FILTRATION PLANT AT LORAIN, OHIO
In 1855, Mr. George W. Rafter, civil engineer, was engaged by the waterworks board of the city of Lorain to report upon a change in the water supply of that place, which became necessary by reason of the rapid growth of the town in the few preceding years and the large increase in typhoid fever rate. In his report dated June I, 1895, he says: “As a whole, the present arrangement is such as to give serious pollution of the Lorain water supply, and it is a matter of little surprise that typhoid fever has been seriously prevalent in Lorain in recent years.” On June 23, 1896, the president of the waterworks trustees wrote to the State board of health asking permission to install a Jewell mechanical filter plant, and in the summer of the same year, the work of construction was started. This plant consists of six filtertanks of cypress ^7 ft. in diameter and 14 ft. in height, known as the high-type Jewell filter. In this the lower chamber consists of the coagulating-basin; above is the filter proper carried on supports inside the tank, the total coagulating capacity of the six filters being about 60,000 gal.— about one-half hour’s supply; the guaranteed capacity of the six units being 3,000,000 gal. per day and guaranteed reduction in bacteria of ninetyseven per cent., this being the first filter plant, to the writer’s knowledge, in the United States, that was installed with a bacterial guarantee attached.The filter building a brick structure located on the hill adjacent to the pumping station, the basement of it being concrete-lined and forming a receiving well for the clear water. On the first floor, carried on T beams supported on concrete walls, were located the filter-tanks. These filters have mechanical agitators, driven by a line of shafting operated from a 10-h. p. engine at the end of the building. In a convenient position were located two 8 x 12 solution-tanks for sulphate of aluminum, with a pump for delivering the solution of the unfiltered water on its way to the filters. From the clear-water basin below the filters the service-pumps took the water and delivered it to the city. On completion of the plant in 1897, a test was made by Dr. A. J. Raumhart, who in a report signed August 13. 1897. states that the general average for the period between March and August, with the exception of a number of samples which were thrown out, for one reason or another, was 2,ior bacteria in the raw water and 4,183 in the filtered water, and in no case was there any trace of alum in the filter ed water. The amount of alum used varied from 3.9 grains to 1.7—the average being 2.01. The average rate of filtration, however, was only 1.18 gal. per sq. ft. The plant continued in operation from 1897 until 1000, with the use of alum as a coagulant. At Lorain it will be noted in the yean 893, the typhoid rate was 180, dropping to fifty in 1894, increasing to 140 in 1895, dropping to twenty-five in 1897, where from that time on until 1901 there was a continual decrease. In 1922 it was as low as five and one-half—the average for six years, after the filter was established being 18.8. For the first seven months of 1903, it was nothing. In July, 1903, however, repairs to the filters necessitated the closing-down of the plant for a period of three months, during which time the rate rose to eighty per 100,000. At Youngstown. Ohio, it will be noted the rate consistently increase.! until 1903, at which time it reached 250 per 100,000. From the time that the filter plant was established at Youngstown, the rate has consistently fallen. At Lawrence, Mass., the rate in 1892 was 120. The plant was established in 1903. and it will be noticed that the rate has consistently remained low since that time, gradually fall ing. At Albany, N. Y., in 1895, the rate was about 180. dropping to too in 1896 and averaging about ninety in 1897-8-9, in which year the filter plant was established, after which a short curve downwards is noticed, since which time the curve is consistently low. These curves are the best demonstration of the value of filtration. In September. 1900, contract was made with the Jewell HI ter company for the installation of a process of manufacturing sulphite of iron to use as coagulant to replace alum. The guarantee under which this plant was installed w^as that an equal degree of purification would be obtained at a cost not to exceed one-half the cost of alum based on a standard price of scrap iron, sulphur, lime and sulphate of aluminum. In the fall of the same year this plant was installed. It was of a process similar to one that previously had been installed at Quincy. 111., and consisted of four tanks 14 ft. in diameter and 8 ft. in height, two sulphur burners, condenser for condensing the fumes of the sulphur into sulphuric acid, tank for containing iron scrap, over which the sulphur-solution was run, allowing it to come in contact with iron for several hours, using these tanks alternately and lime-tanks for making the lime-water solution to be used in connection with the iron solution. This process is rather a complicated and delicate one, requiring the attention of a man of considerable technical ability in its handling. The material composed of the sulphate of iron or crystaliron used in water-purification is a byproduct of steel mills or plants using sulphuric acid for cleaning iron, when the waste sulphuric acid, instead of being dumped into rivers, is crystalised and sli pped in this form in bags or barrels somewhat similar to the alum crystals. In 1 the original Lorain plant had become so much overworked that it became necessary to consider the installation of additional filter-capacity, and several schemes were outlined, one of which was to build on