The Disposal of Garbage in 
the City of Providence, 
Rhode Island. THE DISPOSAL Of GARBAGE II IE CHI OF 
PROVIDENCE, RHODE ISM 
By CHARLES V. CHAPIN/M. D., 
Superintendent of Health, 
Providence, R. /., U S. A. 
Presented at the Twentieth Annual Meeting of the American 
Public Health Association, held in the Citt of Mexico. 
[Reprintedfrom Vol. XVIII of the Transactions of the American Public Health Ass’n.] 
CONCORD, N. H.: 
REPUBLICAN PRESS ASSOCIATION, 
1893. THE DISPOSAL OF GARBAGE IN THE CITY OF PROVI- 
DENCE, RHODE ISLAND. 
The swill or house garbage of Providence is collected and disposed of 
by contract. The present contract is for five years from May i, 1889. 
The contractors receive 15£ cents per annum for each inhabitant, and 
they are for this amount to collect and dispose of the garbage. At the 
present time the population of the city is estimated at 139,000, and they 
therefore receive $21,545 per annum. When the contract was entered 
into, the contractors expected to dispose of the garbage by delivering it 
F. O. B. on the cars in the city to a,hog-grower, who owned an exten- 
sive piggery some distance out in the country, and who had agreed to 
receive the garbage and pay the expense of transportation. The 
contract price therefore was estimated to give merely a small margin of 
profit over the cost of collecting alone, as the disposal was supposed to 
cost the contractors nothing. After the contract with the city was signed, 
the arrangement with the piggery people fell through, and the contract- 
ors were obliged to seek some other method of disposal. As a result a 
stock-company was formed and a process adopted for disposal by means 
of naphtha. Arrangements were made with I. M. Simonin, of Philadel- 
phia, who had for many years been conducting the business of extracting 
grease and oil from various waste products by means of naphtha. Works 
were constructed near the center of the city in accordance with plans fur- 
nished by him. There is in Providence a large area of swampy land, 
recently filled in, almost in the center of the city. It was on this land, 
quite a distance from all buildings except two or three large manufac- 
tories, that the garbage works were established. 
The use of naphtha for the extraction of fats and oils on a large scale 
is not a new art. It has been employed by a number of large firms in 
this country for many years. It was first applied to the utilization of 
garbage, I believe, by the Baynes Garbage Company, of Buffalo, New 
York, operating under the patents of the Merz Company of that city. 
By the Merz process the garbage is first dried as completely as possible 
in closed, steam-jacketed driers, the moisture being driven oft, con- 
densed, and discharged into the sewer or river. The dried garbage, or 
“tankage,” as it is technically called, is then treated with hot, liquid 4 
DISPOSAL OF GARBAGE IN PROVIDENCE, R. I. 
A is the extractor containing the carriage B, on which are the pans C which contain the garbage. The cover 
is fastened in front by means of swinging bolts which fit into slots D. The extractor is filled with naphtha through the pipe 
E, the naphtha being drawn by the pump F from the holder G. The naphtha is heated by the coil H which is filled with 
steam through the pipe I. The open-steaming is done through the perforated pipe J, which is filled with live steam through 
the pipe K. During the process of evaporation the naphtha and water vapor pass through the pipe L to the condenser M, 
which is cooled by water dropping from the pipe N. The condensed water naphtha vapor flows into the separator O from 
which the water passes to the sewer through the pipe P, and the naphtha to the reservoir through the pipe Q. The grease 
which is extracted from the garbage is forced through the pipe R to the settling tank S, from which it passes to the still T, in 
which it is finally separated from the remnants of naphtha which it contains and from which it is drawn into barrels for ship- 
ment. The still is provided with heating coils and open-steam pipes similar to those in the extractor. DISPOSAL OF GARBAGE IN’ PROVIDENCE, R. I. 
5 
naphtha, which percolates through it and dissolves the grease. It is 
impossible to thus extract the grease unless the garbage has been 
thoroughly dried. The drying of the garbage by steam heat, which is 
necessary under the Merz patents, is an expensive operation. The Prov- 
idence company at first experimented with the Anderson drier, which is 
constructed on an entirely different principle from the one used by the 
Merz people and is continuous in its operation and very economical. It 
failed, however, to dry the garbage, and hence was abandoned. Garbage 
contains so many different ingredients and so much grease that it is one 
of the most difficult substances to dry. The finer portions would come 
out of the Anderson drier in a very satisfactory condition, but larger 
masses, like potatoes and apples, were almost unaffected. It is necessary 
that the whole mass should be finely pulverized so as to become homo- 
geneous and to be subjected to a high temperature for many hours in 
order to remove all the moisture. 
