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Controlled struvite precipitation from belt press filtrate of anaerobic digester in a CSTR
Author(s) -
Lew Beni,
Phalah Somaya,
Rebhum Menachem
Publication year - 2011
Publication title -
environmental progress and sustainable energy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.495
H-Index - 66
eISSN - 1944-7450
pISSN - 1944-7442
DOI - 10.1002/ep.10561
Subject(s) - struvite , aeration , hydraulic retention time , continuous stirred tank reactor , clogging , precipitation , pulp and paper industry , wastewater , volumetric flow rate , environmental engineering , environmental science , anaerobic digestion , biogas , chemistry , waste management , engineering , methane , physics , archaeology , organic chemistry , quantum mechanics , meteorology , history
Struvite (MgNH 4 PO 4 ·6H 2 O) is known to precipitate and clog pipes and pumps, causing operational difficulties and expenses downstream of the anaerobic digester in wastewater treatment plants around the world. This work focused on determining the most appropriate reactor operational conditions (focus on hydraulic retention time and aeration rate) required for attaining the most homogeneous controlled struvite precipitation in order to reduce pipes and pumps clogging downstream of the digester. To this end a continuous laboratory‐scale completely stirred tank reactor aerated (for CO 2 stripping) reactor was operated at different hydraulic retention times and aeration rates and precipitate composition was determined. A minimum pH of 8.0 was calculated and experimental observed as necessary to attain struvite precipitation to its maximum potential to prevent clogging. To reach this pH value a minimum HRT of 0.5 hours with aeration flow rate of 11.2 m 3 /h/m 3 and/or 15‐min HRT with an air flow of 46.7 m 3 /h/m 3 was necessary for the reactor studied. Struvite precipitation kinetics was observed to be much faster than other minerals that can precipitate and a decrease in HRT promoted a precipitate richer in struvite. However, for all HRT and air flows studied the precipitate obtained can be considered to be poor in struvite and can hardly be reused in agriculture. © 2011 American Institute of Chemical Engineers Environ Prog, 2011