This study investigated the treatment performances of H 2 O 2 oxidation alone and its combination with granular activated carbon (GAC) adsorption for raw leachate from the NENT landfill (Hong Kong) with a very low biodegradability ratio (BOD 5 /COD) of 0.08. The COD removal of refractory compounds (as indicated by COD values) by the integrated H 2 O 2 and GAC treatment was evaluated, optimized and compared to that by H 2 O 2 treatment alone with respect to dose, contact time, pH, and biodegradability ratio. At an initial COD concentration of 8000mg/L and NH 3 -N of 2595mg/L, the integrated treatment has substantially achieved a higher removal (COD: 82%; NH 3 -N: 59%) than the H 2 O 2 oxidation alone (COD: 33%; NH 3 -N: 4.9%) and GAC adsorption alone (COD: 58%) at optimized experimental conditions (p≤0.05; t-test). The addition of an Fe(II) dose at 1.8g/L further improved the removal of refractory compounds by the integrated treatment from 82% to 89%. Although the integrated H 2 O 2 oxidation and GAC adsorption could treat leachate of varying strengths, treated effluents were unable to meet the local COD limit of less than 200mg/L and the NH 3 -N of lower than 5mg/L. However, the integrated treatment significantly improved the biodegradability ratio of the treated leachate by 350% from 0.08 to 0.36, enabling the application of subsequent biological treatments for complementing the degradation of target compounds in the leachate prior to their discharge.