the lake-front a large basin as a preliminary sedimentation basin—the idea being that by some preliminary sedimentation the filter capacity could be considerably increased. After making the contract for the construction of this basin, however, on ex pert advice, the board of public service determined that the results that might be obtained were not sufficient to justify the cost and determined to build an entirely new filter plant of modern construction and of such capacity and design as would provide for any reasonable future growth of the city, the location of the old plant being such that any material additional capacity was almost impracticable, except at a very great expense. It was determined, therefore, to use the sedimentation-basin, for which the contract had been awarded which, also, was partly constructed, and place a filter plant over it. This necessitated a design that to a certain extent within limitations. was more or less a disadvantage: but the money already contracted for would otherwise have been uselessly expended, and it was determined to proceed on this basis. The present plant, therefore, is located oh the lakeshore be low the old filter building and within too ft. of the water. The basin, which was under construction, was excavated to a depth of 21 ft. below the water-level on the lake, 66 ft. in width by 123 ft. in length. The plant was designed for a present 6,000.000-gal. plant on a basis of rate of filtration of 100,000.000 gal. per acre, but arranged so that in future it may be doubled without in any way affecting the present installation. This almost equally divided the basin into two parts, one-half of which contained the coagulating-basin and the other half the clear well, upon which was superimposed the filterbeds. The concrete wall for the coagulating-basin was built up 9 ft. above the mean water-level in the lake, making this basin 30 ft. in depth and about 66 ft. square, and cont titling about 800,000 gal. of water—a shape not of the best design for securing the highest efficiency in sedimentation, there being too great a depth. It was decided that the best method of baffling this basin to secure displacement was vertical haffles. The basin was divided lengthwise into two compartments, one of which would hold one hour’s supply of the filters at maximum rate, and the other two hours’ supply or, running in series total of three hours’ sedimentation to be secured. On account of the fact that the bottom of the sedimentation-basins are 21 ft. below the lake-level. it is, of course, impossible to drain the basins, and for this purpose it was necessary to install a pumping plant. This is located in an independent well beside the main basin, and the sludge deposited is from time to time pumped out and into the lake. Plate 9 gives a general view of the building, which is of red brick, covered with a tile roof supported on steel trusses. The nar row portion of the building covers the operating part of the filters; the balance of it covers the machinery room, laboratory, storage-room and a portion cf the coagulating-basin. The balance of the basin can be seen projecting beyond the end of the building covered with a flat, concrete cover; at one side is located the small building containing the pump for pumping the sludge from the basin when required. The water is taken from the present intake-well located between the present pump and the new filter building by a 24-in. main which is brought into the f.lterhouse, through the basin below the machinery room, whence it branches with connections for three pumps, two of which have been installed. The two water pumps used are each of 6,ono,030-gal. capacity, DeLaval steam-turbine driven. These pumps lift the water from the intake-well and deliver it into the mixing-chamber, located between two compartments of the coagulating basin. Here the flow is diverted to either side by means of a 24-in. sluicegate and carried to the bottom, where it is forced to cross the width of the basin through a perforated concrete conduit and, passing up and down and up over the baffles, is carried out over a weir collecting trough at the opposite end of the basin and allowed to flow into a concrete conduit on either side by means of regulating gates. From this concrete conduit is carried to the filterbeds. Plate II shows the arrangement of one of these filterbeds showing the central concrete gutter into which the water flows from the conduit. Rising in the central gutter, it is dis tributed by the metal gutters over the entire bed. Passing down through the sand it is gathered through the numerous strainers shown, distributed over the bottom of the bed into the lateral conductors, thence taken out below through four outlet manifolds arrarged so that they devide each filterbed into four areas. These outlets unconnected into one large pipe, which is carried through into the filter-gallery