Another experiment was tried by the Providence company for remov- 
ing moisture. A press was set up, but it was soon discovered that the 
most powerful hydraulic pressure could not remove much more water 
than would drain from a pile of garbage in a few hours when merely 
left upon the floor or in a bin. The failure of the press was also due to 
the lack of homogeneity in the garbage. If it could be ground before 
pressing, much more liquid could be squeezed out; but grinding gar- 
bage is a very difficult operation and moreover would complicate the 
process too much. Thus from repeated trials it was found that from an 
economic as well as from a sanitary standpoint, pressing and drying 
garbage in the ordinary way were impracticable. 
By the process finally adopted and now in operation, the garbage is 
dried and the grease removed at one and the same time, by treating it, in 
a closed receptacle to the action of hot naphtha and naphtha vapor. 
In Providence the owners or occupants are required to dispose of 
ashes and all other refuse, except garbage, at their own expense. The 
garbage, separated from everything else, is kept in tubs or barrels in the 
yard and is called for by the contractors three times a week during the 
summer and twice a week during the winter, and oftener in special cases 
when required by the health officer. The separation of garbage in this 
way is very thoroughly carried out, and it is only exceptionally that it is 
mixed with ashes. The contractors use for the collection 16 two-horse 
carts. These carts are constructed of wood, are water-tight, with covers, 
and are of the following dimensions: width, 3 ft. 8 in., length, 11 ft. 
5 in., depth, 2 ft. 6 in., and weigh about 3,300 pounds. The weight of 
a wagon-load of garbage is on an average about two tons. A consider- 
able portion of this weight is due to water, and when the garbage has 
been left to drain for a few hours it is found to diminish about 50 per 
cent, in weight though it does not diminish very much in bulk. The 
garbage, immediately after its collection, is carried to the disposal works 
previously referred to, near the center of the city, which are operated by 
Mr. I. M. Simonin, to whom the contractors deliver the garbage. 6 
The garbage is here unloaded upon a concrete floor, where it is al- 
lowed to drain of superfluous water, which runs into a river that flows 
close by. The amount of the liquid is of course in the aggregate not 
very large, and could be without offense discharged into a small stream 
or a well-constructed sewer. After it has been allowed to stand here 
for a few hours, it is loaded into carriages which are at once rolled 
into the extractors. The carriages carry a series of trays made of sheet- 
iron and coarse wire netting, so that the garbage is spread in layers about 
six inches in thickness. This is to prevent the matting together of the 
garbage, which would result from the pressure of its own weight if it 
were loaded into the extractor in bulk. The carriages with their trays 
are made of such a form that they fill the extractors as completely as 
possible, so that the naphtha will be forced to pass through the interstices 
of the garbage rather than around the sides of the mass. The extractors 
are wrought-iron tanks six feet in diameter and eighteen feet long, and 
calculated to stand a considerable internal pressure. The extractors are 
placed horizontally, and one head is removable, being lifted off by a 
tackle from above, and made tight when in place by screw-bolts around 
the rim. When loaded, an extractor contains about eight tons of gar- 
bage as it comes from the floor. The head of the extractor is then 
screwed on and the extractor pumped full of hot naphtha. In the bottom 
of the extractor is a closed coil of steam pipe. The steam is now turned 
into this and the naphtha vaporized. The hot naphtha vapor as it passes 
up through the garbage takes up the water vapor, just as hot air would do 
under the same circumstances. The mixed naphtha and water vapor is 
led off from the top of the extractor to a condenser formed by a coil of 
pipe over which cold water is kept flowing. The condensed water and 
naphtha pass to the “ separator,” where they separate in two layers, the 
naphtha floating on top. The naphtha is drawn off continuously to the 
naphtha tanks and the water passes off into the river, or could well be dis- 
charged into the sewer if there was one. From the naphtha tanks the 
naphtha is pumped directly to the extractors again, passing through a 
heater on its way. This heater is so arranged as to heat the cold naph- 
tha by means of the hot naphtha vapor which comes from the extractors, 
thus forming a sort of secondary condenser and economising both the 
heating of the naphtha and the cooling of the naphtha vapor. As the 
naphtha in the extractor is brought in contact with the garbage it dis- 
solves out some of the grease. The naphtha vapor also, as it passes through 
the garbage, dissolves out the grease, which trickles down into the liquid 
beneath. As the evaporation continues, the level of the liquid in the ex- 
tractor sinks lower and lower. It is a solution of grease and naphtha, 
which is constantly becoming more and more concentrated. When 
it is evaporated so that there is only a small amount in the bottom 
of the extractor, not reaching the level of the bottom of the carriages 
containing the garbage, it is forced off into the “ settler.” The extractor 
is then filled with naphtha again and the process repeated seven or eight 
times, until all the grease and water are removed. Open steam is then 
DISPOSAL OF GARBAGE IN PROVIDENCE, R. I. DISPOSAL OF GARBAGE IN PROVIDENCE, R. I. 
