Platform- and label-free detection of lead ions in environmental and laboratory samples using G-quadraplex probes by circular dichroism spectroscopy

Guanine-rich quadruplex (G-QD) are formed by conversion of nucleotides with specific sequences by stabilization of positively charged K+ or Na+. These G-QD structures differentially absorb two-directional (right- and left-handed) circularly polarized light, which can discriminate the parallel or anti-parallel structures of G-QDs. In this study, G-QDs stabilized by Pb2+ were analyzed by a circular dichroism (CD) spectroscopy to determine Pb2+ concentration in water samples. Thrombin aptamer (TBA), PS2.M, human telomeric DNA (HTG), AGRO 100, and telomeric related sequence (T2) were studied to verify their applicability as probes for platform- and label-free detection of Pb2+ in environmental as well as laboratory samples. Among these nucleotides, TBA and PS2.M exhibited higher binding constants for Pb2+, 1.20–2.04 × 106/M at and 4.58 × 104–1.09 × 105/M at 100 micromolar and 100 mM K+ concentration, respectively. They also exhibited excellent selectivity for Pb2+ than for Al3+, Cu2+, Ni2+, Fe3+, Co2+, and Cr2+. When Pb2+ was spiked into an effluent sample from a wastewater treatment plant (WWTP), its existence was detected by CD spectroscopy following a simple addition of TBA or PS2.M. By the addition of TBA and PS2.M, the Pb2+ signals were observed in effluent samples over 0.5 micromolar (100 ppb) concentration. Furthermore, PS2.M caused a Pb2+-specific absorption band in the effluent sample without spiking of Pb2+, and could be induced to G-QD structure by the background Pb2+ concentration in the effluent, 0.159 micromolar concentration (3.30 ppb). Taken together, we propose that TBA and PS2.M are applicable as platform- and label-free detection probes for monitoring Pb2+ in environmental samples such as discharged effluent from local WWTPs, using CD spectroscopy.

Microbial Population Inhibition Method Through Spectrophotometry Absorption of Visible Light Applied to Ecotoxicological Analyses

Ecotoxicology is a science that studies the effects of pollutants and forecast their transformations on the environment. Ecotoxicological studies have been used in soil and water quality assessment, development and implementation of new techniques of water and effluent treatment, tools for better industrial management, bioremediation techniques and sustainable agriculture approaches. Microorganisms, which were seen to detain a fundamental importance in nutrient cycling and energy flow, have been increasingly used as bioindicators in ecotoxicological analyses. The populational inhibition of microbiological strains may be measured through the absorbance of visible light, an efficient, fast, low-cost and reliable method that has been widely used in qualitative and quantitative analysis. In this manuscript, a real textile effluent sample was analyzed regarding its electric conductivity, pH, turbidity, solids, alkalinity, biochemical oxygen demand (BOD5), chemical oxygen demand (COD) and a spectrophotometry microbial population inhibition (MPI) method using the Bacillus subtilis bacteria and the Saccharomyces cerevisiae yeast. The EC20, EC50 and acute toxicity indexes were satisfactory in relation to the widely used method of light reduction of the Vibrio fischeri luminescence bacteria. The MPI was shown to be a feasible method to determine the hazardous effects caused by the textile effluent sample towards the microbial populations.

Characterization of pharmaceuticals industrial effluent using GC–MS and FT-IR analyses and defining its toxicity

The physicochemical analysis of collected effluent sample for different parameters shown results as pH (pH 5.6 ± 0.11) slightly acidic, high conductivity (1563.34 ± 176 μs cm−1), total dissolved solids (920.34 ± 137 mg L−1), high BOD (7253.34 ± 1022 mg L−1), and COD (756.67 ± 1124 mg L−1) in the effluent sample. The results of heavy metals concentration are viz. as [Cu (1.98–2.56), Co (0.26–0.53), Cd (0.10–0.50), Ni (0.04–0.07), Pb (0.58–1.2), Mn (0.58–1.05), Cr (1.47–1.51), Zn (2.61–3.5), Fe (1.72–2.13), As (0.05–0.09), and Hg (0.003–0.006)]. Results revealed the higher concentration of BOD, COD, TDS, and conductivity and also the concentration of lead. Results of GC–MS also confirmed the high levels of organic pollutants in effluent. Further the effluent toxicity was evaluated by employing genotoxocity assays with the use of Allium cepa L. (onion) root tip cells. Genotoxicity measured mitotic index (MI) and chromosomal aberrations (CAs) in root tip cells obtained after treatment with effluent of 6.25, 12.5, and 25% concentration (v/v). The results of root growth test showed that inhibition of root growth occurred at effluent concentration ≥ 50% (v/v). The lowest MI was recorded (MI = 9.6%) in 25% of effluent concentration, showing a significant reduction in mitotic index compared with control which MI = 64.1%. Further, the chromosomal aberration was investigated in root tip cell after treating with different concentration ranges of effluent exhibiting various CA, viz. c-mitosis, chromosome loss, chromosome break, micronucleated cells, etc. The result suggests that the effluent contained toxic constituents, which imposed cytotoxic and genotoxic hazard.

