_______________________________________________________

_______________
|
|              Parts in 100,000.
|________________________________________________
|             |           |           |
|   May 15.   |  June 7.  |  June 30. |  July 25.
|_____________|___________|___________|__________
|Not filtered.|           |           |
Total solids.      |   109       |  125      |  141      |  132
Loss on ignition.  |    33       |   21      |   29      |   23
Chlorine.          |    32       |   44      |   42      |   43
Oxygen required    |             |           |           |
for 15 minutes.  |     2.56    |    0.76   |    0.27   |    0.79
Oxygen required    |             |           |           |
for three hours. |     4.27    |    0.79   |    0.50   |    1.00
Free ammonia.      |     2.20    |    0.88   |    0.50   |    0.92
Albuminoid am-     |             |           |           |
monia.           |     0.32    |    0.17   |    0.092  |    0.19
_____________________|_____________|___________|___________|

__________

The electrical shoot was built in brick and contained 28 cells arranged in series.

Each cell contained 13 cast iron plates 4 in. x 2 ft. 8 in. x 1/2 in. thick connected in parallel.

The available electrode surface in each cell was 256 sq. ft.

The ampere hour treatment required for Salford was found to be about 0.37 ampere hours per gallon, and the I.H.P. per million gallons based on these figures would be 37.

NOTE.—­In estimating for the plant necessary for treating the whole of the Salford sewage, a margin was allowed on above figures.  The A.H.T. was taken at 0.4 and the I.H.P. per million at 39 to 39.5.

Mr. Octavius March, electrical engineer, who has followed the process from the commencement, and who superintended the electrical details both at Crossness and Salford, will give you on the blackboard a rough sketch of the above trial plant.

The Salford tanks are admirably adapted to the application of the electrical or in fact any process of precipitation.  They are 12 in number, and it is proposed to take two end tanks for the electrical channels, in which the iron electrodes would be placed.

The total I.H.P. required for treating the whole of the Salford and Pendleton sewage, taken at 10,000,000 gallons per 24 hours, is calculated at 400 I.H.P., based on the actual work done during the trial.  The electrical plant would consist of four engines and dynamos, any three of which could do the whole work, and three boilers, each of 200 I.H.P.

The total cost of plant, including alterations, is estimated at L16,000, to which must be added the cost of about 5,000 tons of iron plates—­ordinary cast iron—­at say L4 per ton.  These plates would last for several years.

If filtration were required, there would be an extra expenditure for this, but it will be remarked that as the treated sewage is practically purified when it leaves the electrical channels, these filters would be only required for complete clarification, which for most places would not be a necessity.