Gravity Filtration Research Articles

Isolation of benzoic and boric acids from Listerine. An introductory organic chemistry experiment

The experiment described here is a separation scheme which introduces the student to fractional distillation, extraction, decolorization with activated carbon, hot gravity filtration, vacuum, filtr...

A Review of Waterflood Filtration

Abstract A basic review of waterflood filtration, this paper covers the history of filtration, theory, different types of filters and types of filter media. Gravity, pressure, diatomaceous earth and cartridge-type filters are described and their operation discussed. Filter media, such as sand, and coal are presented, and drain systems are discussed. Many of the common operating problems are also listed and described. Introduction For the engineer who must design a filter plant, the selection of the proper media, underdrain, etc., can be a bewildering task. Unfortunately, the theory of filtration has not advanced to the point where it can be of significant help. Experience thus becomes the engineers' best hope; however experience does not always assure optimum results, but it at least narrows the field. The following discussion is toprovide a description of the materials commonly used in the oil field and the advantages and disadvantages of each andprovide guidelines that will aid the engineer in operating the unit that is installed. History of Filtration in the Oil Fields The first two filters for the clarification of water to be used for injection purposes were installed 30 years ago in the Bradford-Allegany fields. These filters were of the pressure type and contained a graded sand and gravel bed. They were soon followed by gravity filters which were constructed of wood, steel or concrete and contained either sand or anthracite coal as the filter media. In 1937 the first pressure-type filter to contain a graded bed of anthracite coal as the filter media was put into service. Theory of Filtration Filtration may be defined as the process of passing a liquid containing suspended material through a suitable medium in such a manner as to effectively remove the suspended solids from the liquid. Basically this is a mechanical action, and the larger suspended particles will not pass through the interstices of the filter media due to their size; however this action alone may not effect complete clarification, since some of the suspended solids are small enough to pass through the filter media. If there is appreciable turbidity in the filter effluent, coagulation may be necessary.' Coagulation, which may be employed in open pits, tanks or even in the line prior to the filter, tends to agglomerate the smaller suspended material and forms floc particles which are large enough to be retained by the filter media. Usually in the coagulation process sufficient retention time is provided to allow the larger and heavier coagulated particles to settle out and to prevent some of the unreacted coagulant passing through the filter and precipitating in the distribution system. For optimum filter operation, the water from the settling basin or tank contains some floc particles. Initially these particles penetrate the filter media through the numerous voids to a depth of from 2 to 4 in, The actual depth of this penetration into the media depends, to a great extent, upon the rate of filtration, the thoroughness of the pretreatment and the effective size of the filter media. As the filtration process is continued additional suspended solids are trapped in this upper portion of the media. This results in the formation of a thin blanket of sludge, commonly called the Schmutzdecke. The Schmutzdecke is a bulky mass of material composed of floc particles and bacteria and contains millions of small capillaries. When the water is properly pretreated and some floc particles are continuously being carried over to the filter, a good Schmutzdecke is formed initially and filtration continues to improve during the filter cycle. Normally it can be expected that with good filter operation all particles larger than 45 microns will be removed, although in many cases effective removal of smaller size particles is obtained. It is apparent that the presence of floc particles in the water entering the filter contributes to more effective filtration. On the other hand, it is seldom desirable for the turbidity of the incoming water to be in excess of 10 ppm. If the amount of floc entering the filters is too large, the length of filter cycle will be substantially reduced. JPT P. 1220ˆ

Automatic Valveless Gravity Filters

This article discusses the automatic valveless gravity filter. The essential revolutionary aspect of this new filter is that it operates without butterfly valves, pilot mechanisms, rate controllers, gages, graphic panels, or air compressors. The article discusses operation of the valveless filter, its benefits and its costs.

Theory of Flow in Filter Media Douglas Feben

This article discusses the theory of flow in filter media. The media discussed include sand, anthracite (coal), and gravel as used in rapid sand gravity filters. The hydraulic and other physical characteristics of these media will be especially noted. Topics covered include: size distribution analysis; grain arrangement and porosity; flow problems; initial head loss; rate of head loss; backwash; and gravel. An appendix provides terminology, definitions, and formulas.

