Removal of silver from wastewater using cross flow microfiltration

Removal of silver from wastewater was investigated using continuous cross flow microfiltration (MF) technique hollow fiber membranes with a pore size 0.2μm, with sorbent coated material Al2O3/SDSH2Dz particle size (8 μm). The coating investigated was dithizone (Diphenylthiocarbazone) in 0.005M ammonia solution. In the filtration of silver ion solutions, the effects of the permeate flow rate and cross flow velocity on the absorption of silver ion solutions, and since the pore size of membrane (=0.2 μm) is smaller then that of the (Al2O3), no need to consider the variation of (Al2O3).rejection as it can be considered to be 100%. The amount of silver absorbed into sorbent material Al2O3/SDSH2Dz was (25.35, 39.68 ppm) for the cross flown velocity of 5, 2.5 L/hr respectively, and were the results as function of permeate flow was (25.35, 39.68 ppm) for the velocity of 5, 2.5 L/hr respectively

Assessing the effects of metal mining effluents on freshwater ecosystems using biofilm as an ecological indicator: Comparison between nanofiltration and nanofiltration with electrocoagulation treatment technologies

Abandoned mines cause serious environmental damage to their surroundings with considerable impacts on freshwater ecosystems. These impacts occur mainly due to the uncontrolled discharge of polluted effluents, which may contain high concentrations of heavy metals. Currently, no real solution exists for this important environmental problem, leaving a legacy of global pollution. This study aimed to assess the impact of a metal mining effluent from an abandoned mine on freshwater ecosystems, using aquatic biofilms as an ecological indicator. At the same time, the efficiency of different innovative treatment technologies in reducing the ecological impacts caused by mining effluents was evaluated, consisting of nanofiltration and nanofiltration combined with electrocoagulation. To do that, aquatic biofilms obtained from a pristine stream, were exposed, under microcosms conditions, to a metal mining effluent, untreated or treated by the innovative treatment technologies and responses were compared with unexposed biofilm which served as control. The structural and functional responses of the biofilm were measured with throughout time. Biofilms that were exposed to the untreated mining effluent showed significant differences respect to the rest of treatments and the control, particularly exhibiting inhibitory effects on photosynthetic efficiency just after 24 h of exposure and a progressive shift of the photosynthetic community composition throughout the exposure period. The treatment technologies significantly reduced the ecological impact caused by the metal mining effluent. However, metal bioaccumulation in biofilm revealed a potential long-term impact. These observations evidenced the biofilm as a useful ecological indicator to assess the ecological impact caused by metal mining effluents on freshwaters and the efficiency of different treatment technologies to reduce it.This work was supported by the European Commission LIFE program throughout the LIFE DEMINE project (LIFE16 ENV/ES/000218)