January, 19C6.J 



KNOWLEDGE & SCIENTIFIC NEWS. 



319 



or, indeed, of liquid of any kind on to the farm. So 

 desperate had the situation become that instead of 

 allowing the fetid swamp to increase the Leek authori- 

 ties might have been obliged to send the raw sewage 

 down the storm overflow into the river and to continue 

 doing so until a partial recovery of the farm had taken 

 place. 



Under these conditions a chance was offered for the 

 introduction of the new and untried process. The 

 tanks which received the sewage on its arrival at the 

 farm were so small that none of the common processes 

 of precipitation were applicable, but they were quite 

 large enough to admit of excellent work being accom- 

 plished by the new process. 



The installation of the new process was quickly ac- 

 complished, viz., in three weeks, and the cost was in- 

 significant. 



On April 3, 1903, the sewage began to flow into the 

 first aerater charged with wood charcoal. On April 11, 

 1903, the discharge of liquid on to the sewage farm 

 was stopped. Instead of the liquid being run from 

 the tanks on to the surface of the farm and then left to 

 percolate through the land, the liquid was provided 

 with a connecting channel so that it might pass from 

 the upper distributing system of channels into the lower 

 collecting system and into the river without deluging 

 the land. 



Under the new order of things the Leek Sewage 

 Farm recovered rapidly, the fetid marsh dried up and 

 was ploughed and became cultivated land. The 

 flourishing condition of the vegetables on the farm at- 

 tracted public attention as the summer advanced, and 

 there was a prospect of making a profitable employment 

 of sewage. 



The quality of the liquid discharged by the Leek 

 Sewers is most variable, and the rate of flow irregular. 

 The Leek water supply contains very little foreign 

 material of any kind, the total solid residue amounting 

 to only six grains per gallon. On Sundays when the 

 sewers do not carry manufacturing refuse, the sewage 

 contains about 60 grains per gallon, some of which is 

 suspended matter, the rest being dissolved matter. The 

 week-day sewage is very different. An average 

 sample, taken on Wednesday, August 12, 1903, was 

 very carefully analysed by the writer with the following 

 results : — 



Specific Gravity 1001.6. 



One Gallon contained : — 



Grains. 



Organic Matter . . . . 350 



Soda Na^O 330 



Silica Si Oz . . . . . . 130 



Ahimina and Oxide of Iron fi 3 



Lime Ca O . . 3-5 



Clilorine 8 8 



Undetermined . I2'4 



Total solid residue .. 112 o 



The immediate effect of the treatment with charcoal 

 and the action of the aerater was to reduce the solid 

 contents to 90.3 grains per gallon ; and there was a 

 further reduction to 66.0 grains when the eflluent was 

 allowed to deposit its suspended matter. 



The importance of these results depends upon the 

 care which was taken to ensure that the samples of 

 sewage and sewage-ettluent were true average samples 

 and were strictly comparable with one another. They 

 were the official samples collected by Mr. Farrow, the 

 .Sanitary Inspector, whose trustworthiness and accuracy 

 in m.ilters of this description are proverbial in Leek. Be- 

 ginning at nine o'clock on the morning of Atigust I2, 

 1903, Mr. Farrow collected a sample once in the hour 



and continued the work of collection until five o'clock 

 in the afternoon. The nine samples were mixed to- 

 gether so as to form the average sample of the week- 

 day sewage, which was sent to the writer's laboratory 

 by the Sanitary Authority of Leek. In like manner the 

 effluent collected just as the liquid issued from the two 

 small tanks was obtained by Mr. Farrow and sent to 

 the writer's laboratory. 



The rate of flow through the two small tanks which 

 had been converted into aeraters and charged w'ith 

 wood charcoal was about two-hours ; that is to say, 

 each gallon of sewage issued from the tanks in the con- 

 dition of sewage-effluent two hours after it had entered 

 the tanks in the condition of raw sewage. 



The alteration in the composition of the sewage 

 during its two hours' sojourn in the tanks and its con- 

 version into sewage-effluent is expressed as follows : — 



Raw Sewage. Tank Effluent. 

 Specific Gravity .. iooi'o6 .. 1000-82 



Total solid contents ) 1120 



grains per gallon ) 



903 



The removal of the 21.7 grains corresponds fairly 

 well with the diminution of density. The tank-effluent 

 was turbid, and on keeping afrest for a period, and 

 afterwards subjecting it to careful decantation it lost 

 24.3 grains of solid contents, the total solids per gallon 

 having fallen to 66 grains. 



On August 12 when the average samples were col- 

 lected by Mr. Farrow, the connecting channel was not 

 in use, and it was therefore impossible to collect a 

 sample of liquid at the outfall into the Churnet which 

 would exhibit the degree of purification attainable in 

 the channels in the absence of land treatment. 



In the next month, viz., on September 9 and 10, the 

 connecting channel was brought into play, and after a 

 twenty-four hours' employment of that channel a 

 sample of effluent was collected at the outfall into the 

 Churnet. The total solid contents was found to be 67.3 

 grains per gallon. 



Under the actual circumstances prevailing at the 

 Leek sewage farm these diminutions in the total solid 

 contents of the liquids afford a most satisfactory proof 

 of the accomplishment of the purification. The sub- 

 stances employed in bringing about this purification are 

 atmospheric oxygen, water, and wood charcoal. The 

 purification begins in the two small tanks, and goes on 

 in the long channels (a third of a mile in length) which 

 intervene between the tanks and the river Churnet. 



The writer of this notice was present when, on April 

 3, 1903, the raw sewage, laden with a forty-eight hours' 

 acciinuilation of solid excrement, was suddenly turned 

 into the left-hand tank (which had been fitted up with 

 the proper partitions and the requisite charcoal), and he 

 can vouch for the instantaneous and complete success 

 of ^he arrangements. Standing close to the tank he 

 noted that there was no fetid smell whatever, but only 

 a slight odour of soapsuds. Properly applied wood 

 charcoal is, indeed, a most potent sanitary agent ; and 

 the reintroduction of this agent into the working of 

 sewage farms marks the beginning of a new era in 

 sewage-purification. 



In the year 1903 the writer spent 78 days in Leek 

 and watched over the operation of the new system at 

 the sewage farm. His last visit to Leek w^as on 

 May 2, 1904. Up to that day (being a period of 13 

 calendar months) the new system was in operation in 

 Leek, and the writer is now in a position to give an 

 estimate of the consumption of charcoal. It is at the 

 rate of one ton per thousand persons per annum. 



