Grain separating device without power

The utility model provides a grain separating device without power. Cultivation sewage enters a bypass channel through the water inlet of the separating device, flows evenly and slowly towards an arc-shaped sieve mesh along the surface of a horizontal water-distributing plate arranged on the upper portion of the arc-shaped sieve, and flows downwards along the arc of the arc-shaped sieve mesh. Organic grains are rushed by water and accumulated on the surface of the arc-shaped sieve mesh, slide downwards in the direction of the flow, accumulate in a dirt-storage tank, and are drained out through the dirt-draining port. Seawater flows into a water-storage tank through the slit of the arc-shaped sieve mesh after being separated and enters a pump tank through a water outlet. Grains larger than 70 mum in sizes can be effectively separated, and a stable grain organic material and colloid material separating device is formed by combining the grain separating device and a protein separator. Compared with a drum-filter