In anaerobic treatment, bacteria convert organic compounds (COD) to biogas in an environment without oxygen. Not only do the bacteria remove contaminating compounds from the effluent, thereby reducing discharge costs, they produce green energy at the same time.
For what range of COD level anaerobic digestion is carried out?
around 1500-2000 mg/L
For what range of COD level anaerobic digestion is carried out? Explanation: The COD level would be around 1500-2000 mg/L if it is subjected to anaerobic digestion. In case if it is around 1300 mg/L then aerobic digestion is carried out. In anaerobic digestion, methane is produced.
What is the COD reduction in conventional anaerobic sludge treatment?
For good biodegradability of any wastewater, a minimum BOD: COD ratio (BI) of 0.3-0.4 is considered to be ideal, with a ratio of ≥0.3 desirable for coupling with aerobic treatment and ≥0.4 for anaerobic treatment (Metcalf & Eddy, 2nd ed., 1979).
How does anaerobic digestion work?
The anaerobic digestion process
Anaerobic digestion is a process in which bacteria break down organic matter such as food waste, without oxygen. As the bacteria consume the food waste, they give off biogas which rises to the top of the digester. This consists mostly of methane, the primary component of natural gas.
What is the COD of methane?
The COD of methane can be calculated using 1 g COD = 0.35 L CH4, while specific VSS values vary between 1 g VSS ≈ 1.21–1.61 g COD (Contreras et al. 2002). Digested sludge from the observed WWTP and from the residual gas laboratory scale tests had a COD to VSS ratio in the range of 1.42–1.43 g COD/g VSS.
What is the limit of cod?
The chemical oxygen demand (COD) concentration in a treated effluent, if observed to be persistently greater than 250 mg/l before disposal to any receiving body (public sewer, land for irrigation, inland surface water and marine coastal areas), such industrial units are required to identify chemicals causing the same.
What is the range of cod?
The COD of surface water normally ranges from 5 to 20 mg l−1. The COD as standardized method has found its way into wastewater legislation.
What is COD in biogas production?
In anaerobic treatment, bacteria convert organic compounds (COD) to biogas in an environment without oxygen. Not only do the bacteria remove contaminating compounds from the effluent, thereby reducing discharge costs, they produce green energy at the same time.
What is COD removal?
COD Removal by Microbial Action
Aerobic COD removal introduces microorganisms or bacteria that break down organic compounds present in wastewater into carbon dioxide and water in the presence of air. Aerobic COD removal is ideal for wastewater with COD
What is a good BOD level?
1-2 ppm
A BOD level of 1-2 ppm is considered very good. There will not be much organic waste present in the water supply. A water supply with a BOD level of 3-5 ppm is considered moderately clean.
What are the disadvantages of anaerobic digestion?
The disadvantages of wet anaerobic digestion are low processing capacity, high operating costs; high requirements for the pretreatment of food waste and the ammonia nitrogen; salts are easy to inhibit wet anaerobic digestion. There is a risk of secondary pollution that is difficult to handle biogas residue.
What are the benefits of anaerobic digestion?
The Benefits of Anaerobic Digestion
- Diversified Farm Revenue.
- Rural Economic Growth.
- Conservation of Agricultural Land.
- Energy Independence.
- Sustainable Food Production.
- Farm-Community Relationships.
Is anaerobic digestion good?
Soil Health Benefits
Anaerobic digestion produces digestate, a nutrient-rich slurry. Digestate can be applied to agricultural land as a fertilizer and/or soil amendment to improve soil health. Digestate that is applied to land is subject to both state and federal regulations.
How do you treat COD in wastewater?
You can reduce COD and BOD by adding hydrogen peroxide to the wastewater solution. The hydrogen peroxide will chemically attack the organics in the wastewater, degrading them and reducing the measured COD and BOD.
How do you improve anaerobic digestion?
Grit removal, sludge screening and primary scrapers are key to improving biogas yield and improving process performance. If not effectively removed, grit not only takes up vital space in the digester but also causes significant wear on vital assets such as pumps.
How much methane does anaerobic digestion produce?
(55-75 vol%)
Anaerobic digestion is an established technology for the treatment of wastes and wastewater. The final product is biogas: a mixture of methane (55-75 vol%) and carbon dioxide (25-45 vol%) that can be used for heating, upgrading to natural gas quality or co-generation of electricity and heat.
What is good COD level?
According to standards of Central Pollution Control Board, permissible value of BOD is 30 mg/l and COD is 250 mg/l. Hope this helps, it mentions standards for India relating to different uses.
What causes high COD in wastewater?
COD increases as the concentration of organic material increases. It also increases if inorganic compounds susceptible to oxidation by the oxidant (typically dichromate) are present. Water with high COD typically contains high levels of decaying plant matter, human waste, or industrial effluent.
What happens if COD is high?
Higher COD levels mean a greater amount of oxidizable organic material in the sample, which will reduce dissolved oxygen (DO) levels. A reduction in DO can lead to anaerobic conditions, which is deleterious to higher aquatic life forms.
Is COD equal to BOD?
COD is closely related to BOD or Biochemical Oxygen Demand, the difference being that BOD is a test of the level of organic matter that can be biologically oxidised while COD is a test of the amount of organic matter that can be chemically oxidised.
Which is better COD or BOD?
COD is always higher than BOD because chemical oxidation is easier than biological oxidation.
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