Blowers for wastewater treatment:
Two of the most crucial factors at a wastewater facility are proper aeration and blower selection. Most of the electricity used at wastewater treatment facilities—60% of it is usually used for aeration. Blowers can help reduce some of the energy needs.
The air provided by the blowers to the aeration basin serves multiple purposes. The first is to provide the oxygen required for the wastewater's organic substances to be metabolized. The term "BOD5" (biochemical oxygen demand) for the organic compounds refers to the 5-day measurement used to determine their concentration. To be utilized by the microbes, the oxygen needs to be dissolved in the wastewater. The diffusers effectively dissolve oxygen into the wastewater using microscopic air bubbles.
Nitrification, the process by which microbes change ammonia (NH3) into nitrate (NO3), calls for additional oxygen. Most of the time, nitrification accounts for half of the overall process oxygen demand.
By preventing the air from flowing, the entire blower mechanism generates pressure (back pressure). The working air flow can be determined by adding flow rate and back pressure. When the amount of pressure in headers is just enough to outweigh the static pressure, optimal energy use is obtained. Since numerous wastewater treatment facility operators are likely to set the pressure points higher than necessary, extra blower discharge pressure takes place – that consumes power.
The first stage in selecting a suitable wastewater-blower is to determine the system's required flow. That is decided by considering the requirement of microorganisms for oxygen in the treatment system. The amount of oxygen needed in the wastewater stream depends on the metabolism of the organic substance, the effectiveness of oxygen exchange in the tank, and the site conditions.
The waste products, microorganisms, and oxygen (O2) used in the metabolism of the organic material generate carbon dioxide (CO2), ammonia, and the energy required to produce additional microorganisms. Ammonia, microorganisms, and oxygen are transformed into nitrous gas, water, and additional microorganisms in a subsequent reaction.
The standard cubic feet per minute (SCFM) demand for the system can be calculated using data and an engineering computation based on the biological oxygen consumption, ammonia levels, and oxygen transfer efficiency.
The selection of the blower will also be significantly affected by site circumstances. Positive displacement and multistage centrifugal units typically perform better in more adverse conditions and outdoor use, while high speed turbos and integrally geared centrifugal units are typically better adapted for domestic or cleaner uses.
How to calculate Power Consumptions for Pump Blowers?
Power (kW) = Airflow rate (m3/min) x Pressure (kPa) x Specific gravity x Blower efficiency
Where Blower Efficiency is the ratio of the blower's air output to its energy intake and Specific Gravity is the density of the air being delivered.
Let us consider a wastewater treatment plant with a 1000 m3/h capacity as an illustration. The factory has four blowers, each with a 100 m3/min airflow rate, 50 kPa pressure, and 70% blower efficiency. Given that the air has a specific gravity of 1.2, the following formula can be used to determine how much electricity each blower uses:
Power (kW) equals 100 x 50 x 1.2 x 0.7 kW.
Consequently, the four blowers' combined power usage is 16,800 kW.
Blowers for wastewater aeration are part of a complex treatment system. The need for air during the procedure is ever-changing. The system needs are unlikely to be satisfied by supplying a single blower that operates at a single flow rate and discharge pressure. Variable process demand, present and prospective loadings, and the effect of surroundings on performance will all be considered in a good design. The range of operation that the blower system must support should be specified consequently.