Electrolytic degradation of biorefractory organics and ammonia in leachate from bioreactor landfill.
Electrochemical oxidation was applied to treat the effluent from bioreactor landfill with leachate recirculation, characterised as poor biodegradability and high NH3-N concentration. In this study, the effluent was electrolysed in a batch reactor with Ti/TiO2-IrO2-RuO2 anode and stainless steel cathode. The oxidation of dissolved organic matter (DOM) during electrolysis was evaluated based on the evolution of molecular weight grade, hydrophilic fractionation (humic acid, fulvic acid and hydrophilic fractions), specific ultraviolet absorbance (SUVA254) and AOX. The impact of the initial NH3-N concentration on the oxidation was discussed. The results showed that at a current density of 100 mA/cm2, electrolysis time of 1.5 h and electrode gap of 1 cm, NH3-N with an initial concentration of 1.2 g/L could be completely eliminated and 56% of COD with an initial concentration of 1.2 g/L could be removed, which illustrated that the electrolysis-produced chlorine preferentially oxidised ammonia. The electrolysis mainly resulted in the degradation of humic substances and other high molecular DOM, followed by the increase of BOD/COD ratio and decline of SUVA254 of the leachate. The current efficiencies for COD and ammonia oxidation gradually decreased during the electrolysis, with the latter obviously higher than the former. At the optimal electrolysis time of 1.5 h, NH3-N could be totally removed and the BOD/COD ratio could be enhanced to 0.3, which was also favourable to control the AOX at a reasonable level.
Shao
L
L
State Key Laboratory of Pollution Control and Resources Reuse, Tongji Univ, Shanghai, China. solidwaste@mail.tongji.edu.cn
He
P
P
Xue
J
J
Li
G
G
D000641:Ammonia / Q000032:analysis*; D019149:Bioreactors; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D004572:Electrolysis; D009930:Organic Chemicals / Q000032:analysis*; D010100:Oxygen / Q000737:chemistry; D012037:Refuse Disposal / Q000295:instrumentation* / Q000379:methods*; D012722:Sewage; D014865:Waste Disposal, Fluid / Q000295:instrumentation* / Q000379:methods*; D018505:Waste Management; D018508:Water Purification
D009930:Organic Chemicals; D012722:Sewage; D000641:Ammonia; D010100:Oxygen