Effect of Rhamnolipids and Lipopolysaccharides on the Bioleaching of Arsenic-Bearing Waste

The adsorption of biosurfactants and polysaccharides changes the surface properties of solid particles, which is important for controlling the release of arsenic compounds from the solid phase and preventing undesirable bioleaching. Microbial leaching and scorodite adhesion experiments, including pure and modified mineral material, were conducted in a glass column with a mineral bed (0.8–1.2 mm particle size) to test how rhamnolipids (Rh) and lipopolysaccharides (LPS) affect surface properties of mineral waste from Złoty Stok (Poland) and secondary bio-extraction products (scorodite). Adsorption tests were conducted for both solid materials. The adsorption of Rh and LPS on the solids was shown to modify its surface charge, affecting bioleaching. The highest bio-extraction efficiency was achieved for arsenic waste with adsorbed rhamnolipids, while the lowest, for the LPS-modified mineral. Under acidic circumstances (pH~2.5), the strongly negative zeta potential of arsenic-bearing waste in the presence of Rh creates conditions for bacteria adhesion, leading to the intensification of metal extraction. The presence of a biopolymer on the As waste surface decreases leaching efficiency and favours the scorodite’s adhesion.

Numerical Analysis of Crack Propagation in Tubular Glass Column

The demand for transparency has increased in the construction industry and contemporary architecture over the last decade. The prior researchers focused on glass columns because their uniqueness and transparent characteristics generate an impressive visual feature. Past studies on structural glass entailed numerous experimental investigations, but FEA was applied in a few investigation exercises. This study aims to validate the experimental data and analyse the crack in the tubular glass column and determine the effectiveness of different slenderness ratios of the glass column. This study investigated the column structural behaviour under compression with different geometrical dimensions of hollow section laminated glass columns to determine their load-carrying capacity, buckling performance, and failure mechanism. Finite element analysis using the explicit method was performed by using ABAQUS. The study found that the failure mechanisms depend on the slenderness ratio classified into two failure modes, either buckling or crushing. The glass column failed due to buckling when the slenderness ratio is more than 40, while it failed due to crushing when the slenderness ratio is less than 40. The finite element analysis did not correlate perfectly with the experimental data since the FEA underestimating the glass performance.

Studying the transport and retention of naturally occurring microplastics (MPs) in sandy soils using column experiments

<p>In the 1950’s, plastics were introduced as a miracle material and since then it has revolutionised human society in almost every domain of our daily life. The benefits of plastics are countless but their inherent resistance to degradation has ultimately led to their accumulation in the environment in the form of micro and nano plastics. In recent years, the presence of microplastics (MP) in fresh water sources has raised questions related to the protection of drinking water. In Austria, the exact status of groundwater contamination by MP is unknown. To understand the behaviour of MP that are present in the environment, a study was conducted to investigate the transport and distribution of MP in groundwater using column experiments.</p><p>Polyethylene MP were produced from 3D fluorescent printing material using a milling technique and in a well-defined size range of 1-200 μm. A borosilicate glass column (1.5 cm diameter and 10 cm long) was used as our experimental setup. The columns were packed with quartz and coarse sand. A layer of homogenized MP-sand mixture (approximately 3 to 5% w/w) was applied at the top of a soil column. The transport behaviour of MP were analysed in terms of various physical and chemical factors like MP-concentration, soil particle size, inflow rate, ionic strength and straining effect. The outflow from the column was collected at different pore volume intervals and analysed for the presence of MP. The breakthrough curves (BTCs) were obtained by measuring the MP concentrations of the effluent.</p>

Microfluidic Flow Injection Immunoassay System for Algal Toxins Determination: A Case of Study

A novel flow injection microfluidic immunoassay system for continuous monitoring of saxitoxin, a lethal biotoxin, in seawater samples is presented in this article. The system consists of a preimmobilized G protein immunoaffinity column connected in line with a lab-on-chip setup. The detection of saxitoxin in seawater was carried out in two steps: an offline incubation step (competition reaction) performed between the analyte of interest (saxitoxin or Ag, as standard or seawater sample) and a tracer (an enzyme-conjugated antigen or Ag*) toward a specific polyclonal antibody. Then, the mixture was injected through a “loop” of a few μL using a six-way injection valve into a bioreactor, in line with the valve. The bioreactor consisted of a small glass column, manually filled with resin upon which G protein has been immobilized. When the mixture flowed through the bioreactor, all the antibody-antigen complex, formed during the competition step, is retained by the G protein. The tracer molecules that do not interact with the capture antibody and protein G are eluted out of the column, collected, and mixed with an enzymatic substrate directly within the microfluidic chip, via the use of two peristaltic pumps. When Ag* was present, a color change (absorbance variation, ΔAbs) of the solution is detected at a fixed wavelength (655 nm) by an optical chip docking system and registered by a computer. The amount of saxitoxin, present in the sample (or standard), that generates the variation of the intensity of the color, will be directly proportional to the concentration of the analyte in the analyzed solution. Indeed, the absorbance response increased proportionally to the enzymatic product and to the concentration of saxitoxin in the range of 3.5 × 10–7–2 × 10–5 ng ml−1 with a detection limit of 1 × 10–7 ng ml−1 (RSD% 15, S N−1 equal to 3). The immunoanalytical system has been characterized, optimized, and tested with seawater samples. This analytical approach, combined with the transportable and small-sized instrumentation, allows for easy in situ monitoring of marine water contaminations.

