Worm Ova Separation System Design

I need a complete, practical design for a small-scale batch system that can recover live worm ova from wet soil without resorting to chemicals. Each batch will start with about 2 litres (≈1–2 kg) of moist soil containing roughly 500 000 ova... (Budget: £20 - £250 GBP, Jobs: 3D Design, 3D Modelling, CAD / SolidWorks, CAD/CAM, Engineering, Mechanical Engineering, Process Engineering, Product Design, Prototyping, Solidworks)