The microorganisms we use in the activated sludge system only grow well within a certain temperature range….usually between 10°C and 38°C (50°F and 100°F). For every 10°C rise in temperature, microorganism respiration rate doubles.  We can’t do a whole lot to control raw influent temperature.  However, we can and should adjust our wasting practices seasonally (summer/winter) in response to the more significant swings in temperature.  During cold temperatures (winter months) a higher population will be needed to achieve the same treatment results.  This means a longer solids retention time (SRT) is required. The opposite is true during summer months.

How do you adjust wasting practices to accommodate changes in temperature at your WWTP?