Water Industry Network HC : Abstract By analyzing the existing aerator device, based on research and development HNBQ elastic porous disk Membrane Aerators with high oxygen transfer efficiency, economy, energy, etc., and have broad prospects for development and practical significance.
Key words wastewater treatment equipment; disk type; elastic membrane; Aerator
CLC X703 Overview Aeration equipment Urban sewage and industrial wastewater treatment plant one of the key equipment, its energy-saving wastewater treatment plants play a decisive role. Therefore, the research, development and application of new high-performance low-power consumption of aeration is important.
80 early, the first time by German IFD microporous rubber diaphragm instead of rigid porous aerator of success, and gradually applied to a number of sewage treatment plants, this flexible membrane diffusers high utilization rate with oxygen, power efficiency, pressure loss, non-corrosive, non-blocking, the airflow can be adjusted and so on.
This end, we carried out this new energy efficient, and affordable aeration device development work.
1HNBQ elastic membrane disc aeration device operating principle and characteristics
1.1 works HNBQ elastic membrane disc aeration device, the pass into the air, the membrane swollen from the increased membrane orifice open and thus release small bubbles, the expansion of the degree of air pressure; When stopped ventilation, the orifice closed, the membrane cover to a certain PC chassis close to the round arch, with the result that the aerator can remain sealed for years.
1.2 features the work of
(1) will not be blocked. This aeration system with its one-way closed structure of production " Valve Door "effect, flexible microporous membrane aeration only when open, stop the aeration closed, resulting in sewage sludge particles and will not enter the aeration device, and therefore will not be because of microbial growth and plug aerator.
(2) corrosion-resistant and durable. Chassis and cover are due to film Plastic , Rubber and other raw materials, resistance to air and water corrosion.
(3) Adjustable large-minded, each aerator aeration in 0 ~ 5m3 / h between the changes.
(4) easy to install. This aerator can be directly connected through the threaded pipe is connected with the cloth trachea, replacement without tools into unilateral and bilateral, and all the bottom laid.
(5) service area, the pressure loss. Each aerator service area 05 ~ 10m2, water resistance to 326 ~ 491mmH2O column.
(6) high efficiency of oxygen utilization and power. When the 5 ~ 6m depth utilization is 200% O2 259%, power efficiency is 39 ~ 45kgO2/kWh.
HNBQ elastic membrane disc aeration device is arched by a cylindrical rigid plastic chassis and a set of their hit many small holes on the elastic rubber chimney. Hard plastic chassis of the main components of polypropylene, and a small amount of fill additives. Plastic chassis surrounded by a rubber membrane covers the main ingredient is natural rubber, mixed with a small amount of other ingredients.
3HNBQ disk elastic membrane aerator experiment
3.1 Determination of oxygen transfer performance
3.1.1 measuring device Oxygenation measured performance tests for the single disk clean water, high in 0.8 7.5m PVC cylindrical aeration tanks to test flow shown in Figure 1.
3.1.2 Determination Theory 1. Eliminate oxygen It 2Na2SO3 + O2 = 2Na2SO4 principle, in water (tap water) in the delivery of anhydrous sodium sulfite and cobalt chloride as a catalyst, water Pump Stir in the dissolved oxygen to clean water only to zero.
2. Oxygenation Wait dissolved oxygen (DO) to zero, start the aeration device, start oxygenation, while dissolved oxygen was measured by changes in the pool of DO and record instantaneous changes in dissolved oxygen, until the DO saturation, oxygen end. When measured DO Probe Place one half of depth, and test sampling points in the same section. Flow meter with regulator valve before, stable gas flow, water only to repeat experiment, each data under the same conditions were repeated in test 2 to 3 times, so that oxygen transfer coefficient KLa values similar to, and take the average calculated.
3. Formula (1) KLa20 method: According to the Whitman two-film theory of gas-liquid interface area is difficult to consider the determination of the total oxygen transfer coefficient KLa instead of KL.
Oxygenation rate it The formula: KL for the film mass transfer coefficient; Cs saturation for the dissolved oxygen concentration; C is the concentration of dissolved oxygen.
The formula (1) integration was The formula: C1, C2 respectively, t1, t2 time measured dissolved oxygen values (mg / l).
KLa value and temperature as related projects are the temperature at 20 for KLa20 value standard, the test temperature KLaT value correction, example is shown below:
The formula: KLa20 standard condition (20 ), the total aerator oxygen transfer coefficient (min); T for testing water temperature, ; 1024 for the temperature correction factor.
(2) oxygen utilization EA The formula: E for the test conditions, oxygen aerator utilization; Q for the test conditions, aeration and oxygenation capacity (kgO / h); 0.28 for the standard state of oxygen in the air 1cm3 Weight (kg/m3); Q marked as standard conditions (01MPa, 20 ) aeration flux (m3 / h)
(3) Power efficiency Ep Ep = Qc / N (5) The formula: E for the test conditions aerator power efficiency of oxygen; (k / kWh); Q for the test conditions aerator oxygen transfer capacity (kgO2 / h); N when oxygenation for the Aerator theory of power consumption (kW) by type (8) basis.
N = Q real H/102 (6)
The formula: H as a gas Pressure Gauge Reading means (MPa).
3.1.3 Measurement Results This study were changed in the same water depth of four aeration and gas under the same aeration and water depth changes in four different conditions of oxygenation in 16 tests.
(1) the total oxygen transfer coefficient (KLa20)
KLa20 value is the evaluation of aeration devices is one important performance index. KLa20 value is maintained at 0111 ~ 024min-1's high level; aeration same, the water depth increases KLa20 value increased; water depth is constant, increasing aeration, KLa20 value also increased, shown in Figure 2.
(2) oxygen utilization EA Oxygen utilization evaluation of aeration devices is another important indicator of performance. In the depth of 5 ~ 6m, aeration volume from 2m3 / h to 5m3 / h time, EA value is maintained at 200% to 259% of the higher level; oxygen utilization increased with the aeration rate decreased under the same aeration, oxygen utilization of the water depth increases, see Figure 3.
