Removal of solids is invariably the first step in the downstream. The dead biomass, cell debris and other insoluble salts from the fermentor broth are removed by one of these techniques. Immobilized biocatalyst is also removed and recycled for reuse. If the desired product is intracellular then the cells have to be harvested for lysis. So in the last two situation, the solid is the desired product, whereas in the first case the solids are collected and disposed. Treatment of liquid effluent also requires the removal of insoluble or suspended solids. There are several different solid removal techniques that are common to both, chemical and biochemical processes.