BY EDWIN H. WILKINSON. 



105 



jeen found impracticable. It is now cus- 

 omary to use a small quantity of water 

 Or flushing purposes— about 1 gallon per 

 )erson. The house slops at Amsterdam 

 ire not taken into the sewerage system, 

 Dut are discharged into the various canals 

 :hat intorsept the city- 

 According to Mr. D. I. Sanche? tbe et- 

 rineer in charge of the works, the total 

 3opulation of Amsterdam is about 500,000, 

 jnd of these about one-fifth, or 100,000, are 

 jerved by the Liernur system. The street 

 pipes are now laid to an uniform grade 

 from the upper end to the district receiv- 

 3rs and with ordinary junctions, as it was 

 found that the vertical junctions, with 



Bight-angled bends, which were originally 

 .esigned, readily got stopped. 

 The average number of persons connect- 

 ed with a district receiver (of which there 

 are 50) is 2,000. The greater portion of 

 the closets are of the special Liernur kind 

 The mode of treating the sewage devised 

 by Liernur has been entirely abandoned. 

 The expense of drying the sewage was so 

 great, even without the household slops, 

 and with only the small quantity of wa- 

 ter used as a flush, that it was found ne- 

 cessary to discontinue the method. 



The sewage, as soon as convenient, after 

 its arrival at the works, is precipitated by 

 means of lime, and the supernatant liquor 

 and the sludge are boiled separately for 

 the purpose of throwing off the ammonia. 

 This is sold, ^nd a fair revenue is derived. 

 The supernatant water is thereupon dis- 

 char^red without further treatment into 

 the canal, and the sludge is mixed with 

 house rubbish and removed in barges aa 

 manure. 



Such a process is wholly objectionable. 

 Thousands of gallons of sewage are stored 

 in large, open tanks, waiting for a number 

 of days to be treated. Another source 

 of no ^inconsiderable nuisance is the me- 

 thod of mixing the sludge (previously de- 

 prived of its ammonia) with the house re- 



fuse. In cases where the town to be 

 served is flat some mechanical means of 

 raising and removing the sewage is neces- 

 sary, and it becomes apparent that each 

 case therefore must be taken on its merits. 

 However desirable it may appear to 

 evaporate the moisture and produce the 

 powder manure, the question of cost would 

 make the method prohibitive. With the 

 knowledge we now possess as to the bac- 

 terial action, which can be so readily en- 

 gaged in resolving sewage into its ele- 

 ments, there is certainly no necessity to 

 resort to evaporation as a means of dis- 

 posal. 



Coming to Hobart the author said that 

 within the next few months the citizens 

 would be asked to say whether or not a 

 scheme for the drainage of the city on 

 modei«Li sanitary principles was desurable. 

 Many were averse to allowing crude sew- 

 ao-e to empty itsMf into the harbour, on 

 the grounds of pollution, but, at the pre- 

 sent time the foul slop waters from the 

 houses Avere allowed to discharge into the 

 street chanrnvls, whence they found their 

 wav into the natural water-courses, and 

 so on to the waters of the Derwent estuary. 

 From the configuration of the city and its 

 environs, and from an engineering point 

 of viftw, the natural place for discharging 

 the sewage was at Macquarie Point where 

 there was deep water, enhanc2d by an 

 ample tidal flush. With the expenditure 

 of a few thousand pounds, over and above 

 the sum required for a complete systeni of 

 sewerage, the sewage of Hobart could be 

 rendered quite innocuous, and purified to 

 such an extent that the Avaters of the 

 harbour would always retain their present 

 standard of purity. It could readily be 

 accepted as a fact, from the knowledge we 

 now possessed of bacterial action, tha., by 

 passing all the solid matters through sep- 

 tic tanks before they entered the harbour, 

 the liquefaction of the sewage could be as- 

 sured, and the pollution of th* estuary re- 

 duced to a negligible quantity. 



