The most intriguing results were obtained on UASB reactors, both at laboratory and pilot scale, fed on diluted waste, and the most promising results were obtained on UASB reactors, both at laboratory and pilot scale, fed on diluted waste. With these digesters, volumetric loading rates were observed and 70 percent removal efficiency was achieved. The start-up of UASB reactors fed with waste from olive oil mills is a complicated process that must be carefully monitored and optimized. Starting with very diluted trash yielded the greatest results. Granulation of the sludge, as seen in UASB digesters fed on sugar beet wastewaters, was not attained; however, the sludge's settleability was observed to be excellent. Since the olive oil industry has been blamed for a lot of pollution, there has been a lot of pressure to improve olive oil waste treatment facilities. Bioremediation (ex-situ, in-situ), thermal processes (incineration, pyrolysis, gasification), evaporation, membrane processes, electrolysis, ozonation, digestion, Coagulation/flocculation/precipitation, and distillation are among the many methods currently in use. Per the waste treatment approach, both advantages and downsides were described, along with the methodology and explicit flow diagrams. Furthermore, the most recent studies were provided, with around twenty–five figures primarily illustrating the efficacy of current waste treatment procedures versus time or temperature. The comparison of the various olive oil waste treatment approaches revealed that, while bioremediation is the most environmentally beneficial option, it is not the only one.