Real Water Treatment Plant Research Articles

Competitive kinetics of adsorption onto activated carbon for emerging contaminants with contrasting physicochemical properties.

Activated carbon (AC) can be used for the removal of emerging contaminants (e.g., drugs) in water and wastewater treatment plants. In the present study, we investigated the performance of two ACs (from coconut shell and Pinnus sp.) in the adsorption of caffeine, carbamazepine, and ricobendazole considering the compounds separately and in combination in batch-scale experiments. The concentrations of the drugs were determined by a validated method using solid-phase extraction with on-line ultra-high performance liquid chromatography-tandem mass spectrometry. The most mesoporous AC provided higher drug removal. The kinetic data were described by the pseudo-second-order, Elovich, and Weber-Morris models, while the adsorption isotherms showed a better fit to the Freundlich model, indicative of multilayer adsorption. The Dubinin-Radushkevich model was used as a first approach to estimate the mean adsorption energy (E) and the results indicate that chemisorption governed the adsorption process, with E higher than 8 kJ mol-1. In the multicomponent assays, the adsorption of caffeine showed the greatest hindrance caused by the presence of other drugs. Multicomponent assays are fundamental to evaluate the potential adsorption capacity in real water treatment plants. Our study suggests that drugs with different structures and physicochemical properties may interact differently with ACs, especially in multicomponent solutions, with important implications for the design (e.g., volumes and areas of treatment plants) and operation (e.g., water residence time) of the treatment plants.

Integrated framework for behaviour analysis in a process plant

The fact that system reliability is influenced by numerous factors (model, assembling, installation, upkeep and use) makes it particularly challenging to identify, evaluate and anticipate the failure causes of system. To this effect, the current research work seeks to propose a quantitative and qualitative approach based integrated framework for the behaviour analysis of a process plant system. In the quantitative analysis, series/parallel combination of the considered system has been modelled using Petri net (PN) approach. Various reliability parameters were computed at different spreads and the system's behaviour is studied in crisp, fuzzy and defuzzified terms. Further, in order to improve system's availability and maintainability characteristics, an extensive qualitative analysis is performed using Root Cause Analysis (RCA) and Failure Mode and Effect Analysis (FMEA) for listing the various failure causes. Limitations of traditional FMEA in risk ranking of risky/critical components were overcome by using a Fuzzy Decision Making System (FDMS) and Grey Relation Analysis (GRA). The ranking results so obtained were compared with those of FMEA raking results for better decision making of risky components of the considered system. The framework has been employed to carry out the behavioural analysis of a real Water Treatment Plant (WTP) of a coal fired thermal power plant in North India.

An Ultrasonic Multi-Beam Concentration Meter with a Neuro-Fuzzy Algorithm for Water Treatment Plants.

Ultrasonic concentration meters have widely been used at water purification, sewage treatment and waste water treatment plants to sort and transfer high concentration sludges and to control the amount of chemical dosage. When an unusual substance is contained in the sludge, however, the attenuation of ultrasonic waves could be increased or not be transmitted to the receiver. In this case, the value measured by a concentration meter is higher than the actual density value or vibration. As well, it is difficult to automate the residuals treatment process according to the various problems such as sludge attachment or sensor failure. An ultrasonic multi-beam concentration sensor was considered to solve these problems, but an abnormal concentration value of a specific ultrasonic beam degrades the accuracy of the entire measurement in case of using a conventional arithmetic mean for all measurement values, so this paper proposes a method to improve the accuracy of the sludge concentration determination by choosing reliable sensor values and applying a neuro-fuzzy learning algorithm. The newly developed meter is proven to render useful results from a variety of experiments on a real water treatment plant.

Increasing of drinking water quality at real water treatment plant by recarbonization process

Increasing of drinking water quality at real water treatment plant by recarbonization process According to the World Health Organization, chemical and microbial contaminants in drinking water will continue in the interest of suppliers of drinking water. The review establishment of new knowledge for drinking water including the potential benefits of the mineral content is necessary. The paper is focused on an assessment of the quality of water from surface source for drinking water preparation and quality of drinking water produced at the real plant. The lab-scale verification of water recarbonization with lime and carbon dioxide was chosen based on the results of full scale plant data analysis. Recarbonization tests were carried out with the raw water and the impact of recarbonization on coagulation process at different coagulant doses was studied. The results show that water recarbonization had adverse influence on the water treatment processes.

