Search results for "Magnesium"
showing 10 items of 490 documents
Design, assembly and characterization of silicide-based thermoelectric modules
2016
ID: 1143 In: Energy conversion and management, 13-21. Summary: Highlights•Novel silicide-based thermoelectric modules were experimentally investigated.•The modules produced high power of 1.04 W at 405 °C and 3.24 W at 735 °C.•An estimated module efficiency of 5.3% represent the highest reported for silicide systems.AbstractSilicides have attracted considerable attention for use in thermoelectric generators due mainly to low cost, low toxicity and light weight, in contrast to conventional materials such as bismuth and lead telluride. Most reported work has focused on optimizing the materials properties while little has been done on module testing. In this work we have designed and tested mod…
Application of a fuzzy algorithm for pH control in a struvite crystallisation reactor
2006
A struvite crystallisation process is highly dependent on pH. To achieve a high phosphorus recovery as struvite it is important to have an accurate control of pH in the reactor. The high non-linear response of pH value makes manual pH control difficult. Therefore, a software based on fuzzy logic control (FLC) has been developed to maintain the pH at a set value in a stirred reactor to crystallise struvite. The FLC developed has been based on Larsen's inference. In order to confirm the improvement of the pH stability using FLC software, different experiments have been carried out with manual control of the pH value, and with the FLC software. It has been demonstrated that using FLC software …
Release of phosphorus under reducing and simulated open drainage conditions from overfertilised soils
2014
Does removal of cations from soil solution during soil reduction stimulate phosphorus (P) release? An ion-exchange resin system was employed to provide a sink during the incubation of twelve soils under fully reducing conditions. This experimental design was considered to better simulate the loss of ions likely to occur under field conditions than more routine batch type closed extraction systems where solutes build-up in the extract solution. The small solute concentrations that remain in the equilibrating solution suggest the mixed resin system acted as an effective sink over the whole experimental period. By maintaining a small P concentration the resin system mimics soil drainage condit…
Photo-induced fluorescence of magnesium derivatives of tetracycline antibiotics in wastewater samples
2009
Abstract An analytical strategy, for the determination of tetracyclines (TCs), based on a HPLC system coupled with a photo-reactor followed by post-column derivatization was developed. Higher fluorescence emission after coupling the resulting photo-fragments with magnesium ions was observed for the determination of minocycline (MC), epitetracycline (ETC), tetracycline (TC) and doxycycline (DC). The manifold included a HPLC system with a photo-reactor (PTFE tubing helically coiled around a low-pressure mercury lamp), a mixing T-piece and a fluorescence detector. The derivatization reagent was delivered at 0.5 mL min −1 by a pump. After HPLC separation using a gradient system with a mobile ph…
A pilot-scale study of struvite precipitation in a stirred tank reactor: Conditions influencing the process
2008
Currently, the two most developed techniques for recovering phosphorus from wastewater consist of the formation of calcium phosphates and struvite (MgNH(4)PO(4).6H(2)O). In this work the influence of the operational conditions on the struvite precipitation process (pH in the reactor, hydraulic retention time, and magnesium:phosphorus, nitrogen:phosphorus, and calcium:magnesium molar ratios) have been studied. Twenty-three experiments with artificial wastewater were performed in a stirred reactor. In order to obtain the pH value maintenance during the crystallization process, a fuzzy logic control has been developed. High phosphorus removal efficiencies were reliably achieved precipitating t…
Preparation of fouling resistant and highly perm-selective novel PSf/GO-vanillin nanofiltration membrane for efficient water purification
2022
International audience; To meet the rising global demand for water, it is necessary to develop membranes capable of efficiently purifying contaminated water sources. Herein, we report a series of novel polysulfone (PSf)/GO-vanillin nanofiltration membranes highly permeable, selective, and fouling resistant. The membranes are composed of two-dimensional (2D) graphite oxide (GO) layers embedded with vanillin as porogen and PSf as the base polymer. There is a growing interest in addressing the synergistic effect of GO and vanillin on improving the permeability and antifouling characteristics of membranes. Various spectroscopic and microscopic techniques were used to perform detailed physicoche…
Sludge management modeling to enhance P-recovery as struvite in wastewater treatment plants
2017
[EN] Interest in phosphorus (P) recovery and reuse has increased in recent years as supplies of P are declining. After use, most of the P remains in wastewater, making Wastewater Treatment Plants (WWTPs) a vital part of P recycling. In this work, a new sludge management operation was studied by modeling in order to recover Pin the form of struvite and minimize operating problems due to uncontrolled P precipitation in WWTPs. During the study, intensive analytical campaigns were carried out on the water and sludge lines. The results identified the anaerobic digester as a "hot spot" of uncontrolled P precipitation (9.5 gP/kg sludge) and highlighted possible operating problems due to the accumu…
Sewage sludge management for phosphorus recovery as struvite in EBPR wastewater treatment plants
2008
The influence of separate and mixed thickening of primary and secondary sludge on struvite recovery was studied. Phosphorus precipitation in the digester was reduced from 13.7 g of phosphorus per kg of treated sludge in the separate thickening experiment to 5.9 in the mixed thickening experiment. This lessening of the uncontrolled precipitation means a reduction of the operational problems and enhances the phosphorus availability for its later crystallization. High phosphorus precipitation and recovery efficiencies were achieved in both crystallization experiments. However, mixed thickening configuration showed a lower percentage of phosphorus precipitated as struvite due to the presence of…
Struvite formation from the supernatants of an anaerobic digestion pilot plant
2009
This work studied the influence of the characteristics of the supernatants on the struvite precipitation process. Eighteen experiments with the supernatants generated in an anaerobic digestion pilot plant were performed in a stirred reactor. In order to obtain the pH control during the crystallization process, a Fuzzy Logic based controller was used. High phosphorus precipitation and recovery efficiencies were obtained. The composition of the supernatants was analyzed in order to study its influence on the solids formed from those solutions. The presence of calcium reduced the percentage of phosphorus precipitated as struvite leading to the formation of amorphous calcium phosphate (ACP), wh…
Optimisation of sludge line management to enhance phosphorus recovery in WWTP
2008
The management of the sludge treatment line can be optimized to reduce uncontrolled phosphorus precipitation in the anaerobic digester and to enhance phosphorus recovery in WWTP. In this paper, four operational strategies, which are based on the handling of the prefermented primary sludge and the secondary sludge from an EBPR process, have been tested in a pilot plant. The separated or mixed sludge thickening, the use of a stirred contact tank and the elutriation of the thickened sludge are the main strategies studied. Both the reduction of phosphorus precipitation in the digester and the supernatant suitability for a struvite crystallization process were assessed in each configuration. The…