Land-based Industrialized Recirculating Aquaculture System (RAS) Process and Parameter Design (Part 1)

Process Design

Land-based Industrialized Recirculating Aquaculture System (RAS) (RAS)

Land-based Industrialized Recirculating Aquaculture System (RAS) (RAS) employs modern industrial technologies—including engineering, biotechnology, mechanical equipment, information systems, and scientific management—to comprehensively control the aquaculture process. It creates optimal environmental conditions for aquatic organisms, enabling year-round high-density, high-efficiency, and healthy production, and represents a pivotal direction for the future of aquaculture.

Design Workflow

The design of Recirculating Aquaculture System (RAS) water treatment processes is based on material balance principles, with the core objective of rapidly removing harmful substances (e.g., suspended solids, ammonia nitrogen). Balance equations for these pollutants are established to derive system parameters, which are then refined using engineering practical experience to enhance model reliability.

Key design parameters depend on: Cultured species and Maximum Biomass Carrying Capacity ( Biomass Carrying Capacity=Density×Effective Water Volume ) From this, daily feed input and total waste (solid particles, ammonia nitrogen) are calculated. These values determine equipment specifications (e.g., biofilter size, bio-media volume, microscreen filter capacity).

Step-by-Step Workflow

Step 1: Determine Aquaculture Water Volume

The water volume should be determined based on land availability, financial capacity, and operational scalability.

Step 2: Select Aquaculture Species

Species selection must consider: Water quality compatibility, Farming complexity, Growth cycle, Market demand, Economic viability.

Step 3: Define Stocking Density & Maximum Daily Feed Input

Calculate a reasonable breeding density based on the selected breeding species and the size of the breeding water body, and use this to calculate the maximum daily feeding amount.

Step 4: Quantify Maximum Waste Production

The core of the design of industrialized circulating water treatment process is how to quickly remove the breeding waste generated after feeding. In other words, before feeding, all water indicators in the aquaculture pond are balanced and meet the standards. But after injecting a large amount of feed, the balance of the breeding pond will be disrupted, and a large amount of solid, liquid, and gaseous waste will be generated.

Step 5: Design Water Treatment Equipment

Calculate the performance parameters of water treatment equipment based on the maximum total amount of waste.

Reference Process Parameters

Special Operational Modes

In addition to the normal aquaculture mode, the following normal factors should also be considered during the process of Recirculating Aquaculture System (RAS) System (RAS).

1. Power outage emergency mode

Power outages during the aquaculture process can cause fatal losses to the circulating water aquaculture system, so it is necessary to have a power outage emergency mode in the design to prevent power outages from occurring.

1) Install backup generator: Quickly start the generator in case of power outage to ensure the normal operation of the circulating water system.

2) Design overflow pipeline: When the circulating pump is powered off and not working, the overflow pipeline can promptly drain the water in the pump pool to prevent water from overflowing the pump pool.

3)Equipped with emergency oxygenation: farmed animals may die quickly under low dissolved oxygen conditions. The liquid oxygen system does not rely on electricity and can continuously supply oxygen to the breeding pool in the event of a power outage, ensuring the short-term health of the breeding animals.

Disinfection Mode

Relying solely on physical sterilization to disinfect the water is not enough if the breeding animals develop diseases during the breeding process. At this time, some chemicals may be used for disinfection and sterilization. The residue of chemical drugs is likely to enter the biochemical filter through water circulation. The nitrifying bacteria in the biochemical filter are very fragile. The influx of chemicals is likely to kill nitrifying bacteria on a large scale. Therefore, when designing a Recirculating Aquaculture System (RAS) system, there must be a separate disinfection mode. When chemical disinfection is required, ensure that the circulating water does not flow through the biochemical filter.

Idle Mode

In humid environments, metal components of valves (such as valve stems, valve cores, etc.) are prone to chemical reactions with oxygen and moisture in the air, resulting in rust formation. During the breeding process, valves often rotate, and rust is removed by friction between components. However, long-term maintenance will accumulate a large amount of rust between valve components, increase the friction between valve components, and make it difficult for the valve to rotate or even open. In view of this, in the maintenance mode, all valves will be opened once a day to avoid valve failures caused by prolonged disuse.

Given the above special mode, if it is considered that the operation is relatively complex, it will cause unnecessary losses if workers make mistakes. Bang Bang has launched a smart control system for circulating water, which can switch between different operating modes according to different scenarios.