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 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 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 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).
What is Tcod and SCOD?
TCOD represent the total COD in the bioreactor while SCOD represent the soluble (suspended of effluent) in the bioreactor. COD variations is important to evaluate microorganism activities toward environmental changes during
How is biogas production measured?
Biogas volume was measured using a 1,000-ml syringe. The syringe was connected to the reactors by injecting the needle through the butyl bung, then drawing the plunger out until the pressure in the headspace dropped to ambient pressure. The volume of gas in the syringe was taken as a measurement of the gas produced.
What is COD anaerobic digestion?
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 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.
Why do we measure COD?
COD is a water quality measure used not only to determine the amount of biologically active substances such as bacteria but also biologically inactive organic matter in water [8]. It is an important and rapidly measured variable for characterizing water bodies, sewage, industrial wastes, and treatment plant effluents.
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 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.
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.
How hot does biogas burn?
Biogas is about 20 percent lighter than air and has an ignition temperature in the range of 650 C to 750 C (1,200 F to 1,380 F). It is an odorless and colorless gas that burns with a flame similar to that of natural gas.
How is COD calculated?
There is a formula for calculating COD. Consider the formula for COD calculation: (a – b) X C X 8,000 / the volume of the sample in mL. Let “a” represent the titrant used for your sample expressed in mL. Let “b” represent the titrant used for your blank sample in mL.
Why is COD higher than BOD?
The COD test uses a chemical (potassium dichromate in a 50% sulfuric acid solution) that “oxidizes” both organic (predominate) and inorganic substances in a wastewater sample, which results in a higher COD concentration than BOD concentration for the same wastewater sample since only organic compounds are consumed
Why Sulphuric acid is used in COD?
Chemical Oxygen Demand (COD) 1% Silver Sulphate in Sulphuric Acid (conc.) provides the primary and secondary digestion catalysts for oxidation of carbon during chemical oxidation.
What is biogas formula?
Biogas is primarily methane (CH. 4) and carbon dioxide (CO. 2) and may have small amounts of hydrogen sulfide (H. 2.
How much biogas is produced from 1 kg of biomass?
6) Thus, the biogas yield of 1 kg kitchen waste could somewhat range between 100 and 225 LN. The total biogas yield of both waste and inoculum together would be much higher ranging from 300 to 450 LN.
How much biogas is normal per day?
The gas demand can also be defined using the daily cooking times. The gas consumption per person and meal lies between 150 and 300 liter biogas. For one liter water to be cooked 30-40 l biogas, for 1/2 kg rice 120-140 l and for 1/2 kg legumes 160-190 l are required.
What is the difference between BOD and COD in wastewater?
Biochemical oxygen demand (BOD) is the amount of oxygen required by the microorganisms to break down the organic materials, whereas chemical oxygen demand (COD) is the amount of oxygen required to break down the organic material via oxidation.
How can biogas yield be increased?
One method of enhancing biogas potential is the supplementation of anaerobic digesters with small amounts of trace inorganic nutrients, e.g. nickel; cobalt; manganese; iron, which stimulate bacterial activity.
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