Co-treatment of landfill leachate and domestic wastewater using a submerged aerobic biofilter.

This study used a pilot-scale submerged aerobic biofilter (SAB) to evaluate the co-treatment of domestic wastewater and landfill leachate that was pre-treated by air stripping. The leachate tested volumetric ratios were 0, 2, and 5%. At a hydraulic retention time of 24 h, the SAB was best operated with a volumetric ratio of 2% and removed 98% of the biochemical oxygen demand (BOD), 80% of the chemical oxygen demand (COD) and dissolved organic carbon (DOC), and 90% of the total suspended solids (TSS). A proposed method, which we called the "equivalent in humic acid" (Eq.HA) approach, indicated that the hardly biodegradable organic matter in leachate was removed by partial degradation (71% of DOC Eq.HA removal). Adding leachate at a volumetric ratio of 5%, the concentration of the hardly biodegradable organic matter was decreased primarily as a result of dilution rather than biodegradation, which was confirmed by Fourier transform infrared (FTIR) spectroscopy. The total ammoniacal nitrogen (TAN) was mostly removed (90%) by nitrification, and the SAB performances at the volumetric ratios of 0 and 2% were equal. For the three tested volumetric ratios of leachate (0, 2, and 5%), the concentrations of heavy metals in the treated samples were below the local limits.

Solvent extraction of Fe(III) by dehydrated castor oil fatty acids.

The effect of temperature on the extraction of FE(III) by dehydrated castor oil fatty acids (DCOFA) has been studied in the temperature range 283-313 K at 1.0M constant ionic strength (NaClO(4)). The temperature dependence of the conditional constant of extraction is given in the form: ln K(ext)=31.95 - 12800(1/T). Also, it was found that the average thermodynamic parameters, DeltaH degrees (ext), DeltaG degrees (ext), and DeltaS degrees (ext) are 106.5 kJ/mole, 27.3 kJ/mole, and 0.3 kJ. mole(-1).K(-1), respectively. The extracted species in toluene solution were identified as FeR(3).HR and Fe(OH)R(2), where HR represents the fatty acid used.