During the past decades, contaminated water has been a major concern due to industrial and agricultural wastes. Therefore, the importance of waste treatment has been increasing. Coagulation and flocculation is one of the most widely used treatment technologies for the contaminated water, however, existing coagulants (e.g., polyacrylamide, polyaluminum chloride) have been known to have harmful influences to our environment and human health. As an alternative eco-friendly coagulant, this study suggests polylysine, a cationic biopolymer fermentated by Streptomyces. Experiments for various polylysine concentrations were performed, and the efficiency of polylysine was compared to natural settlement. Consequently, the performance of polylysine as a coagulant for soil was determined. Results indicates that polylysine functioned efficiently as coagulants. This paper suggests polylysine shows promising results and efficiency to be an alternative eco-friendly coagulant to remove chemical contaminants from soil and water.