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20
As complaints were received of noxious smells in the neighbourhood
of the Sewage Works I made frequent visits, and found by experiments
that the smell arose from the presence of sulphuretted hydrogen, and
that this gas was liberated owing to the force with which the effluent
from the septic tank was sprayed on to the filter.
To remedy the above defect, further experiments are being carried
out, and so far with very satisfactory results. The effluent from the
septic tank is forced by a pulsometer into a tank holding a day's supply,
viz.: 250 gallons ; from this tank the effluent is delivered by gravitation
on to a 6-in. tile, and from thence on to the surface of clinker.
The effluent not being forced on to the filtering medium, no
gases are disengaged.
The following are the analyses of the two effluents, viz.: the
precipitation process, and the bacterial treatment. The superiority
of the latter is obvious, and I have no hesitation in advising the Council
to adopt the bacterial treatment in place of the precipitation method ;
the saving to Acton will be considerable, and we shall have no sludge
to deal with.
Effluent from
Precipitation Tank.
Effluent from
Bacterial Filter.
Parts per 100,000.
Total Solids in Solution 129.0 847
Solids in Suspension 1.50 Traces
Chlorine 10.65 7.5
Free Ammonia 2.55 1.15
Albuminoid .165 .075
Oxygen absorbed .84 .54
Appearance Cloudy Clear
Smell Slight None
Nitrates Trace Abundant