Blackburn Wastewater Treatment Plant Upgrade Study

Section 4.0 - Blackbum Treatment Options
out of senice for maintenance and emergencies while allowing the other to
perform adequately. Only one clarifier would be provided at first; the second
would be installed when flows and populations warrant.
Secondary Clarifier
Clarifiers
Overflow rate, m3/m2/d
Surface area, m2
Diameter, rn
SWD,m
2 (1 now; 1 future)
10
85
10
4.0
RAS Pumps
b p s
Capacity, Lls
TDH,m
Power, hp
Nitrifying Activated Sludge Process
The above activated sludge process will not be able to produce a nitrified
effluent. If nitrification is required, the HRT of &he bioreactor will have to be
increased to approximately 24 h by increasing the volume from 500 m' to
1,700 m3. The ancillary processes included with this option with nitrification
are essentially identical to those described above, i.e. the headworks,
secondary clarifiers, etc. will be the same size. The mechanical components
(mixers, pumps, etc) should be of similar size and quantity. The aeration
system, however, will be larger to meet the oxygen requirements for
nitrification. The blowers will be more powerful and the size of the aeration
diffuser grids will be increased proportionally.
The major cost increase will be in construction costs rather than mechanical
furnishings. The amount of excavation, concrete, and other structural elements
required for the bioreactor will be increased by a factor of at least two.
Nitrifying Bioreactor
HRT,h
SRT,d
Anoxic cells
Volume (anoxic selector cell) m3
Power (anoxic cell mixer), hp
Aerobic cells