Traditional installation scheme of intercepting well

The sewage first enters the factory through the intercepting well (allowing the sewage that can be treated by the factory to enter the factory for treatment), then enters the coarse grid (salvaging larger dregs), then enters the sewage pump (raising the sewage height), then enters the fine grid (salvaging smaller dregs), and finally enters the grit chamber (separating, precipitating and removing inorganic particles with higher specific gravity in sewage based on gravity) to the biochemical tank (removing BOD5, SS and various forms of nitrogen or phosphorus in activated sludge process sewage), to the final sedimentation tank (removing excess sludge and reflux sludge), to the D-type filter (further reducing SS effluent to meet the national first-class standard), to ultraviolet disinfection (killing Escherichia coli in water) and then to the effluent.

Part of the sludge in the biochemical tank and the final sedimentation tank is used as the return sludge of the biochemical tank, and the rest is sent to the sludge dewatering room for dehydration and transportation.

There are mainly physical treatment, biochemical treatment and chemical treatment. Biochemical treatment methods are often used. The mainstream treatment method mainly depends on the treated water quality and receiving water body. Usually, the mainstream treatment methods of municipal domestic sewage are biochemical treatment methods, such as activated sludge method and mbr.

sewage disposal

Sewage treatment. Wastewater treatment refers to some measures or methods taken by sewage after being treated in a certain way, reaching a certain standard, discharged into water body, discharged into water body or reused.

Modern sewage treatment technology can be divided into primary, secondary and tertiary treatment according to the degree of treatment.

Primary treatment mainly removes suspended solid pollutants from sewage. Most physical processing methods can only meet the requirements of primary processing. After primary treatment, the BOD of sewage can generally be removed by about 30%, which can not meet the discharge standard. Primary treatment belongs to the pretreatment of secondary treatment.

Secondary treatment. It mainly removes colloid and dissolved organic pollutants (BOD. COD substance). The removal rate can reach more than 90%, which makes the organic pollutants reach the discharge standard.

Tertiary treatment. Further treatment of refractory organic matter, soluble inorganic matter such as nitrogen and phosphorus which can lead to eutrophication of water body. The main methods include biological nitrogen and phosphorus removal, coagulation and sedimentation, sand ratio, activated carbon adsorption, ion exchange, electrodialysis and so on.

The whole process is that the raw sewage after the coarse grid is removed is lifted by the sewage lifting pump and then enters the grit chamber. Sewage separated from sand and water enters the primary sedimentation tank, which is primary treatment (i.e. physical treatment). The effluent from the primary sedimentation tank enters the biological treatment equipment. There are activated sludge process and biofilm process. (The reactors of activated sludge process include aeration tank and oxidation ditch, etc. ) Biofilm method includes biofilter, biological turntable, biological contact oxidation method and biological fluidized bed. Effluent from biological treatment equipment enters the secondary sedimentation tank. The effluent from the secondary sedimentation tank is discharged after disinfection or enters the tertiary treatment. The tertiary treatment includes biological nitrogen and phosphorus removal, coagulation and sedimentation, sand filtration, activated carbon adsorption, ion exchange and electrodialysis. Part of the sludge in the secondary sedimentation tank flows back to the primary sedimentation tank or biological treatment equipment, and the other part enters the sludge concentration tank and then enters the sludge digestion tank. After dehydration and drying equipment, sludge.

Energy consumption analysis of various treatment structures

1. Sewage lifting pump house

The sewage entering the sewage treatment plant enters the sewage lifting pump house through the coarse grid, and then is lifted to the front of the grit chamber by the sewage pump. The operation of pumps consumes a lot of energy, which accounts for a considerable proportion of the total energy consumption of sewage treatment plants. This is related to the sewage flow and the elevator to be lifted.

2. grit chamber

The function of grit chamber is to remove inorganic particles with high specific gravity. Generally, it is located in front of pumping stations and inverted siphons to reduce the abrasion of pumps and pipelines by inorganic particles, and it can also be located in front of primary grit chambers to reduce the load of grit chambers and improve the treatment conditions of sludge treatment structures. Commonly used grit chambers are advection grit chamber, aeration grit chamber, Dole grit chamber and bell grit chamber.

The main energy sources in the grit chamber are sand-water separator and sand suction machine, as well as the aeration system of aerated grit chamber, the power system of Dor grit chamber and Bell grit chamber.

3. Primary sedimentation tank

The primary sedimentation tank is the main treatment structure of the first-class sewage treatment plant, or it is set in front of the biological treatment structure as the pretreatment structure of the second-class sewage treatment plant. The treatment targets are SS and part of BOD5, which can improve the operating conditions of biological treatment structures and reduce their BOD5 load. The primary sedimentation tank includes advection sedimentation tank, radial sedimentation tank and vertical sedimentation tank.

The main energy-consuming equipment of the primary sedimentation tank is the sludge discharge device, such as chain scraper, sludge scraper and sludge suction pump. However, due to the influence of sludge discharge cycle, the energy consumption of the primary sedimentation tank is relatively low.

4. Biological treatment structure

The energy consumption of sewage biological treatment unit process accounts for a considerable proportion of the direct energy consumption of sewage plants. The sum of energy consumption of sewage biological treatment unit process and sludge treatment unit process accounts for more than 60% of the direct energy consumption of sewage plants. The aeration system of activated sludge process consumes a lot of electricity. Basically, it works in cooperation with each other and has high power. Otherwise, better aeration effect can not be achieved and the treatment effect is not good. The aerator installed in oxidation ditch treatment process is also a kind of high energy consumption equipment. Compared with activated sludge process, biofilm treatment equipment consumes energy.

