Ammonia is converted into nitrogen by autotrophic bacteria in anaerobic conditions. Under aerobic conditions ammonia is converted to nitrogen by aerobic bacteria. Organotrophs and lithotrophs are a type of heterotrophic bacteria.

Chemical adsorption takes place at high temperature whereas physical adsorption takes place at low temperature and is reversible.

Because carbon to nitrogen ratio of wastewater is typically on order of 4:1 to 6:1, re will be excess nitrogen after secondary biological treatment that cannot be assimilated by micro-organisms.

Many platers will over-chlorinate ir cyanide wastewater to ensure y meet requirements for cyanide concentrations. However, 40 to 50 mg/L excess chlorine can be corrosive to equipment and dangerous to personnel servicing a pump station.

The first step is nitrification, which is conversion of ammonia to nitrate through action of nitrifying bacteria. The second step is nitrate conversion (denitrification), which is carried out by facultative heterotrophic bacteria under anoxic conditions.

Activated carbon filters are efficient to remove certain organics such as unwanted taste, odour and micro-pollutants, chlorine, fluorine or radon from drinking water or wastewater.

The retention time considered for aerobic zone for University of Cape Town treatment process for removing phosphorus is 4-12 hrs. The MLSS level maintained is 3000-4000 mg/L. The internal recirculation considered is 200-400%.

Higher quality filtration simply means cleaner water. This depends on geometry of channels, including size, length, angle and number of generated intersection points.

The retention time considered for anaerobic zone for A2O process for removing phosphorus is 0.5-1.5 hrs. This process is a modification process of AO process. This is a very effective method to remove phosphorus compounds.

Total operating cost = 1.45 x electrical cost + Peroxide cost. This cost would be in $ per 1000US gallon. The cost of hydrogen peroxide is hydrogen peroxide concentration in ppm x ($ 0.005 / ppm/1000 US gallon).