Development of the Simulation Model to Predict Dissolved Ozone Concentration for a Real Water Treatment Plant

Development of the Simulation Model to Predict Dissolved Ozone Concentration for a Real Water Treatment Plant

Biofouling of reverse osmosis membranes: Microbial quorum sensing and fouling propensity

Fouled RO membranes from a real water treatment plant were analyzed biochemically to investigate the role of quorum sensing in controlling the rate and the extent of biofilm formation on the membrane surface. The results showed that 60% of bacterial species found on the fouled membrane surface contribute to biofilm formation through the active intraspecies as well as interspecies communication. It was confirmed that N-acylated homoserine lactones (AHL) produced from microorganisms involved in the quorum sensing transferred bacterial signal. In addition, flow field-flow fractionation (Fl-FFF) analyses demonstrated that most microorganisms contributing to biofilm formation through quorum sensing exhibited favorable adsorption on the membrane surfaces. The skewness values of these microorganisms were noticeably greater than those of organic macromolecules (i.e., natural organic matter) and particles. The study suggests that biochemical control of interfering quorum sensing could be an effective alternative to control biofilm formation and, thus, the reduction in biofouling of RO membranes.

Chlorination kinetics of glyphosate and its by-products: Modeling approach

Chlorination reactions of glyphosate, glycine, and sodium cyanate were conducted in well-agitated reactors to generate experimental kinetic measurements for the simulation of chlorination kinetics under the conditions of industrial water purification plants. The contribution of different by-products to the overall degradation of glyphosate during chlorination has been identified. The kinetic rate constants for the chlorination of glyphosate and its main degradation products were either obtained by calculation according to experimental data or taken from published literature. The fit of the kinetic constants with experimental data allowed us to predict consistently the concentration of the majority of the transitory and terminal chlorination products identified in the course of the glyphosate chlorination process. The simulation results conducted at varying aqueous chlorine/glyphosate molar ratios have shown that glyphosate is expected to degrade in fraction of a second under industrial aqueous chlorination conditions. Glyphosate chlorination products are not stable under the conditions of drinking water chlorination and are degraded to small molecules common to the degradation of amino acids and other naturally occurring substances in raw water. The kinetic studies of the chlorination reaction of glyphosate, together with calculations based on kinetic modeling in conditions close to those at real water treatment plants, confirm the reaction mechanism that we have previously suggested for glyphosate chlorination.

By-products formation during degradation of isoproturon in aqueous solution. II: chlorination

After a previous study in which the considered oxidant was ozone (Part I), a laboratory investigation has been carried out to study the degradation of the herbicide isoproturon during its reaction with another oxidant, i.e. chlorine, in aqueous solution (Part II; this paper). The specific aim was to identify the by-products formed. The effects of pH and the presence of bromide ions were studied. Reactions have been carried out at room temperature, in phosphate buffered aqueous solutions, at four pHs (6, 7, 8 and 9). By-products identification was first performed using relatively high initial reagent concentrations which were analytically convenient ([isoproturon]=40 mg/l, [HClO+ClO −]=160 mg Cl/l, [Br −]=80 mg/l). In follow-up studies, the by-products identified during this preliminary step were searched for when using concentration values closer to those actually encountered at real water treatment plants ([isoproturon]=0.4 and 0.004 mg/l, [HClO+ClO −]=1.6 mg Cl/l, [Br −]=0.8 and 0.008 mg/l). Under all of the studied conditions, the results showed that isoproturon is completely degraded and that it decays much faster in the presence of bromide. The pH has a negligible influence when bromide ions are absent. On the contrary, if bromide ions are present, the isoproturon decay is slower at higher pH values. High-performance liquid chromatography-mass spectrometry (HPLC-MS) analyses have led to the identification of several by-products as a result of simultaneous oxidation and substitution reactions, both occurring on the aromatic ring of the herbicide. However, the more abundant by-products are those resulting from the oxidation of the isoproturon aromatic ring. As far as halogenated by-products are concerned, the higher the bromide ion concentration the higher the ratio of brominated to chlorinated by-products. On the basis of the analytical results, a pathway for isoproturon degradation under the studied conditions is proposed.