Mercury removal and recovery from aqueous solutions by coupled complexation–ultrafiltration and electrolysis

International audienceRemoval of mercuric ions from wastewater by complexation-ultrafiltration using polyethylenimine (PEI) as complexing agent was previously studied. Conditions for rejection coefficients of mercury higher than 99.7% were obtained. The present work deals with the next operations: recycling of the PEI and recovery of the mercury from the concentrate of the first ultrafiltration. Direct electrodeposition of mercury using a packed bed flow-through (PBFT) cathode was carried out. Influence of operating parameters such as current intensity, pH, PEI and chloride ion concentration was studied. Depletion of mercury from 100 to 20 mg l(-1) was achieved with a current efficiency of about 100%, when the current density was 1.09 mA g(-1) of graphite. A process based on coupled complexation-ultrafiltration and electrodeposition on PBFT cathode was proposed and tested. Design elements of the whole process were given

Mercury removal from aqueous solutions by complexation—ultrafiltration

International audienceThe separation of mercury from aqueous solutions by complexation-ultrafiltration was investigated. Polyethylenimine (PEI) was used as polymeric complexing agent. Effects of pH and chloride ions concentration on mercury retention were studied. Mercury retention depends strongly on both pH and chloride ions concentration. For neutral solutions mercury retention values close to 100% were obtained. A process allowing mercury separation and concentration was studied. It couples two ultrafiltration stages: the first one concentrates mercury/PEI complex and the second one enables mercury separation and polymer recycling. This process was experimentally tested. Results showed that it is possible to concentrate mercury ten fold while a permeate with very low mercury concentration is collected. Recycling of PEI does not modify operation performance

Current status of arsenic contamination in drinking water and treatment practice in some rural areas of West Bengal, India

The aim of the present investigation was to draw the current scenario of arsenic (As) contamination in drinking water of community tube well and drinking water treated by tube wells installed with different adsorbent media-based treatment plants in districts Nadia, Hooghly and North 24-Parganas districts, West Bengal, India. As removal efficiencies of different treatment plants varied from 23 to 71%, which is largely governed by adsorption capacity of adsorbent and influencing environmental factors. Though investigated treatment plants removed substantial amount of As from tube well water, high As concentration in treated drinking water was retained after passing through the treatment plants. This high level of As concentration in tube well water and retention of high As concentration in treated drinking water were severe for the consumers which therefore, indicating the improvement of removal efficiency of treatment plant by meticulously considering favorable influencing factors or/and application of other high capacity treatment alternatives to adsorb the excess As retained in drinking water and regular monitoring of As concentration in the treated drinking water are indispensable