Regulation of air supply in aerotechs at treatment facilities is an opportunity to effectively save electrical energy.

The object of control is the technological process of cleaning Wastewater using bacteria contained in activated sludge. Waste water is supplied to the aerotec sections, where activated sludge with bacteria is located. To activate bacteria and mix the sludge mixture in the section, air is supplied from turbo blowers. Control over the content of dissolved oxygen in aeration tanks is carried out by laboratory analysis, on the basis of which the air supply to aeration tanks is regulated by the system stop valves in manual mode.

This system is complex in terms of requirements for control algorithms due to the influence of a large number of factors:

The amount of oxygen supplied;

Ambiguities in the behavior of the biological system of activated sludge;

Ambient temperatures;

Degrees of concentration of pollutants in wastewater and other structures.

In general, the description of such systems does not fit into the traditional models of the theory of automatic control due to factors, the account of the influence of which is almost impossible to predict. For example, air density and air compressibility depend significantly on temperature, and therefore the air supply control loops must be reconfigured depending on environmental conditions.

Continuous monitoring of the concentration of dissolved oxygen in aerotechs is the key to high-quality cleaning and reducing power consumption on blowers. Available equipment at the enterprise (turboblowers TV-175) and method laboratory measurement concentrations of dissolved oxygen are obsolete and create the problem of high instability and excessive consumption of electrical energy

To date, the most advanced is an automatic regulator in combination with an air blower for the biological treatment of wastewater and a continuous oxygen measurement system. The performance of such installations is controlled by means of a diffuser guide vane with adjustable blades or an inlet guide vane with a preliminary swirl of the flow, and a combination of the two named systems is also possible. The continuous oxygen measurement system, which includes a primary transducer with a sensor immersed in water, as well as a secondary transducer using modern microprocessor signal processing technology, generates a signal in accordance with the concentration of dissolved oxygen that enters the air injection unit and then automatically changes the amount of air entering the aerotheca.

In accordance with the methodology for calculating the specific air consumption for the volume of incoming effluents, the amount of air supplied to the aerotheca was determined - 18030 m 3 / h.

Let's calculate the specific air consumption for the volume of incoming wastewater 28000 m 3 /day.

Specific air consumption

where: q 0 - specific consumption of oxygen in the air, per 1 mg removed BOD-total.

For complete purification of BOD20, 1.1 is taken.

K 1 - coefficient taking into account the type of aerotheca, we take 2.0 for the first stage, 1.95 - for the second stage;

K 2 - coefficient depending on the depth of immersion of the aerator:

2.08 = first stage;

2.92 - second stage

K t - coefficient taking into account the temperature of wastewater

K t \u003d 1 + 0.02 (T w -20), where: T w is the average water temperature for summer period;

K 3 - water quality coefficient, taken for urban wastewater 0.85.

Са – solubility of air oxygen in water, mg/l;

Tables of air oxygen dissolution in Lex water - BOD 20 of treated waste water, taking into account the decrease in BOD during primary settling. Data on BOD 20 were obtained from information on the qualitative composition of standard treated wastewater, by the testing laboratory of KZhUP "Unicom": BOD pol.post. 53.9 mg/l, BODpol.pur. 5.1 mg/l.

K t \u003d 1 + 0.02 (22.1-20) \u003d 1.042

С а = 1+ · С t, where: Н – immersion depth of aerators, m;

C t is the solubility of oxygen in water. (We accept according to table 27, Vasilenko. Water disposal. Course design).

Сal \u003d 1 + 8.83 \u003d 10.12

qairl = 1.1 = 18.75

qairll = 1.1 = 12.16

The daily air consumption by specific consumption, we determine by the formula:

Q = q air + q average day , m 3 / day,

where: q air - specific air consumption;

q cf.day - the average daily consumption of wastewater entering the treatment, m 3 / day (28000 m 3 / day).

Q I \u003d 18.75 14000 \u003d 262500 m 3 / day

Q II \u003d 12.16 14000 \u003d 170240 m 3 / day

Determine the hourly air flow

Q 4 I \u003d \u003d 10938 m 3 / h

Q 4 II \u003d \u003d 7093 m 3 / h

Total consumption equals

O p \u003d Q 4 I + Q 4 II \u003d 10938 + 7093 \u003d 18031 m 3 / h

Thus, the required amount of air supplied to the aeration tanks will be 18031 m 3 /h.

The following injection equipment is currently installed:

1. turboblower TV-175 with a capacity of 10,000 m 3 / h - 2 pcs.

2. turboblower TV-80 with a capacity of 6000 m 3 / h - 2 pcs.

