(a) PRIMARY TREATMENT (b) SECONDARY TREATMENI (c) DISINEECTION AND RELEASE (Biological oxidation) ( sCreening 3 Primary effluent Effluent is disinfected Amng undergoes aeration by chlorination and grinding of microorganisms Trickling fiter released sewage, Solid matter Primary effluent Chlorinator Settling tar systerm Aeration tank ffluent Secondary sludge trom settling tank sLudge effiuent(7) Sludge is dr removed and isposed of in landfill or (5 Remaining sludge agrieultural digeste pically, land producing methane □w rocesses Anaerobic sludge digeste Drying bed processes d)SLUDGE DIGESTION