Gold and platinoids in sewage sludges

Publisher Website
Google Scholar
Abstract
Sewage sludges from German municipal wastewater treatment plants possess high gold concentrations (280 to 56,000 μg/kg in dry matter) similar to some ore deposits which are being mined for gold. In addition, the sludges exhibit elevated platinum (<10 to 1,070 μg/kg) and palladium values (38 to 4,700 μg/kg), and low osmium (<3 to <51 μg/kg), iridium (0.6 to 26.5 μg/kg), ruthenium (<2 to 390 μg/kg), and rhodium contents (<2 to 352 μg/kg). Major amounts of these metals are already present within the wastewater solids before the raw sewage reaches the treatment works. Sludges from industrial areas tend to possess higher precious metal values than those from rural regions. Thus industrial discharges contribute significant quantities of precious metals to municipal wastewaters and sewage sludges. However, elevated precious metal contents in sludges from rural areas show that additional sources are present which remain to be determined by future studies.