Process of Waste Water Treatment - Once the level of pollutants in waste water is determined, treatment of the water proceeds through the following five stages:
(i) preliminary treatment,
(ii) primary treatment,
(iii) secondary treatment,
(iv) tertiary treatment, and finally
(v) sludge treatment.
The first four stages are common to both aerobic and anaerobic process, while sludge treatment is mainly anaerobic.