What is the relationship between biochemical oxygen demand and dissolved available for fish

Dissolved Oxygen and Biochemical Oxygen Demand | Monitoring & Assessment | US EPA

what is the relationship between biochemical oxygen demand and dissolved available for fish

DO is the actual amount of oxygen available in dissolved form in the water. The decrease in the oxygen supply in the water has a negative effect on the fish and other according to common styles from the Modern Language Association ( MLA), The Biochemical oxygen demand (BOD) is a measure of how much organic. Relationship between the COD and BOD is in a ratio that a man can not be materials using dissolved oxygen, thus reducing the DO present for fish. Chemical oxygen demand (COD) does not differentiate between biologically available. Fish and other aquatic animals depend on dissolved oxygen (the oxygen present in water) to live. The amount of dissolved oxygen in streams is dependent on the water oxygen demand (COD) does not differentiate between biologically available and inert . These chemicals are often found in association with each other.

5.2 Dissolved Oxygen and Biochemical Oxygen Demand

A number of pure cultures, e. Trichosporon cutaneum, Bacillus cereus, Klebsiella oxytoca, Pseudomonas sp.

what is the relationship between biochemical oxygen demand and dissolved available for fish

On the other hand, many workers have immobilized activated sludge, or a mixture of two or three bacterial species and on various membranes for the construction of BOD biosensor. The most commonly used membranes were polyvinyl alcohol, porous hydrophilic membranes etc.

Such a formulated consortium can be immobilized on suitable membrane, i. Suitability of charges nylon membrane lies in the specific binding between negatively charged bacterial cell and positively charged nylon membrane.

So the advantages of the nylon membrane over the other membranes are: The dual binding, i. Adsorption as well as entrapment, thus resulting in a more stable immobilized membrane. Such specific Microbial consortium based BOD analytical devices, may find great application in monitoring of the degree of pollutional strength, in a wide variety of Industrial waste water within a very short time.

Consequently, biosensors are now commercially available, but they do have several limitations such as their high maintenance costs, limited run lengths due to the need for reactivation, and the inability to respond to changing quality characteristics as would normally occur in wastewater treatment streams; e.

what is the relationship between biochemical oxygen demand and dissolved available for fish

Another important limitation is the uncertainty associated with the calibration function for translating the BOD substitute into the real BOD Rustum et al. The whole area of EKW can be differentiated into zones based on the quality and availability of sewage. These organic components with time degrade and mineralize releasing nutrients, which through food chain reach fish system and thus serve as fish food and in this process sewage also gets rectified.


It is true that BOD is an indicator of pollution level and BOD has an inverse relationship with dissolved oxygen, hence increased BOD might be harmful for aquatic life. This problem is mitigated by two fold factors at EKW. The depth of the fish ponds vary between 50 cm to cm, this shallow depth allows full vertical circulation of water to the surface. This is also favourable for photosynthesis due to better ratio between pond volume and pond surface than a deeper pond.

This helps providing sufficient oxygen for efficient BOD reduction [ 5 ]. Above all the farmers have acquired considerable skill and experience in feeding the ponds with raw sewage to avoid de-oxygenation, thus maintaining a healthy aquatic system.

Biological Oxygen Demand

This region consists of water spread area of Total number of fish ponds isdistributed on both sides of the main sewage canals, out of which ponds are used for commercial aquaculture practice through sewage water [ 6 ].

This region is suitable for solar radiation. The map shows study area, red marked areas for weak zone and the green marked areas for strong zone and green line represents main DWF canal.

Methods Objective of the study involves two major aspects quantity of fish produced and supplementary feed cost. Selection of method was done accordingly, on one hand getting the cost and productivity related data and on the other hand getting the BOD value.

Major part of the work is based on primary data analysis. The cost and productivity related information was collected directly by survey with specific target population. BOD measurement was done by collecting sample from selected ponds.

what is the relationship between biochemical oxygen demand and dissolved available for fish

Sample selection Sample selection was done based on available secondary data and discussion with experts. Sample has been taken from six selected regions based on certain criteria to make it a representative of the whole area.

The criteria has been set to incorporate the maximum possible variations. The fish ponds are distributed on both sides of the main canal. The main waste water canal, i. DWF canal enters from one side along the green line in the map hence the ponds on both sides are not equally fed with waste water.

Based on the quality of waste water entering into the ponds the whole area can be approximately differentiated into two zones though there is no demarcation. The portion which is nearer to the main canal receiving better quality of waste water is considered as strong zone, the portion away from the main canal receiving poor waste water as weak zone strong and weak considering productivity, according to the information provided by the experts. Place the second water sample in an incubator in complete darkness at 20 oC for 5 days.

If you don't have an incubator, wrap the water sample bottle in aluminum foil or black electrical tape and store in a dark place at room temperature 20 oC or 68 oF. After 5 days, take another dissolved oxygen reading ppm using the dissolved oxygen test kit.

Record your final BOD result in ppm. There will not be much organic waste present in the water supply. A water supply with a BOD level of ppm is considered moderately clean. In water with a BOD level of ppm, the water is considered somewhat polluted because there is usually organic matter present and bacteria are decomposing this waste. At BOD levels of ppm or greater, the water supply is considered very polluted with organic waste.

This is because the demand for oxygen by the bacteria is high and they are taking that oxygen from the oxygen dissolved in the water. If there is no organic waste present in the water, there won't be as many bacteria present to decompose it and thus the BOD will tend to be lower and the DO level will tend to be higher.