Selenium and sulphur reactions involved in manganese reduction from sulphate solutions.

Electrochemical reduction of ionic species during manganese deposition from sulphated aqueous solutions has been studied in an electrochemical reactor with two anionic exchange membranes. Thermodynamic analysis, voltammetries, and chronopotentiometries were used to determine the reaction mechanism of the reductions developed, with the results demonstrating that the effect of the elemental selenium on the hydrogen evolution leads to the formation of elemental sulphur by reducing the sulphate ions with both membranes. It was also evident that in the range of -25 to -50 A m the electrodeposition of metallic manganese begins, with minimal interference from parasitic reactions.

Closed cycle of recycling of waste activated sludge.

The recycling of waste activated sludge (WAS) formed in the process of biological purification of sewage is an urgent ecological problem. In the present work, two ways of recycling of WAS containing from 8 to 30% free water, namely, the synthesis of a carbon-containing component and synthesis of porous building ceramics (bricks) with the use of WAS and waste carbonizate, have been considered. For the preparation of a carbon adsorbent, the carbonization of WAS has been carried out in an argon atmosphere.