Septic tank

“ Supplying water under pressure in the farmhouse demands a septic tank to get rid of the waste. A septic tank is a scientific receptacle to take the poison out of sewerage. It is a simple affair consisting of two underground compartments, made water-tight, with a sewer pipe to lead the waste water from the house into the first compartment and a drain to carry the denatured sewerage away from the second compartment. ”

“ The Septic Tank.—A septic tank is a horizontal, continuous-flow, one-story sedimentation tank through which sewage is allowed to flow slowly to permit suspended matter to settle to the bottom where it is retained until anaërobic decomposition is established, resulting in the changing of some of the suspended organic matter into liquid and gaseous substances, and a consequent reduction in the quantity of sludge to be disposed of. ”

“ There is no question as to the suitability of the affluent from a septic tank for irrigation purposes. Waste waters are sometimes injurious when they are loaded with antiseptics, but the septic tank will not work unless it has a chance for free fermentation in the absence of antiseptics, therefore, this objection against waste water does not hold with the out-flow from septic tanks. ”

“ No chemicals should be used in a septic tank; garbage, rags, newspaper, and other solids not readily soluble in water should be kept out of sewers and tanks. The plant should be inspected often, noting particularly if the siphon is operating satisfactorily. If scum forms in the settling chamber it should be removed, and the sludge should be bailed or pumped out yearly. Frequently tanks are not cleaned out for three or four years, resulting in large quantities of solid matter going through to the distribution system and clogging it. ”

“ The principal advantage of septic action in sewage treatment is the relatively small amount of sludge which must be cared for compared to that produced by a plain sedimentation tank. The sludge from a septic tank may be 25 to 30 per cent and in some cases 40 per cent less in weight, and 75 to 80 per cent less in volume than the sludge from a plain sedimentation tank. The most important results of septic action and the greatest septic activity occur in the deposited organic matter or sludge. ”

“ Operation of Imhoff tanks costs nothing as city allows a man to use two acres of land to compensate him for caring for tank. The septic tank is attended to only once a year, and probably does not cost more than $30 annually. ”

“ Labour increased by the greater deposit carried on to the land under septic liquid.
3. The removal of sludge and washing out the clean tank gives an hour’s work with very little smell ten yards to leeward of the site, but drawing off sludge from the septic tank is a very unpleasant operation, and, at all times, the vicinity of tank and carriers is malodorous for a radius of at least fifty yards from the septic tanks.
Loam on sand and gravel the best medium for aerobic organisms to work in. ”

“ Roofs are not essential to the successful operation of Imhoff tanks. They are sometimes used, however, as for septic tanks, to assist in controlling the dissemination of odors, to minimize the tendency of the sewage to freeze, and to aid in bacterial activity. In the construction of a roof, ventilation must be provided as well as ready access to the tank for inspection, cleaning, and repairs. ”

“ The sludge may be removed through drains in the bottom of the tank as described for sedimentation basins, or where such drains are not feasible the sludge and sewage are pumped out. For this purpose a pump may be installed permanently at the tank, or for small tanks portable pumps are sometimes used. Septic tanks should be cleaned as infrequently as possible without permitting the overflow of sludge into the effluent. The less frequent the cleaning the less the amount of sludge removed since digestion is continuous throughout the sludge. ”

“ A tight, underground septic tank with shallow distribution of the effluent in porous soil generally is the safest and least troublesome method of treating sewage upon the farm, while at the same time more or less of the irrigating and manurial value of the sewage may be realized. ”

“ A septic tank for treating 1,000,000 gallons of sewage per day will cost less than $10,000 and the cost of maintenance will be about $1.00 per 461,000,000 gallons treated.
Conclusion In selecting a method of sewage disposal, the conditions, surroundings, and requirements of the city should be carefully studied and analyzed, and judgment and discretion must be used. A matter of so much importance to the community should be placed in the hands of men qualified to make a proper solution of the problem. ”

“ When it is remembered that less than one-half of the organic matter in sewage is in suspension and that the best results in any sort of a tank succeed in depositing only one-half of those suspended solids, it can readily be seen that a tank, whether called septic or settling, cannot be a complete method of treatment. In reality, such a tank does little more than take out from the sewage the greasy material and a certain proportion of the suspended matter. ”

“ Makeshift methods, materials, or devices should be avoided or used sparingly. Do not place a vent pipe in the top of a cesspool or septic tank if near a dwelling. Siphon chamber and siphon may be omitted in those rare instances where it is feasible to discharge into salt water or into a large stream already badly polluted. Disposal of sewage in a running stream should be a last resort. Such practice endangers water supplies downstream, and unless the volume and velocity of flow are good nuisance may be created in the vicinity. ”

“ The dissemination of odors is especially marked when treating a stale or septic sewage. The treatment of a fresh sewage seldom results in the creation of offensive odors.
440
441Raw sewage cannot be treated successfully on a trickling filter. Coarse solid particles should be screened and settled out, in order that the distributing devices or the filter may not become clogged. The effluent from an Imhoff tank has proven to be a satisfactory influent for a trickling filter. A septic tank effluent may be so stale as to be detrimental to the biologic action in the filter. ”

“ Some firms supply advertising matter from which to work out the actual size and proportions of the different compartments and all connections. The making of a septic tank is simple when the principle is once understood. ”

