Abstract: The increasing of the population has enhanced the generation of waste in Malaysia, a country of which depends on landfill as a method to dispose of solid waste in which the leachate generation will play a major impact to the environment. Leachate can potentially contaminate the nearby surface water, groundwater and soil. In Malaysia, food waste is a major waste composition which can lead to the generation of leachate due to their high moisture content. Citrus fruit wastes classified as one of food waste which become a concern because of its potential to create environmental pollution. Leachate from citrus fruit is acidic, high BOD and COD, high turbidity, total suspended solids and high nutrient such as nitrogen and phosphorus. This characteristic may interfere the effectiveness of wastewater treatment. The method that can be implemented as citrus leachate treatment is membrane process. Membrane process had been proven their effectiveness and had been used in many applications. The previous membrane composition is used, but the suitability of citrus waste is needed to investigate. The MWCO of newly developed flat sheet membrane is determined to study the performance of the membrane in citrus fruit waste leachate treatment.