PROJECT DESCRIPTION
BACKGROUND
Galicia (Spain) is highly dependent on fisheries, with fishing (including shellfish), aquaculture and related activities accounting for 10% of gross internal product. The region accounts for the highest production of transformed fish products in Europe and in some cases in the world (e.g. mussel canning).
The southern Galician estuaries are considered one of the world’s most biodiverse marine ecosystems. However, the intrinsic nature of the canning industry (e.g. small family-run companies) and the difficultly in treating the generated effluent has threatened the ecological and environmental integrity of the Galician estuaries in recent decades. As an example, a medium-size fish cannery can release, on average, around 51 tonnes of nitrogen, six tonnes of phosphorous and 143 tonnes of organic matter into the environment. Therefore, there is a need for effective solutions to reduce the environmental impact of these activities.
OBJECTIVES
The LIFE SEACAN project will demonstrate the feasibility of applying biofilm-based wastewater treatment systems to reduce the impact of the effluents generated from fish canneries located in coastal zones.
In particular, the project will test and compare two biofilm-based processes: biomass grown in carriers and biomass grown as granular sludge. These technologies will be tested in a fish cannery through a newly-built pilot wastewater treatment plant, with a capacity ranging from 4-8 m3/h. It will be divided into two units: a packed bed reactor, where biofilm will grow attached to carriers, and a granular sludge reactor, where biofilm will grow in the form of granules. The two bio-film systems will operate in parallel, allowing for a direct comparison. The demonstration period will take into account the time needed to monitor biodiversity change around the cannery site and to quantify the environmental impact associated with the implementation of this technology.
The project results will be used to produce a good practice manual with regard to wastewater treatment in the fish canning industry.
Expected results: The project expects to develop an effluent treatment process with a 25% lower environmental footprint in comparison with conventional treatment processes implemented in fish canneries. In particular, this new process will produce the following concrete environmental benefits:
RESULTS
LIFE SEACAN helped reduce the environmental impacts of fish canning effluents in the marine ecosystem, by successfully demonstrating the feasibility of biofilm-based processes for the treatment of wastewater. These technologies have significant environmental and economic advantages over current treatments, such as conventional activated sludge (CAS).
Two biofilm-based technologies, namely Aerobic Granular Sludge (AGS) and Moving Bed Biofilm Reactor (MBBR), were applied for the treatment of fish canning wastewater in two pilot prototypes. These were installed and operated in a fish canning factory in O Grove (Galicia, Spain). The fish canning wastewater was segregated into two streams: (i) water derived from cleaning processes, sterilisation and washing of cans, and (ii) water derived from defrosting, cooking and bleeding of fish. In addition, a wastewater mixture of both streams was also treated in the prototypes, with different proportions of each.
In the MBBR treatment system, microorganisms form a biofilm on the surface of external carriers. The system operates continuously, with wastewater flowing through several tanks under aerobic conditions. The organic loading rate applied was 2 kg COD/m3/d. The main results were: good biofilm formation on carriers; COD removal efficiency higher than 70%; total nitrogen removal of 70%; grease removal efficiency of 89%; concentration of grease and fats admitted by the MBBR system (system operational limit) was 200 mg/L; and compliance with current discharge limits.
In AGS technology, microorganisms grow in compact aggregates called granules. Anoxic and aerobic conditions are feasible, allowing the simultaneous removal of organic matter and nitrogen in the same unit using a sequencing batch mode operation. The technology was tested with two organic loading rates: (i) a low-strength wastewater mixture (as for MBBR), and (ii) a high-strength wastewater mixture of 5-7 kg COD/m3/d. The main results for the low-strength wastewater were: COD removal efficiency of 70-80%; total nitrogen removal efficiency up to 90%; fast formation of aggregates (30 days); and discharge limits met, except for COD, BOD and grease. The main results for the high-strength mixture were: high and stable COD removal efficiency of 80-90%; total nitrogen removal efficiencies between 30% and 40%; though discharge limits were not met for any parameter. Therefore, despite the high removal efficiencies of the latter system, an additional treatment is necessary to remove the remaining COD and nitrogen to fulfil discharge requirements.
The project team monitored benthic species in two locations to evaluate the impact of fish canning on marine ecosystems, and made recommendations to reduce this impact. Life Cycle Assessment (LCA), comparing both innovative systems to current fish canning wastewater treatment (e.g. CAS), found an 80% reduction of footprint for the project’s technology. AGS CAPEX was 20-50% lower than CAS for the treatment of high-strength wastewater. The total cost savings calculated for AGS and MBBR prototypes ranged between 49-51%, compared to the current technology, including the additional investment required to renovate the plant (if only OPEX is considered, savings reached 72%). There was an important reduction in estimated environmental damage for both biofilm-based technologies for the case of eutrophication. The expected value of damage to river ecosystem and marine ecosystems decreased by up to 74% and nearly 90%, respectively, for AGS; and by 65% and 70%, respectively, for MBBR.
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).