“ The work in the septic tank is chiefly done by obligatory anaerobes.
[Pg 83] (c) Explanation of Process.—Although the processes taking place in septic tanks are at present but imperfectly understood, they may be said to be in the main due to anaerobic micro-organisms, i.e. due to such micro-organisms which carry on their life’s work in the absence of oxygen. They split up or peptonise the organic compounds in the absence of air, and the group of changes brought about by them has been termed “anaerobic fermentation” or “putrefaction.” ”

“ Whilst it would, therefore, appear to be correct to say, generally, that closed septic tanks afford no material advantages over open ones, so far as the purification of the sewage is concerned, they may become necessary in special cases, when the smells emanating from open ones might create nuisances in crowded neighbourhoods. ”

“ The modern farmer no longer puts up with such barbaric practice. Cess-pools have long been prohibited in cities, where immense sums of money are spent for the proper disposal of sewage. It is not possible to provide farms with these expensive plants, nor is it necessary. Through the use of an inexpensive septic tank all of the conveniences of the toilet and bath may be installed in the house and the danger from sewage removed. ”

“ No septic tank, tile field, seepage pit or system or structure designed to provide sewerage facilities to any realty improvement shall be covered from view until the same has been inspected by an authorized representative of the board of health and permission to cover the same has been given by the board or its authorized representative. ”

“ Intermittent downward filtration may be used where there is a considerable area of sandy soil, and also where a high degree of purification is necessary.
Chemical precipitation does not require a large area for its operation and used alone does not give a high degree of purification. Where land and material for beds is expensive, and partial purification is sufficient, this system may be used.
The septic tank requires a small area. The odors are not offensive and cannot be noticed 100 feet away. The effluent may be discharged into small streams and soon loses its identity. ”

“ If a drain has not been provided, sludge may be removed by bailing or by pumping with a sludge or bilge pump. It is not necessary to remove the entire liquid contents. Burial in a shallow pit or trench with at least 18 to 24 inches of earth cover at a point remote from water sources is the most practical method for disposing of these wastes.
A septic tank is intended to handle sewage only. Coffee grounds and ground garbage may be included if there is an ample supply of water for flushing and the tank is cleaned more frequently than would otherwise be done. ”

“ Unoxidized liquid sewage being in a condition to flow readily thru the earth, is more dangerous than fresh sewage because it is more likely to seep into wells.
Fig. 81-a. Septic tank.
153. Construction of the Septic Tank. The septic tank is composed of two chambers—one the liquefying chamber and the other the oxidizing chamber. Both are water-tight (Fig. 82) . The fresh sewage comes into the liquefying chamber thru a pipe placed near the top of the tank. ”

“ The splitting up of organic substances is frequently carried out in the presence of air. It has been maintained—probably with a view to justifying the necessity of a septic tank—that the preliminary process of splitting up is best carried out in the absence of oxygen, but sufficient proof does not appear to have been advanced in support of this statement, and in some cases at any rate it is evidently carried out quite satisfactorily in the presence of air. ”

“ Wastes from milk rooms, strong chemicals used in sterilizing equipment or in photographic work, and the wastes from filters or water softeners not only reduce bacterial action but also cause abnormally rapid accumulations of sludge and clogging of the tile lines.
PROTECTION AGAINST FREEZING
Septic-tank systems seldom freeze when in constant use. Warm water and the decomposition of the sewage usually maintain above-freezing temperatures. In cold regions there is trouble from freezing if various parts of the system are not covered adequately. ”

“ Grease, coffee grounds, and other similar materials that adhere to the sides of containers can be removed by scraping with a little sand prior to scalding.
Electrically operated units grind garbage and bones and discharge the material through the kitchen-sink drain. They will not handle tin cans, glass, and the like. They may be used on farms if the septic tank is larger than normal and if sufficient water is available for flushing the drain to prevent clogging.
Garbage to be fed to animals should be preserved as carefully as is human food. ”

“ It is desirable to build in the fireplace flue a damper which can be open when the fire is burning and can be shut when it is desired to keep heat from escaping from the room via the chimney. It is also a convenience to have a trap opening placed in the back of the fireplace on the floor so that ashes may be removed in this manner, eliminating the labor of carrying them from the fireplace.
Sewerage of Farm Homes.—All wastes from the farm home coming under the term of sewage should go direct to a septic tank. ”

“ The placing of baffles must be considered carefully as injudicious baffling may lessen the effectiveness of a tank by so concentrating the currents as to prevent sedimentation or the accumulation of sludge. Baffles should be built of concrete or brick, as wood or metal in contact with septic sewage deteriorates rapidly. In designing the sludge storage chambers it may be assumed that one-half of the organic matter and none of the mineral matter will be liquefied or gasified. The net storage volume allowed is about 2 to 3 cubic yards per million gallons of sewage treated. ”

“ Sewage generally contains the forms of bacteria necessary for this action but it has occasionally been found necessary to seed new tanks in order to start septic action.
The sludge from septic tanks is usually black, with a slight odor, though in some cases this odor may be highly offensive. The sludge will flow sluggishly. It can be pumped by centrifugal pumps and it will flow through pipes and channels. It has a moisture content of about 90 per cent and a specific gravity of about 1.03. It is dried with difficulty on open-air drying beds, and it is worthless as a fertilizer. ”

“ Most authorities now agree that before turning sewage upon land, a preliminary treatment is required to remove as much as possible of the suspended matter, and then reduce the latter by subsidence in liquefying or septic tanks, so that the quantity remaining in the effluent is so small and finely divided that it may be readily decomposed and oxidized by bacterial action without risk of clogging the surface or interstices of the land upon which it may discharge. ”