Industrial fermenters are used to grow cells on a large scale by carefully controlling the environment. They are made of stainless steel and can hold up to 200,000 liters. Nutrients are fed in through sterile pipes and conditions like temperature, pH, oxygen, and carbon dioxide levels are monitored electronically and automatically regulated. Fermenters require sterile conditions and cooling to control cell growth and regulate temperature increases from microbial activity that could kill the cells. Most fermentations are batch processes but some use continuous culture systems with steady nutrient input and waste removal.