ABSTRACT
Leachate originating in landfills, where industrial solid wastes are disposed of, is a complex wastewater that could exert high environmental impact. In this paper, treatment of landfill leachate, particularly removal of chemical oxygen demand (COD) through adsorption, chemical oxidation (KMnO4), electrocoagulation and electrochemical oxidation processes was studied. The combined processes, viz. KMnO4 and hypo, electrocoagulation and KMnO4, electrocoagulation and hypo, adsorption and KMnO4, adsorption and hypo were also investigated and the comparison was studied. The treatment of landfill leachate by electrochemical oxidation was carried out in a batch electrolytic parallel plate (Stainless Steel (SS)// Carbon) and fixed bed three dimensional electrode reactor using granular activated carbon as particle electrode. The removal of COD obtained was 8.9% by electrocoagulation, 12.3% by KMnO4, 12.7% by adsorption and 22.2% by electrochemical oxidation using parallel plate electrode reactor. A maximum of 78.2% COD reduction was achieved by electrochemical oxidation in three dimensional electrode carbon bed reactor. The electrooxidation of leachate in three-dimensional electrode reactor required less electrical energy compared to parallel plate configuration. It was inferred that the use of three-dimensional electrode reactor can have more practical advantages.
Subject(s)
Electrochemistry/methods , Refuse Disposal , Adsorption , ElectrodesABSTRACT
The study related to photocatalytic degradation of three reactive dyes, namely, Reactive Red 141 (RR141), Reactive Orange 16 (RO16) and Reactive Violet 13 (RV13) was carried out. Further, two simulated textile dyebath wastewaters were prepared and examined for photocatalytic degradation. Three dyes were subjected to photodegradation in a batch annular immersion well photoreactor equipped with a 400W Medium Pressure Mercury Lamp (MPML). The UV illuminated TiO2 containing aqueous suspensions found to remove colour as well as chemical oxygen demand (COD). The photocatalytic activity was monitored by measuring the rates of decolorization and COD removal as a function of concentration of the dye and treatment time. The photodegradation efficiency of these three reactive dyes was found in the order of RR141 > RO16 > RV13. The first order rate constant (k(app)) for decolorization was 3-9 times higher than the k(app) for COD removal. The rate constants for degradation of simulated wastewater were also of the similar order of magnitude. These results suggest that TiO2/UV photocatalysis may be envisaged as a method for treatment of diluted coloured wastewaters not only for decolourization, but also for polishing of the COD parameter.
Subject(s)
Coloring Agents/chemistry , Industrial Waste , Textile Industry , Water Pollutants, Chemical/chemistry , Water Purification/methods , Coloring Agents/isolation & purification , Kinetics , Photochemistry , Water Pollutants, Chemical/isolation & purificationABSTRACT
A co-culture acclimatized to H-acid was used to degrade Reactive Black 5 (RB 5), a bis azo dye having central H-acid function. The effect of substrate concentration, pH and medium composition on the decolorization has been investigated. Decolorization was found independent of pH. Luria-Bertani broth favored decolorization over Yeast Extract; however further decolorization experiments have been conducted using Yeast Extract. The Michaelis-Menten Kinetic model is found to describe the dependence of specific decolorization rate on the RB 5 dye concentration.
Subject(s)
Coloring Agents/metabolism , Models, Theoretical , Naphthalenesulfonates/metabolism , Waste Disposal, Fluid/methods , Water Pollutants, Chemical/metabolism , Coloring Agents/chemistry , Hydrogen-Ion Concentration , Industrial Waste , Kinetics , Naphthalenesulfonates/chemistry , Textile IndustryABSTRACT
Electrochemical oxidation of ammonium (NH4+) at Ti/PbO2 anode in chloride-free and chloride containing aqueous solutions was studied. The experimental results have shown that oxidation of NH4- is ensured only in the presence of chloride. The oxidation of NH4+ is found to follow pseudo first-order kinetics. Bromide in the electrolyte is found to cause substantial rate enhancing effect on the ammonium removal. The dependence of k on the current density as well as halide concentration is also discussed in this study.
Subject(s)
Ammonia/isolation & purification , Bromides/chemistry , Lead/chemistry , Oxides/chemistry , Waste Disposal, Fluid/methods , Water Purification/methods , Ammonia/chemistry , Coloring Agents/chemistry , Electrochemistry , Kinetics , Titanium/chemistryABSTRACT
Phosphoric acid plant wastewater containing fluoride, phosphate and chemical oxygen demand etc., was treated using electrooxidation and electroflocculation methods. A maximum of 82% F- and 22.7% COD were removed using Ti/Pt(5c) under electrooxidative conditions. Electrooxidation with respect to F- removal is found mass-transfer limited, and removals below 5-6 mg/L F- are not achievable. Electroflocculation using Al anode resulted in better removal of F-, COD and PO4(3-). The various results obtained are discussed in this paper.
