Aquaculture Feed Bag Waste Management
The growth of the salmonid aquaculture industry in the Coast of Bays region of Newfoundland has highlighted the need for better waste management strategies within the sector. The volume of waste generated, in forms such as plastic feed bags, is placing significant strains on the rural landfills (i.e., dump sites) which were designed to accommodate small volumes of residential wastes. As a result of inadequate capacity, some municipalities have requested the industry not use the dumps, and no other infrastructure has been developed for the recycling of feed bags from aquaculture sites. This has forced some aquaculture companies to resort to burning the feed bags as a means of managing the volumes. This is not considered an acceptable alternative by industry or the Government of Newfoundland & Labrador (NL), and the Department of Environment and Conservation (DEC) has sent a clear message that the burning of such waste will be prohibited at all but the most isolated locations where alternatives are not presently feasible.
The salmonid aquaculture industry in Atlantic Canada is supplied feed in either 25 kg or 1000 kg bags, with the 25 kg bags being used at sites where feed is handled manually and the 1000 kg bags being used on at sites where feed is stored and distributed from large capacity feed barges. These feed bags are made of either low density polyethylene (LDPE) or polypropylene (PP) respectively. In some cases the one tonne bags comprise an inner and outer bag, where the inner is polyethylene and the outer polypropylene. In 2006 the production level of farmed salmonids in NL was approximately 7300 metric tonnes. At that time it was estimated that approximately 186,720 LDPE (25 kg) bags and 10,728 PP (1000 kg) bags were being used in sea water production per annum. This accounted for an estimated 19 tonnes of LDPE and 18 tonnes of PP.
The volume of feed bags generated by the industry continues to rise proportional to production, which is estimated could reach as high as 45,000 MT. Using production numbers from 2006 and extrapolating to 45,000 MT, estimates of the weight of feed bags would by about 115 tonnes of both LDPE and PP. (Extrapolation here has overestimated the weight of HDPE and underestimated the weight of PP since the trend is for companies to switch to bulk feed handling and away from the use of the smaller bags).
Recycling of aquaculture feed bags has been challenging as municipal recycling infrastructure does not exist in the Coast of Bays region, and indeed is rudimentary in Newfoundland. Even if such infrastructure was in place recycling of feed bags would still be problematic as they are seen by most recyclers as unacceptable because residual fish oils remaining in the bags from the feed are typically considered a contaminant. Cleaning of the bags doesnt seem to be a cost effective option.
The Newfoundland Aquaculture Industry Association is interested in research into the reuse or recycling of HDPE and PP feed bags for uses within and outside the aquaculture industry. Feasibility studies or pilot scale projects for innovative processes or products will be considered.