3. turboblower TV-80 with a capacity of 4000 m 3 / h - 2 pcs.

To obtain the calculated specific air consumption, it is necessary to turn on at least two blowers: one TV-175 blower with an installed electric power of 250 kW and one TV-80 blower with an installed electric power of 160 kW at rated load.

Taking into account the physical and moral deterioration of the injection equipment operating since 1983, it is proposed to install a single-stage centrifugal compressor with a multi-blade open turbine-type impeller in combination with an air supply control system using linear servomotors with the requirements and indicators listed below technological equipment:

Initial data

To ensure air supply in the amount of 12000 m 3 /h, it is necessary to turn on two TV-80 blowers with a total power of 320 kW.

Installed electrical power of the operating technological equipment - 320 kW - at 12000 m 3 / h

The installed electric power of the new technological equipment is 315 kW at 16,000 m 3 /h, and at 12,000 m 3 /h - 249 kW.

We determine the annual savings in electrical energy when installing new equipment:

E e \u003d (320 - 249) 0.75 24 365 10 -3 \u003d 466 thousand kWh or 130.5 tce

The cost of saved fuel at the price of 1 ton of fuel equivalent = $210 (according to the Department of Energy Efficiency):

C \u003d 130.5 210 \u003d $ 27405 \u003d 232942.5 thousand rubles.

Payback period of the event:

where K - investment in the event, 2000000 thousand rubles;

C - savings from the implementation of the measure, thousand rubles;

T = == 8.6 years.

Note: Clarification of all amounts of capital investments for the implementation of the proposed measures and payback periods is carried out after the development of design estimates

Yu.V. Gornev ( CEO LLC "Vistaros")

It is well-known fact that 60 to 75 percent of the energy consumption of sewer treatment facilities(KOS) cities and large industrial enterprises account for the air supply to the aeration system. This article discusses the issues of possible savings in energy consumption in the aeration system through the use of energy-efficient elements of the system.

Reserves for saving energy consumption in the WWTP aeration system are huge, they can be 70% or more. Consider the main elements of this system, which significantly affect energy consumption. If we omit such issues as the need to maintain air supply pipelines, etc. in good working order, then these include:

1. Availability of primary settling tanks at WWTP, which allow to reduce Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) of effluents at the inlet of aerotanks. As a rule, primary settling tanks are already present at most large WWTPs.
2. Implementation of the nitrification-denitrification process, which allows increasing the amount of dissolved oxygen in the return activated sludge. This process is increasingly being introduced during the construction and reconstruction of the WWTP.
3. Timely maintenance and replacement of aerators.
4. The use of controlled blowers of optimal power, implementation unified system controls for all blowers.
5. The use of specialized controlled valves in the air distribution system for aerotanks.
6. Introduction of a control system for each valve and all valves based on data from dissolved oxygen sensors installed in aeration pools.
7. Application of air flow meters to stabilize the air distribution process and optimize the set point for the minimum level of dissolved oxygen for the valve control system.
8. Introduction to the control system of additional feedback on the ammonium sensor at the outlet of the aerotanks (used in certain cases).

The first two points (primary settling tanks and the introduction of nitrification-denitrification) relate to a greater extent to the issues of capital construction at the WWTP and are not considered in detail in this article. Below we consider the issues of introducing modern high-tech modules and systems that make it possible to achieve a significant reduction in electricity consumption at the WWTP. These modules and systems can be implemented both in parallel with the solution of the first two points, and independently of them.

Blowers are the main consumer of electricity in the aeration air supply system. Them right choice is the basis of energy saving. Without this, all other elements of the system will not give desired effect. However, we will not start with blowers, but will follow the order in which it is necessary to select all modules.

Aerators

One of the main characteristics of aerators is the specific efficiency of oxygen dissolution, measured as a percentage per meter of aerator immersion depth. For modern new aerators, this value is 6% and even 9%, for old aerators it can be 2% or lower. The design of aerators and the materials used determine their service life without loss of efficiency, which for modern systems ranges from 6 to 10 years or more. The choice of design, number and location of aerators is carried out according to such parameters as BOD and COD of effluents at the inlet to the aeration system, by the volume of incoming effluents per unit of time and by the design of aeration tanks. If we are dealing with a WWTP reconstruction with very old aerators in poor condition, then, in some cases, only the replacement of aerators and the installation of blowers matching the new aerators will reduce energy consumption by 60-70%!

