Executive Summary
The Auckland Regional Council’s (ARC) Stormwater Action Plan (SWAP) has several work streams, one of which is to investigate innovative technologies. As part of this, ARC has been investigating the potential of using crushed shellfish shells to remove contaminants from stormwater. The ARC has undertaken a series of projects investigating the potential of New Zealand green-lipped mussel (Perna canaliculus) shells for the removal of dissolved metals from stormwater. This report compiles findings from that series of projects. The first part of the work was a literature review, which found that marine shells have considerable potential for removing metals from aqueous solution. A laboratory experiment was performed in which crushed Perna canaliculus shell was exposed to dissolved zinc (Zn2+ (aq)) and copper (Cu2+ (aq)). The analytical results show that the mussel shell has a significant capacity for removing these metals from solution, most probably due to an exchange mechanism with calcium (Ca2+) ions from CaCO3. Further laboratory experiments were carried out to investigate how crushed Perna canaliculus shell could be implemented in stormwater filter systems. This was done by using flow-through rather than static experiments, the first of which had a long solution-solid contact time of around six hours and found that the absorption capacity was being exceeded at a loading of around 650 μm of Zn per gram of mussel shell. The second flow-through experiment decreased the solution-solid contact time to 30 mins, extended the shell particle size range and increased the amount of shell being used, each column containing 150 g of shell in contrast to 20 g initially used. The results of the second flow-through experiment demonstrated the near-equivalent relationship between zinc loading and calcium release and found that the column absorption efficiency was not