2. Artificial self-purification of sewage in intermittent
contact beds:
_a._ Name of process 70
_b._ Explanation of process 71
_c._ Water capacity of bed, and silting up 73
_d._ Absorbing powers of filling material 78
_e._ Consumption of oxygen by the filling material 79
_f._ Formation of carbonic acid 80
_g._ Nitrogen 80
_h._ Formation of nitric acid 80
3. Artificial self-purification of sewage in septic
tanks:
_a._ Name of septic tank 81
_b._ Covered or open septic tank 81
_c._ Explanation of process 83
_d._ Velocity of flow through tank 85
_e._ Destruction and liquefaction of sludge in
septic tanks 87
_f._ Formation of gas in septic tank 88
_g._ Mixing action of septic tank 89
_h._ Micro-organisms in effluent from septic tank 89