Blowers

As mentioned above, blowers are the main element that saves energy consumption. All other elements reduce the need for air supply or reduce the resistance to air flow. But if at the same time you leave the old uncontrolled blower with low efficiency, there will be no savings. If the aeration station uses several uncontrolled blowers, then, theoretically, by optimizing other elements of the system and achieving a reduction in the need for air supply, it is possible to decommission and transfer to the reserve several blowers from among the previously used ones and, thus, achieve a reduction in energy consumption. You can also try to compensate for daily fluctuations in the aeration system's oxygen demand by simply turning the standby blower on or off.

However, it is much more efficient to use a controlled blower, more precisely, a block of several controlled compressors. This ensures that the air supply is exactly according to the demand, which varies significantly during the day, and also varies depending on the season and other factors. The usual constant supply of air by uncontrolled blowers is always excessive and leads to excessive consumption of electricity, and in some cases to a violation of technological process nitrification-denitrification due to excess oxygen in the aerotanks. At the same time, the lack of air supply leads to the excess of pollutants in the effluent at the WWTP outlet of the maximum permissible concentrations (MPC), which is unacceptable.

Precise control of the air supply with constant monitoring of the level of dissolved oxygen in the aerotanks (and in some cases, with constant automatic monitoring of the concentration of ammonium and other pollutants in the effluent at the outlet of the aerotanks) provides an optimal level of energy consumption while ensuring that the treated effluents comply with existing regulations.

The need for several blowers in the block (for example, two large and two small ones) is due to the fact that the control range of the air compressor is very limited. It is in the range, at best, from 35% to 100% of power, more often from 45% to 100%. Therefore, one controlled blower is not always able to provide optimal air supply, taking into account daily and seasonal changes in demand. Today, the most famous are three types of blowers: rotary, screw and turbo.

The choice of the right type of blower is made mainly on the basis of the following parameters:

- the maximum and nominal air supply demand - depends on the parameters of the installed aerators, which, in turn, are selected based on their efficiency and on the need of the entire aeration system in dissolved oxygen, as described above;

- the required maximum overpressure at the outlet of the blower - is determined by the maximum possible depth of the aeration basin effluents, more precisely by the depth of the aerators, as well as pressure losses during the passage of air through the pipeline and through all elements of the system, such as valves and so on.

As a rule, each controlled blower has its own control unit; it is also important to have a common control unit for all blowers, which ensures their optimal operation. In most cases, the control is carried out by the pressure at the outlet of the blower unit.

Controlled air valves

If the system has one blower (or blower unit) supplying air to only one aeration basin, then it is possible to work without air valves. But, as a rule, at aeration stations, a block of blowers supplies air for several aeration tanks. In this case, you need air valves at the entrance to each aeration tank to control the distribution of the air flow. Additionally, valves can be used on pipes that distribute air supply to different zones of one aerotank. Previously, manually operated butterfly valves were used for these purposes. However, remote control valves must be used to effectively control the aeration system.

To important characteristics controlled valves include:

1. The linearity of the control characteristic, i.e. the degree to which a change in the position of the valve actuator (actuator) corresponds to a change in air flow through the valve over the entire control range.
2. Error and repeatability of working out by the valve actuator of a given set point for the air flow. It is determined by the quality of the valve (linearity of the control characteristic), the actuator and the actuator control system.
3. Pressure drop across the valve in the operating opening range.

The pressure drop across butterfly valves at partial opening can be very significant and reach 160-190 mbar, which leads to large additional energy costs.

If the system uses even the highest quality, but universal valves (designed for both water and air), then the pressure drop across such valves in the operating opening range (40-70%) is usually 60-90 mbar. Easy replacement such a valve to a specialized air valve VACOMASS elliptic will lead to additional savings of at least 10% of electricity! This is due to the fact that the pressure drop on the VACOMASS elliptic does not exceed 10-12 mbar over the entire operating range. An even greater effect can be achieved when using VACOMASS jet valves for which the pressure drop in the operating range does not exceed 5-6 mbar.

Piloted Specialty Air Valves

VACOMASSfirmsBinder GmbH, Germany.

Often, at the installation site of a controlled valve, a narrowing of the pipeline is made to use the valve of the optimal size. Since the contraction and expansion is carried out in the form of a Venturi tube, this does not lead to any significant additional pressure drop in the area with the valve. At the same time, the smaller diameter valve operates in the optimal opening range, which provides linear control and minimizes the pressure drop across the valve itself.

