“…Biological methods are very effective for the treatment of landfill leachate with a high value of BOD (biological oxygen demand) but are ineffective if recalcitrant organic compounds are present, so that they must be supported by a physical−chemical process (). Up to now, great attention has been directed toward either new techniques, based on chemical or physical processes ( − ), or older techniques, like electrochemical oxidation, never applied for this particular purpose. 1 Experimental apparatus.…”
Leachate originating in landfills where municipal solid wastes are disposed is a wastewater with a complex composition that could have a high environmental impact. The primary goal of this research was to investigate the feasibility of removing refractory organic pollutants and ammonium nitrogen from landfill leachate by electrochemical oxidation. The effects of current density, pH, and chloride concentration on the removal of both chemical oxygen demand (COD) and ammonium nitrogen were investigated. Titanium coated with lead dioxide (PbO 2 ) or tin dioxide (SnO 2 ) was used as the anode. An effective process was achieved in which the leachate was decolorized, COD was removed up to a value of 100 mg L -1 , and ammonia was totally eliminated. Average current efficiency of about 30% was measured for a decrease of COD from 1200 to 150 mg L -1 , while efficiency of about 10% was measured for a near complete removal of ammonium nitrogen, starting from an initial value of 380 mg L -1 . Results indicated that the organic load was removed by both direct and indirect oxidation. Indirect oxidation by chlorine or hypochlorite originating from oxidation of chlorides is believed to be mainly responsible for the nitrogen removal.
“…Biological methods are very effective for the treatment of landfill leachate with a high value of BOD (biological oxygen demand) but are ineffective if recalcitrant organic compounds are present, so that they must be supported by a physical−chemical process (). Up to now, great attention has been directed toward either new techniques, based on chemical or physical processes ( − ), or older techniques, like electrochemical oxidation, never applied for this particular purpose. 1 Experimental apparatus.…”
Leachate originating in landfills where municipal solid wastes are disposed is a wastewater with a complex composition that could have a high environmental impact. The primary goal of this research was to investigate the feasibility of removing refractory organic pollutants and ammonium nitrogen from landfill leachate by electrochemical oxidation. The effects of current density, pH, and chloride concentration on the removal of both chemical oxygen demand (COD) and ammonium nitrogen were investigated. Titanium coated with lead dioxide (PbO 2 ) or tin dioxide (SnO 2 ) was used as the anode. An effective process was achieved in which the leachate was decolorized, COD was removed up to a value of 100 mg L -1 , and ammonia was totally eliminated. Average current efficiency of about 30% was measured for a decrease of COD from 1200 to 150 mg L -1 , while efficiency of about 10% was measured for a near complete removal of ammonium nitrogen, starting from an initial value of 380 mg L -1 . Results indicated that the organic load was removed by both direct and indirect oxidation. Indirect oxidation by chlorine or hypochlorite originating from oxidation of chlorides is believed to be mainly responsible for the nitrogen removal.
“…Advanced oxidation processes (AOP) e.g. UV/Fe 2 þ þ H 2 O 2 , (Kim et al, 1997), (Wenzel et al, 1999) and UV/TiO 2 (Bekbolet et al, 1996) have been proposed as an effective alternative for the mineralisation of recalcitrant organics in landfill leachate. However, the complete degradation (mineralisation) of organics by AOP for the treatment of large-scale effluents is not economically viable (Scott and Ollis, 1995).…”
Landfill leachates are a problematic wastewater due to their variable concentration, volume changing in time and presence of refractory and hazardous components. In this paper, the results of a new approach to photocatalysis assisted by biological process for the detoxification of stabilised landfill leachate are presented. The biologically pre-treated leachate still contained a significant amount of non-biodegradable COD and TOC amounting to 500 and 200 mg/L, respectively. The 300 min of photocatalytic treatment (UVC/TiO2) brought about a significant decrease in more than 80% refractory organics remaining in leachate. The effect of pH and catalyst loading on mineralisation, colour removal rate and biodegradability (BOD/COD) improvement in the photoreactor were discussed. The bio-accessibility of formed photocatalytic oxidation intermediates was confirmed by oxygen uptake rate (OUR) measurements. Consequently, a part of COD was successfully removed in post-biological treatment.
“…These effluents may contain chemical components of high toxicity and frequently are not treatable by biological methods. Conventional physical−chemical methods may remove the pollutants from the aqueous phase, but do not destroy them, resulting in a problem of subsequent disposal of these contaminants ( − ).…”
The photo-Fenton process utilizes ferrous ions (Fe2+), hydrogen peroxide (H2O2), and ultraviolet (UV) irradiation as a source of hydroxyl radicals for the oxidation of organic matter present in aqueous effluents. The cost associated with the use of artificial irradiation sources has hindered industrial application of this process. In this work, the applicability of solar radiation for the photodegradation of raw gasoline in water has been studied. The photo-Fenton process was also applied to a real effluent, i.e., oil-field-produced water, and the experimental results demonstrate the feasibility of employing solar irradiation to degrade this complex saturated-hydrocarbon-containing system.
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