Technical Abstract: Natural flocculants have potential to replace the use of synthetic flocculants used for enhanced solid-liquid separation of livestock effluents, especially with increased cost of energy and renewed interest on organic farming systems. We conducted a study to determine the effectiveness of natural flocculants to reduce solids and nutrient loads in dairy wastewater using solid-liquid separation; chitosan was used as a model. Its use efficiency and optimum application rate were determined using flushed dairy manure of varied strengths - 0.4, 0.8, 1.6 and 3.2% total solids (TS) content. Treatments consisted of nine rates of chitosan. The flocculated manure was dewatered using 1-mm and 0.25-mm screens. Separation by screening alone was not effective; average efficiencies were about 60% for total suspended solids (TSS), 22% for total Kjeldahl N (TKN), and 26% for total P (TP). Mixing manure with chitosan before screening substantially increased separation. At optimum rate (0.5 g/L for the highest strength effluent), separation efficiencies were higher than 95% for TSS, 73% for TKN, and 54% for TP. The results of this study indicate that natural flocculants such as chitosan are useful for the solid-liquid separation treatment of livestock wastewater.