Basics of recirculating aquaculture systems (RAS)

Virtually all new land-based aquaculture systems built in Norway are recirculating aquaculture systems (RAS). This course will give a broad introduction to RAS. It will focus on the contribution of the water treatment system to a stable and optimal water environment for the fish. The course will briefly touch upon design, dimensioning, start-up, operation, monitoring and troubleshooting of RAS. The course will highlight the importance of good physicochemical and microbiological water quality in RAS. The students will participate in an excursion to a RAS. The course has a laboratory component where students will gain practical analytical skills for analyzing water quality in RAS.

At the end of the course, the student should be able to

Knowledge

1. List the most important water quality parameters for fish welfare
2. List the different physical, chemical and biological water treatment processes that are necessary in a RAS
3. Outline the common technologies and components used for water treatment in RAS, including drum filter, protein skimmer, membrane filter, fixed bed biofilter, moving bed biofilm reactor, UV disinfection, disinfection with an oxidizing agent, and CO2 degasser.
4. State the working principle of the each of the water treatment components
5. State the critical factors for functioning of the water treatment components
6. Recognize how the water treatment components affect each other
7. Explain qualitatively how changes in pH affect alkalinity and efficiency of the biofilter and CO2 degasser
8. Explain the most important factors during startup and operation of RAS
9. List different types of sensors and methods to measure the most important water quality parameters
10. Recognize the maintenance needs, uncertainties, problems and errors associated with sensors
11. Identify how physiochemical and biological factors can threaten the health of the farmed organism in RAS
12. Identify the main types of microorganisms in a RAS and their related reactions
13. Explain the factors affecting the efficiency of the nitrifying bioreactor
14. Recognize and recount RAS terminology used in industry

Application

1. Calculate and express the concentration of ammonia, nitrite, and nitrate in terms of nitrogen content
2. Given the peak feeding rate, dimension the nitrifying bioreactor and CO2 degasser. Calculate the intake water flow rate, sludge and effluent production
3. Calculate the recirculation flow rate and hydraulic retention time, given the required information
4. Calculate the consumption/production of compounds in chemical reactions, given the necessary stoichiometric information
5. Estimate the amount and form (dissolved in water, as gas or as a particle) of the most important waste products, given the feeding rate in RAS

Analysis

1. Predict how changes in pH affect the equilibrium and toxicity of CO2, NH3 and H2S
2. Predict how changes in water quality can affect the competition between nitrifying and heterotrophic microorganisms, and thereby the bioreactor function

Synthesis

1. Design a simple RAS and suggest the placement of water treatment components
2. Propose a sampling and measurement plan for analyzing the water quality in a RAS, including efficiency of water treatment components
3. Formulate a plan for management or use of the waste streams from RAS
4. Propose alternatives for disposal and use of wastes from RAS in an economical, practical and environmental perspective

Evaluation

1. Justify choice of water treatment technologies and their placement in the RAS
2. Assess if the water quality is within the safe limits of the production organism
3. Advocate measures and simple action plans to troubleshoot simple water quality problems during operation of a RAS, when the major water quality parameters are outside the recommended safe limits.

Lab skills

1. Explain basic working principle of spectrophotometer, pH sensor
2. Perform water quality analyses using analytical chemistry techniques, including pipetting and dilution of samples
3. Analyze relevant water quality parameters using analytical chemistry techniques
4. Identify possible sources of uncertainties and errors in laboratory measurements
5. Writing a lab report - Describe theory of lab study, record and describe lab procedures, record lab observations, analyze measurement data, construct appropriate graphs or tables to illustrate the observed data, describe results, justify and evaluate results in the context of theory, identify flaws and possible sources of errors that can explain the results, advocate measures to mitigate flaw/errors and recommend future studies or improvements.

The course will be taught in English.

The course consists of lectures (40 hours), laboratory work, report and presentation (40 hours), assignments (10 hours), excursion (10 hours), and self-study (100 hours). Total workload is estimated to 200 hours.

Compulsory assignments - 1. Excursion and excursion presentation, and 2. Lab work, lab report and lab presentation