RECENT IMPROVEMENTS IN THE SANITATION OF MELBOURNE,
A PAPER BY A. C. MOUNTAIN, M. INST. C.E., CITY SURVEYOR.
Read before the Victorian Institute of Engineers on Sept. 6, 1893.
I PROPOSE to-night to describe certain works that have been under- taken by the City Council of Melbourne within the past five years, for the purpose of improving the sanitary state of the city, in the hope that the subject may be of some interest to the members of this Institute, affecting as it does the health and comfort of the citizens generally. I will first of all refer to the most expensive, and in many ways the most important of these works, viz., the
CITY SANITARY WORKS.
In the year 1889, consequent on the action taken by the Board of Public Health, and the strong objection made by other muni- cipal authorities to the organic waste of the City of Melbourne being conveyed through or deposited upon their territories, the City Council determined to adopt a system whereby this evil could be avoided, and the establishment now in use for the purpose of treating this objectionable waste product by converting it into a valuable and inoffensive manure, is the result. After lengthy and careful investigation of the merits of the several systems adopted in other countries for this purpose, the desiccating and pulverizing machinery manufactured and patented by Sir James Farmer and Sons, of Salford, near Manchester, was that selected. Its ex- cellence had already been demonstrated in this city by the manner in which it has, for more than four years, converted all the slaughter-house refuse of the City Abattoirs into a saleable and valuable manure, whilst the exceedingly favorable reports of its efficiency in dealing with part of the organic waste of Birmingham (where it was found superior to other machines), was a still further recommendation.
The principle of this machine is that of desiccating and Pulverizing the contents by steam. It consists of a twin cylinder with closed ends and hollow sides to form steam jackets, fixed on solid piers or pillars at sufficient height above the floor to allow of access beneath. Two hollow steam-heated axles are mounted in this chamber, central with the two curves which form the " twin- cylinder" section. These axles are provided with three rows of blades or beaters placed at equal distances round the circumference
36 RECENT IMPROVEMENTS IN THE
of the shaft. These beaters are so geared that they barely scrape the inner surface of the machine (truly bored for that purpose), and are adjusted at such a varying inclination as to traverse its entire surface during a revolution, and so that a slow and gradual movement of the material undergoing treatment is produced towards the emptying doors. There are ioa of these blades or beaters in a machine. Steel paddles, rivetted to ends of the beaters, are of such width, and are so pitched around axes that no two scrape the same surface. The entire cleansing of the inside surface of the steam-heated casing above referred to is thus ensured.
As the two hollow shafts carrying each its set of beaters revolve in opposite directions, care has to be taken that the radial paddles pass one another. By this means the disadvantage so often met with in machines consisting of one cylinder only (of finding the material rolled up into lumps or balls, in which moisture may be retained) is avoided. The two sets of beaters, by working in opposite directions tend to break up and disintegrate the stuff, thus ensuring a manure of equal character, and also preventing the offence that is sometimes occasioned by breaking up imperfectly- dried lumps of manure. The type of machine used in this city is 13 ft. long, and the diameter of each cylinder (about one third of its circumference being removed, as previously explained) is 7 ft.—
both internal measurements. The steam-heated casing forming the sides of the machine are of cast iron, in eight longitudinal parts or segments, with external flanges planed to proper angles and bolted together. The internal surface is then bored out truly cylindrical, so that the beaters or scrapers may work freely, and also to prevent any of the material adhering to the casing. This being a non-conductor would retard evaporation greatly if allowed to cake on the sides of the desiccator. A double diagonal engine, each cylinder being 1 in. diameter and 18 in. stroke, drives a spur pinion keyed on to a shaft, which in turn actuates a pair of equal-sized spur wheels fastened on the hollow axles, so that they revolve in opposite directions. Provision is made to convey steam to the jackets and axles, and also to drain off con- densed water in same by pipes at the rear of the machine. The desiccator is charged from the top by means of pipes from store tanks, and balanced doors are truly fitted in the bottom of cylinders to enable the manure to be withdrawn when properly dry. The vapours resulting from the process of desiccation are drawn off by means of a blower, or exhauster, to a condenser, and thence passed on to a muffle.
