Monolithic Methane Digester Cover Helps Recycle Waste Into Energy Monolithic Airform — At our Airform factory in Italy, Texas, we design and manufacture Airforms for companies such as USFilter that incorporates the Airforms into its waste treatment systems. A working Airform — Monolithic Airforms used in waste treatment systems are made of heavy, 31-ounce fabric, according to design specifications so that they fit tightly around the circumference of a waste digestion tank.