The study aimed to find a simple way to treat tannery wastewater effectively. By testing different conditions, the researchers discovered that using the activated sludge process with specific levels of MLVSS, DO, and aeration time can achieve high efficiency in removing pollutants. The results showed that by operating the ASP at certain concentrations and aeration time, the treatment process could remove over 90% of BOD5, COD, total Cr, SO4 2-, S2-, SS, TDS, and TS from the wastewater.