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Disease causing pathogens endemic in BC coastal waters may be found in farmed and wild finfish and shellfish. Following the outbreak of Infectious Hematopoietic Necrosis virus (IHN) in farmed Atlantic salmon in 2001-2003, fish processing facilities became interested in the development of environmentally sound, practical and cost-effective methods for treating blood water effluent to neutralize pathogens and minimize waste impact on the surrounding environment. Disinfection of discharged water in fish processing plants is particularly important since pathogens may become concentrated due to the large volume of fish being processed. Implementation of an established disinfection system that is currently employed by other industries that deal with treatment of effluent water would increase the industry’s environmental stewardship and decrease the chances of spreading pathogens to the surrounding environment. In this project, a novel industrial-scale ultraviolet sterilization system was implemented at a fish processing facility (Walcan Seafood Ltd. Quadra Island, BC). In addition, preliminary tests to evaluate the efficacy of UV technology for neutralizing viral and bacterial pathogens were conducted on a laboratory-scale unit and, finally, on the commercial scale unit. The results of the assessment demonstrated that 1) at the laboratory level, common fish viruses and enteric bacteria were sensitive to UV treatment, and their inactivation response was UV dose-dependent, and 2) for the full-scale unit, there was a reduction in total bacterial counts as the effluent blood water flowed through the UV system. Another resulting outcome from the evaluation performed at the processing plant facility was that efficacy of the UV system was affected by the presence and size of the particles of suspended solids in the effluent. Exploring alternatives to reduce the presence and size of solids such as high speed spinning or pre-screening systems such as mesh screens of different sizes (in addition to the existing 500 micron filtration unit) would be highly recommended. This is the first time that an UV system has been tested in a processing plant facility, and the success of this pilot study funded by AIMAP invites further applied investigation to address not only the technical challenges that emerged, but also to make UV treament of processing plant effluent a safe and reliable innovation application that would add further value to fish processing facilities.
Canada’s reputation for high quality fish and seafood depends on keeping our wild and farmed aquatic animals protected against serious infectious diseases. Infectious agents, such as naturally occurring viral or bacterial diseases, can spread through water and do not distinguish between cultured and wild aquatic organisms. There are many infectious agents that are endemic to Canadian coastal environments. These pathogens may be found in farm-reared finfish, commercially harvested finfish and shellfish species, and free-living (endemic) in the environment. Treatment of discharged water from a facility that processes any of these organisms should be considered, especially at facilities where pathogens may be concentrated during the processing procedure. Proper disinfection is not only good environmental stewardship, but also important to reduce the risk of exposure and spread of pathogens. Although Canada enjoys a good reputation for healthy resources, maintaining this reputation requires vigilance. After the Infectious Hematopoietic Necrosis (IHN) viral outbreak in 2001-2003 in farmed Atlantic salmon, Walcan became interested in the development of a safe, practical, and cost-effective method of treating blood water and plant effluents to neutralize any potential bio-hazardous agents. Currently, processing plants screen effluent for particles (>0.5 mm) which are collected and transported off site. However, the remaining blood water is generally released into the water for natural dilution to take place. Some fish processors disinfect blood water effluent with chlorine prior to discharging it into the environment. However, this type of treatment is labour intensive and leaves room for miscalculation and contamination of the environment with a toxic substance.
Walcan Seafood processes both wild and farmed finfish products on Quadra Island in Johnstone Strait, BC. As a stakeholder in the community and a supporter of Quadra Island’s commitment to a cleaner marine environment, Walcan feels compelled to make changes in its use of a public resource to ensure that water returned to the environment is not harmful to marine life. Furthermore, it is anticipated that there will be more stringent federal and provincial regulations and; therefore, it is essential to develop the appropriate measures that will effectively neutralize any pathogens in blood water. The Canadian Food Inspection Agency (CFIA) already recognizes that a processing plant’s proximity to fish farms can be a risk to the farm. Therefore, a proactive strategy to mitigate any risk of catalyzing a disease outbreak from blood water is the implementation a sterilization procedure for blood water effluent prior to discharge into the environment.
