Phosphorous removal from anaerobically digested municipal sludge centrate by an electrocoagulation reactor using metal (Al, Fe and Al-Fe) scrap anodes

Phosphates are a major cause of eutrophication and growth of algal blooms in surface waters. The current study investigated phosphorus removal from sludge centrate effluent (SCE) of a municipal wastewater plant by packed-bed electrocoagulation (EC) reactor. Distinctively, iron (Fe), aluminum (Al) an...

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Bibliographic Details
Published in:Process safety and environmental protection 2021-08, Vol.152, p.188-200
Main Authors: Kobya, Mehmet, Omwene, Philip Isaac, Sarabi, Sanaz Mohammadzadeh, Yildirim, Sadullah, Ukundimana, Zubeda
Format: Article
Language:English
Subjects:
Al and Fe scraps
Algal blooms
Aluminum
Anode effect
Anodes
Blooms (metal)
Electrocoagulation
Eutrophication
Mathematical analysis
Metal scrap
Metals
Municipal wastes
Municipal wastewater
Operating costs
Phosphates
Phosphorus
Phosphorus removal
Reactors
Scrap iron
Sludge
Sludge centrate
Sludge digestion
Sludge disposal
Surface water
Wastewater
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Summary:Phosphates are a major cause of eutrophication and growth of algal blooms in surface waters. The current study investigated phosphorus removal from sludge centrate effluent (SCE) of a municipal wastewater plant by packed-bed electrocoagulation (EC) reactor. Distinctively, iron (Fe), aluminum (Al) and Al-Fe hybrid scrap anodes were used. The influence of initial pHi, applied current and packed anode bed density were evaluated. Phosphorous removal efficiency of 99.99 % was obtained at applied current of 0.20A with anode bed densities of 0.18 kg Al/m3 (pHi 5.0) and 0.48 kg Fe/m3(pHi 7.0). Optimum operating costs entailing sludge disposal, chemical, energy and electrode consumption were calculated as 0.379 US $/m3 (6.04 $/kg PO4-P) for Fe scrap, 0.494 US $/m3 (9.46 $/kg PO4-P) for Al scrap and 0.501 US $/m3 (9.59 $/kg PO4-P) for Al-Fe hybrid scraps. Phosphorus removal per electrochemically generated metal was 191.22 mg P/g Al, 104.88 mg P/g Fe, and 61.08 mg P/g (Al + Fe). The molar metal to phosphorus ratio at optimum conditions were calculated as 5.41, 3.97 and 7.65 mol/mole for Al, Fe and Al-Fe, respectively. The key mechanisms for phosphorus removal were metal-phosphorus precipitation and adsorption. Herein, metal scrap anodes have been proved effective for phosphorous removal from SCE.
ISSN:0957-5820
1744-3598
DOI:10.1016/j.psep.2021.06.003