104 



SEWAGE PURIFICATION AND DISPOSAL, 



the maximum flow the resiilts show that 

 the suspended matter varies from 11.6 to 

 4.9 grains per gallon. 



Exhaustive experiments have been made 

 to determine the effect the efflueut from the 

 bacteria beds would have upon the waters 

 of the Manchester Ship Canal. Average 

 samples of the filtrates were caken from 

 the bacteria beds in operati:/n on 132 days. 

 A similar quantitj" of water was taken 

 from the Ship Canal, and the two were 

 mixed. The Ship Canal water, except 

 in a few cases, when it had been diluted 

 by heavy falls of rain, was putrescible to 

 a high degree, but when mixed witn an 

 equal quantity of the filtrate, the mix- 

 tures in 117 cases were non-putrefactive. 

 This shows clearlj^ that the organic im- 

 purities of the Canal water had been oxi- 

 dised at the expense of the nitrates in the 

 filtrate, and thus vastly improved. It 

 also bears out the fact demonstrated by 

 Air. Scott-Moncrieff, and already alluded 

 to. 



Of several the following were among tue 

 ■conclusions and recommendations made 

 to the Council by the three experts: — 



1. That the bacterial sys'tem is the sys- 

 tem best adapted for purification of the 

 se<vage of Manchester. 



2. That any doubts which may ha^e 

 arisen in the first instance as to its suita- 

 bility .... have .... been entirely banish- 

 ed. The results obtained have altogether 

 exceeded our expectations. 



3 by passing the sewage as it ar- 

 rives at the works through an adequate 

 system of screens, etc., the further im- 

 portant advantage is gained, -whereby 

 those anaerobic or septic processes are de- 

 veloped, and which resolve into gaseous 

 and soluble products the organic suspend- 

 ed matter present in the sewage. A large 

 proportion of the seAvage sludge which 

 otherwise accumulates, and the disposal of 

 which causes so much trouble and expense, 

 is thereby abolished. The above anaero- 

 bic or septic process is found to take place 

 as efi^ectively in an open tank as in a closed 

 one. 



It has been demonstrated that the sep- 

 tic tank can effectually dispose of between 

 40 and 60 per cent, of the suspended mat- 

 ter present m the sewage. A kind of di- 

 gestive process goe-s on whereby much of 

 the insoluble suspended organic matter, 

 especially that of animal origin, is lique- 

 fied or dissolved. This is probably entire- 

 ly due to the action of those living organ- 

 isms previously alluded to, by whose vital 

 processes some ferment or ferments are 

 produced which digest these substances. 

 Vegetable fibre is more resistant, and is 

 but little afi^ected. In alluding to this 

 phase of the subject. Dr. Thresh, in a re- 

 cent paper, «ay«»: -"What ia waiited i« 

 the discovery of some organism capable 



of lieing cultivated and utilised, whic 

 possesses the special power of digestii 

 vegetable fibre." In the same paper 

 mentions a vi?it he iiairi \(. il»e old sei 

 a{tje works at Buxton, where he found tl 

 ftBttliug tank almost full of deposited maf 

 ter. IJsing his own words, he states thi 

 "a few days later some kind of ferment^ 

 tion had set in, and the fluid was cff( 

 vescing vigorously and in a very short 

 time practically the whole of the solid 

 matter had been dissolved and carried 

 away.'' 



At Leeds, where tlie Corporation are 

 carrying out extensive experiments with 

 the bacterial purification of their sewage, 

 the oldest of their septic tanks had been 

 working over fi»;teen months. Three- 

 quarlers of the solids in suspension were 

 left tlierein, and no sludge had been re- 

 moved, yet after inspection il was found 

 that the tank contained no more sludge 

 than it did six months earlier. ^uch a 

 condition showed that there ha:l unques- 

 tionably been an enormous consumptioa 

 of sludge in the tank by septic proce.sses. 



Before concluding this paper a refer- 

 ence to the Liernur system of sewerage 

 might prove of interest. The town or city 

 to be served is divided into districts, ac- 

 cording to circumstances, and in a cen- 

 trally situated position a c'osed receiver 

 is provided for each district, into which 

 the feecal matter is drawn by vacuum. 

 There are cast iron pipes laid along the 

 streets, and go situated as to enable house 

 oonnections to be conveniently made. 

 These pipes convey the sewage to the dis- 

 trict receivers. From the central sta- 

 tion the vacuum there formed is conveyed 

 to the district receiver, and the influence 

 of this causes the sewage to flow by suc- 

 tion to the receiver. The district re- 

 ceivers are in turn emptied by applying 

 the vacuum to the main receiver at the 

 central station. Briefly then, the Lier- 

 nur system consists of ordinary street sew- 

 ors (4in.) connected to a main sewer (10 

 to 12in.), without any openings. At one 

 end, by the house, is a patent syphoned 

 box. At the outfall works is a steel plate 

 cylinder, in which a vacuum is created, 

 say once a day. The result is, the sew- 

 age remaining in the boxes and .aewers is 

 carried off to the works at six times the 

 speed of water-carried sewage, the air 

 flush being depended upon to cleanse the 

 pipes thoroughly. 



From information supplied by the Eng- 

 lish representatives of the system, and 

 also by their engineer, Mr. Theodore Ren- 

 nert, M. Inst. C.E.. there are three instal- 

 lations at work; one at Amsterdam, one 

 at Trouville-sur-Mer, and the other at a 

 gold mine in Johannesburg. 



It is understood that at Amsterdam it 

 was the intention of the designers only to 

 evaporate the faecal matter, but this has 



