Aquaculture is an industry that has enormous potential to grow. It is estimated that Ireland’s annual output for seafood (captured and farmed) will be worth €1.25 billion by 2025, with an additional 250 jobs created and with the largest growth being from aquaculture (1). Farmed fish is an efficient foodsource when compared to traditional protein production (2). There are still areas in the production of freshwater fishes that must be addressed but, with the application of innovative engineering and novel technologies, these can be addressed. The main challenges facing the industry is minimising environmental impacts, reduction in energy consumption and reduction in mortality rates. This article outlines some of the challenges and opportunities facing the industry, the work being carried out by MOREFISH (a collaborative research project) and how engineers can play a major role in the future success of this sector. MOREFISH is a multidisciplinary collaboration between the National University of Ireland, Galway, Athlone Institute of Technology and the aquaculture industry, which is developing innovative technologies and processes which could significantly improve production management and efficiencies at inland aquaculture sites. [caption id="attachment_35640" align="alignright" width="300"]Morefish1 CLICK TO ENLARGE Fig 1: The standard method taken by the MOREFISH team when assessing an aquaculture site. Using this methodology, a holistic assessment of a site can be achieved and allows practitioners to focus on the areas that require attention[/caption] Key areas of focus for the project include (i) enhancing production efficiency and sustainability, (ii) ensuring environmental impacts are minimised in the context of a growing industry and (iii) improving fish health and reduce diseases/mortalities in rearing systems due to improved operating conditions (Figure 1). The project draws on the experience of industry stakeholders in the development of new technology and process control methods while also carrying out extensive monitoring campaigns on site to benchmark the efficiency and impacts of various facilities. To date, the MOREFISH project has conducted various on-site trials at freshwater aquaculture sites and has tested at laboratory and site scale a number of novel aeration and disinfection technologies. Irish aquaculture currently ranks as fifth in value and seventh in volume for aquaculture products in Europe (3). Irish aquaculture is valued at €90.7 million, achieved largely through the organic status of salmon reared at sea. In 2015, the Department of Agriculture, Food and the Marine (DAFM) published the National Strategic Plan for Sustainable Aquaculture Development (4). The aim of this plan is to sustainably increase production of the Irish aquaculture sector to 45,000 tonnes per annum across all species by 2020. The volume of freshwater species produced is also expected to increase under the new plan, with the greatest increase being in smolt (juvenile salmon) and rainbow trout production, respectively.

The WFD and Section 4 licences

The majority of Irish freshwater aquaculture units consist of flow-through-systems (FTS). These sites generally do not treat incoming water and some farms are not required to treat their discharge. The introduction of the EU Water Framework Directive (WFD) and its incorporation into Irish law has been the most significant event in Irish freshwater aquaculture since the 1950s. Each inland fish farm in Ireland is issued with a Section 4 discharge licence under the 1977 Local Government (Water Pollution) Act (5). These licences stipulate the conditions, parameters and values that must be met by the farm. Complying with a Section 4 licence is imperative if a farm is to maintain its aquaculture licence from DAFM. The introduction of S.I. 272 of 2009(6), has lowered the threshold values previously used(7) and has warranted the introduction of a standardised approach that is used by local authorities in the issuance of licences for the sector. The discharge limits are defined as differential concentrations between inlet and outlet water for a given farm. This has resulted in a paradigm shift, in that industry must now move from traditional FTS with minimal or zero treatment to a programme of intensive remediation in order to comply with licence conditions. The next WFD management cycle involves the second river basin management plan that will end in 2021, which could impact significantly on the industry. Thirteen current licences were reviewed by the project. The limits (given as the difference in concentration between the influent and effluent) for ammonia range between 0.1-0.5mg N/l. One farm has a licence which is based on an absolute concentration rather than a differential between influent and effluent. [caption id="attachment_35641" align="alignright" width="300"]MOREFISH2 CLICK TO ENLARGE Fig 2: Data gathered by discharge licensing authorities was reviewed for 2005-2015. The red dashed line in each graph represents the 95%ile. Each farm in this site was in compliance with discharge limits (8)[/caption] On other Section 4 licences, differential values for total ammonia are stipulated. The values for this range from 0.03-0.8mg N/L. These newer discharge limits set for ammonia (under both titles used on licences) are very low in comparison to the values listed on some licences prior to 2009. A grace period was granted by some local authorities in order to give farms time to comply. But without significant changes in operation and capital investment it is unlikely that all farms can/will be able to comply without a reduction in their output. With that being said, analysis by the team conducted on one of the largest trout production facilities in the country, showed that effluents were compliant (Figure 2). Furthermore on-site monitoring, at a similar trout facility, by the MOREFISH team demonstrated limited changes in water quality for the majority of parameters, apart from ammonium.

