Effluent

“ For instance, on the Berlin sewage farms the degree of purification attained has averaged for a period of 20 years 97 per cent., and on the farm at Gennevilliers—one of the Paris sewage farms—the effluent is so sparkling, bright and clear that the inhabitants drink it in preference to other available water. ”

“ When the heavy rains of spring and fall occur, the effluent water from those slopes is dilute sewage, dilute human excrement, and, especially if the land has been recently ploughed, a large quantity of the surface-soil, and with it the freshly-applied human excreta, and the remaining noxious parts of the previously-applied batch of filth still present in the soil, must necessarily be, and is, washed down-hill and into the water-supply of the town. ”

“ Advantages and Disadvantages.—Some of the advantages of the process are: a clear, sparkling, and non-putrescible effluent is obtained; the degree of nitrification is controllable within certain limits; the character of the effluent can be varied to accord with the quantity and character of the diluting water 470available; more than 90 per cent of the bacteria can be removed; the cost of installation is relatively low; and the sludge has some commercial value. ”

“ If, to take the other extreme, the soil particles are increased until they are as large as hen’s eggs, then, if the rate of application is not greater than 200 gallons per square yard of surface per day, 9and if the method and rate of application are suitable to this large amount, the resulting effluent is sufficiently freed from its objectionable matter so that the liquid can be turned into any body of water without danger of odors or other nuisance. ”

“ The control of sewage treatment plant effluents so as to avoid the poisoning of fish life or the contamination of shell fish is likewise important. The study of plankton and macroscopic life in the treatment of sewage is an open field for research.
216. Variations in the Quality of Sewage.—The quality of sewage varies with the hour of the day and the season of the year. Some of the causes of these variations are: changes in the amount of diluting water due to the inflow of storm water or flushing of the streets or sewers ”

“ Effluents from maximum standard treatment processes, for instance, can be injected into underground strata as recharge water for aquifers—a process mentioned earlier as one alternative in the emerging package of water supply techniques—or may be spread over the surface of large areas of rural land [Pg 54a] where they serve as irrigation water and fertilizer combined, as well as soaking down into underlying aquifers. ”

“ Such water, when it penetrates only to shallow wells still retains a considerable proportion of its polluting organic matter in an unoxidized condition: but when it descends through one hundred feet or upwards of porous soil or rock, the exhausted filtration to which it has been subjected in passing downwards through so great a thickness of material, and the rapid oxidation of the dissolved organic matters in a porous and aerated medium, afford a considerable guarantee that all noxious constituents have been removed.”— (Rivers Pollution Commission, 1874.) ”

“ Absorption and Filtration.—The process of under-draining is a process of absorption and filtration, as distinguished from surface-flow and evaporation. The completeness with which the latter are prevented, and the former promoted, is the measure of the completeness of the improvement. If water lie on the surface of the ground until evaporated, or if it flow off over the surface, it will do harm; if it soak away through the soil, it will do good. ”

“ From a comparison of data in regard to the actual purification of polluted streams we may draw the following inference: Rivers not to be used for water-supplies, but to be inoffensive to communities , residing a few miles below, to remain fit for ordinary manufacturing purposes, and to sustain the life of fish, may receive the sewage from one thousand persons for at least every one hundred and fifty to two hundred cubic feet of minimum flow per minute, supposing that natural subsidence of the heavier matter takes place immediately below the town discharging the sewage. ”

“ DISPOSAL OF SEWAGE.
The vital thing which thus presents itself is the disposal of fecal matter and other refuse so that the wells, upon which most rural families depend for their drinking water, may remain pure. To this matter we will first turn our attention.
Every person who tills the soil is acquainted with the remarkable transforming power of the superficial layers of the earth upon manure and excrement. Out of these offensive wastes harmless substances are produced which are essential to the growth of vegetation. ”

“ Its fresh air, and the air which follows the descent of the water-table, carries oxygen to the organic and [pg 025] mineral parts of the soil, and hastens the rust and decay by which these are prepared for the uses of vegetation. The water itself supplies, by means of their power of absorption, the moisture which is needed by the particles of the soil; and, having performed its work, it goes down to the level of the water below, and, swelling the tide above the brink of the dam, sets the drains running, until it is all removed. ”

“ The practice of discharging sewage into fresh-water streams and lakes from which the water supplies of towns are taken has given rise to many of the most perplexing problems that sanitary engineers have had. to deal with. Accordingly, the pollution of streams by sewage and manufacturers' waste and the self-purification of streams thus polluted are among the earliest topics treated in this work, their legal as well as their scientific aspects being duly considered. ”

“ That in time of flood a large proportion, both of the suspended and dissolved filth, is conveyed down to the intakes, and in ordinary weather considerable portion of soluble organic matter makes its way to the pumping works, and is still present in the water distributed to the consumers. ”

“ In order to properly understand a reasonable method of treatment some consideration must be given to the composition of sewage. This is chiefly water with which is mixed a small amount of animal, vegetable, and mineral matter. Roughly speaking, the amount of mineral dirt is about one tablespoonful to a barrelful of water, and the combined amount of animal and vegetable matter amounts to another tablespoonful. ”

“ Thus, instead of a field of uniform condition, as to moisture and temperature and fertility, we have strips of wet, cold, and poor soil, alternating with dry, warm, and rich soil, establishing a sort of gridiron system, neither beautiful, convenient, nor profitable.
5. The manure washes off and is lost. The three or four feet of water which the clouds annually give us in rain and snow, must either go off by evaporation, or by filtration, or run off upon the surface. ”

