High biochemical oxygen demand can be caused by: high levels of organic pollution, caused usually by poorly treated wastewater; high nitrate levels, which trigger high plant growth.
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What increases the BOD of water?
Organic loading is occurrence of excess organic matter inside water due to sewage disposal and eutrophication. This leads to an increase in biological oxygen demand (BOD) for putrefaction. Explosive multiplication of alga leads to algal bloom.
What causes high BOD in wastewater?
Sources: BOD represents the amount of organic matter in a water supply; therefore, it increases when decaying plants, human or animal waste, and other organic compounds are added to water.
What influences biological oxygen demand?
Biological oxygen demand directly affects the amount of dissolved oxygen in rivers and streams. The rate of oxygen consumption is affected by a number of variables: temperature, pH, the presence of certain kinds of microorganisms, and the type of organic and inorganic material in the water.
What causes BOD to decrease?
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.
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.
How does BOD relate to dissolved oxygen and result in fish kills?
How does BOD relate to dissolved oxygen and result in fish kills? BOD is the amount of oxygen used by microorganisms, when it is high there is not enough oxygen left for fish and they die.
Which of the following will have the highest biological oxygen demand?
Oxygen use can also be measured per 100 gm of an organ to indicate concentrations of use; heart usage is highest, followed by the kidneys, brain, and liver. During exercise, the biochemical oxygen demand increases for active tissues including the heart and skeletal muscles.
How BOD is related with water quality?
The dissolved oxygen readings are usually in parts per million (ppm). Higher BOD indicates more oxygen is required, which is less for oxygen-demanding species to feed on, and signifies lower water quality. Inversely, low BOD means less oxygen is being removed from water, so water is generally purer.
How can we reduce BOD in waste water?
- Focus on removing TSS from wastewater first.
- Get a properly sized EQ tank.
- Control the pH of the waste stream.
- Install a modern plate pack DAF made of stainless steel or plastic.
- Use a regenerative turbine air dissolution pump.
Which is higher BOD or COD?
COD is always higher than BOD because chemical oxidation is easier than biological oxidation.
What does it mean if BOD is high?
Biochemical Oxygen Demand (B.O.D.) is a measure of the quantity of oxygen used by microorganisms in the oxidation of organic matter. Many animals need high oxygen amounts to survive. If the B.O.D. is high, that means that microorganisms are using most of the Oxygen.
What food source can cause an increase in BOD?
Sources of BOD include leaves and woody debris; dead plants and animals; animal manure; effluents from pulp and paper mills, wastewater treatment plants, feedlots, and food-processing plants; failing septic systems; and urban stormwater runoff.
Why is COD so important?
In wastewater treatment, the Chemical Oxygen Demand (COD) is an important measurement for the amount of oxygen that is required to break down pollutants (organic substances) in water. The chemical oxygen demand can be measured using different methods, direct or indirect.
What is COD and its significance?
COD is a measure of the oxygen equivalent of the organic matter in a water sample that is susceptible to oxidation by a strong chemical oxidant. COD is widely used as a measure of the susceptibility to oxidation of the organic and inorganic materials present in water bodies and in the municipal and industrial wastes.
Why is BOD important in water quality?
The BOD is an important parameter for assessing water quality. It deals with the amount of oxygen consumption (mg O2 L− 1) by aerobic biological organisms to oxidize organic compounds. Sewage with high BOD can cause a decrease in oxygen of receiving waters, which in turn can cause the death of some organism.
Why a low BOD is important in wastewater treatment?
Generally, a higher BOD value indicates a higher level of water pollution, while a lower BOD value indicates less polluted, or cleaner water.
What is the ratio of COD to BOD?
BOD : COD (Chemical oxygen demand) ratio using the formulated seed comes in the range of 0.7-0.8 whereas that using BODSEED comes in the ratio of 0.5-0.6.
Why COD is higher than BOD in wastewater?
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 …
Does aeration reduce COD?
Aeration should help reduce the COD in 2 ways. First it may evaporate some volatiles like hexane. Second it will add oxygen to the water speeding up any biological oxidation of the less volatile organics by the bacteria (microbial growth).
How much dissolved oxygen do fish need?
A concentration of 5 mg/L DO is recommended for optimum fish health. Sensitivity to low levels of dissolved oxygen is species specific, however, most species of fish are distressed when DO falls to 2-4 mg/L. Mortality usually occurs at concentrations less than 2 mg/L.
How does dissolved oxygen affect fish?
When dissolved oxygen becomes too low, fish and other aquatic organisms cannot survive. The colder water is, the more oxygen it can hold. As the water becomes warmer, less oxygen can be dissolved in the water.
Does BOD increase with time?
Both BOD and COD is increasing with time. Join ResearchGate to ask questions, get input, and advance your work.
Does chlorine reduce BOD?
BOD reduction: Chlorine accomplishes BOD reduction by oxidation of organic compounds present in wastewaters. 4. Oxidation of metal ions: Metal ions which are in reduced state are oxidized by chlorine (e.g., ferrous to ferric ion and manganous to manganic ions).
Does aeration reduce BOD?
Aeration is used to operate activated sludge process units and is perhaps the most frequently used process to remove biochemical oxygen demand (BOD) from wastewater.