Public works . one tank to another that the second pumping waseconomical when compared with the prospect of an in-creased capacity; it was soon discovered also that inocu-lating raw sludge with ripe sludge thus obtained from thesecondary tanks had an excellent effect upon the speed-ing-up process. Further, temperature was too obviouslya beneficial factor in the success of the process to beignored. The following mode of operation was adopted at thebeginning of 1912 and has been continued ever since. Incold weather the sludge is transferred from the particularsedimentation tank whose turn it is
Public works . one tank to another that the second pumping waseconomical when compared with the prospect of an in-creased capacity; it was soon discovered also that inocu-lating raw sludge with ripe sludge thus obtained from thesecondary tanks had an excellent effect upon the speed-ing-up process. Further, temperature was too obviouslya beneficial factor in the success of the process to beignored. The following mode of operation was adopted at thebeginning of 1912 and has been continued ever since. Incold weather the sludge is transferred from the particularsedimentation tank whose turn it is to be cleaned out intothe selected digestion tanks (generally five or six in num-ber) by the main set of pumps; simultaneously some ofthe ripest of the available sludge is pumped by a smallpump into the same delivery main in the proportion of 1to 4, thus inoculating at the earliest possible moment thefresh sludge with the fermentative organisms; in addi-tion steam from one of the Lancashire boilers is injected. into the delivery main to produce temperature conditionsmost favorable to fermentation. In moderately warm weather steam injection is aban-doned, and during the heat of summer neither inoculationnor steam injection are resorted to. The biological factorgoverning the digestion process must necessarily besomewhat complicated, and it is only by the most carefulobservation of the conditions which bring about theright .balance of living organisms that success can beachieved. The following tables of analyses supplied by F. , consulting chemist, indicate two differ-ent sets of conditions. Table A where the fermentingmass was very offensive, and Table B where the vigorousfermenting mass was quite inoffensive. TABLE A. Total per Gelatin-Peptone-Bouillon at 20°C Mean 24,000 Agar-Peptone-Bouillon at 37° C 130,000,000 Coli group 7,000 Proteus group (including Enteritidis sporogenes) 100,000 Denitrifiers 500 Fat-splitting organisms 10,000 Cellulo
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectmunicip, bookyear1896
