Filtration Heat-sensitive solution Depth filters: diatomaceous; unglazed porcelain Membrane filters: membranes with pores about 0.2um in diameter are used to remove most vegetative cells. but not viruses Air: 1. Surgical masks and cotton plugs on culture vessels 2. Biological safety cabinetsFiltration • Heat-sensitive solution • Depth filters: diatomaceous; unglazed porcelain. • Membrane filters: membranes with pores about 0.2m in diameter are used to remove most vegetative cells, but not viruses. • Air: 1. Surgical masks and cotton plugs on culture vessels. 2. Biological safety cabinets