Suspended growth reactors are bioreactors where microorganisms are suspended in a liquid medium, allowing them to grow and multiply. This type of reactor is commonly used in wastewater treatment and fermentation processes, as it provides a large surface area for microbial activity. The mixing of the liquid ensures that the microorganisms remain evenly distributed, enhancing their efficiency in breaking down organic matter. These reactors can be classified into different types, such as activated sludge systems and stirred tank reactors. The design and operation of suspended growth reactors are crucial for optimizing the growth conditions of the microorganisms, leading to improved productivity and treatment performance.