Construccion de un prototipo anaerobio para el tratamiento de aguas residuales

It has been proposed systems that adapt economically and technically to the conditions of most places that have a considerable water consumption. The work consisted of an anaerobic biological reactor in which the treatment of domestic wastewater was carried out. Sedimentation characteristics of the activated sludge were achieved after the second stabilization period. Throughout the treatment three samples were characterized (key, effluent and influent) in three times of hydraulic retention, of which were analyzed: pH, temperature, conductivity, turbidity, SST and COD. Additionally, the samples were analyzed in the laboratory to determine COD, BOD5, fats and oils, and fecal coliforms. With the designed system removal percentages higher than 45% (key sample) and 34% (effluent sample) were obtained for COD and greater than 71% (key sample) and 57% (effluent sample) for SST. The parameters analyzed met the maximum permissible limits established in NOM-003-SEMARNAT-1997 and in PROY-NOM-001-Semarnat-2017. A filtration system was installed that increased the percentages of removal in the treated samples reaching a better water quality. Chlorine was also added to ensure the elimination of fecal coliforms.

Assessment of the use of red mud as a catalyst for photodegradation of bisphenol A in wastewater treatment

This study aimed to investigate the use of red mud (RM) – a byproduct of aluminum production, as a photocatalyst, which was characterized physical-chemically and used in the photodegradation of the target compound bisphenol A (BPA). Chemical processing was performed in the RM (acid treatment, chemical reduction and calcination) to verify the most active catalyst. From the results obtained, a complete degradation kinetics of BPA was carried out using a synthetic matrix (BPA in deionized water) and a real matrix (BPA in wastewater) using natural RM/calcined and TiO2 for comparison. The results indicated the potential use of the RM/calcined, which was able to degrade between 88 and 100% of the pollutant in a synthetic sample. Tests on a real effluent sample resulted in degradation rates that ranged from 59 to 100% with chemical oxygen demand reductions of up to 23% using natural RM/calcined in comparison to TiO2. The blank system (irradiation of the solution without the use of a photocatalyst) and the natural RM/calcined one, resulted in reductions of the toxicity in the effluent sample (measured by EC20 using the marine bacteria Vibrio fischeri) of about 12 times, whereas the same treatment using TiO2 resulted in a toxicity reduction of only seven times. Within these results, the RM/calcined showed potential to be used in wastewater treatment in polishing processes.

Performance of the freshwater shrimp <i>Atyaephyra desmarestii</i> as indicator of stress imposed by textile effluents

Textile plants consume large volumes of water and produce a great amount of wastewaters, which can be important sources of toxic discharges in receiving environments. The objective of this study was to evaluate the acute toxicity of textile effluents on the freshwater shrimp A. desmarestii. A whole effluent toxicity test procedure was used to determine the aggregate toxicity of three samples taken before and after wastewater treatment in a textile mill. The following LC50 − 48 h values (%, v/v) were calculated: Untreated effluent −29% effluent (sample 1), 22% effluent (sample 2), and 47% (sample 3); Treated effluent −73% effluent (sample 1), 74% effluent (sample 2), and > 100% (sample 3). Based upon acute toxicity units (TUa = 100/LC50), untreated effluent varied from toxic in samples 1 and 3 (2.00 ≤ TUa ≤ 4.00) to very toxic in sample 2 (TUa > 4.0), whereas treated effluent varied from no toxic in sample 3 to moderately toxic in samples 1 and 2 (1.33 ≤ TUa ≤ 1.99). Despite some limitations and constraints related to innate variability of industrial effluents, our results suggested that A. desmarestii can be a promising and potential test organism for assessing toxicity of complex chemical mixtures.

Alkaline protease production using a membrane bioreactor

Alkaline proteases are an important class of industrial enzymes that are mainly used in detergents, and also in industries like leather, food, photography and pharmaceuticals. Most industrial processes use submerged fermentation (SMF) for alkaline protease production. Recently, solid state fermentation (SSP) has been used. This research presents the potential of an additional process for alkaline protease production, namely membrane bioreactor (MBR) system. lts application has been extended from ultrafitration operation to a potential enzyme production system. This research is therefore based on the evaluation of skinless polysulphone capillary membrane for the production of enzymes. The initial step in this project involved the experimental determination of the most suitable test organism for immobilization and biofilm formation on the membrane. This involved the use of a flow-cell chamber system with strains of Thermomyces lanuginosus ATCC 38905, T. lanuginosus ATCC 46882, Cryptococus laurentii, Aspergillus aculeatus DSM 2344, Gliocladium roseum, Penicillium grabrum, P. chrysogenum CCRC 31619, P. italicium, Saccharomyces cerevisiae, E. coli B8, Sclerotium rolfsii and a winery effluent sample comprising of a consortium of unidentified bacteria. Biofilm formation on the surface was observed visually over a period of seven days, while immobilization of the organism within the microvoids was observed microscopically using fluorescent and electron microscopy. Experimental data provided evidence that the T. lanuginosus strains ATCC 38905 and ATCC 46882, A. aculeatus DSM 2344, S. cerevisiae, E. coli and S. rolfsii were poor biofilm producers and did not demonstrate the ability to immobilize onto the membrane. G. roseum, P. glabrum, P. chrysogenum CCRC 31619, P. italicium, C. laurentii and the effluent sample were adequate biofilm producers with the ability to immobilize onto the membrane. The alkaline protease producing strain of P. chrysogenum CCRC 31619 was chosen for use for the next phase of this research.