With this system in place, Walcan will become part of an integrated approach to aquatic animal health thereby protecting the health of Canada’s aquatic resources, wild and farmed, and providing greater economic stability and potential for growth for the industries and regions that depend on these resources.
Currently, the technology used for waste water disinfection at fish processing plants is largely dependant on chemicals that are eventually released into the environment. Therefore, a green technology is needed to mitigate any bio-hazardous threat fish processing effluent may contain to ensure its safe discharge into the surrounding marine environment. Lateral technology transfer of a waste water treatment strategy to the seafood processing industry is the most direct approach for implementing a cost-effective and environmentally conscientious industrial treatment process. Implementation of a UV sterilization system to neutralize pathogens, such as IHNV, that may be associated with processing plant effluent is one-such technology. It is important to test the efficacy of the system using a virus that is commercially important to the aquaculture industry. Losses to IHN have been high in outbreaks of 1997, 1999, and 2001-2003 and have caused significant economic loss.
Walcan Seafood seeks to be the leader in implementing the first UV Sterilization unit in a commercial fish processing facility and perhaps set a new standard for the environmentally safe and cost effective treatment of fish processing effluent. This project sought to provide Walcan Seafood Ltd. with a state-of-the-art system for treating fish processing plant effluent and set a new standard of environmentally conscientious, non-toxic waste treatment in Canada’s aquaculture industry. Furthermore, installing such a system has provided the opportunity for regulatory agencies to observe the effectiveness of such a system first-hand, and may lead to the establishment of new environmental safety regulations based on actual data within the aquaculture industry.
Installation of an industrial grade U.V. sterilization system at Walcan Seafood’s processing plant.
This AIMAP project provided Walcan Seafood Ltd. with an innovative system for treating fish processing plant effluent and set a new standard of environmentally conscientious, sustainable waste treatment in Canada’s fisheries and aquaculture industry. Furthermore, this system has provided the opportunity for regulatory agencies to observe the effectiveness of such a system first-hand and may lead to the establishment of new environmental safety regulations based on actual data within the aquaculture industry.
Originally, quotes to acquire the UV sterilization unit were provided by several companies, and eventually two of them (Trojan Technologies and American UV) were chosen as possible suppliers of the equipment. Trojan technologies approached Walcan to inform them they had the newest UV system design for low transmittance fluids stating this would be a superior system. After further discussion between Walcan and Trojan technologies, it was decided that Trojan Technologies would be the company providing the full scale UV sterilization unit.
The equipment consists of a UV system chamber section containing a total of thirty (30) lamps. The system is comprised of a completely skidded package, which is designed to fit into the space available at Walcan (~ 8’ deep X 10’ long X 12’ high). The system require four (4) feet of clearance space for removal of lamps and sleeves and four (4) feet around the perimeter of the skid for additional clearances and safety. The system will consume approximately 7.0 kW of energy and be configured to operate on 120 Volt, single phase, 60 Hz power. The skidded package shall consist of:
1. UV System Chamber:
2. Control System:
3. Cleaning System:
To evaluate the efficiency of the commercial-scale system, baseline measurements of UV sensitivity of common fish virus and enteric bacteria were obtained using a laboratory scale unit.
The laboratory-scale unit used for UV treatment tests was an industry-standard collimated beam supplied by Trojan. The collimated beam allows the direct assessment of the efficacy of the UV treatments by generating dose-inactivation curves for selected pathogens exposed to different doses of UV irradiation at laboratory level.
