Sono-electrochemistry (Electrolysis with assisted Power Ultrasound) Treatment Trials of discharges from Cwm Rheidol - Ystumtuen mines, Ceredigion, Mid Wales, UK

摘要

The Cwm Rheidol-Ystumtuen metal mines discharge acidic waters adversely effecting 18 km of the River Rheidol to the sea. Collectively Adits 6 and 9 discharge c. 4.8 tonnes zinc, 160 kg lead, 11 kg cadmium and 4 tonnes iron into small ineffective limestone filter beds before reaching the river at the mouth of the Rheidol gorge. The Metal Mines Strategy for Wales has Cwm Rheidol ranked as the seventh most polluting. Previous Passive treatment trials confirm that such treatment would require a large area of unavailable flat land. Laboratory sono-electrochemistry trial success on Parys Mountain discharges indicated that magnesium electrodes could be trialled at Cwm Rheidol to produce magnesium hydroxide, raise the pH of the water and precipitating the metals as insoluble hydroxides. These highly successful electro-chemistry treatment trials (sono EC reactor, flocculator and lamella clarifier) identify that 99.5% of metals can be safely recovered using 1 kW/m~3. Full scale treatment (32 m~3/hr flow rate) is now a viable Active treatment process that can be applied in NRW's feasibility options for Cwm Rheidol at full scale, demonstrating an additional treatment tool to help failing water bodies achieve compliance with the EU Water Framework Directive (WFD).