Generally speaking, the oxygen bubbles in water in aquaculture water should be maintained above 5 Mg-8 mg, at least at any time during the culture cycle should be maintained above 3 mg. In the process of culture, especially in high temperature season, the demand for dissolved oxygen in the culture pond is greater with the increase of feeding amount and the decomposition of organic matter by microorganisms. Therefore, it is feasible to pass through. Frequent injection of fresh water, rational allocation and use of oxygen-increasing machinery according to the situation of the pond, so that the pond dissolved oxygen more reasonable and balanced. For the thinner pond, if given proper fertilization, it can promote the growth of planktonic algae and expand the source of dissolved oxygen pond. Grasp every sunny day to open the aerator, the aquaculture water surface supersaturated dissolved oxygen timely transport to the bottom of the pond, and pay off the bottom of the pond formed “oxygen debt”. In the emergency moment that fish and shrimp are short of oxygen, choose the right aerator. During the emergency treatment process, we should first choose oxygen release water or powder aerator, and improve the dissolved oxygen as soon as possible.
In the process of culture, especially in the management of dissolved oxygen in shrimp culture, it is easy to ignore that ponds have excessive water quality and high algae abundance sometimes. The consumption of dissolved oxygen by over-dense planktonic algae in ponds at night often makes the dissolved oxygen at the bottom of ponds lower than the need of normal physiological activities of shrimp, and it will last for a long time. However, the shrimp physique is in a sub-healthy state, and it will increase the risk of infection. In the process of shrimp culture, this should be paid enough attention.
Dissolved oxygen plays an important role in the actual wastewater treatment operation. The deterioration or excessive fluctuation of this index will quickly lead to the fluctuation of activated sludge system, and then affect the treatment efficiency. Therefore, it is necessary to strictly control the content of dissolved oxygen in the actual treatment process. Today, we will discuss in detail about what is dissolved oxygen.
What is the definition of dissolved oxygen DO? Dissolved oxygen literally means the content of oxygen in water. It is expressed in DO, the unit is mg/L. And theoretically, when the dissolved oxygen value monitored at each point of the aeration tank is slightly greater than 0, it can be considered that aeration just meets the requirements of dissolved oxygen for microorganisms in activated sludge. As for the whole aeration tank, the distribution of dissolved oxygen is different from the demand of dissolved oxygen in each aeration tank area, so in order to conservatively stabilize the demand of dissolved oxygen in the process of decomposition of organic matter or self-metabolism of activated sludge, it is necessary to theoretically control the dissolved oxygen in the outlet water of the aeration tank within the range of 1-3 mg/L.
However, in actual operation, it is found that the only result of controlling DO in the range of 1-3 mg/L is to waste electricity and cause the effluent to contain fine suspended particles, which is unnecessary. Therefore, we only need to control dissolved oxygen at about 1.0mg/L, which is reasonable and energy saving.
Dissolved oxygen is easily affected by oxygen, temperature, humidity and other factors in the air, so it is often monitored by on-line detection instrument or portable dissolved oxygen detector. During the test, the whole aeration tank should be divided into several areas, and the monitoring values of dissolved oxygen in the whole area should be statistically analyzed to find out the distribution of dissolved oxygen at different stages and time points of the system, which is very helpful to the overall grasp of the follow-up system and the analysis of activated sludge failure. If such detection conditions are not available, the dissolved oxygen at the outlet of the aeration tank can be monitored as the final result of the degradation process of organic matter in the activated sludge system.
Generally speaking, the effect of oxygenation in winter is much better than that in summer. The main reason is that the water temperature is low in winter and the saturation of dissolved oxygen is high. On the contrary, the saturation of dissolved oxygen is low in summer.
The relationship between dissolved oxygen and the composition of raw water is focused on the relationship between the content of organic matter and dissolved oxygen in raw water. The more organic matter in raw water is, the more dissolved oxygen is consumed by microorganisms in order to metabolize and decompose these organic matters. Therefore, when controlling aeration, we should pay attention to the matching of water content and organic matter in the waste water. If the inflow does not increase, but the concentration of organic matter in the wastewater is too high, the demand for dissolved oxygen will also increase, and then the dissolved oxygen in the effluent of the aeration tank will be too low.
The existence of some special components in raw water will also affect the oxygenation effect. For example, the existence of detergent in the water makes the surface of the aeration tank have an isolation layer to isolate the atmosphere, which affects the enhancement of the aeration effect.