Here it passes through the controler shown in the gallery, and into the clear well located Inlow the filters. Referring again to plate it : You will note the small tubes covering the bottom of the filterbed between the strainers. These are the brass air-tubes, through which is conducted the compressed air used in agitating the sandbed during washing. Plate 14 illustrates the arrangement of this controler. It is a large closed cast iron case, inside of which is a brass-lined cylinder, with angular orifices. Operating in this cylinder is a brass cylinder valve, which is operated by a floating plate, the weight of the valve and piston being designed for a certain head of water. With the increase of this head, the piston is forced upwards, cutting off the supply to the chamber. As the head in filters decreases, the piston slowly drops, increasing the area of the openings and allowing more water to pass. The readings of these controlers show an almost perfect regulation to the rate of flow, and an advantage possessed bv this type of controler over the more common gravity type is that they will operate equally well under a submergence where the difference between the heads is greater than that under which the controler is designed tp operate. The controler is so arranged that the rate of flow may be increased from the operating gallery b an arrangement for increasing the orifice-discharge through a secondary outlet controled by cover plates. The plant is designed for the use of sulphate of iron and lime as a coagulant, and these are mixed in four tanks 10 ft. in diameter and 14 ft. 6 in. in depth, located below the floor of the machinery room. Solutions are then pumped to elevated concrete head-tanks located in the machinery room and arranged to maintain a constant head by means of an overflow, which allows the surplus to flow back into the main tanks. From here it is delivered through graduated orifices by gravity to the raw water, the iron being delivered to a point in the suction-inletpipe, as it enters the building, the lime being delivered in the mixing chamber located between the two compartments of the coagulating basin. A reflector over each head-tank gives the operator on the floor below a constant means of observation. Each one of the solution-tanks is equiped with a recording gauge recording constantly the rate of consumption of solutions. In this way an accurate knowledge of what is being done is al ways available to the superintendent of the plant, irrespective of the reports of operators. In addioon the two main pumps, raw-water pumps, the third pump, which is used as a wash-pump for washing the filters, and it is also a DeLaval turbine; also, a blower of the same type for supplying the air for agitating the filterbeds during washing. These pump* operate under unusually severe conditions for a pump of this character, the vacuum-gauge on the suction of the raw-water pumps showing a constant working of from 20 to 23 ft., and they have been worked to a total lift of 25 ft. actual measurement, while the wash-water pump has an extreme lift of about 27 ft., and the discharge from each pump is below the level of the centre line of the pump. That on the raw-water pumps is about 4 ft. 6 in. from the centre line of the pump to the water-level in the basin below, into which the water is dropped from the pumps— that on the wash-pump being about 6 ft. 6 in. below the centre line of the pump to the overtlow-line of the troughs. These conditions not having been fully realised in the start caused some considerable trouble in securing satisfactory results from the pumps when they were first started, but, after making certain changes, they are now fulfilling all requirements with the utmost satisfaction. The operating room also shown on plate 16 is equiped with operating tables, irotn which the hydraulic valves which control the various operations of the filter are handled. On tl;e » perating table is also placed the loss of-head-gauge, which is also of the recording type, and, to the writer’s knowledge, this is the first plant that has been equiped with recording loss of head gauges. This is a place, where, in the writer’s opinion, they are probably of the greatest assistance, as it gives an accurate record of the condition of the filterbeds at all times more than anything else can do. These tables are cabinet-finish, with marble top and polished brass handles and dials.
Another feature of this plant that has not been incorporated in any’ plant of which the writer has any knowledge—namely, a sampletable for observing the operation of the filters. On the top of the table will be noted the glass cylinders, one of which connects to the outlet of each filter and ode to the raw-water, treated water and clear well. Through these cylinders is kept a continual circulation of the water from each one of these points, so that the operation of each filter is apparent, while, also, the comparison is easily made in observation. It is likewise a convenient point for taking samples, obviating the necessity of climbing down into a wet, dripping pipe-gallery whenever it is necessary to take samples for analysis, w’hich should be at least once a day. The circulation is kept up through the cylinders by means of the multiple pump, which is illustrated by plate 19. This pump is operated by a small water-motor and has an independent pump for each supply. This sampletable and pump is now being installed in other plants as well. Plate 21 is a view of the lab oratory which is maintained at this plant and has been one of the features of the Lorain filter plant since its installation. Lorain started out as the first city in the State of Ohio to filter its water with a bacterial guarantee and is consistently endeavoring to keep at the head of the procession. It requires considerable nerve for a public board to abandon a plant of any kind which has been in use but a few years and, to all intents and purposes, is good for many years to come, if kept up in proper repair, whose efficiency, also, at its capacity is satisfactory; but it also show’s wisdom that many boards wou’d not be willing to display in building a complete and up-to-date plant which, ultimately, in economy, will justify the scrapping of the old plant by reason of its increased cost for maintenance, due to its temporary character and costly construction for extension. The filter plant at Lorain is well worth a visit from any municipality or water company that is contemplating improvements of this character and will insure Lorain’s advanced position in water-purification for some time to come.