Fast Detection of 2,4,6-Trinitrotoluene (TNT) at ppt Level by a Laser-Induced Immunofluorometric Biosensor

The illegal use of explosives by terrorists and other criminals is an increasing issue in public spaces, such as airports, railway stations, highways, sports venues, theaters, and other large buildings. Security in these environments can be achieved by different means, including the installation of scanners and other analytical devices to detect ultra-small traces of explosives in a very short time-frame to be able to take action as early as possible to prevent the detonation of such devices. Unfortunately, an ideal explosive detection system still does not exist, which means that a compromise is needed in practice. Most detection devices lack the extreme analytical sensitivity, which is nevertheless necessary due to the low vapor pressure of nearly all explosives. In addition, the rate of false positives needs to be virtually zero, which is also very difficult to achieve. Here we present an immunosensor system based on kinetic competition, which is known to be very fast and may even overcome affinity limitation, which impairs the performance of many traditional competitive assays. This immunosensor consists of a monolithic glass column with a vast excess of immobilized hapten, which traps the fluorescently labeled antibody as long as no explosive is present. In the case of the explosive 2,4,6-trinitrotoluene (TNT), some binding sites of the antibody will be blocked, which leads to an immediate breakthrough of the labeled protein, detectable by highly sensitive laser-induced fluorescence with the help of a Peltier-cooled complementary metal-oxide-semiconductor (CMOS) camera. Liquid handling is performed with high-precision syringe pumps and chip-based mixing-devices and flow-cells. The system achieved limits of detection of 1 pM (1 ppt) of the fluorescent label and around 100 pM (20 ppt) of TNT. The total assay time is less than 8 min. A cross-reactivity test with 5000 pM solutions showed no signal by pentaerythritol tetranitrate (PETN), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). This immunosensor belongs to the most sensitive and fastest detectors for TNT with no significant cross-reactivity by non-related compounds. The consumption of the labeled antibody is surprisingly low: 1 mg of the reagent would be sufficient for more than one year of continuous biosensor operation.

Remediation of Artificially Hydrocarbon Polluted Vadose Zone Soil in Glass Column through Percolation with Solution of Nutrient, Nutrient-Surfactant or Surfactant

Remediation of hydrocarbon polluted vadose zone (HPVZ) through percolation with solution of nutrient, nutrient-surfactant, or surfactant in glass columns was investigated in this study using standard methods. Percolated liquids from the columns and soils retrieved at the end of the experiment were analyzed for nitrate, phosphate, sulphate, total-petroleum hydrocarbon, and selected microbial groups. Results obtained showed that there were nitrate, phosphate, and sulphate in the percolated liquids. Cumulative hydrocarbon in the percolated liquids was 5.35 – 7.59 % of cumulative hydrocarbon start-up concentration in the columns. Cumulative hydrocarbon attenuation across soil layers in column flooded with solution of nutrients (column NT), nutrient-surfactant (column NTS), and surfactant (column SF) were 89.29, 95.27, and 66.92 % respectively. There was more phosphate reduction in column NTS, and more sulphate reduction in column NT. Hydrocarbon-utilizing fungi in columns NT and NTSincreased from 3.5 Log10 CFU.g-1 to between 4.0 – 5.0 Log10 CFU.g-1, whereas a decrease was observed for column SF. Hydrocarbon-utilizing bacteria in all the columns increased from between 1.0 – 2.5 Log10 CFU.g-1 to between 2.0 - 3.5 Log10 CFU.g-1. Emergence of hydrocarbon utilization among anaerobic bacteria population was also observed in all the columns. It is concludedthat percolation with nutrient-surfactant solution will be more effective in remediation of HPVZ, and that consequential migration of nutrients alongside hydrocarbons into groundwater canaid in enhancing biodegradation of the infiltrated hydrocarbons. Keywords: Biodegradation; petroleum hydrocarbons; vadose zone; inorganic nutrients; surfactant

Fast detection of 2,4,6-trinitrotoluene (TNT) at ppt level by an immunosensor based on kinetic competition

The illegal use of explosives by terrorists and other criminals is an increasing issue in public spaces, such as airports, railway stations, highways, sports arenas, theaters, and other large buildings. Security in these environments can be achieved by a set of different means, including the installation of scanners and other analytical devices to detect ultra-small traces of explosives in a very short time-frame to be able to take action as early as possible to prevent the detonation of such devices. Unfortunately, an ideal explosive detection system still does not exist, which means that a compromise is needed in practice. Most detection devices lack the extreme analytical sensitivity, which is nevertheless necessary due to the low vapor pressure of nearly all explosives. In addition, the rate of false positives needs to be virtually zero, which is also very difficult to achieve. Here we present an immunosensor system based on kinetic competition, which is known to be very fast and may even overcome affinity limitation, which impairs the performance of many traditional competitive assays. This immunosensor consists of a monolithic glass column with a vast excess of immobilized hapten, which traps the fluorescently labeled antibody as long as no explosive is present. In the case of TNT occurring, some binding sites of the antibody will be blocked, which leads to an immediate breakthrough of the labeled protein, detectable by highly sensitive laser-induced fluorescence with the help of a Peltier-cooled CMOS camera. Liquid handling is performed with high-precision syringe pumps and chip-based mixing-devices and flow-cells. The system achieved limits of detection of 1 pM (1 ppt) of the fluorescent label and around 100 pM (20 ppt) of the explosive 2,4,6-trinitrotoluene (TNT). The total assay time is less than 8 min. A cross-reactivity test with 5000 pM solutions showed no signal by PETN, RDX, and HMX. This immunosensor belongs to the most sensitive and fastest detectors for TNT with no significant cross-reactivity by non-related compounds.