5. Secondary sedimentation tank

The volume consumption of the secondary sedimentation tank is mainly to suck mud and remove sewage floating objects, and the energy consumption is relatively low.

6. Sludge treatment

In the process of sludge treatment, the concentration tank, sludge dehydration and drying all consume a lot of electricity. The energy consumption of sludge treatment unit is quite large. These devices consume a lot of electricity.

Energy-saving ways of various treatment structures

1. Sewage lifting pump house

Energy consumption of sewage lifting pump house should be saved. The main consideration is how to save the electric energy of sewage lift pump. Correct and scientific selection of pumps is an effective means. It is also an effective method to reduce the shaft power n of the pump by reasonably using the terrain and reducing the lifting height of sewage. Regular maintenance of the pump can also reduce power consumption.

2. grit chamber

Adopting advection grit chamber, avoiding grit chambers that need power equipment, such as advection grit chamber, adopting gravity grit chamber and avoiding mechanical grit chamber can greatly save energy consumption.

3. Primary sedimentation tank

The energy consumption of the primary sedimentation tank is low. The main energy is spent on sludge discharge equipment. Hydrostatic pressure method will undoubtedly greatly reduce energy consumption.

4. Biological treatment structure

Foreign scholars have compared biological treatment processes through energy consumption and cost-benefit analysis. They believe that most of the energy consumption of processing facilities occurs on a single device, such as a motor. Therefore, energy saving should start with improving the power factor of the whole plant, selecting high-efficiency electromechanical equipment and reducing the peak power consumption requirements. Their energy-saving measures include not only improving the electrical performance of the motor, but also solving technical problems in operation, including recovering energy from the products of the sewage plant.

Recovery).

The energy consumption of aeration system is quite large. The research on energy consumption and energy efficiency of aeration system always involves the transformation and innovation of aeration equipment. Although new aeration equipment emerges one after another, it can still be divided into two types: 1 is a method of transferring oxygen into aqueous solution by using submerged porous diffuser or air nozzle to generate bubbles. The second is the method of mechanically stirring sewage to dissolve the oxygen in the atmosphere in water. Microporous aeration. Layout and arrangement of aeration diffuser. The adjustment of ventilation system is an effective measure to save energy. Pre-anaerobic zone is set in the aeration tank of traditional activated sludge treatment plant. Immersion agitator is used to save energy. Biological phosphorus removal scheme. This simple transformation can save nearly 20% of aeration energy consumption. If mixed energy is included, the energy consumption can also reach 12%. Energy saving of automatic control system in sewage treatment. The aeration system performs graded aeration. There is a concentration gradient of dissolved oxygen, which not only reduces energy consumption.

Using anaerobic treatment in biofilm process can obviously reduce energy consumption.

5. Secondary sedimentation tank

It is an effective way to reduce energy consumption to study the sludge discharge equipment and improve the sludge discharge mode of the secondary sedimentation tank.

6. Sludge treatment

The energy-saving research of sludge treatment system mainly focuses on the energy recovery of sludge treatment. Recovering energy from organic pollutants in sewage sludge for treatment was put into practice as early as the beginning of last century, but it was not paid attention to before the energy crisis. At present, there are two recycling ways: one is the utilization of anaerobic digestion gas of sludge, and the other is the utilization of sludge incineration heat.

Digestive gas has stable properties and is easy to store. It can be converted into mechanical energy or electrical energy by internal combustion engine or fuel cell. Waste heat can also be recovered for heating and digesting sludge. Therefore, the utilization of digested gas can solve the energy self-sufficiency problem of sewage plants. Lin et al. compared biogas generator and fuel cell, and thought that fuel cell has a good development prospect. Maximizing the utilization of digested gas is the main way to improve energy efficiency. The research and application of grid-connected biogas generator set has been applied in China.

Another way of energy recovery is to build a municipal solid waste incineration plant next to the sewage treatment plant to incinerate solid waste together with sewage sludge. The obtained electric energy is used for the operation of the treatment plant.

The research on energy consumption analysis of urban sewage treatment is often out of step with the development of energy-saving technologies and means. Due to the lack of research on the energy balance analysis method of sewage treatment, the formulation and implementation of energy-saving measures are often ahead of schedule. Most energy-saving ways and methods are often put forward by the operation and management personnel of the treatment plant in combination with the actual situation of various treatment facilities. They are empirical and individual, and may not be applicable to other sewage plants, or even to sewage plants with similar processes. On the other hand, in a broad sense, technological innovation, the use of new materials and new equipment in the field of sewage treatment all contain the potential of energy saving and efficiency improvement, so the ways and means of energy saving are often very extensive.

conclusion

Sewage treatment is energy intensive. For some time, high energy consumption and high operating cost have hindered the construction of urban sewage treatment plants in China. Some completed treatment plants are also in shutdown or semi-shutdown due to energy consumption. For a long time to come, energy consumption will become the bottleneck of urban sewage treatment. Whether it can solve the energy consumption problem of sewage treatment plant and allocate energy reasonably has become the key factor to determine the operation efficiency of sewage treatment plant. Is the energy consumption low? It is also a decisive factor in the feasibility analysis of new sewage treatment plants in the future. Developing energy-efficient sewage treatment technology and designing and operating sewage treatment plants rationally will be the only way for the design and operation of sewage treatment plants in the future.

Downstairs, don't copy! ! ! !