This paper reports an approach to estimate the sludge density in a physicochemical treatment of municipal wastewater, experiments considered 4 coagulants (aluminum sulfate SAl, iron sulfate SFe, aluminum polychloride ...This paper reports an approach to estimate the sludge density in a physicochemical treatment of municipal wastewater, experiments considered 4 coagulants (aluminum sulfate SAl, iron sulfate SFe, aluminum polychloride PAX, iron polychloride PIX), and 2 flocculant products (cationic CP and anionic AP polymers). Experimental approach is based on running a set of jar tests at different coagulant concentrations. After the stirring and resting times took place, pH and conductivity were registered finding that SAl and SFe either with or without polymers are the coagulants producing the higher pH drop. Conductivity measures also establish two kind of data since higher conductivity (about 2000 ) was observed for SAl, and PIX, PIX + CP, PIX + AP;otherwise a conductivity about 1300 was observed for SAl + PC, SFe and PAX alone and with CP or AP. Settleable solids (SST) determined with an Imhoff cone were similar for sulfates and polychlorides, but dry sludge (DS) clearly set up two groups the one with higher sludge content corresponds to sulfates group. The quotient of DS divided by the SST provided an estimation of the apparent sludge density, in this way it was observed that higher densities were obtained for sludge from sulfates at lower coagulant concentrations;also sludge from SFe was heavier than the one from SAl. Otherwise, polychlorides produced a lighter sludge in respect to the one obtained with sulfates, and between them the PIX coagulant provided a heavier sludge than the PAX coagulant.展开更多
In this study, it is reported an analytical approach to recover organochlorine pesticides from a clay soil. Soil was physical and chemically characterized. Also pesticides extraction was carried out using packed colum...In this study, it is reported an analytical approach to recover organochlorine pesticides from a clay soil. Soil was physical and chemically characterized. Also pesticides extraction was carried out using packed columns and various aqueous media (H2O-milliQ, NaOH, HCl, SDS, Triton X-114, Humic acids and Acetonitrile). The leachate samples were analyzed on an Agilent Technologies 6890N Gas Chromatograph with electron capture in a# AB002 Column 30.0 m × 250 μm × 0.25 μm calibrated, 25 psi pressure, flow 2.9 ml/min, temperature 25°C, ultra-high purity Helium as the entrainment gas and an elution time of 50 min. The results show that the highest extraction percentage of pollutants in the soil washing was obtained with acetonitrile recovering: p, p’-DDT (91.0%);p, p’-DDE (92.0%);p, p’-DDD (96.0%);aldrin (98.6%);dieldrin (98.0%). With Triton X-114, the extractions recovery was: p, p’-DDT (63.0%);p, p’-DDE (64.0%);p, p’-DDD (65.0%);aldrin (67.0%);dieldrin (72.0%). This study illustrates the potential Applicability of SPME for routine analysis of organochlorine pesticides in soils.展开更多
文摘This paper reports an approach to estimate the sludge density in a physicochemical treatment of municipal wastewater, experiments considered 4 coagulants (aluminum sulfate SAl, iron sulfate SFe, aluminum polychloride PAX, iron polychloride PIX), and 2 flocculant products (cationic CP and anionic AP polymers). Experimental approach is based on running a set of jar tests at different coagulant concentrations. After the stirring and resting times took place, pH and conductivity were registered finding that SAl and SFe either with or without polymers are the coagulants producing the higher pH drop. Conductivity measures also establish two kind of data since higher conductivity (about 2000 ) was observed for SAl, and PIX, PIX + CP, PIX + AP;otherwise a conductivity about 1300 was observed for SAl + PC, SFe and PAX alone and with CP or AP. Settleable solids (SST) determined with an Imhoff cone were similar for sulfates and polychlorides, but dry sludge (DS) clearly set up two groups the one with higher sludge content corresponds to sulfates group. The quotient of DS divided by the SST provided an estimation of the apparent sludge density, in this way it was observed that higher densities were obtained for sludge from sulfates at lower coagulant concentrations;also sludge from SFe was heavier than the one from SAl. Otherwise, polychlorides produced a lighter sludge in respect to the one obtained with sulfates, and between them the PIX coagulant provided a heavier sludge than the PAX coagulant.
文摘In this study, it is reported an analytical approach to recover organochlorine pesticides from a clay soil. Soil was physical and chemically characterized. Also pesticides extraction was carried out using packed columns and various aqueous media (H2O-milliQ, NaOH, HCl, SDS, Triton X-114, Humic acids and Acetonitrile). The leachate samples were analyzed on an Agilent Technologies 6890N Gas Chromatograph with electron capture in a# AB002 Column 30.0 m × 250 μm × 0.25 μm calibrated, 25 psi pressure, flow 2.9 ml/min, temperature 25°C, ultra-high purity Helium as the entrainment gas and an elution time of 50 min. The results show that the highest extraction percentage of pollutants in the soil washing was obtained with acetonitrile recovering: p, p’-DDT (91.0%);p, p’-DDE (92.0%);p, p’-DDD (96.0%);aldrin (98.6%);dieldrin (98.0%). With Triton X-114, the extractions recovery was: p, p’-DDT (63.0%);p, p’-DDE (64.0%);p, p’-DDD (65.0%);aldrin (67.0%);dieldrin (72.0%). This study illustrates the potential Applicability of SPME for routine analysis of organochlorine pesticides in soils.
