( Update: 09/11/2018 )
Air pollution control in biofilter technology (using microbial disinfection) is a measure pollution emissions processing with low investment cost, low operation and environmentally friendly, it is a suitable method to handle foul-smelling gases and volatile organic compound concentrations as low as factory fodder, starch, ethanol, producing chitin ...
Coconut shell is a very simple materials found in our country. Dried coconut is removed the outer shell to be easily transported than the factory or in the hands of consumers. Crust leave that actually is a valuable raw material for us to use as biological scaffold material for microbial development
Describe the process
Biofiltration system provides an environment for microbial growth and decomposition gases and odor substances organic pollutants in emissions. Filtration system is a sealed tank up coconut shells for shelter and microorganisms absorb moisture, keep them in the filter material. Coconut shells have large water absorption, high durability, and low pressure reduces airflow passing through it. The filter material units are called "biomass" (Biocube). The use of coconut shell restriction air filter of this type is that the filter material is compressed and the air flows constantly into the road to escape through the filter material. Moreover, it also provides the convenience of maintenance or replacement of filter material. The main principle of the system is to facilitate processing of biomass exposed to pollutants in the exhaust gas as much as possible. Coconut shell filter material and a breeding ground for microorganisms. In this system, the microorganisms will form a biofilm (biofilm), which is a thin membrane surrounding moist coconut shell. During filtration, air pump thaiduoc slowly through the filtration system, the emission of pollutants in the filter material will be absorbed filtering mechanisms of biological processes including adsorption, absorption and decomposition by microorganisms. The microorganisms in biofilms continuously absorb and metabolize pollutants. Polluting gases will be absorbed by biological membranes, where microorganisms will decompose to create energy and byproducts are CO2 and H2O salts according to the following equation:
Air pollution + O2 à CO2 + H2O + heat + biomass
In the process of biological filtration, air polluting substances moistened and then pumped into a chamber below the filter material. As the gas passes through the filter material, the contaminants are absorbed and decomposed. Exhaust gas purification after being released into the atmosphere from the top of the filter system. Biofiltration systems our design capacity to treat odors and volatile organic compounds greater than 90%.
Filter materials: coconut shell
Layer of moist filter material create conditions for chemical and facilitate the conversion of pollutants from the gas phase to the liquid phase and the process of biodegradation of contaminants by biofilm. This filter material to provide a large surface area to absorb and adsorb contaminants. It also makes the task of providing nutrients for microorganisms. During operation could exhaust shortfall nutrients for microorganisms, so we must be corrected by adding the nitrogen and phosphorus compounds.
Coir has a lifespan of 2-5 years prior to renewal.
Moisture holding capacity of coconut shell to produce biofilm
- There is a large surface area to facilitate the absorption and development of micro-organisms
- Contains nutrients to provide microorganisms
- Creating a low air resistance (pressure drop and reduce the energy required to pump use)
- The physical properties such as stability and easy physical manipulation.
Coconut shells capable of providing nutrients for microorganisms do not cause reduced pressure and airflow much. Coconut shells are available in VN materials and surfaces exposed to huge emissions (350-450m2 / m3). In addition, the moisture content of the filter material must be maintained at 30-60% of the microbial population development. Therefore, besides moisten emission devices, people often install sprinkler systems for the filter material layer
DATA DESIGN
Area:
Designing biofiltration systems need large areas deodorant. To handle the flow of air around 100,000m3 gas / h, a biological filtration system can be an area of nearly 100m2. For greater air flow, we need a larger area of land should be calculated before selecting biology.
The chemical composition and concentration of pollutants in the exhaust gas:
Analysis of the chemical composition and its concentration in the exhaust gas needed to determine whether the measures are appropriate biological filter or not. The biological filter system works well when the pollution compounds (insoluble in water) with low concentrations (<1000 ppm). Some compounds hardly biodegradable (such as chlorine compounds) occupies an area larger biofilters.
Save time and gas:
The longer retention time and gas going to handle the higher performance, but product prices will rise. Accurately calculate the concentration of the pollutant, exhaust velocity, a measure to design biological filtration system. Typically, the length of stay of biofiltration systems ranged 30 seconds to 1 minute.
Humidity:
Humidity of the gas stream requiring treatment is important because it keeps the moisture necessary for biofilm. Thus, the flow of exhaust gas is usually pumped through a spray system before pumping into the biological filtration system to ensure the moisture content of the waste gas stream enters the biological filter system must be greater than 95%.
PH control:
The byproduct of the biodegradation process as organic acids. To maintain the pH from 6 to 7.5 for good microbial activity, we need to systematically pH cotroller
Reduce pressure:
The reduction of air flow pressure passing grade filter materials should be minimized. If the filter material layer causing major hindrance to the gas source, we need to spend more energy for air blower, causing increased processing costs. Potential obstacles to gas resources depends on the moisture content and porosity of the filter material layer. Humidity increases, the decrease is empty classroom materials causes increased resistance to gas resources. For a typical system reduces pressure level in the range of 1 -10 hPa.
Maintenance:
When you start putting into operation, the system should be supplemented nutrients for microbial leaned once / day. After the system has stable operation and has solved all the problems that may occur. The frequency of visits can be reduced to 1 times / fortnight or month.
Pros and cons of bio-filtration system
Pros:
+ The main advantage is low cost, low operating cost, less chemical use.
+ Design flexibility, which can adapt to all kinds of industries and areas of the enterprise.
+ Biofiltration system flexibility in dealing with odors and volatile organic compounds and other toxic substances.
+ Performance processor is usually greater than 90% of the emissions of pollutant concentrations <1000 ppm.
+ Materials available, cheap and easy to replace.
Cons:
+ Biofiltration system difficult to handle contaminants have low adsorption capacity and speed slow biodegradation such as volatile organic compounds that contain chlorine.
+ The source pollution have higher concentrations required for large systems and large area for installation of filtration systems biology.
+ Source contaminant level of pollutants released high volatility will affect the flora as well as their processing performance.
+ Time for microorganisms to adapt to the environment and form biofilms (biofilm) can last for weeks, especially for the treatment of volatile organic compounds should be the operator understanding of microbiological culture techniques.
The use of biological filtering system processing of volatile organic substances were applied in the following industries:
- Technology Chemical and Petrochemical
- Oil and Gas Technology
- Resin Technology
- Production technology of paint and ink
- Pharmaceutical Technology
- Waste and wastewater
- Handling of soil and groundwater
- Handling of sewage
- Waste and wastewater abattoir
- The recycling technology
- The factory gelatin and glue
- Technology meat processing and agricultural
- Production technology tobacco, cocoa, sugar
- Production technology of spices, artificial odors.
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