Dissolved oxygen sensors and valve control system

BA1 - aeration basin 1; BA2 - aeration basin 2;

PLC - program logic controller;

BV - block of blowers;

F - air flow meter; Р – pressure sensor;

O2 - Dissolved Oxygen Sensor

M - drive (actuator) of the air valve

CPS - gate valve (valve) control system

SUV - blower control system

The figure shows the most common air supply process control scheme for several aeration basins. The quality of wastewater treatment in aeration tanks is determined by the presence the right amount dissolved oxygen. Therefore, the concentration of dissolved oxygen [mg/liter] is usually taken as the main controlled value. One or more dissolved oxygen sensors are installed in each aerotank. The control system sets the setpoint (set average value) of the oxygen concentration, so that the minimum actual oxygen concentration is guaranteed to provide a low concentration harmful substances(for example, ammonium) in wastewater at the outlet of the aeration system - within the MPC. If the incoming volume of wastewater to a particular aerotank decreases (or its BOD and COD decrease), then the demand for oxygen also decreases. Accordingly, the amount of dissolved oxygen in the aerotank becomes higher than the set value and, upon a signal from the oxygen sensor, the valve control system (CLS) reduces the opening of the corresponding air valve, which leads to a decrease in air supply to the aerotank. At the same time, this leads to an increase in pressure P at the outlet of the blower unit. The signal from the pressure sensor is sent to the blower control system (SUV), which reduces the air supply. As a result, the energy consumption of blowers is reduced.

It should be noted that a well-thought-out optimal setting of a given minimum concentration of dissolved oxygen in the CPS is very important for solving the problem of energy saving.

Equally important is the correct and reasonable setting set pressure P at the outlet of the blower unit.

Air flow meters

The main task of air flow meters in the aeration system in terms of energy saving is the stabilization of the air supply process, which makes it possible to lower the dissolved oxygen concentration setpoint for the control system.

The air supply system from the blower unit to several aerotanks is quite complex in terms of control. In it, as in any pneumatic system, there is mutual influence and delay in the processing of control actions and signals from feedback sensors. Therefore, the actual concentration of dissolved oxygen constantly fluctuates around the setpoint (setpoint). The presence of air flow meters and a common control system for all valves can significantly reduce the response time of the system and reduce fluctuations. Which, in turn, allows you to lower the setting, without fear of exceeding the MPC of ammonium and other harmful substances in the effluent at the WWTP outlet. From the experience of Binder GmbH, the introduction of data from flowmeters into the control system allows you to get additional energy savings of about 10%.

In addition, if the WWTP is undergoing a phased aeration system refurbishment process, in which aerators, valves, a valve control system and air flow meters are installed first, while maintaining the old blower, and then proceeding to the selection of new controllable blowers, then data on the actual air flow will help to produce optimal choice blowers, which leads to significant savings in their purchase and operation.

A distinctive feature of the Binder GmbH VACOMASS flowmeters is their ability to work in short straight sections "before" and "after" due to special technological solutions, as well as to be installed directly in the VACOMASS valve block.

ammonium sensor

The ammonium concentration sensor can be installed in the channel at the outlet of wastewater from the aerotank system to control the quality of treatment. In addition, incorporating the readings from the ammonium sensor into the control system further stabilizes the system and provides additional energy savings by further lowering the dissolved oxygen setpoint.

An example of organizing a control system for air supply to aerotanks with feedback based on a dissolved oxygen sensor (DO) and ammonium (NH4).

Aeration is the process of forced saturation of water with air, or oxygen. To ensure this process, a low-pressure compressor or aeration blowers are used, and its purpose is:

• Oxidation of iron compounds (iron removal of water) and manganese, which consists in the oxidation of iron and manganese compounds with oxygen. As a result, these compounds precipitate in the form of flakes, which is retained by a special backfill sediment filter.
• Removal of dissolved gases, including toxic ones, such as hydrogen sulfide and methane.
• Water disinfection as a result of destruction organic matter contained in it, under the influence of oxygen.
• Removal of biocontaminants: when water is saturated with oxygen, the number of beneficial aerobic bacteria grows, which process biomass into carbon dioxide and methane - biogas. Now the biotreatment process is used at all major wastewater treatment plants in Russia. The resulting biogas can also be pumped out of the tanks of the sewage treatment plant using blowers for further use, for example, for the production of electricity or fuel for transport. However, this practice is not widespread in Russia yet.
• Maintaining the Pond Ecosystem by saturating the water with oxygen. In stagnant water, under the action of sunlight, anaerobic bacteria begin to actively multiply. As a result, the reservoir turns into a muddy swamp with an unpleasant odor. Also, due to insufficient concentration of oxygen in the water, a pestilence of fish and other beneficial organisms occurs.

There are 2 main types of liquid oxygen saturation: pressure and non-pressure.

