March 4, 1909] 



NATURE 



TREATMENT AND DISPOSAL OF SEWAGE. 

 (i) Principles of Salvage Treatment. By Prof. Dunbar. 



Translated by Dr. H. T. Calvert. Pp. xxiii + 271. 



(London : Charles Griffin and Co., Ltd.) Price iss. 



net. 



(2) Sewer Construction. By Prof. Henry N. Ogden. 

 Pp. xii+335. (New York: John Wiley and Sons; 

 London : Chapman and Hall, Ltd., 1908.) Price 

 12s. 6d. net. 



(3) Modern Methods of Sewage Disposal. By W. H. 

 Trentham and J. Saunders. (London : Sanitary 

 Publishing Co., Ltd., igog.) Pp. viii + 60. Price 

 2s. 6d. net. 



(i) 'T^HE development of the investigation into 

 -L sewage purification has proceeded on dif- 

 ferent lines in England and Germany, owing largely 

 to the fact that practical necessities have compelled 

 English towns to attempt some measure of purifica- 

 tion in the absence of complete scientific information, 

 whereas it has been possible in Germany to devote, 

 in the first place, more attention to the theoretical 

 aspect of the problem. 



The author of this book is one of the foremost 

 among German investigators, and consequently it 

 cannot fail to be received with interest by those en- 

 gaged in the problem of sewage purification in 

 England ; it fills a place in the literature of the 

 subject, the requirements of which no existing work 

 completely satisfies. 



Presumably the favourable situation of many Con- 

 tinental towns in regard to the discharge of sewage 

 into rivers of relatively large volume is responsible 

 for the fact that the theory of sedimentation and 

 technique of screening has received more attention in 

 Germany than in England, as in certain cases 

 thorough screening or eflicient sedimentation of the 

 sewage is all the prevailing conditions require. 

 Where further biological treatment is necessary, it is 

 doubtful, however, whether any elaborate screening 

 device can be considered economical. 



On pp. 47 to 59 a series of interesting and in- 

 genious methods for screening sewage is described, 

 and, later, valuable experiments of several German 

 investigators are quoted with regard to the effect 

 of varying rates of flow on the deposition of the 

 suspended solids. 



The author's conclusions in regard to the design of 

 sewage sedimentation tanks, viz. that shallow tanks 

 of simple construction are, as a rule, preferable to 

 tanks of great depth, will doubtless meet with genera! 

 approval. 



\\'lKn dealing with septic tanks the author's con- 

 clusion is that preliminary anaerobic treatment, so 

 far from being beneficial, is actually detrimental to 

 subsequent filtration, and he supports this conclusion 

 bv the statement that organic matter can be nitrified 

 without the preliminary production of ammonia. 



In view of the fundamental importance of this 

 latter point, and that the author's results are not in 

 accordance with those of Adeney, Boulanger and 

 Massol, and other workers, it is disappointing that 

 particular experiments are not given or specific refer- 

 ences quoted. 



NO. 2053. VOL. So] 



It may be here mentioned that the value of the 

 extensive bibliography given at the commencement 

 of the book is very considerably diminished by reason 

 of the fact that no reference is made to the text of 

 the book, and in the majority of the cases the subject- 

 title is omitted; this is true for all references to the 

 author's own publications. 



The absorption theory of sewage purification, which 

 is now generally accepted as afi'ording the most 

 rational explanation of one of the important phases 

 in the biological purification of sewage, is very thor- 

 oughly dealt with on pp. 140 to 149, although the 

 experiment given previously in regard to the time of 

 passage of sewage through a filter cannot, on ac- 

 count of insufficient data, be considered conclusive. 

 W. Cliftord' has shown in a thorough manner that 

 this question is dependent on the following factors : — 

 (i) Rate of application of sewage; (2) depth of filter; 

 and (3) interstitial water, which is determined by the 

 size and character of filtering material. As an ex- 

 ample of what may occur in a fine-grade filter he 

 found, when liquid was applied at the rate of 200 

 gallons per sq. yard to a filter 3 feet deep, composed 

 of clean clinker i inch to | inch size, the average 

 time of percolation was rather more than three hours. 



The chapter on contact beds is, in the opinion of the 

 reviewer, one of the most valuable sections of the 

 book, as it contains a series of interesting and com- 

 plete experiments, the results of which help in the 

 elucidation of the purification changes effected. 



In view of the fact that the author appears to be 

 in favour of complete aerobic treatment, it is somewhat 

 surprising to find that Dibdin's slate filters are dis- 

 missed as irrational, although their object is to retain 

 the suspended solids in such a manner that aerobic 

 decomposition may be effective. 



In general, the author favours the adoption of 

 percolating filters, but in stating their disadvantages 

 he omits the question of production of flies and in- 

 creased fungoid growth, attendant on certain types of 

 these filters. The use of a carefully graded layer of 

 fine material on the surface of a filter, as a means of 

 distribution, as recommended by the author, is sup- 

 ported by a considerable body of experience, both in 

 this country and on the Continent. 



Dr. Calvert is to be congratulated upon an admir- 

 able translation. 



(2) A course of lectures given by the author in the 

 College of Civil Engineering, Cornell L^niversity, 

 forms the basis of this book, which is published as a 

 continuation of a previous work of the author's on 

 " Sewer Design." 



Outstanding features of the book are the large 

 number of well-produced diagrams and drawings, 

 illustrative of a great variety of constructional work 

 carried out in various towns in .America, and the 

 numerous references, which the engineering student 

 will find very useful. 



In view of the present tendency in America to use 

 reinforced concrete for the construction of large sewers, 

 the various e.xamples of this class of work de- 

 scribed in chapter vi. will be of interest to the English 

 engineer. 



