Treatment of sewage relies heavily on biological activity. Many factors affect digestion, including temperature, retention time and pH. Microbial activity doubles every time the temperature increases by 18 degrees F. When warm wastewater causes microbial activity to double, the biodegradation of constituents increases. This means that oxygen uptake is more rapid at warmer temperatures, requiring air to be supplied at a higher rate. The waste degrades more quickly at warmer temperatures, so it need not be held in the treatment system as long when it is warm.The converse is also true: In the winter, oxygen uptake is low and air