Pressure aeration

A blower or compressor delivers compressed air through a pipe that extends to about half the height of the aeration tower, or oxidizer tank. The flow of air bubbles oxidizes foreign substances dissolved in water, and also removes gases dissolved in water (hydrogen sulfide, methane, carbon dioxide, and others). These gases are removed through an air valve located at the top of the column.

From the column, water enters the backfill filter, where impurities oxidized by air are neutralized.

As a result, the unpleasant taste and smell of water disappears.

Rice. 1. Pressure aeration system (aeration column).

Advantages:

• Compact installation size.
• There is no need for a pumping unit to supply water to the consumer.
• Efficient removal of gases dissolved in water.

Non-pressure, or open, aeration

For non-pressure aeration, an oxidizing tank with a jet breaking system is used. The water level in the tank is controlled by a level sensor that sends a signal to solenoid valve. This valve closes, or opens, the pipe through which water is supplied to the container.

Air is supplied to the water column by a low-pressure compressor or a blower through a pipe ending in a fine-bubble aerator. Passing through it, the air forms many small bubbles that saturate the water with oxygen, oxidize impurities of iron and manganese.

Oxides, as in the previous case, are removed in the filter into which water is supplied pumping unit from the oxidation tank.

Rice. 2. Non-pressure aeration system

Advantages:

• Due to the long interaction of water with the air flow in the tank, more contaminants are oxidized.
• Allows you to create a supply of water in case it is turned off, which is especially important for private houses, where interruptions in water supply are possible.
• Suitable for houses with low water pressure.

The main disadvantage is that the process takes a long time.

Blowers for water aeration: requirements and price

The blower must have a combination of the following properties for aeration to be effective:

• provide high performance with low pressure drop;
• do not pollute the supplied air with oil vapor;
• long time work non-stop;
• the aeration blower should consume as little energy as possible, otherwise the cost of the process will be very high.

All these requirements are best met by aeration vortex blowers - machines of dynamic action, which are able to provide a clean air flow without pressure pulsations with a capacity of up to 2200 m3/h and an overpressure of up to 1040 mbar. They may also be called vortex fans, or vortex fans. vacuum pumps due to its versatility.

If large volumes need to be aerated, such as industrial fish farming ponds or large treatment plants, larger blowers may be needed. This niche is occupied by rotary blowers for aeration of the Roots type, which create an air flow of up to 9771 m 3 / h.

For small volume systems, such as aeration columns, a dry rotary vane compressor for water aeration, such as Becker or VARP Rigel, can be used instead of a swirl blower. Their performance is limited to 500 m 3 /h, but the overpressure is up to 2200 mbar.

The blower for water aeration is selected based on the requirements of the technological process, but if the price is critical, then first of all pay attention to the VARP Alpha vortex blowers. In general, vortex blowers have the most affordable price, followed by rotary vane blowers, and the most expensive, but also the most powerful, are rotary blowers.

Vortex blowers for aeration

Vortex blowers, for which aeration is one of the main applications, are represented by a wide range of sizes and have a large price range, which allows you to choose the most efficient machine just for your task.

Blowers for water aeration, which can be bought in our catalog, are represented by the following brands.

VARP

This is a new brand on the Russian market, which is represented by a wide range of swirl blowers that meet all modern requirements for machines of this type. The main advantages of VARP blowers:

• affordable price with high quality workmanship and assembly;
• durability, due to the use of original SKF and NSK bearings, a resource of more than 20 thousand hours of continuous operation;
• high reliability is ensured by the use of high-strength aluminum alloy and simple design;
• excellent performance thanks to modern methods design.

If you need a standard blower for aerating water, such as a pond, then take a look at the Alpha series. They can deliver high airflow with low pressure drop. Their capacity is up to 2050 m3/h and overpressure up to 670 mbar.

For deep ponds or tanks small area better fit the Beta series, which provides a high pressure drop up to 1040 mbar with a small capacity up to 170 m 3 / h.

For industrial applications such as sewage treatment plants, or large fish farms, you need a powerful blower to aerate the water of the Gamma series. It provides high air flow up to 750 m 3 /h at overpressure up to 1020 mbar.

Busch Samos

High-performance German blowers, which are often used to aerate water in large reservoirs and wastewater treatment plants. Their productivity is up to 2640 m 3 /h, and the pressure drop in the compressor mode is up to 500 mbar.

Advantages of Busch blowers:

• Energy-saving motors are used, which reduces power consumption. This is especially true for industrial wastewater treatment plants, since aeration requires high energy costs.
• The quality of German equipment at a low cost, as Busch has set special prices for Russia.
• They can work for a long time without stopping and do not need maintenance.
• Easy mounting in horizontal or vertical position.

