Not known Facts About biological oxygen demand procedure
Not known Facts About biological oxygen demand procedure
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バクテリアの種類と量：バクテリアが合わなかったり不足していると、有機物の分解が進まず測定値が低くなるため、植種が必要
The biological oxygen demand is a common method for expressing the focus of natural resources in waste water samples. It quantifies the level of dissolved oxygen utilised by microbes in water.
This means a lot less oxygen is accessible to better kinds of aquatic lifestyle. The implications of high BOD are similar to All those for reduced dissolved oxygen: aquatic organisms come to be stressed, suffocate, and die.
Wastewater from sewage cure crops often is made up of natural and organic supplies which have been decomposed by microorganisms, which use oxygen within the process. (The quantity of oxygen eaten by these organisms in breaking down the squander is referred to as the biochemical oxygen demand or BOD.
The COD test uses a chemical (potassium dichromate in a very 50% sulfuric acid Resolution) that “oxidizes” each natural (predominate) and inorganic substances in a very wastewater sample, which leads to a greater COD focus than BOD concentration for a similar wastewater sample because only organic compounds are eaten for the duration of BOD testing.
Decaying vegetation might be ample, or many lifeless and dying algae may be detected under a microscope.
Việc thử nghiệm chỉ số BOD là phép đo tốc độ hấp thụ hết oxy của vi sinh vật có trong mẫu nước thử ở nhiệt độ cố định (twenty °C - mẫu thử nghiệm được đặt trong tủ ủ giống như tủ lạnh) và trong một khoảng thời gian chọn trước (thường là 5 ngày) trong bóng tối. Để đảm bảo mọi điều kiện là tương đương, một lượng rất nhỏ vi sinh vật mầm mống được thêm vào trong mỗi mẫu cần thử nghiệm cũng như trong một mẫu đối chứng chỉ chứa nước cất.
Biochemical oxygen demand is the level of oxygen eaten by bacteria and also other microorganisms when they decompose natural make any difference under aerobic situations.
In some circumstances, on the other hand, you will find compounds that could interfere Using the colorimetric analysis, and titration is needed to find out COD stages.
Equally are known to occur under spillways and waterfalls on account of retention of sediment driving the dam, and the power of water turbulence beneath the dam which can remove sediment and dislodge organisms.
Estimate the per cent saturation, by dividing your actual dissolved oxygen by the utmost focus with the sample temperature.
Take into consideration suboptimal DO to be a prospect cause whenever you see variations in aquatic Group composition or acute biotic effects as explained under. You should Observe, nonetheless, that observations of those results usually do not confirm a causal partnership. In some cases exactly the same noticed BOD analysis influence may be due to other stressors or numerous agents.
In some water website bodies, natural matter is a good source of BOD. These natural and organic issues include things like sewage and various pollutants existing during the water bodies. The larger the BOD, the decreased could be the dissolved oxygen accessible for aerobic animals such as fishes as well as other aquatic organisms.
Having said that, DO meters are more fragile than field kits, and repairs into a damaged meter may be highly-priced. The meter/probe have to be diligently maintained, and it have to be calibrated before Each individual sample run and, If you're accomplishing lots of tests, between samplings.