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Ezio Ranieri, Politecnico di Bari (Italy)
Pietro Calabrese, Engineer (Italy)
Domenico Petruzzelli, Politecnico di Bari (Italy)
Valentina Petruzzelli, Engineer (Italy)
Vincenzo Simeone, Politecnico di Bari (Italy)
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Interest in the use of Recycled Porous Glass (RPG) from Municipal Solid Waste sorting operations, as a filtration/sorption media for stripping out at least part of the pollutant load present in effluent streams is strong. It is a material that can be suitably used for constructed wetlands substrate or also as a filtration/sorption for groundwater recharge installations. A wide range of technologies are available providing Water Authorities and Industries of waste treatment services where effluent streams are generated and in this field recently a strong interest has been manifested in constructed wetland. Recent research has shown that RPG as a filtration/sorption media may offer improved performance over traditional media such as, e.g., silica sand and activated carbon, in a range of rapid gravity and pressure dual media filter applications. To meet this opportunity, properly designed laboratory experiments have been carried-out to fully quantify performance and benefits of the reference media under operative conditions likely to be adopted in constructed wetland by the use of partially treated (waste)water from municipal and/or different economical activities. To this aim laboratory scale investigation was carried-out by the use of a commercial RPG to test hydrodynamic and physico-chemical operative performance as a dual filtration media in coastal groundwater recharge operations. Dynamic (column) experiments were carried-out by the use a permeameter (ID= 0.3 m, H=0.4 m) which was loaded with ~ 2kg RPG at two different bead size in the range (0,5-1.0 mm and 1.0-1,5 mm respectively) and flowed with tapwater at 2 cm3/s. After stationary flow conditions a point injection of a tracer solution (50 cm3, 1M NaBr) was made and bromide ion breakthrough curve (i.e., concentration Vs. time) was followed in the effluent solution. After application of credited advection/diffusion models Darcy's permeability and Fick's molecular diffusion coefficients were evaluated. Pb2+ and Cd2+ ions retention capacity onto RPG materials was also evaluated by column experiments with promising results. Experimental results demonstrated the potential benefits associated with the use the new filtration/sorption media under conditions simulating constructed wetland. This work was developed as part of the explorative research project ?Constructed wetland for metals and organics removal. Evaluation of full scale applicability in Apulia (COWMAN)? financed by Apulia Region (Southern Italy)
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