The above brief description will convey a general idea of the machines selected to treat the city excreta, which (at the time of adopting the new system), amounted to a weekly average of from 300 to 325 tons, requiring from 38 to 4o carts for its removal. Of course to desiccate such an amount of material containing so large a per- centage of moisture, namely, from 93 to 95 per cent., necessarily involved the erection of expensive works, and a large annual expenditure for labour, fuel, etc. ; hut, heavy though these items undoubtedly are, a very great economy in the cost of transport has
SANITATION OF 1VMELBOtiRNt.
been effected owing to the proximity of the new works to the city, which has enabled the carts to be reduced to nearly one-third of the number formerly needed, in addition to which it is anticipated that the value of the manure produced by this means will be recognised by farmers once they become familiar with its use, and thus lead to its ready sale at good rates. Analyses and reports of this class of manure produced from the same class of machine at Birmingham have been obtained by the authorities of that city from Dr. Voelcker, an eminent London chemist, to the effect that it contains 7.11 per cent. of ammonia, in the form of nitrogen, tribasic phosphate of lime, 7 per cent. ; 3 per cent. of potash ; 2i per cent. of soda ; and over 7 per cent. of chloride of sodium.
Dr. Voelcker also, states:—"It is no doubt a good and rich nitro- genous manure, and may be used with advantage for cereal crops and garden produce. For general agricultural purposes, and especially for root crops, I would recommend its being mixed with an equal quantity of mineral super-phosphates.' The concluding remarks in the Report of the Birmingham Health Committee submitted to the Council in 1884, and bearing on the question of desiccating the city excreta, are worth quoting :—" Experience has convinced your committee that it is possible to deal with town refuse in the midst of a densely populated locality without nuisance, and in such a way as to restore to the land a very large proportion of the waste products of town life. While seaside towns are elaborating more or less expensive processes of carrying out to sea what they think can only be thrown away, while inland places are glad to dispose at any cost of what they regard as simply a nuisance to be got rid of, your committee are resolved to prove that the true method of disposal is utilization, and that this can be carried out not merely effectually, but economically, in the town itself."
I will now endeavour to describe the scheme adopted by the City Council on my recommendation, which has been in active operation since November, 1802. The City of Melbourne sanitary works occupy a 4-acre block granted by the State for that purpose, situated a little south of the Footscray road, on the,West Melbourne Swamp, close to the new Railway Dock Canal. Excellent as this site undoubtedly is, so far as position is concerned, it was an exceed- ingly expensive and difficult one on which to erect substantial buildings and heavy machinery. As you are all aware, the West Melbourne Swamp has been formed by the gradual silting-up of what was formerly part of the Bay, and for a depth of from 4o to 7o ft. discloses nothing but running sand, clay, silt, and mud. To make a pile foundation to carry buildings of the size necessary would have increased their cost very materially ; on considering the matter it was therefore decided to risk a few cracks and carry the whole building—including the chimney stack, 120 ft. high—by flotation. Accordingly, the natural level of the swamp was raised some four feet (the swamp itself being only about the level of high water) two layers of 2 in. red gum sheeting planks (laid diagonally and bolted together) were placed on this filling after it had been well consolidated by the traffic of carts over it, and a concrete 3/:
38 RECENT IMPROVEMENTS tN ri
foundation of varying thickness—according to the weight to be supported—was then formed on the planking, on which the walls and foundation piers were erected. Although settlements have shown themselves in places in the building, as was fully expected, the result has been so far satisfactory that the cost of making good same, either to the foundations of the buildings or the machinery is very slight when compared with the thousands of pounds of additional expense that would have been entailed, had piling to a hard bottom been resorted to. The chimney in par- ticular has stood remarkably well ; being designed with hollow walls, each one brick thick, and possessing an internal flue- diameter of 6.o. it was possible to distribute the weight so that the pressure in no case exceeds more than one-half ton to the
• square foot on the supporting ground.
