Phosphorus removal using Ca-rich hydrated oil shale ash as filter material – The effect of different phosphorus loadings and wastewater compositions

Reuse potential of phosphorus-rich filter materials from subsurface flow wastewater treatment filters for forest soil amendment

“…According to Kõiv et al (2010), the weighted average P concentration in inflowing water at the Tapa treatment system was 4.8 mg total P l -1 , but varied significantly from 0.14 mg l -1 to a maximum of 13.0 mg l -1 . Hydraulic loading to the horizontal flow filters was 53 mm days -1 , and the filter systems were periodically loaded, 12 times days -1 .…”

“…Hydraulic loading to the horizontal flow filters was 53 mm days -1 , and the filter systems were periodically loaded, 12 times days -1 . Experimental results indicate that the reduction of total phosphorus (hereinafter P) from wastewater in the filter systems was high (average efficiency [90%), especially with hydrated oil shale ash in horizontal flow filters, whereas the P-removal efficiency in peat filters was about 60% (Kõiv et al, , 2010.…”

“…The chemical analysis of the filter materials showed that before the wastewater treatment experiment Kõiv et al, 2009Kõiv et al, , 2010, the hydrated oil shale ash sediment had an average of 530 mg P kg -1 , and after the experiment (6 months) 651 mg P kg -1 . Mineralised peat had an average of 330 mg P kg -1 before and 451 mg P kg -1 after the wastewater treatment experiment.…”

Open-Air Deposition of Estonian Oil Shale Ash: Formation, State of Art, Problems and Prospects for the Abatement of Environmental Impact

“…However, the mineralogical data presented by Mõtlep et al [40] suggests the dissolution of amorphous glass phases and precipitation of secondary smectite-type clay phases. The high activity of dissolved Si and the specifically high K (>500 mg/l) [55] in the water in contact with ash would suggest the precipitation of secondary mixed-layer clays, zeolites and/or authigenic K-feldspar phases, similar to the hydration of volcanic glasses in evaporitic alkaline hypersaline or diagenetic environments. Nevertheless, secondary silicates other than smectite-type clay have not yet been identified in ash field sediments.…”

“…Ash has also been a valuable soil liming agent in agriculture [65][66][67]. Recent studies have shown that ash sediment can be used as an effective filter material for wastewater treatment [55,[68][69][70]. However, the secondary use of ash is very limited and is less than 5% of its annual production.…”