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Chemical dissolution of struvite precipitates in pipes from anaerobic sludge digestion

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ARTICLE DOWNLOAD

Chemical dissolution of struvite precipitates in pipes from anaerobic sludge digestion

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Stanislava Kecskésová, Zuzana Imreová, Marek Martonka & Miloslav Drtil 

Abstract

Prevention of struvite formation at wastewater treatment plants (WWTPs) is currently possible using several approaches. However, failure of these measures and subsequent spontaneous struvite formation may lead to serious operational problems. A similar problem occurred at a municipal WWTP with enhanced phosphorus removal and anaerobic sludge digestion, where spontaneous struvite precipitation caused clogging of the pipes with digested sludge. For direct struvite dissolution in the sludge pipes, organic and inorganic acidic solutions were investigated. It was shown that using solutions of pH < 1 complete dissolution can be reached within 1–5 days. However, the use of such strong acids was not recommended by the WWTP operator because of a corrosion hazard (old pipes and fittings not made of stainless steel). At pH 2 and 3, the use of acetic acid (CH3COOH) solution can be considered promising. However, because of the heterogeneity of precipitates in the sludge pipes and insecure dissolution, measures for mechanical cleaning, in addition to chemical dissolution, were proposed.

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Year 2020
Language English
Format PDF
DOI 10.1007/s11696-020-01096-3