“ Pipes run under the streets from the river to all the buildings of the town. There are big pumping stations on the river bank to pump the water out of the river through pipes to the houses. Millions of gallons of water are pumped each day into the homes, schools, mills and factories. For what is this water used?
7
Plants need more than good soil to make them grow. They will wither and die unless they have plenty of rain to keep the earth soft and moist. There are many places in the world where no trees, nor grass, nor plants of any kind can grow. ”

“ They retain a mass of filth in a decomposing condition deep in the ground, where it is but slightly affected by the bacteria and air of the soil. In seeping through the ground it may be strained, but there can be no assurance that the foul liquid, with little improvement in its condition, may not pass into the ground water and pollute wells and springs situated long distances away in the direction of underground flow. ”

“ Sewage is purified in passing through the soil by one or more of three processes: 1. By simple filtration or removal of the suspended matter; 2. By the precipitation and retention, in the soil, of ammonia and various organic substances previously in solution; and, 3. The oxidation of ammonia and of organic matter with the aid of living organisms. ”

“ We have seen that a sea of water, more than three feet deep over the whole face of the land, falls annually from the clouds, equal to 4,000 tons in weight to every acre. We would use enough of this water to dissolve the elements of fertility in the soil, and fit them for the food of plants. We would retain it all in our fields, long enough to take from it its stores of fertilizing substances, brought from reeking marshes and steaming cities on cloud-wings to our farms. ”

“ The teaching of it all is that the amount of water which can be utilized by the soil, not merely for the sake of the growth of the plants themselves, but to make up for the demands of evaporation, is very high. ”

“ Chapters three and four deal with the artificial and natural purification of water. These are the most important portions of the book to the engineer and taxpayer, taking up the question of water supply in its economic and commercial aspects, both as regards the general town supply and also in reference to individual household filtration. The physical forces and forms with which we have to reckon are next considered under Rain, Ice, Snow, and River and Stream Water. ”

“ The vast quantity of water which Nature pours upon every acre of soil annually, were it all to be removed by evaporation alone, would render the whole country barren; but Nature herself has kindly done the work of draining upon a large proportion of our land, so that only a healthful proportion of the water which falls on the earth, passes off at the surface by the influence of the sun. ”

“ Amongst causes of variation in the quantity of water needed will be its quality and temperature and rate of flow, the climate, the season, the soil, the subsoil, the artificial drainage, the slope, the aspect and the crop. In actual practice the amount of water varies from 300 gallons per acre in the hour to no less than 28,000 gallons. Where water is used, as in dry and hot countries, simply as water, less is generally needed than in cold, damp and northerly climates, where the higher temperature and the action of the water as manure are of more consequence. ”

“ When town sewage is pumped through a long rising main, it can often be spread on the land in its really crude state, and if the soil is clay ploughed up to receive it the sludge is most beneficial to its texture. ”

“ Instead of opening the spaces of the soil for the more free passage of water and air, as is done by descending water, that which ascends by evaporation at the surface brings up soluble matters, which it leaves at the point where it becomes a vapor, forming a crust that prevents the free entrance of air at those times when the soil is dry enough to afford it space for circulation. ”

“ The common methods of rendering water clear by filtration, or soft, by exposing it to the sun and air, &c. are so generally known, that it is unnecessary to spend time in explaining them. We shall only, in general, advise all to avoid waters which stagnate long in small lakes, ponds, or the like, as such waters often become putrid, by the corruption of animal and vegetable bodies with which they abound. ”

“ The water passes through the three feet of soil and loam, and afterward through an average of six feet of drained coarse sand or gravel in which it meets air, and afterward filters laterally through the saturated gravel to the wells. The water so obtained is invariably of good quality in every way, colorless, free from odor and from bacteria. ”

“ In towns the rain carries down with it blacks, dust, and organic matter in suspension in the air. Rivers are probably the most usual sources of supply for our drinking-waters, and where due care is exercised to prevent contamination from sewers, factories, etc., this variety of water is one of the least objectionable. ”

“ The occasional flow of pure water over the surface, as in our irrigated meadows, and its descent into the drains, where the drainage is perfect, washes out acid and other noxious substances naturally generated in the soil, and thus purifies and sweetens it. ”

“ Important safety measure.—The farmer can do no other one thing so vital to his own and the public health as to make sure of the continued purity of the farm water supply. Investigations indicate that about three out of four shallow wells are polluted badly.
Wells and springs are fed by ground water, which is merely natural drainage. Drainage water usually moves with the slope of the land. It always dissolves part of the mineral, vegetable, and animal matter of the ground over or through which it moves. ”

“ We have seen, that evaporation proceeds much more rapidly from a surface of water, as a pond or river, than from a land surface, unless it be fully saturated, and that evaporation from the water exceeds the whole amount of rain, about as much as evaporation from the land falls short of the amount of rain. ”

“ The method to be employed in ascertaining the exact position of the float from time to time is a matter which requires careful consideration, and is dependent upon the degree of accuracy required according to the importance of the scheme and the situation of neighbouring towns, frequented shores, oyster beds, and other circumstances likely to be injuriously affected by any possible or probable pollution by sewage. ”

“ A stream has a natural capacity for hastening the decay of organic wastes, which is determined by such things as the volume of its flow, the pollution already in it, its velocity and depth, and its temperature. When that capacity is exceeded, as we have noted, too much of the stream's oxygen is used up by the process of decay and the stream, which is an intricately complex work of living things, begins to die. ”

“ Every sewer which we construct pollutes some stream, every stream flows into some river, and every river sends up a pestilential exhalation, which decimates our population, by zymotic diseases, and sows the seed of future maladies in thousands who are unconscious of its immediate effects. ”