ABSTRACT
Anaerobic processes are seldom used for domestic or municipal wastewater treatment except where the ambient temperature is of tropical nature and/or where its use will bring about a significant reduction in oxygen requirement for post-aerobic treatment. Anaerobic pretreatment can thus encourage the use of less energy intensive oxygen transfer systems, such as constructed wetland, for posttreatment. Anaerobic treatability of wastewater depends on the constituents of the wastewater. Wastewater pretreatment may be necessary to enhance the anaerobic treatment process. Common pretreatment techniques include sole or combinations of physical, chemical, or biological processes and operations. Anaerobic treatment of microorganisms requires sufficient quantities of macronutrients, notably nitrogen and phosphorus, and micro or trace nutrients for growth. Anaerobic processes are commonly used in the treatment of sludge produced from aerobic processes for energy recovery in the form of biogas and pasteurization prior to their reuse for agriculture.
