Evaluation of iron ochre from mine drainage treatment for removal of phosphorus from wastewater

Abstract

Treatment of polluting discharges from abandoned coal mines in the UK currently produces ca 30,000 t y(-1) of hydrous iron oxides ("ochre"), for which there is no major end-use, but which has previously been shown to have potential for removing P from wastewater and agricultural runoff. The efficiency of ochre for P removal from wastewater was investigated in experiments at two sites in the UK: Leitholm in Scotland and Windlestone in England. The three-year experiment at Leitholm involved diverting secondary-treated wastewater effluent through a trough which contained granular and pelletized ochre at different times. In the nine-month experiment at Windlestone, beds of ochre pellets in horizontal and vertical flow configurations were tested. The ochre treatment systems at Leitholm reduced influent concentrations of total P (TP) and TP mass by ca 80% and 50%, respectively, during optimal flow conditions, and achieved a removal rate of up to 65+/-48 mg TP kg(-1) ochre d(-1). There was no detectable release of potentially toxic metals from the ochre during the experiments. P removal rates by concentration were inversely related to flow and declined during the different phases of the experiments, probably due to clogging. At Windlestone, higher removal rates up to 195 mg TP kg(-1) ochre d(-1) were achieved for short periods of time following cleaning of the experimental system. Ochre has considerable potential to remove P from wastewater in a multi-stage treatment system and has a lifetime estimated to be 10 times longer than other substrates tested for P removal.

Fosfilt filters in an agricultural catchment: a long-term field-scale

“…Dobbie et al (2009) observed similar effects in their iron ochre-based P filters. P removal rates by concentration were inversely related to flow and declined during the different phases of the experiments, probably due to clogging.…”

“…Different reactive mateManuscript received September 2011 rials have been tested and studied to intensify nutrient removal, e.g. side-products containing iron or other metals (Dobbie et al 2009, Penn and Bryant 2006, Shilton et al 2006, and natural deposits (Arias et al 2001, Gill et al 2011, Renman 2008, Søvik and Kløve 2005. The idea of removing nutrients from agricultural runoff water using filters has recently arisen in many countries (Penn and Bryant 2006, Ballantine & Tanner 2010, Falk Øgaard 2010, Kjaergaard, 2010.…”

Potential and limitations of phosphate retention media in water protection: A process-based review of laboratory and field-scale tests

“…Large-scale wastewater treatment Dobbie et al (2009) investigated P retention by ochre (hydrous iron oxide) filters at the Leitholm (south-east Scotland) and Windlestone (north-east England) wastewater treatment plants (the experiments were also described in Heal et al 2004). At Leitholm, with settling as the primary treatment and biological filter as the secondary treatment, they studied a tertiary treatment step with granular ochre or ochre pellets (volume 2.1 m 3 ).…”

Application of waterworks sludge in wastewater treatment plants

“…Iron-rich sludge from treatment of acidic mine wastewater (MWS), which has similar or higher iron content compared to iron-rich WWS, has also been tested for its sorption capacity for phosphate from biologically treated wastewater (Dobbie et al 2009;Heal et al 2003Heal et al , 2005Sibrell et al 2009;Wei et al 2008) with maximum sorption capacity of 30 mg-P/g-MWS-dw (Heal et al 2003;Wei et al 2008). This is comparable to the values reported by Ippolito et al (2011) in a recent review on WWS uses, and 30 to[200-fold better than other minerals and waste products like slags and ashes of different origin (Heal et al 2003).…”