In recirculating aquaculture system, physical filtration is the first barrier of water purification. It is mainly responsible for removing impurities such as suspended matter, organic particles, feed residue and fish excrement in the water, laying a solid foundation for subsequent biological filtration and chemical treatment.
Today, we will talk about physical filtration technology and equipment in RAS water treatment units.
Tank bottom sewage collector
The bottom of the tank is mainly responsible for collecting fish excrement and feed residue. Common traps include fish toilets and swirl traps.
Fish toilet: Fish toilet is usually installed at the bottom of the aquaculture tank, it has two functions, to prevent the escape of farmed organisms and discharge dirt.
Cyclone sewage collector: Cyclone sewage collector collects the feces and bait at the bottom of the pool to the sewage collector by rotating the water flow. This equipment not only improves the efficiency of pollution collection, but also reduces the frequency of manual cleaning, further improving the stability of the breeding environment.
Vertical flow separator
The aquaculture wastewater is filtered first through the vertical flow separator. It uses the natural sedimentation principle of water flow under the action of gravity to separate suspended matter and particulate matter in water. The vertical flow separator usually has a high removal efficiency, which can remove 50%-60% of the settling particle dirt and reduce the pressure of the subsequent microfilter.
The design of a vertical flow separator usually includes an inlet, a separation chamber and an outlet. After the water enters the separation chamber from the inlet, suspended matter and particulate matter gradually settle to the bottom under the combined action of gravity and water velocity, while the clean water is discharged from the upper outlet and enters the next stage of treatment.
microfilter
The micro-filter is a purification device for solid-liquid separation by intercepting solid particles in the sewage body, and the micro-filter can remove 30%-40% of suspended dirt.
The working principle of the micro-filter is to pump the water in the aquaculture tank into the equipment, after the filtration of the micro-hole filter medium, the clean water is discharged from the outlet pipe, and the impurities are collected on the surface or inside the filter medium. Regular cleaning or replacement of the filter medium can maintain the filtration efficiency and stability of the microfilter.
According to the flow classification: box drum microfilter (small flow) and open drum microfilter (large flow);
According to the material classification: PVC (PP) box-type drum micro-filter and stainless steel drum micro-filter.
Sum up
Physical filtration is an important means to realize efficient utilization of water resources and environmental protection. Through the joint action of the bottom of the tank, the vertical flow separator and the micro-filter, the suspended matter, particulate matter and harmful substances in the water are removed, and the fish are provided with a stable and clean growth environment.