SEKO BL

SEKO economy class blowers meet modern requirements for swirl blowers. Affordable price combined with reliability and high quality devices. They can also aerate reservoirs, providing a large air flow with a capacity of up to 1110 m 3 / h at a pressure drop of up to 650 mbar, and have a number of advantages:

• Equipped with two-pole electric motors, which allow a long time to work without interruption.
• Wide the lineup allows you to choose a blower and aerators with optimal parameters and not overpay for more powerful blowers if they are not needed.
• Minimum noise and vibration due to built-in silencers and lack of imbalance.

FPZ SCL

Italian high-pressure blowers FPZ SCL create a maximum pressure drop of 650 mbar and are available in models with a capacity of up to 1022 m 3 /h and a power of up to 22 kW. This blower is great for aerating small fish ponds as well as large wastewater treatment plants.

Main advantages:

• Only original SKF and NSK bearings are used, which provide at least 25,000 hours of continuous operation.
• Low energy consumption due to the use of high efficiency Italian Bonora Motori electric motors.
• Even greater energy savings are provided by frequency control up to 70 Hz, which allows you to fine-tune the performance in accordance with the specified parameters.
• Long-term operation is possible thanks to the built-in motor protection against overheating.

Becker SV

Another brand of vortex blowers that are produced and assembled in Germany. They create a differential pressure of up to 865 mbar and provide a continuous flow of air with a capacity of up to 1050 m 3 /h and a power of up to 15 kW.

Becker blowers are used for aeration - for cleaning and oxygenating water in fish ponds and treatment facilities, and although their price is higher than, for example, VARP or SEKO, they have gained an excellent reputation and are very popular in Russia.

Advantages:

• Economical energy consumption, which is most important for high-performance machines.
• Completely oil-free due to the use of non-lubricated bearings.
• Manufacturers guarantee a high resource - at least three years of continuous operation.
• The use of a built-in rotor speed control system increases efficiency, allows you to increase the service life and allows you to adjust the performance to optimal value each specific task.

Rotary blowers for aeration

A swirl blower is not the only blower suitable for water aeration - for a large volume aeration tank, it makes sense to buy a high-performance Roots blower.

Our catalog includes 2 types of rotary blowers:

• VARP Altair provide a gas flow with a capacity of up to 7548 m 3 / h and an overpressure of up to 980 mbar.
• LUTOS DT operate with a capacity of up to 9771 m 3 /h and create a pressure drop of up to 1000 mbar.

These machines outperform vortex machines in performance, but are more expensive. They have all the properties required for the devices of aeration plants of treatment facilities:

1. Environmental friendliness: they do not pollute the injected gas with oil vapor, since the flow path is reliably isolated from the oil sump by a dynamic labyrinth seal.
2. Low noise and vibration levels.
3. High efficiency.
4. Reliability and stable operation.
5. The resource of work is not less than 100 thousand hours.
6. The rotors are carefully balanced to allow them to spin at high speeds and deliver high performance in a small package.
7. Can work for a long time without interruption.

Blowers for wastewater aeration

Aeration blowers are presented in a wide range of sizes, so to buy suitable model, it should be remembered that the main purpose of wastewater aeration is to supply aerobic microorganisms that form sludge with the necessary amount of oxygen. As well as providing mixing to create conditions for the interaction of bacteria with organic matter.

Wastewater aeration accounts for 50..90% of the total power consumed by sewage treatment plants. This is a very energy-intensive process, so electric blowers for aeration are selected based on the conditions for optimal operation.

How is wastewater treated?

There are many options for wastewater treatment systems. Blowers are used in aerobic cleaning systems to supply oxygen to aerobic bacteria that digest organic contaminants. To understand how the purification process takes place, consider a biopurification system with a membrane unit.

Rice. 3. System biological treatment wastewater with membrane block

First, wastewater enters the device mechanical cleaning such as sand traps or special nets.

After that, they enter the equalizer, in which effluents with different compositions are actively mixed, and then they are moved by liquid pumps to the biotreatment system. This system consists of a denitrifier and an aeration tank-nitrifier.

Anoxic mode is set in the denitrifier - there is no dissolved oxygen in the water, but there is chemically bound in the form of nitrites and nitrates. Organic pollutants contained in wastewater are oxidized by activated sludge (AI) to gaseous oxides and molecular nitrogen. To prevent silt from settling on the bottom, an agitator is installed in the anoxic zone.

