What is the difference between dissolved oxygen and biological oxygen demand

COD analysis on the other hand is a measurement of the oxygen-depletion capacity of a water sample contaminated with organic waste matter. Specifically, it measures the equivalent amount of oxygen required to chemically oxidize organic compounds in water thus removing the pollution. COD is an integral part of all water quality management programmes. Since cold water retains oxygen better than warmer water, DO is usually lower in summer months.

The biggest challenge in the BOD test relates to time, as the holding time for a BOD sample is 48 hours from collection. For BOD to operate properly there must be a sufficient population of healthy bacteria in the bottle. Biological oxygen demand is often used in wastewater treatment plants as an index of the degree of organic pollution in water.

Industries that discharge wastewater into municipal sanitary sewers or waterways are facing strict regulations on levels of BOD. Tuser can be reached at [email protected]. All projects must have been in the design or construction phase over the last 18 months.

Industrial Top Projects. What is Aeration for Wastewater Treatment? Drinking water is tested as well to check, if there is any organic matter present. This TOC methode is faster and can be done online, whereas the methode to measure the biochemical oxygen demand takes several days to get results. The biochemical decomposition of organic substrates is carried out by microorganism. For this work the bacteria need energy. Aerobic bacteria, that do this work, need dissolved oxygen to produce energy.

This oxygen is consumed in this process and the amount of dissolved oxygen in the water gets less. If there is a lot of organic material present in the water, the oxygen demand is correspondingly high to carry out the decomposition.

This oxygen is then lacking the plants and animals that also live in this water. The water quality is controlled by the authorities to protect users form health and other adverse effects of poor water quality. A high BOD level can indicate the existence of faecal contamination. Or particulate and dissolved organic carbon from various sources, neither from human nor from animal. This kind of contamination can seriously affect human health and cause problems to the industry.

The dissolved oxygen content DO of a sample is measured in milligrams per liter, or parts per million. This measurement indicates the actual amount of free oxygen dissolved in water and is an important requirement to support aquatic life in our streams and rivers.