Fish processing plant effluent water samples were collected at Walcan during normal operational loads (between 178 and 603 m³ daily) and were transported on ice to the BC Centre for Aquatic Health Sciences (BC CAHS) for further analysis. In order to test the efficacy of the UV system, effluent water samples were first seeded with viral pathogens, infectious hematopoietic necrosis virus (IHNV) and viral hemorrhagic septicemia virus (VHSV), and a bacterial (Escherichia coli) pathogen at known concentrations. The viral pathogens tested are of special concern for fish processing plants. The bacterial pathogen was initially tested to determine whether this pathogen could be used as a surrogate organism for viral pathogens. Doses of UV ranging from 0 to 4 mJ/cm² (viral pathogens) and from 0 to 25 mJ/cm² (bacteria) were applied. Efficacy of the treatments was determined by laboratory culture viability assays using established protocols at BC CAHS.
The unit is composed of four trains and six reactors (containing the UV lamps) per train. Each reactor should provide a UV dose of 1.4 mJ/cm². Therefore, after the effluent has passed through the six reactors, it should receive a total UV dose of approximately 8.4 mJ/cm². Processing plant effluents generated during normal operational loads (between 178 and 603 m³ daily) were exposed to a total UV dose of approximately 8.4 mJ/cm². . Samples were collected from ports at each reactor (six points) along the UV treatment system: 1) post-screening prior to UV treatment and 2-6) after each UV unit in series. For each of the 7 treatment points, triplicate samples were collected in sterile 500ml plastic vials and kept refrigerated at 4ºC. Effluent water samples were assayed for total bacterial counts, E. coli, and viral loads using standard plate count (SPC) and total culturable viral assay (TCVA), respectively.
The UV doses tested were: 0, 0.5, 1.0, 1.5, 2.5, and 4.0 mJ/cm². The test carried out on the laboratory scale unit showed that both IHNV and VHSV concentrations were reduced, in a dose-dependent manner, after exposure to UV. For IHNV, the concentration of virus decreased from 1.65 million on dose 0 (no exposure to UV) to 10 thousand on dose 4.0 mJ/cm². In a log scale this corresponds to approximately a 2 log reduction. For VHSV, the concentration of virus decreased from 425 thousand on dose 0 (no exposure to UV) to 1 thousand on dose 4.0 mJ/cm², corresponding to approximately a 2.63 log reduction. A dose-inactivation curve was also developed for IHNV and VHSV seeded in culture media (no suspended solids). The log reduction values at the highest UV dose tested (4.0 mj/cm²) of IHNV and VHSV seeded in culture media were 3.1 and 5.3, respectively. The log reduction values observed in effluent blood water and media were higher for VHSV, suggesting that this virus is more sensitive than IHNV to UV treatments.
The UV doses tested for E. coli were: 0, 5, 10, 15, 20, and 25 mJ/cm². Prior to applying the UV treatments, the stability of E. coli in effluent blood water was tested for 72 hours.
The results revealed that E.coli remained viable when seeded in fish processing plant effluent water. There were 9 x 108 colonies/mL at day 1, and 2.22 x 108 colonies per mL at 72 hours.
The concentration of E.coli decreased from 29000 colonies/mL on dose 0 (no exposure to UV) to 900 colonies/mL on dose 25 mJ/cm². In a log scale this corresponds to approximately a 1.5 log reduction.
For this component of the project evaluation, effluent blood water samples were assayed for E. coli and total bacterial counts. The diagram below is a representation of the commercial scale unit installed at Walcan. The coloured squares represent the ports (P) from where effluent samples were collected. The first sample was collected of the “in port” (yellow square on the left): prior to exposure to UV. Effluent blood water samples were also collected from ports 1-6, which were exposed to UV.
The results showed that total bacterial counts were reduced, in a dose-dependent manner, after exposure to UV. Effluent blood water collected at ports 1, 3, and 6 had total bacterial counts reduced by 26%, 87%, and 98.5%, respectively. In a log scale, the value observed at port 6 corresponds to approximately a 1.83 log reduction. Effluent blood water samples collected at all ports were negative for the presence of E. coli.
