Vietnam is known as an agricultural country with a variety of agricultural crops. In addition to agricultural by-products, bio-waste is the by-product from livestock waste, forestry, industry, and daily life. They affect the soil, water, and air environment by self-degradation processes in the environment. Therefore, researchers have come up with ideas for the usage of the by-products to decrease the amount of waste and minimize the environmental effects. In Vietnam, the by-products were used by researchers to produce bio-ethanol, fertilizers, composites, and activated carbon (AC). AC is one of the materials used to rapidly reduce the number of agricultural by-products by researchers. The synthesis process is optimized for the highest yield, while the physicochemical properties are also clearly analyzed through the X-ray diffraction, Fourier transform infrared, and Bacterial endotoxin testing assays. The average recorded specific surface area was about 300 m2 g−1. The functional groups and surface structure showed that the material has an amorphous structure with –OH, –CH, –CC, –C═C, –C═O groups. The AC from agricultural waste had been studied and applied to treat pollutants present in water.