Different types of anaerobic treatment systems can be used as pretreatment devices for high-strength wastewater and some onsite pretreatment applications. Two examples are in shown in figure 5. Anaerobic treatment systems are widely used in hot climates. These systems can reduce high BOD and TSS to levels that can be readily treated by typical aerobic processes such as suspended and fixed growth aerobic units or recirculating/intermittent media filters. International literature contains numerous references to anaerobic treatment systems.

Figure 5: Two different types of Anaerobic treatment systems: Schematic of the upflow anaerobic filter process (left) an upflow anaerobic sludge blanket process