The wastewater disposal system and all structures used for these purposes are part of engineering devices, the purpose of which is to improve the city, residential or industrial complex. If you describe a liquid of this type, then it can be characterized as follows. This is water that was used for any purpose, after which its properties were significantly impaired, and for further use it became unsuitable.
General description of the concept
Most often, those fluid flows in which the initial properties have been changed become sewage. Most often, such changes occur due to the fact that various impurities enter the composition. In addition, this class also includes those waters that are removed from cities and settlements with the help of sewers or run off from any industrial enterprise.
If we consider the type and composition of wastewater, then they can be divided into three categories: domestic, industrial, atmospheric.
Description of the household type of liquid
Wastewater - these are streams that have been contaminated as a result of human activities and activities. Most often in the water of this category there is a high content of mineral and organic impurities. If we talk about mineral mixtures, it is most often ammonium, chloride, etc. Of the organic substances, the presence of nitrogen-free and nitrogen-containing components is most often observed. Most often, such substances are presented in the form of proteins, fats or carbohydrates. Less often, but still there are impurities in the form of microorganisms or viruses and bacteria that carry a variety of diseases.
Types of Production Wastes
If we talk about industrial category wastewater, then the nature of the industrial enterprise that creates these wastewaters plays an important role. Depending on this, they can be divided into several groups.
The first group is a liquid, in the composition of which impurities of inorganic origin are observed. These compounds carry a variety of special toxic substances. It can be drains of galvanic companies, construction enterprises, factories for the production of mineral substances and others. Wastes from these enterprises alter the pH structure of water. Wastewater with this structure contains heavy metal salts. These substances are considered toxic to potential residents of the reservoir where the waste water will descend.
There is a group of waters that contains inorganic compounds that are considered non-toxic. Wastes of such waters are created by such plants as cement, ore dressing and others. Waste from this industry is not considered too hazardous for those bodies of water where water flows.
Another category is industrial wastewater containing organic non-toxic elements. Such waste is characterized by the food industry. This may be factories for the production of dairy, meat, microbiological and other products. When this kind of liquid enters a reservoir, such a parameter as oxidizability significantly increases in it.
The last group, which is considered the most dangerous, is a liquid containing organic elements with special toxic substances. This type of waste is characterized, for example, by the oil refining industry. Also, it is worth adding those factories that are engaged in the production of sugar or canned food.
Consumption rates
Wastewater treatment methods are also of various types. The presence of several options is due to the fact that for each industry it is necessary to have its own way. In order to develop a suitable purification method, a variety of scientific methods are used. Another important condition is that the company should consume exactly as much water as is necessary for its functioning, so as not to create excess contaminated liquid.
Determination of water consumption
The first thing that needs to be done in order to choose a method of wastewater treatment is to determine the same liquid consumption rate for a plant, factory, etc. There are two ways to do this: scientific and sound calculations or best practices. There is also the concept of aggregated water consumption by an enterprise.
However, the definition of the norm is suitable only for industry, and what to do with precipitation, which wash away all the dirt from the street, and then carry it through the sewers and drain it in a certain place? To influence these factors, it is necessary to periodically dry clean the street. However, it’s worth mentioning right away that this will not solve the problem 100%. In any case, polluted water from the roads, which carries particles of organic matter, biogens, oil products, and metal salts, will fall into the atmospheric groundwater.
Description of urban waters
In practice, the concept of urban wastewater is often used. This category most often combines household and industrial flows. It is worth paying attention to the fact that it is possible to divert industrial, domestic and atmospheric waters separately or together. The most popular wastewater systems are alloy and split structures. The advantage of using the first category of the system is that it will not be difficult for it to remove any type of polluted water from the city through sewage pipes. Most often, such networks lead to treatment plants, facilities. As for separate systems, there are several pipeline networks here, each of which carries a different type of fluid. For example, rainwater and unpolluted water can be transported through the first channel, and water with various harmful impurities through the second canal.
What criteria influence the choice of a challenge system?
When choosing a network for treatment, it is necessary to take into account the following parameters: substances of wastewater contained inside the composition of the liquid, the technical, sanitary, and economic components of the enterprise are evaluated. It is also necessary to provide for the intensification of the activity of the selected object.
