Process control of solid particles in circulating water (I): Control objectives and monitoring system construction!

Process control of solid particles in circulating water aquaculture     

Suspended particles in recirculating aquaculture systems are mainly composed of feces, leftover bait, bacterial flocs and fish mucus, which mainly come from the compound feed fed, of which 25% of the feed is eventually converted into suspended matter. Inappropriate feeding strategies and removal methods can easily cause the accumulation and decomposition of suspended particles in the system, which in turn has a negative impact on fish health and aquaculture water quality. The accumulation of suspended particles causes stress responses in farmed animals, affects gill respiration, and reduces the disease resistance of fish. The accumulation of suspended particles can also easily cause clogging of aquaculture facilities. The decomposition and mineralization of suspended particles in the recirculating aquaculture system leads to an increase in the content of ammonia nitrogen and nitrite in the aquaculture water, increases the biochemical oxygen demand, increases the load on the biofilter and affects its nitrification function. Therefore, the rapid removal of suspended particles in the recirculating aquaculture system is crucial to maintaining the normal operation of the water treatment system, avoiding water quality degradation, and ensuring the normal growth of farmed animals.

Ⅰ. What is circulating water solid particle process control?     

Recirculating aquaculture solid particle process control refers to the process of monitoring, removing and regulating the suspended solid particles (Total Suspended Solids, TSS) in the water body through a series of technical and management measures in the recirculating aquaculture system to maintain stable water quality, ensure the health of aquaculture organisms and improve the operating efficiency of the system. In the recirculating aquaculture system, solid particle process control is a key link to ensure the efficient operation of the system, maintain stable water quality and ensure the health of aquaculture organisms. Circulating water solid particle process control includes the following parts:

(1). Control objectives

1. Keep the water clean: By controlling solid particles, prevent them from accumulating in the water and causing water quality deterioration, such as reducing the transparency of the water body and providing a good living environment for farmed organisms. Control the TSS concentration in the water body within the acceptable range for farmed organisms (generally TSS is controlled at 10-30 mg/L)

2. Reduce the occurrence of diseases: Solid particles may carry pathogens or provide a place for pathogens to breed. Effective control of solid particles helps reduce the risk of farmed organisms contracting diseases.

3. Improve system efficiency: prevent equipment blockage, extend equipment service life, and reduce operating costs.

(2). Control link

1. Reasonable feeding: Accurately calculate the feeding amount to avoid excessive feeding and excessive residual feed. According to the type, size, growth stage and feeding conditions of the cultured organisms, formulate a scientific feeding strategy. It is recommended to install an automatic feeding machine and adopt a scientific feeding strategy, such as feeding in small amounts and multiple times, to reduce the residual feed from entering the water body to form solid particles.

2. Optimize the breeding density: According to the carrying capacity of the breeding water body and the growth characteristics of the breeding organisms, reasonably determine the breeding density. Excessive breeding density will lead to an increase in biological metabolites and a corresponding increase in the amount of solid particles generated. Therefore, it is necessary to adjust the breeding density in a timely manner to prevent overcrowding.
(3). Real-time monitoring and process control

 1. Water quality monitoring: Install a turbidity meter to monitor the concentration of solid particles, turbidity and other indicators in the water body in real time or regularly, as well as other related water quality parameters such as dissolved oxygen and pH value, so as to understand the changes in solid particles and water quality.

2. Intelligent control: Based on the monitoring data, the intelligent control system is used to automatically adjust the operating parameters and treatment processes of related equipment, such as adjusting the operating time and frequency of the filtration equipment, the aeration intensity of the biological treatment unit, the dosage of the added chemical agent, etc., to achieve precise control of solid particles.

Ⅱ. Monitoring system for process control of solid particles in circulating water   

 Establishing a monitoring system for the process control of solid particles in circulating water is an important step in realizing the intelligent management of recirculating aquaculture systems. Only by real-time monitoring and controlling the concentration of suspended solid particles (TSS) in the water body can timely regulation be carried out to ensure stable water quality and the health of aquaculture organisms. Establishing a monitoring system for the process control of solid particles in circulating water requires selecting appropriate monitoring equipment, installing and debugging the system, managing and analyzing data, and integrating it with the control system. Through real-time monitoring and intelligent regulation, the concentration of suspended solid particles in the water body can be effectively controlled to ensure the efficient operation of the recirculating aquaculture system and the healthy growth of aquaculture organisms.

(1). Choose the right monitoring equipment     

The monitoring of suspended particles in water requires the use of a total suspended solids concentration TSS sensor.

Working principle: Measure the concentration of suspended particles in water using optical or ultrasonic technology.

Technical parameters:

Measurement range: 0-100 mg/L or higher.

Accuracy: ±2% or higher.

Output signal: 4-20 mA, RS485, Modbus, etc.

(2). Sensor installation     

Installation location:

Aquaculture pond: monitor TSS concentration in aquaculture pond.

Inlet and outlet of filtration equipment: evaluate the removal efficiency of filtration equipment.

Installation method:

Immersion: immerse the sensor directly in the water body.