Water contamination from mining activities is a global problem, damaging many freshwater ecosystems. This water, which can seep into the natural environment is high in heavy metals and can be very acidic. Options for treating this water can be very expensive or impractical for many of these contaminated sites, which can include abandoned mines. A new, inexpensive way of treating this water is being studied by CRL Energy in New Zealand, using mussel shells, a waste product itself from the food industry.