Sequencing biological acidification of waste-activated sludge aiming to optimize phosphorus dissolution and recovery. Issue 11 (3rd June 2017)

• Record Type: Journal Article
• Authors: Guilayn, Felipe; Braak, Etienne; Piveteau, Simon; Daumer, Marie-Line
• Is Part Of: Environmental technology. Volume 38:Issue 11(2017)
• Page Start: 1399
• Page End: 1407
• Publication Date: 2017-06-03
• Subjects: Phosphorus solubilization -- nutrient recovery -- waste-activated sludge -- WAS fermentation -- organic waste; Environmental engineering -- Periodicals; Environmental protection -- Periodicals; 628.05
• DOI: 10.1080/09593330.2016.1230653
• Languages: English
• ISSNs: 0959-3330

Abstract

ABSTRACT: Phosphorus (P) recovery in wastewater treatment plants (WWTP) as pure crystals such as struvite (MgNH4 PO4 .6H2 O), potassium struvite (KMgPO4 .6H2 O) and calcium phosphates (e.g. Ca3 (PO4 )2 ) is an already feasible technique that permits the production of green and marketable fertilizers and the reduction of operational costs. Commercial crystallizers can recovery more than 90% of soluble P. However, most of the P in WWTP sludge is unavailable for the processes (not dissolved). P solubilization and separation are thus the limiting steps in P-crystallization. With an innovative two-step sequencing acidification strategy, the current study has aimed to improve biological P solubilization on waste-activated sludge (WAS) from a full-scale plant. In the first step (P-release), low charges of organic waste were used as co-substrates of WAS pre-fermentation, seeking to produce volatile fatty acids to feed the P-release by Polyphosphate-accumulating organisms, while keeping its optimal metabolic pH (6–7). In this phase, milk serum, WWTP grease, urban organic waste and collective restaurant waste were individually applied as co-substrates. In the second step (P-dissolution), pH 4 was aimed at as it allows the dissolution of the most common precipitated species of P. Biological acidification was performed by white sugar addition, as a carbohydrate-rich organic waste model, which was compared to chemical acidification by HCl (12M) addition. With short retention times (48–96 h) and without inoculum application, all experiences succeeded on P solubilization (37–55% of soluble P), principally when carbohydrate-rich co-substrates were applied. Concentrations from 270 to 450 mg were achieved.