This project brought together partners from the industry and academia with expertise in UV disinfection technology (Aquafine Corporation – A Trojan Technologies Company), Fish Processing Plant operation (Walcan Seafood Ltd.), microbiological analysis (BC Centre for Aquatic Health Sciences), and viral aquatic organisms (Pacific Biological Station – Fisheries and Oceans Canada) to assess the application of UV technology for effluent blood water disinfection.
One of the main findings of this project was that the UV technology was effective in controlling pathogens, leading to reduced loads of pathogens in effluent blood water from fish processing plants. The pilot tests also revealed that the efficiency of the UV treatment varies with the effluent, UV dose, and the pathogenic organism being targeted. This indicates that there might be different technical requirements to achieve disinfection.
The project also documented that the performance of the commercial scale unit installed at Walcan was significantly affected by the presence of suspended solids in the effluent blood water. After a few hours of operation the equipment clogged with suspended solids that passed through the Walcan’s 500 micron screen filtration unit. Although the equipment is functional, this operational challenge, not anticipated by the company that designed and supplied the equipment (Aquafine Corporation - a Trojan Technology Company), can lead to decreased UV disinfection system performance and cost-ineffectiveness of the commercial scale unit. Engineers and technical staff at Walcan are working towards solving this challenge. Additional assessment of the commercial scale UV unit to address the issues above mentioned is deemed necessary before adequate recommendations for proper implementation and utilization can be made.
This AIMAP project provided Walcan Seafood with an innovative system for treating fish processing plant effluent water. This was a very important first step towards setting a new standard of environmentally conscientious, sustainable treatment in Canada’s Fisheries and Aquaculture Industry.
In order to build on the findings of this project and to refine the technology, the system requires further assessment. The following project aspects are being prioritized by Walcan Seafood to address and overcome the system’s technical challenges:
We wish to thank Gerald Murphy (Walcan Seafood Ltd) for coordinating all aspects related to field sampling; Jeff Forbes (Co-op student from UVic at BC CAHS) and Debbie Collins, Zina Richmond, and Elan Downey (BC CAHS) for their support during field sampling and laboratory analysis. We wish to thank AIMAP for providing funds that allowed installing and testing an innovative system for treating fish processing plant effluent water.
After the U.V. system plugged during the July 2010 trial run Walcan hired Aqua Terra Consultants who were mandated to develop a system to treat the waste water feed to the U.V.
In October Aqua Terra Consultants arrived and bench top tested 3 technologies, during 1 week of trials, which would clean up the waste water prior to the U.V. System:
After the analysis was completed and all the lab data was complied, Aqua Terra Consultants recommended that Walcan pilot test (at 50 gallons per minute – this is one bank of the 200 gallon per minute system installed) a combined treatment system that would include a Air flotation tank (to float fatty material) with the option to inject ferric chloride to help float some solid material, in combination with a 54 micron fine screen prior to the U.V. System
Components were located in both Canada (fine screens) and the USA (Air Flotation system) and arrangements were made to transport the pilot systems to Walcan. Everything arrived in late December and a Technician from the Air Floatation system arrived on January 3, 2011 along with Aqua Terra Consultants. All components had been installed by Walcan’s maintenance department and ready to go in the morning of January 3, 2011.
Pilot testing was done January 4, 5, 6 and 10 (days when the plant had fish to process). On all 4 days the U.V. system performed as expected – did not plug. No testing was done on bacterial kill since this pilot test was concerned with ensuring the system would run continuously at the rate each bank of lamps was designed for by the manufacture.
Result of the pilot test was clear – the waster water provided by the pilot system did not plug the U.V. system. Aqua Terra Consultants is now designing a full scale treatment system to be placed in front of the U.V. system to ensure a consistent quality and volume of effluent is available to operate the U.V system throughout the day.
The U.V. manufacturer now has some maintenance to perform on the U.V. system along with assisting Walcan with sourcing the IHN-V substitute plus assisting with the test protocols to prove their system functions as they stated.