According to the large amount of fly ash waste generated from the use of lignite coal as the primary fuel for electricity generation in the Mae Moh district of Lampang province, Thailand, efforts have been made in waste management to reduce and repurpose this industrial byproduct. In this study, lignite coal fly ash was used to synthesize zeolite A adsorbents for the treatment of wastewater contaminated with heavy metals. Characterization of the synthesized zeolite using XRD, XRF, BET, and SEM methods confirmed that it is zeolite A, with a calculated Si/Al molar ratio of approximately 1.19, closely matching the theoretical ratio of zeolite A. This zeolite A exhibited a high crystalline phase and a mesoporous structure, having a specific surface area of 37.10 m