The aerotank is an important part of the treatment system, in which the biological treatment process takes place. In most cases, it is a single or multi-chamber tank rectangular section, made of concrete with a waterproofing coating, through which wastewater passes. The contaminated liquid is constantly mixed with activated sludge (colonies of beneficial aerobic microorganisms, bacteria and protozoa), and an air stream is forced into the tank. It saturates the water with oxygen, ensuring the vital activity of beneficial microorganisms, and also maintains the sludge in suspension. Compressors or blowers supply compressed air through the water column to saturate it with oxygen through fine-bubble aerators located at the bottom of the aeration tanks.

Compressors or blowers supply compressed air through the water column to saturate it with oxygen through fine-bubble aerators located at the bottom of the aeration tanks.

To oxidize organic substances and ensure nitrification, the concentration of oxygen dissolved in water should be about 2..3 g/m 3 , and the concentration of AI should be about 4..10 g/m 3 .

AT this option of the purification system, instead of a secondary settling tank, a block of finely porous membranes is installed in the aeration tank-nitrifier, in which pure water and AI are separated.

The filtered water (permeate) is supplied by a water pump to a container with clean water, from where it moves to the ultraviolet disinfection system, after which it is supplied to the consumer.

The separated activated sludge from the nitrifier is pumped to the denitrifier. To remove phosphorus, a solution of ferric chloride is supplied to the displaced AI flow. Thanks to AI circulation, its concentration in the biological treatment zone is maintained.

Calculation of the blower for aeration (aerotank). How to define performance?

The aeration process takes place in the aerobic zone, so in fact we are solving the problem of how to choose a blower for the aeration tank.

Water from sewage flows into aerotanks, where it must be saturated with sufficient oxygen to oxidize organic substances.

Therefore, it is possible to select a blower according to the size of the tank, knowing the dimensions of the water treatment system, the biochemical oxygen demand (BOD) of wastewater and their average daily flow rate, it is possible to determine the required volumetric flow rate and air pressure that will be supplied to the aerotank.

Specific air consumption required for aeration:

q aeration=2 L a/kh (m 3 air / m 3 wastewater),

h , m - working depth of the aeration tank - the depth to which the aerator is immersed;

L a , kg / m 3 - BOD of wastewater that is fed into the aerotank (0.002..0.003 kg / m 3 for the system considered above);

k , kg/m 4 - air utilization factor, which depends on the ratio of the areas of the aerators and the aerotank and on the ratio between the depth and width of the aerotank. For example, when air is injected through perforated pipes, it is only 0.006 kg / m 4, and when using more effective system porous plates, it is 2 times more than 0.012 kg / m 4.

The air flow, which should be supplied to the aerotank by a blower, is equal to:

Q =q a eration Q w(m 3 / h),

where Q w, m 3 /h - average daily wastewater consumption. If this parameter is not known to you, then in the first approximation it can be estimated, knowing the working volume of the aerotank V slave / t 1 hour = Q w(m 3 / h).

Flow rate Q and the performance of the blowers will be determined. To ensure this flow, several blowers with a capacity of Q i working in parallel.

How to choose a blower for aeration tanks according to the pressure value?

The required pressure is determined based on the depth of the aeration tank:

p=p atm + Δ p+ Δ p g (mbar) ,

p atm - atmospheric pressure, approximately equal to 1000 mbar;

Δ p= Δ p t+ Δ p a(mbar), where Δ p t- pressure loss during the movement of the air flow from the discharge pipe of the blower to the outlet of the aerator. The geometry of the air ducts should be chosen so that this value does not exceed 30..35 mbar. Δ p a- pressure losses in aerators, which depend on the specific model and are given in the attached technical documentation, about 15..30 mbar);

p g =ρgh is the pressure of the water layer in the aerotank, where ρ is the density of the liquid, g - acceleration of gravity.

Most often, the depth of aerotanks is from 1 to 7 m, therefore, the required overpressure is 100..800 mbar, which fits well into the pressure range created by vortex and rotary blowers.

Knowing the performance values Q i and pressure p , you can choose blowers for water aeration according to the operating point, using the calculator on the page

Air Blowers for Aeration in Wastewater Treatment

keywords: biological treatment, air blowers, aeration

Biological treatment today is one of the most environment-friendly methods of treatment of industrial and municipal wastewater. Saturation of the treated water with oxygen is a mandatory condition for an efficient aerobic biological treatment process. This is achieved with air blowers designed for compression and delivery of air, and for creation of vacuum.

Description:

Blowers for aeration in wastewater treatment

Biological treatment is currently one of the most environmentally friendly methods of water treatment for both industrial and domestic wastewater. For the effective flow of the process of aerobic biological treatment, a prerequisite is the saturation of the treated waters with oxygen. For this, blowers are used to compress and pump air, as well as to create a vacuum.

