Optimization of the process of membrane separation of MSW landfill leachate with a high concentration of hardness saltsOptimization of the process of membrane separation of MSW landfill leachate with a high concentration of hardness salts

Summary

The aspects of optimizing the process of reverse osmosis membrane separation of the leachate of a municipal solid waste landfill with a high concentration of hardness salts is considered. The research was carried out in an experimental two-stage reverse osmosis unit. To study possible increasing the efficiency of the membrane reverse osmosis separation of the leachate and, in particular, of the membrane flux, various inhibitors of sediment formation were added to the feed clarified percolating water (before the membrane separation): Avista Vitec 3000, Clarofos 381, and sodium tripolyphosphate. Percolating water of the Mar’inskii solid waste landfill (Vladimir region) with a high concentration of hardness salts was used as a researchable aqueous solution. Based on the results of the executed studies, the effect of various inhibitors of sediment formation on the process of membrane reverse osmosis separation was estimated in terms of the membrane flux. The positive effect on membrane separation of the inhibitors of the sediment formation of hardness salts on the membrane surface added into the feed clarified leachate of the solid waste landfill has been proven. The best results in increasing the membrane flux during the purification of clarified percolating water were obtained with the use of the Avista Vitec 3000 inhibitor. The executed studies have shown that while choosing a sediment formation inhibitor, the specific composition of the feed water, the operating mode of the membrane equipment and the special requirements of the purification technology should be taken into account.

Key words

high concentrated wastewater , membrane separation , scaling inhibitors , two-stage reverse osmosis unit , hardness salts , membrane flux , concentration grade

Ways of reducing the operating costs of membrane units
for the preparation of drinking water from underground water sources

Summary

Experimental investigations have been conducted to determine the main process parameters of membrane units (filtrate yield, the rate of scaling on membrane surface). Basing on the results of the experimental studies the total costs of purification of underground water of various chemical composition were obtained. The studies were conducted on laboratory benches with the use of nanofiltration membranes with various selectivity rates. The consumption of service chemicals and operational costs for the equipment were calculated by the software designed earlier by the authors for determining the process parameters of membrane units. While designing membrane units, nanofiltration membranes with low values of selectivity, power consumption and expenditures for chemicals are preferred. The dependencies of the calcium carbonate scaling rates on membrane types and the multiplicity of volumetric concentration of source water were obtained. A comparison of costs shows that the use of membranes even for cases of water deferrization is more economical than the known traditional technologies.

Key words

calcium carbonate , ground water , concentrate , reverse osmosis , nanofiltration , water softening , scaling on membranes , deposits of slow-soluble salts in water , scaling inhibitors , scaling rate