Life-cycle assessment

Life-cycle assessment (LCA) and other benchmarking tools can measure production efficiency and the associated environmental impacts to help identify improvements in production performance and the flows to and from the environment. LCA assesses the environmental impacts of a product and/or process from ‘cradle to grave’. It can offer an assessment of the environmental performance of the production of an item. The results from a LCA can be used to provide policy makers and industry with information as to how processes can be made more efficient and which stages of a process are performing well. The challenge with the use of LCA in aquaculture is that there is no standardised aquaculture production system. Each site is unique, with variances in water supply, layout, management, energy supply/demand, species grown, feed type, food conversion ratios, assimilation capacity of receiving waters and differing degrees of environmental impacts both on global and local scales. [caption id="attachment_35642" align="alignright" width="300"]MOREFISH3 CLICK TO ENLARGE Fig 3: Based on the compilation of an inventory of the flows to and from a product it is possible to account for the potential impacts that a product cycle can pose to the environment. Traditional factors assessed include: global warming potential, eutrophication potential and acidification potential. Adapting certain key LCA methodologies, it is possible to include biodiversity impact potential into studies on freshwater aquaculture units using WFD techniques used in establishing the ecological status of a waterbody[/caption] Implementation of standardised benchmarking and LCA systems could enable farms to determine the volume of nutrients being released per functional unit, adjust to more appropriate feeding regimes thus potentially the levels of nutrient in their effluent. Another gap in the life-cycle assessments is the measurement of long-term impacts (positive, negative or neutral) on biodiversity. MOREFISH is currently developing a methodology to incorporate a biodiversity impact potential factor for LCA, utilising the techniques used by the WFD in determining the ecological status of a waterbody (Figure 3). There is a distinct gap in reproducible biodiversity metrics in LCA studies and it is envisaged that using WFD techniques to establish impacts on local biodiversity from aquaculture activities will produce a robust metric that can both improve in-house processes but also provide a more holistic measure of life cycle impacts.

Technologies

The aquaculture industry in many ways faces similar engineering challenges to the wastewater sector. These include the efficient supply of oxygen, process control based on data from oxygen, pH and other sensors, removal of suspended solids, organic carbon and nutrients from wastewaters and the opportunity to leverage efficient water re-use systems. MOREFISH has examined a number of these areas with a key focus on aeration, process control and disinfection.
  • Aeration and process control
Micro/nano bubbles have unique characteristics, such as: high surface area to volume (increased contact area for oxygen transfer), high air-water interface area, low rise rates (increased time for gas transfer), negative charge (limits coalescence of bubbles), and self-pressurisation of bubbles with decreasing size (increased dissolution). Following on from pilot scale evaluations, in both aquaculture and wastewater treatment sectors, the potential benefits of microbubble technologies can be realised for aeration/oxygenation, degassing and wastewater applications in the freshwater aquaculture industry. Given microbubble technology has the potential to deliver significant increases in standard aeration efficiency over traditional oxygen cones, thus enabling increased aeration/oxygenation efficiency, efficient degassing, a reduction in power consumption, improved water quality and providing a singular technology for multiple processes. Key process control interventions included the monitoring of energy usage and demand, water quality and feed usage. While a number of complex interventions were proposed by the project team following on-site monitoring campaigns, some very simple changes were also noted that would result in immediate and not insignificant savings. For example, it was discovered that some of the key machinery (oxygenators and aerators) used on the site were highly inefficient. By implementing power factor correction, the annual ‘wattless power’ usage could be reduced by between 53-92% on the range of motors monitored. Applying this PF correction over all of the 11 electric motors used (which would be relatively inexpensive) on this site would yield an annual cumulative saving in the region of €2000. Utilising both existing technology and process control systems alongside new technology such as microbubble aeration systems could enable the sector to reduce its carbon footprint through reduction in energy usage and contribute to its overall sustainability. Improvements in water quality, particularly as part of effluent remediation, will enable production rates to increase while putting the industry in a position to maintain compliance with discharge limits
  • Pulsed ultraviolet technology
Disinfection is a critical part of effective water treatment and is responsible for the removal of and/or inactivation of pathogenic microorganisms to prevent the spread of waterborne disease. Current disinfection strategies include UV; ozone; lime; chlorine dioxide; bromine chloride and gamma irradiation where barrier systems include membrane filtration systems. MOREFISH is currently focused on various next-generation disinfection technologies including pulsed light UV. Pulsed ultraviolet (PUV) technology could offer a radical new approach to energy delivery in the UV market. The intensity of PUV is 50,000 times that of sunlight and has broad-ranging anti-pollutant properties. PUV is efficient in terms of energy delivery and inactivation efficacy as it can dissipate many megawatts of electrical power in the light source unlike conventional alternating-current systems. PUV produces a greater intensity of the shorter biocidal wavelengths of light; thus it is possible to employ an extremely short energisation time of the light source ( PUV has been optimised for reliable and repeatable destruction of finfish pathogens, such as Aeromonas salmonicida and Flavobacterium psychrophilium under varying operation conditions. Related studies from MOREFISH researchers has demonstrated that PUV successfully destroys recalcitrant waterborne parasites (such as Cryptosporidium parvum, Giardia lamblia)(9) and viruses (norovirus)(10).