In order not to make a mistake with the selection of the tap system, it is also necessary to determine such a value as the maximum permissible discharge (MPD). This term refers to the mass of elements contained in water, which can be allowed to lead through the selected system and in the selected mode per unit of time. It is important to ensure a standard for water quality at a checkpoint.
Most often, pollution of water bodies, lakes , etc. occurs due to the fact that sewage from industrial enterprises flows down here. The discharge of contaminated liquid can cause a change in some physical properties, for example, temperature, smell, etc. In addition, such places almost immediately become unsuitable for water supply to the population.
Release monitoring
Of course, there are certain conditions for the release of dirty water into a reservoir. The main criterion is the national economic importance, as well as the nature of use. After the release of contaminated fluid, the quality of the water in the body of water is significantly impaired. Therefore, release is allowed only if it does not affect life in the pond too much, and also if it does not harm fish farming in the future in this place. In addition, the possibility of further use of this reservoir as a source of water for supplying the population should remain.
The fulfillment of all requirements of this kind is monitored by the sanitary-epidemiological service. Another important point is that the rules for the conservation of water bodies are not uniform. It all depends on what purpose the storage will be used in the future. Thus, there is the first group, which includes bodies of water that should remain suitable for centralized and decentralized supply of water to the population. The second type is the preservation of the reservoir for swimming, recreation and sports. Sanitary stations relate all water bodies to one of these two groups.
Self-purification process
Today it is known that such a process as self-purification of water in a reservoir is possible. By this is understood the occurrence of hydrodynamic, chemical, microbiological and hydrobiological reactions, as a result of which the liquid returns to its original state.
However, in order to achieve this result, certain restrictions on the discharge of wastewater must be observed. Firstly, the release of contaminated water should not interfere with the functioning of other facilities. Secondly, the effluent should not contain such substances or impurities that may clog or even deposit inside the pipes. In the event that industrial-type waste water does not meet these requirements, then it is preliminarily treated at the station, and only then it is discharged into the reservoir.
Mechanical cleaning process
Mechanical wastewater treatment is used if there are insoluble mineral or organic matter in the water. Most often, this process is a preliminary way to cleanse the liquid. The use of this method is resorted to before proceeding with the main ones. If you follow this procedure in accordance with all the rules, you can achieve the fact that the amount of suspended mechanical substances is reduced to 92%, and organic - to 23%.
Mechanical water treatment systems include devices such as filters, screens. Suppose a common thing is a sand trap, which is designed to isolate large mineral impurities from the liquid, in this case sand. It uses equipment such as an averager. This device is able to regulate the composition and flow rate of wastewater.
Such objects as initial sedimentation tanks are widespread, where heavy mechanical impurities that settle to the bottom of the sedimentation tank can be separated from the water using gravity. In order to purify the water coming from oil refineries, special oil traps are used. This is a special rectangular-type tank where oil products are separated from water. Here, the principle of the difference in density of these compositions is used.
Biological wastewater treatment
It is worth noting here that the biological method of purification requires additional costs, but it is used quite widely. During this procedure, all organic compounds found in water begin to oxidize. To perform this operation, special microorganisms are used.
Biological purification of wastewater can be carried out both in natural conditions, that is, on irrigation, filtration, etc. fields, and in special systems, for example, in a biofilter. This creates a favorable environment for the development of special microorganisms that significantly speed up the cleaning process. However, the creation of such conditions will require additional financial costs.
Chemical and physico-chemical methods
These methods of liquid purification have gained the greatest popularity and significance when working with industrial wastewater. You can use these methods both separately from the rest, and in conjunction with mechanical or biological. For example, there is a neutralization procedure, which is used in cases where it is necessary to purify industrial wastewater from acids contained in it. Most often, this method is used to avoid the development of corrosion inside metal drainage systems. It also helps to avoid disruption of biochemical processes taking place in a pond.
Precipitation
Sewage sludge is a suspension that is released from contaminated liquid by mechanical, biological, chemical or physico-chemical treatment.
There are several types of precipitation that remain after treatment. Belonging to a particular species depends on which equipment or method was used to improve the quality of the liquid. The coarse impurities remaining on the gratings are trash. The heavy impurities that remain on the sand traps are sand. Floating impurities remaining in sedimentation tanks are fatty substances. There are also sediments dried in silt sites. There are quite a lot of such types. The discharge of sewage into water bodies should be carried out only after the removal of such sediments.