When choosing equipment for wastewater treatment plants, blowers are given Special attention. The air flow required for wastewater treatment depends on the oxygen demand of the process, the required pollutant removal efficiency, and the treatment technology used. The required amount of air supplied during cleaning in aeration tanks depends on the composition and temperature of the wastewater, the geometric characteristics of the aeration tanks, and the type of aerators used.

The design working pressure that the blowers must create should be taken based on the depth of the aerators in the aerotanks and the pressure loss in the air supply network and the aerators themselves.

The range of required blower performance, depending on the given conditions, can vary significantly and range from several cubic meters air up to tens of thousands. At the same time, regardless of size, blowers used for wastewater aeration must meet the following requirements.

1. Aeration is one of the most energy-intensive processes. Up to 70% of the energy in wastewater treatment plants is consumed by aeration systems. Accordingly, one of the most important requirements is the high energy efficiency of the blowers used. According to requirements normative documents heat recovery needs to be considered compressed air for the needs of a wastewater treatment plant. It is recommended to use blower equipment that allows you to control the flow rate of the supplied air. This is due to the daily and seasonal unevenness of the inflow of wastewater, as well as changes in both the temperature of wastewater and the temperature of the air entering the blowers. When using technologies for the biological removal of nitrogen and phosphorus, it is recommended to provide flexible or stepwise control of the air supply system to aerotanks using automation tools.

2. Blowers should have minimal environmental impact. The purity class of compressed air is regulated in accordance with GOST R ISO 8573–1–2016 “Compressed air. Part 1. Pollution and cleanliness classes”, which is identical to the international standard ISO 8573–1:2010* “Compressed air. Part 1: Contaminants and cleanliness classes (ISO 8573–1:2010). Oil-free blowers are currently recommended for use. The absence of oil has a beneficial effect on the maintenance of the vital activity of bacteria and microorganisms in the treatment of sewage sludge, the air of which does not contain oil particles. The air content is especially unacceptable if the water after cleaning must be reused.

3. The blower should operate as quietly as possible, as elevated level noise adversely affects the personnel involved in the operation of the equipment of treatment facilities.

4. The blower must be designed for the operating conditions, that is, it must be resistant to corrosion, temperature extremes and atmospheric precipitation.

5. Blowers should be easy to operate.

Aeration systems, which are equipped with industrial and local treatment facilities, are designed for artificial enrichment of wastewater with oxygen, which oxidizes iron compounds and other impurities. For this, special vacuum equipment is used that meets certain standards and requirements. In particular, aeration blowers of various capacities are installed at treatment plants, making the cleaning process efficient and environmentally friendly. The Megatechnika MSK company is ready to supply interested enterprises with equipment with the parameters you need on favorable terms.

Basic requirements influencing the choice of blowers for water aeration

Natural aeration of water is an indispensable condition for the reproduction of aerobic bacteria that purify water; in nature, it occurs continuously. However, an intensive, forced aeration system requires much larger volumes of air, for which a blower is used to aerate water of a rotary or turbine type, which meets such parameters as:

• the ability to supply dry air around the clock, not containing lubricant microparticles, wear products or other harmful impurities;
• maximum noiselessness of work;
• nominal capacity corresponding to the volume of processed wastewater;
• resistance to corrosion, temperature extremes and the effects of precipitation;
• simplicity and unpretentiousness in maintenance, operation, durability, reliability and energy efficiency of the design.

What are blowers for aeration of sewage treatment plants

There are submersible blowers that do not need additional systems cooling, and centrifugal, with multi-stage compression. For small wastewater treatment plants, we recommend equipment that pumps air into the pneumatic system using a screw block. The principle of operation of the compression chamber of rotary blowers excludes the possibility of contact of oils with air, and the compressors themselves are distinguished by a particularly low level of noise and vibration, efficiency and compactness, which is important when placing treatment plants near residential areas. For treatment complexes of large industrial enterprises, compressors that compress air with the movement of pistons are more suitable.

We will find the most effective solution for you!

The Moscow company "Megatechnika MSK" offers a wide range of blowers for aeration of treatment facilities or artificial reservoirs, with parameters specified in each case. The possibility of changing the performance of the equipment is also taken into account, which is associated with possible seasonal fluctuations in the volume of wastewater, and, as a result, the difference in compressed air consumption. By favorable prices we will equip your enterprise with screw (rotary) or piston blowers from reputable manufacturers that are popular in the world and Russian market. It is enough to make an application online, and our experts will contact you to clarify the details.