that no chemical bonds between barks and oily compounds were established.