The Fundamentals of a Properly Designed and Properly Operating Filter

A FILTER system may be divided into three major parts, each of which jlJl is fundamental and essential to the successful operation of the unit as a whole: (1) the strainer or underdrain system, (2) the layer proper or medium for filtration, and (3) the reconditioning or wash system. A filter is intended to filter or clarify a definite volume of water or solution in a definite time at a definite unit area rate. This rate has been more or less accepted by water works engineers to be 2 gpm. per sq.ft. for ordinary gravity filters. Recently, however, there have been tendencies to increase this by 50 per cent with little change in design. A properly treated water is assumed for the successful operation of any filtration plant, leaving only the three elements for discussion, namely, strainer, filter body and wash system.

Attempted Chemical Isolation of the Virus of Poliomyelitis

The demonstration of the chemical nature of the tobacco mosaic virus by Vinson and Petre, its recent isolation as a crystalline protein by Stanley, and the experiments of Howitt indicating that the virus of poliomyelitis may be also a chemical entity, have led us to employ Stanley's procedure in an attempted isolation of the virus of poliomyelitis in the form of a crystalline chemical substance. This attempt was not successful but, because the results are of interest in that they afford added evidence for the theory of the chemical nature of viruses, they are briefly reported herewith. One hundred grams of spinal cords from monkeys infected with the M.V. strain and developing typical paralysis in from 7 to 11 days after intracerebral inoculation, were finely ground with sand and extracted overnight in the refrigerator with 500 cc. of a solution of disodium hydrogen phosphate at pH 8. The thoroughly mixed suspension was poured onto a fine wire screen and the retained precipitate again extracted for 24 hours with 500 cc. of the phosphate solution, poured through the screen and the combined milky suspensions filtered by gravity through coarse fluted filter paper. A monkey inoculated with 0.5 cc. of this filtrate developed typical paralysis in 9 days. The filtrate was weighed and sufficient solid ammonium sulfate added to bring the final concentration to 30% by weight. The precipitate of crude globulin was separated by gravity filtration and extracted twice with 500 cc. portions of phosphate solution at pH 8. The combined filtered extracts were again precipitated with ammonium sulfate at 30% concentration and again extracted with two 500 cc. portions of phosphate solution. The combined filtered extracts were now precipitated with ammonium sulfate at 20% concentration and the globulin dialyzed against distilled water until free from sulfate.

Proposed Classification of Indiana Public Water Supplies

In Indiana there are now 249 public water supplies, varying in size from the plant at Kirklin, where the water is pumped by windmill, to the up-to-date plant at Indianapolis. The deepest well from which an Indiana supply is drawn is at New Palestine where there is a 1000-foot flowing well. At this place the water is pumped by hydraulic ram. Most of the Indiana supplies are taken from tubular wells. In fact 154 of the 249 supplies come from such wells. As shown by table 1, the majority of the well supplies are drawn from tubular wells varying in depth from 100 to 300 feet. There are 72 of this depth. There are 44 water purification plants in the state, 19 of which practice sedimentation and filtration in gravity filters followed by chlorination. There are, in addition, five supplies which use pressure filters.

An Iron Range Water System: Chisholm

In order to deal as concretely as possible with the problems to be solved in connection with the production and sale of pure water, it may be of value to indicate briefly some of the difficulties encountered in the development of the plant at Chisholm. Chisholm is situated on the west shore of Longyear Lake and has a population of 9000 people. The water works are municipally owned and operated and are governed by a Board of Commissioners. When the author took charge of the water works and filtration plant as superintendent thirteen years ago, the condition of the plant was deplorable. The equipment consisted of a Wofthington 600-gallonper-minute fire pump, a wooden elevated tank with a capacity of 37,000 gallons, giving a maximum pressure of only 65 pounds at the pump station, the lowest elevation, a 1,000,000-gallon mechanical gravity filter of two concrete units, only one of which was equipped and in working condition at that time, and a 100-horse power, return tubular boiler that had not been cleaned since it was installed. The reason advanced for this last condition was that with only one boiler, the time limit on the filtered supply of 50,000 gallons was not sufficient to warrant a shut-down with the limited capacity of the wooden tank and the small suction well. Permission was obtained from the electric light company to connect to one of the boilers of its plant located about 200 feet north of the village boiler room. By running a 4-inch pipe line from the header of the water works boiler to theirs, paying a flat rate for the steam, it was possible to shut down for three days and make a thorough cleaning. Before doing this, however, a 24-hour test run was made on coal consumption, which showed 3 tons used for the 24-hour period. After cleaning and making some changes to the