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

• Published in: Process safety and environmental protection Vol. 152; pp. 188 - 200
• Main Authors: Kobya, Mehmet, Omwene, Philip Isaac, Sarabi, Sanaz Mohammadzadeh, Yildirim, Sadullah, Ukundimana, Zubeda
• Format: Journal Article
• Language: English
• Published: Rugby Elsevier B.V 01-08-2021; Elsevier Science Ltd
• 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; United States > US; Phosphorus; Al and Fe scraps; Electrocoagulation; Sludge centrate
• ISSN: 0957-5820; 1744-3598
• DOI: 10.1016/j.psep.2021.06.003

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.