7 
turned into the extractor and allowed to pass through the garbage for 
three or four hours, until every vestige of the naphtha is removed. This 
steam also, after leaving the extractor, passes through the condenser, so 
that every portion of naphtha that it removes from the garbage is saved. 
The evaporation of a charge of naphtha occupies about four hours, open 
steaming about the same, so that the whole time occupied in extracting 
the garbage is thirty-two to thirty-six hours. After the open steaming, 
the head of the extractor is removed and the charge drawn out and 
carried to another building, where the dried garbage is ground, sifted, 
and bagged, ready to ship to fertilizer manufacturers. The amount of 
dried garbage, or tankage, which is obtained from an extractor varies 
somewhat at different seasons of the year, but averages about a ton and a 
half. To return to the settler: this is a tall, upright, iron tank which 
receives the solution of grease and naphtha from the extractors and also 
a certain amount of water and dirt which comes with it. This latter is 
drawn out from the bottom and passes into the river, while the naphtha 
solution goes into the stills where the naphtha is driven off by distillation 
and open steaming, and the grease is then drawn off and is ready for 
shipment. The amount of grease also varies with the seasons, but will 
average about six hundred pounds to an extractor. 
The works in Providence consist of a building in which are three boil- 
ers aggregating about 235 horse-power; here is also the engine and the 
grinding mill and the store-room for the tankage. Attached to this 
building is a shed where the garbage is unloaded from the teams and put 
on the carriages. The building where the naphtha process is conducted 
is entirely separate from this building, and is merely a frame covered 
with corrugated iron. In it are six extractors, two settlers, two stills, 
and the necessary pumps, tanks, and piping. The condensing appara- 
tus is outside, in order to get the advantage of cold air. The water for 
condensing is supplied by a large steam-pump, which is connected with 
four driven wells supplying about 250,000 gallons every twenty-four 
hours, at a temperature of 50 degrees, which is uniform throughout the 
year. The tanks for storing the naphtha are also in the open air. The 
works are run day and night with the exception of Sunday. The quan- 
tity of coal consumed is about forty-eight tons per week, or a little over 
two tons for each extractor full of garbage treated ; therefore one ton of 
coal evaporates about three tons of water. There is a loss of naphtha in 
various ways, by leakage and evaporation, amounting to nearly 1,000 
gallons a week. 
The amount, value, and composition of garbage varies very greatly at 
different seasons of the year. The bulk is the largest in the summer, 
beginning to increase with the beginning of pea-pod time and reaching 
its maximum during the height of the green-corn season, at which time 
the total volume of the garbage is fifty per cent, greater than it is at the 
minimum. The smallest quantity is in spring and fall. Vegetable 
material in garbage has little value as a fertilizer or for grease. In the 
winter time the bulk and weight of the garbage is, in the climate of Prov- 8 
DISPOSAL OF GARBAGE IN PROVIDENCE, R. I. 
idence, increased considerably by snow and ice. The amount of garbage 
collected during the year is about 15,000 tons as it stands in the carts. 
As has been stated, about fifty per cent, of this drains out on the floor. 
Of the remainder, from seventy-five to eighty per cent, is water, from three 
to six per cent, grease, and the remainder—from fourteen to twenty-two per 
cent.—dry residue or tankage. The grease is very dark in color and can 
be used for any purpose for which dark grease is adapted. The tankage 
shows on analysis from five to twenty per cent, bone phosphate, from 
three to six per cent, ammonia, and a little over one per cent, potash. It 
is exceedingly dry, and is in great demand by fertilizer manufacturers for 
mixing with other ingredients. 
There has been considerable complaint in regard to the nuisance 
caused by the works for the disposal of garbage just described. A part 
of this undoubtedly has some foundation in fact. The garbage as it 
drains upon the floor is undoubtedly a nuisance, though the smell from 
this is somewhat confined by the building and does not travel very far. 
In the construction of new works pockets would be provided similar to 
those used for grain or coal, in which the garbage would be at once 
received and tightly covered. If necessary these pockets could be ven- 
tilated under the fires. The other source of nuisance is from the leakage 
of naphtha vapor. As the naphtha is used over and over again it 
becomes saturated with odors derived from the garbage, and being very 
volatile, whenever a leak occurs the vapor is carried to a considerable 
distance. This source of nuisance I think could also be removed by 
having a different kind of condenser which would not leak.