The scheme, in its entirety, provides for the use of the hermeti- cally sealed pail to he delivered on a platform at the works, by specially constructed vans. The pails, after being emptied of contents, are placed on skeleton frames running on rails, and cleansed in washing boxes designed for the purpose by means of a jet, first of steam, and then of water, which effectually cleanses and purifies the pail. Eighteen of these can be cleansed at a time in each washing box, the time required being about six minutes.
At the present time only a part of this idea is carried out—the pails used in cases of contagious disease being the only ones thus treated, the great bulk of the excreta being delivered by cart.
This is discharged into a screen or " grid," covering a long trough leading to the receiving tank. The screen, as its name implies, prevents large foreign matter from entering the receiving-tank, and doing possible damage to the Desiccators. This coarse stuff is collected into trucks, and destroyed in a muffle furnace. The excreta in receiving-tank is raised by means of a bucket-elevator, and conveyed by a flume or trough (both being encased so as to be air-tight), to three large store tanks, each 16 x ro x6 ft. high, and placed on top of the building so as to command the Desicca- tors, which are fed from them. Whilst in these tanks the excreta receives preliminary heat by exhaust steam from cylinders of the diagonal engines which drive the Desiccators, which is carried by pipes carried in-and out through the lower part of each store tank.
A ventilating pipe takes away all vapors to the main blower pipe.
The desiccating installation consists of six machines and engines (each pair of Desiccators being supplied by " Breeches' " induc- tion pipes from one store tank), three blowers, and three conden- sers erected in a room ioo feet long and 32 feet wide, in which is also placed a h.p. horizontal engine, 14 inch diameter and 24 inch stroke, to drive the shafting for, the blowers and the electric light dynamo. An overhead traveller to lift heavy parts of the ma- chinery is also fitted in this room, likewise a pump to supply water to an overhead tank. When a charge is supplied to the Desic- cator—this is generally 15 tons --the work of drying and pulver- izing goes on for a period of from zo to 3ó hours according to the fluidity of the charge, the foul vapors generated during this opera-
SMiITATÍON OF MELBOÚÍtNÉ. $9 tion being drawn off through 15 in. cast iron pipes by means of the blowers (which are Baker's well-known gas exhausters of large size), and thence passed through the w. iron condensers, 15 in.
X 6 in. x 6 in., with end boxes 18 in. wide, of the type known as surface condensing, and fitted with 156 in. tubes. Any uncondensed vapor after the condensers have been traversed, is carried by c. iron trunk pipe to the muffle furnace, and is dis- charged over a fierce coke fire, before it can get away to the chimney. The condensed water is drained off, disinfected, flushed with the overflow of the water from the condensers and from a large water tank built over the blowers, and thence led into the main drain. During the process of desiccation, the charge can receive a dose of sulphuric acid in order to arrest the escape of ammonia; this is provided by means of an ejector and pipe of regulus which lifts the acid from a lead tank on the ground floor to two overhead gauge tanks, from which it is conducted in sepa- rate pipes to each machine. On emptying the machine after work, the manure is taken by trucks and raised to an upper room where it is spread out to cool. Hoppers through the floor enable it to be filled into bags placed on the room below, where it is stacked for removal, the floor level of this room being convenient for this purpose. To avoid the cost of. using Yan Yean water for con- densing purposes, it was decided to obtain water from the railway dock canal ; this is effected by a direct acting duplex pump of the Worthington type, made by the Austral Otis Company by means of a 6 in. suction pipe, the delivery being to a buckled plate tank carried over the blower room to which it acts as a roof. This tank, which is 4o in. x 20 in. x 5 in., supplies the three condensers with a constant supply of water. The steam required for the whole of the heating and motive power at the works, is obtained from a range of six externally-fired multitubular boilers of steel, specially designed for this work. These boilers are 18 feet long by 7 feet in diameter; the whole of the material used in their con- struction was tested for tensile strain, elongation, and contraction of area, and was clearly defined to be of best mild steel of certain brands, whilst in the execution of the details, every care was taken to ensure satisfactory results. They were tested to a pressure of 200 lbs., the average working pressure being 8o lbs. per square inch, The steam pipes are 5 in. in diameter, and are taken off both ends of a steam chest or monkey dome, and connected by copper-bend pipes with the main 11 in. steam pipes which are in duplicate and unite in the engine-room.
