AIP Conference Proceedings [Author(s) PROCEEDINGS OF THE INTERNATIONAL CONFERENCE OF GLOBAL NETWORK FOR INNOVATIVE TECHNOLOGY AND AWAM INTERNATIONAL CONFERENCE IN CIVIL ENGINEERING (IGNITE-AICCE’17): Sustainable Technology And Practice For Infrastructure and Community Resilience - Penang, Malaysia (8–9 August 2017)] - Influence of dosage, pH and contact time in stabilized landfill leachate treatment using ozone/zirconium tetrachloride catalytic oxidation