Conclusions

In mid-October 2016, the MOREFISH team hosted some of Ireland’s largest fish producers for a day of talks by international and Irish experts in the area of aquaculture. From this meeting, it was agreed that the project could support an independent platform that could help the industry leverage new research with a view to increasing production and high-value exports in a sustainable manner. The work on sustainable, efficient systems and management practices has become a focus in many food production areas. To guarantee the sustainability of the sector requires research and development of innovative engineering solutions in the areas of i) suitable process controls and novel technologies ii) The accompaniment of baseline LCA studies iii) review of regulatory controls and iv) analysis of long-term datasets. The above areas combined with strong ties to industry make it possible to ensure the sustainability of freshwater aquaculture. By focusing on the production stage of Ireland’s freshwater aquaculture sector, MOREFISH is helping to ensure there are ‘more fish’. More information on the MOREFISH project can be found on www.morefish.ie or follow the project on twitter @MOREFISHproject. MOREFISH is funded by the Department of Agriculture, Food and the Marine (Grant Number: 14/SF/872). Authors: Ronan Cooney (1*), Alexandre Tahar (2), Alan Kennedy (1), Conor Behan (1), Sarah Naughton (2), Siobhán Kavanagh (2), Andy Fogarty (2), Richard FitzGerald (1), Neil Rowan (2), Eoghan Clifford (1*). (1) College of Engineering and Informatics, NUI, Galway, (2) Bioscience Research Institute, Athlone Institute of Technology. * Corresponding authors’ email: eoghan.clifford@nuigalway.ie, ronan.m.cooney@nuigalway.ie References: 1. National Economic & Social Council (2016). Sustainable Development in Irish Aquaculture. NESC Report No. 143 April 2016. 2. Cao, L., Diana, J., Keoleian, G. (2013). 'Role of life cycle assessment in sustainable aquaculture.' Reviews in Aquaculture 5(2): 61-71. http://hdl.handle.net/2027.42/98772 3. European Maritime and Fisheries Fund (2015). Ireland Fact Sheet. http://ec.europa.eu/fisheries/cfp/emff/doc/op-ireland-fact-sheet_en.pdf Accessed on: 27/04/2016 4. Department of Agriculture Food and the Marine (2015). National Strategic Plan for Sustainable Aquaculture Development. https://www.agriculture.gov.ie/media/migration/seafood/marineagenciesandprogrammes/nspa/NationalStrategicPlanSusAquaDevel181215.pdf 5. Local Government (Water Pollution) Act, 1977 6. European Communities Environmental Objectives (Surface Waters) Regulations 2009 (S.I. No. 272/2009). 7. European Communities (Quality of Salmonid Waters) Regulations, 1988 (S.I. No. 293/1988) 8. Tahar, A., Kennedy, A., Naughton, S., Cooney, R., Fitzgerald, R., Fogarty, A., Rowan, N., Clifford, E. 2016. 'Long term evaluation of the impact of traditional rainbow trout farming on river quality in Ireland – a 10 year case study.' European Aquaculture Society, Aquaculture Europe 2016. Edinburgh, Scotland. 23rd September 9. Garvey, M., Hayes, J., Clifford, E., Rowan, N. (2015). 'Ecotoxicological assessment of pulsed light-treated water containing microbial species and Cryptosporidium parvum using a microbiotest battery.' Water and Environment Journal. 29 (1): 27-35. 10. Barrett, M., Fitzhenry, K., O’Flaherty, V., Dore, W., Keaveney, S., Cormican, M., Rowan, N, Clifford, E. 2016. 'Detection, fate and inactivation of pathogenic norovirus employing settlement and UV treatment in wastewater treatment facilities.' Science of the Total Environment (568), 1028-1036.