The boilers were built in a very satisfactory manner by Messrs. Johnson and Son, of the Tyne Foundry, South Melbourne, and are very creditable specimens of what can be turned out in the colony. In order to enable the cost of fuel to be minimized as Much as possible, it was decided to apply automatic stoking appliances to the boilers, by which small coal could be used. To still further reduce the cost of the coal, a staging was built from the upper floor of the bunker house,to the railway dock canal, on which a line of coal trucks are worked up and down by a friction winch.
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This enables the coal to be brought by vessel to the jetty at end of the coal stage, and to discharge direct into the trucks which are hauled up, and which are emptied into the coal bunkers from an overhead corridor, thereby reducing the cost of conveyance by cart. The bunker is formed with a sloping floor to assist the coal in sliding to the bottom, a wooden bulkhead sloping in the opposite direction forms the bunker into a V-shaped section, sliding doors in the lower part of this bulkhead are provided to let the coal through as it may be required by the stokers. It thus falls into a conveyor trough, which moves it along to one end of the bunkers, where it is elevated to another conveyor trough passing over the fronts of the range of boilers, from which the hoppers of the several stokers are supplied by vertical shoots attached to the bottom of the trough and controlled by valves. The stokers themselves are of the kind known as Bennis's shovel stokers, and were selected in preference to the coking stoker, in consequence of the exceptional width of the furnaces viz., 4 feet, whereas (most of the English boilers being of the Lancashire type), the stokers are generally designed to feed a fire from 2 feet 9 in. to 3 feet in width. In view of this difficulty, it was considered that the sharper jerk produced by the action of the shovel when throwing the coal on the fire, would have a more distributing tendency than would the more gentle motion of the coking stoker.. The Bennis stoker consists or a hopper, underneath which a box containing a shelf is placed. On this shelf a pusher-plate works by means of a lever worked by a small-cam. This cam is so arranged that the motion of the pusher-plate may be adjusted, and the fuel delivered at each stroke may be measured with exactness. When the pusher-plate is drawn back by the lever, it permits as much fuel to fall in front of it as fills the space left available by its withdrawal ; as it moves forward, the coal is thrust before it over the shelf in front of the shovel, which is actuated by an arm worked by a spring. The spring in turn is held back by a projection on the arm on which a tappet works ; when released by the tappet the arm darts forward imparting motion to the shovel, which casts the fuel before it over the fire with a force proportionate to the distance to which it has previously been drawn back. This force is divided into four quantities, so that for every revolution of the driving shaft four throws of varying power will be given, thus delivering the fuel on four different parts of the grate. This assists in preventing smoke, as time is thereby afforded for the consumption of the newly generated hydro-carbons before a fresh charge of fuel is added.
The firebars are also specially designed to form what the inventor terms a camel furnace. They are about 5 feet long, with a depression of about 3 in. in front, with a rising slope, izin. long, of Sin. A rise of r in 48 proceeds from this, increased at the further end of the bars to r in 6, thus making the end of the bars considerably higher than the front. To cause the fuel to gradually ascend to the back of the bars, they move forward i 34 in. by cams fixed on a revolving cam-bar, and are drawn back in series so as to leave the clinker r Ia in. in advance of its former position on
SANITATION OF MELBOURNE. 41 each revolution of the cam-bar. The advantage derived by this apparatus are :-1. The economy derived from utilizing small coal instead of the large coal required on ordinary grates, and an actual saving in fuel used. 2. A considerable reduction of the cost of stoking by manual labor. 3. An abatement of the smoke nuisance generally produced by the stoking of a large installation of boilers fired in the customary way. Against this there is to be considered the cost of the wear and tear of the working parts; this, however, bears a small proportion to the savings already mentioned.
