工厂化水产养殖中的水体参数监测和控制

Monitor And Control The Parameter Of the Industrial Aquaculture

在工厂化水产养殖中,有许多水体参数需要检测和控制。本文对使用物理手段准确控制的参数,即温度,溶解氧,pH值进行研究,说明控制的意义,提出控制方法,并建立组态工程,方便对重要参数进行在线监测和控制。

In the industrial aquaculture, we build a recirculating aquaculture tank production system so that we can monitor and control the parameter of the aquaculture water with various biological and physical methods. It＇s very important for industrial aquaculture to build water recirculating management and auto control system. Using this system, we can control some important water parameter like temperature, pH, dissolved oxygen （DO） and so on. Some parameters are controlled by biological methods. For example, the nitrifying bacteria that attach and grow in the biological filtration is used to transform ammonia and nitrite-nitrogen, this process could be monitored but couldn＇t be controlled exactly. Other parameters could be monitored on line and controlled exactly by physical methods as mentioned above. Temperature should be maintained within the range for optimum growth of the cultured species. Temperature could be regulated with electric immersion heaters, gas or electric heating units, heat exchangers, chillers, or heat pumps. Continuously supplying adequate amounts of dissolved oxygen （DO） to fish and the biofilter in the recriculating system is essential to its proper operation. DO must be maintained above 60% of saturation or above 5ppm. The air or pure oxygen is injected into the rearing tank water with air pump in industrial aquaculture. We can control the rotation speed of air pump to change amounts of DO, so that DO can be maintained within the optimum range. Generally speaking, Fish could tolerate a range of pH from 6 to 9. 5, although a rapid pH change of two units or more is harmful, especially to fry and the optimum pH range for biofliter bacteria is 7 to 8. So the pH range must be maintained from 7 to 8. We can control transducer, adjust valve or electromagnetic valve to add the alkaline buffers to maintain the pH within optimum range. For being supervised and controlled, these water parameters should be displayed and changed in computer by designing a program. This program can show data as tables and curves, the functions of this program also include how to save and print data and so on.