DISINFECTOR CHAMBER.
In connection with the sanitary works (but apart from the main building) is the disinfector chamber, consisting of a closed entrance for van, and two rooms with separate entrances and divided by a parti-wall into which the apparatus known as
"Washington Lyons' Patent Disinfector" is built. A square of glass let through the wall enables one to see from one room to the other; in all other respects they are absolutely severed. This chamber is for thoroughly disinfecting all mattrasses, bedding, clothing, or similar articles from any contagious or infectious germs by means of superheated steam at a temperature of not less than 25o deg. Fahr. The apparatus selected to perform this work has the approval of many eminent sanitarians in England, where it is much used by municipal authorities for hospitals and for barracks. I believe this is the first that has been introduced into Australia. The machine consists of a strong iron chamber elliptical in section, with steam-tight doors at each end and built into the wall dividing the rooms so that one door opens into each room. For convenience in hanging clothes in it, the larger diameter of the ellipse is placed in a vertical position, and the apparatus is supported by feet. The casing is steam-jacketted by means of double walls of boiler plate. Steam from the boilers is conducted into the inner part of the disinfector and also the casing, both parts of the apparatus being provided with pressure gauge and safety valve; whilst an escape pipe is fitted to let off the steam when no longer required, and an arrangement is pro- vided to drain off condensed water. A cage, or basket, cor- responding with the length and sectional form of the lower half of the machine, runs in and out of same on à pair of rails ; this cage is of open wirework ; and above a rail with sliding hooks is secured. These provisions are for the clothing, bedding, or other articles that are to be treated. These are brought in by van at one end of the disinfector, and after treatment taken out at the other door by another attendant, and removed. The usual way of using the apparatus is to first of all turn steam into the outer casing, and then to let it into the inner chamber at a rather lower pressure. It is customary to give 20 lbs. pressure to 26o deg.
Fahr. in the former, and 15 lbs. pressure = 251 deg. Fahr. in the latter case. The time occupied in disinfecting takes from M. to I hour, according to the character of the articles under treatment.
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42. RECENT IMPROVEMENTS IN THE
At the above-named temperatures it has been ascertained that the contagia of the ordinary infectious disorders, and of yellow fever, are entirely destroyed. It is also claimed that in consequence of the dry steam that is secured by superheating, the articles are in no way injured ; in fact that velvets, laces, etc., may be disinfected without appreciable damage. The rooms in which ,this apparatus is placed, are lined on walls and ceilings with white glazed tiles with close struck joints of Keen's cement, and the floor is of Val de Travers asphalte. The table on which the articles to be treated are laid until placed in the disinfector, is a polished marble slab, so that the entire building can with ease be kept scrupulously clean.
GARBAGE DESTRUCTOR.
At some distance from the sanitary works, a pair of furnaces have been employed since May, 1892, in burning a portion of the worst of the ordinary street and house refuse and garbage.
Although this was an experimental work, and is not of sufficient size to deal with quite one-fourth of the said refuse, its existence has helped to largely minimize the " tip " nuisance, and I am satisfied that it only requires the return of financial prosperity to this city, to see the principle fully extended by the city authorities. The furnaces in question are the invention of an Australian engineer, Mr. E. W. Cracknell, and in view of the fact that they are the first he ever erected, and that, as a matter of course, the experience gained in their working has enabled him to improve some of the details, they are very suitable for their purpose. During the period named, they have daily been burning on an average 4o tons of house and street refuse, and only assisted by private rubbish, used instead of fuel, of which not one pound has been purchased for the purpose. Briefly described, the furnaces are thus arranged :- A receiving room, some 8 or 9 feet above the ground level, is provided for the contents of the scavengers' carts. Adjoining this room, but on the lower level, are the two destructor cells or furnaces, each with a firegrate area of 49 feet, and fitted with an annular boiler 6 feet in diameter by about 8 feet 6 inches long.
The open inner space of this boiler forms a drying chamber, through which the refuse is thrust on its way to the furnace. The cells are so designed that the heat generated by the burning garbage passes under and around the boilers, thus producing in them enough steam to drive 2 ten-inch Sturtevant fans. These are employed in drawing off the foul air from receiving room, and delivering it by means of a cast-iron pipe under the firegrate of the furnace, thus creating a powerful forced draught, which raises the temperature of the fire, and consequently increases the efficiency , of the destructor. Ingenious contrivances also serve to annex the escape of dust and imperfectly burnt paper, etc. to the chimney, an evil often complained of in the older form of destructors.
The inventor has introduced certain improvements in his Destructor since the erection of the one of which I have just spoken, by which he secures a saving of manual labour through
SANITATION OF MELBOURNE. 43 he
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the use of a hydraulic ram for charging the drying chamber, which is also reserved for wet refuse, side-shoots, leading directly into furnace, being provided for moderately dry materia] ; and additional grate-area is obtained, accessible on three sides to the firemen.
With these modifications, I have little doubt that there will be a great demand for this type of Destructor.
ABATTOIRS DESICCATING WORKS.
The blood and offal resulting from the slaughtering of the cattle, sheep, etc., at the city abattoirs, has been treated by Sir James Farmer's process of desiccation (already fully described in connection with the account of the sanitary works), since March, 1889, and has produced a very valuable manure, for which there has been ready sale. The plant consists of three large desiccators and accessories (steam being obtained from two Lancashire boilers, 28 feet by 7 feet diameter), the blood and offal is run in trucks to a steam hoist, where it is raised to an upper floor and shot into hoppers connected with the machines, and treated similarly to the method already explained for the excreta. About 3,300 tons of slaughterhouse waste is thus annually turned into a highly valuable manure, instead of being allowed to discharge into the Saltwater River, or trenched into the abattoir paddocks, as was formerly the case. The manure produced amounts to about 3o per cent. of the weight of the refuse treated, and is being largely bought for local and for foreign consumption, as it shows by analysis, a percentage of from 8 to Io per cent. of ammonia, besides a small proportion of phosphates and potash. In consequence of the solid matter con- tained in the offal, the process of treating this refuse is more speedy than that of desiccating the excreta, or organic waste of the city, and the present consumption of coal per ton of refuse put through, is about 7 cwt., as contrasted with nearly ro cwt. at the sanitary works. I have already given reason for this, but the great difference is also in part due to the fact that at the latter establish- ment steam is used for so many purposes. Directly the existing depression ceases, I have no reason to doubt that the working of the abattoirs desiccating plant will be absolutely of a remunerative character, in view of the fact that the manure contains nearly 9 per cent. of nitrogen, and was sold during the first two years that the works were in operation at the rate of J5 15s. and _5 17s. 6d.
per ton respectively, which absolutely meant for that period a clear profit on the cost of production.
Very gratifying letters have been received from users of this manure as to its great value as a fertilizer for crops and grass- lands ; indeed, in combination with good bone-dust, it would seem that the ideal chemical standard of a manure is attained.
MINOR IMPROVEMENTS.
Although not strictly engineering matters, I cannot conclude this paper without briefly referring to certain sanitary improvements which have been effected in this city within the past 5 years, and
44 RECENT IMPROVEMENTS IN SANITATION OF MELBOURNE.
which seem to be appreciated by the citizens. I allude more particularly to the establishment of the street orderly system in the main business streets, the disinfection of all street gutters, urinals, and most of the lanes and alleys, and the erection of a large number of public conveniences in various parts of the city, all matters which, though in themselves comparatively unimportant, have added largely to the comfort and health of the public.
Before closing this rather random paper, I would desire to acknowledge the admirable assistance I have received from the officers of my department in the designing and execution of works which were in general new to Australia, and which were attended with many difficulties. One and all, my assistants have rendered me the most loyal and intelligent co-operation in carrying out the various works which it has been my privilege to endeavour to describe to you this evening.
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