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On wet chemical phosphorus recovery from sewage sludge ash by acidic or alkaline leaching and an optimized combination of both

Petzet, Sebastian and Peplinski, Burkhard and Cornel, Peter (2012):
On wet chemical phosphorus recovery from sewage sludge ash by acidic or alkaline leaching and an optimized combination of both.
In: Water Research, pp. 3769 - 3780, 46, (12), ISSN 0043-1354, DOI: 10.1016/j.watres.2012.03.068, [Online-Edition: http://www.sciencedirect.com/science/article/pii/S0043135412...],
[Article]

Abstract

The advantages and drawbacks of existing wet chemical phosphorus (P) recovery technologies, their applicability to different types of sewage sludge ash (SSA) and the role of the decay products of detergent zeolites as a source of reactive Al in SSA are analyzed. Since neither a purely acidic nor a purely alkaline treatment are able to provide satisfactory technical solutions a wet chemical phosphorus (P) recovery process for sewage sludge ashes (SSAs) is investigated in detail that is based on a sequential treatment of SSA with an acid and a base. As a result of an acidic pre-treatment, the P fraction of the raw SSA that was bound as – alkaline-insoluble – calcium phosphate (Ca–P) is converted into aluminum phosphate (Al–P). This newly formed Al–P can be easily dissolved via alkaline treatment and then easily separated from the alkaline leachate via precipitation of Ca–P. The Al-component can be reused as precipitant for P-removal in waste water treatment plants (WWTPs). The investigated process requires fewer chemicals than the direct acidic dissolution of all P-compounds contained in the SSA. This is due to the described rearrangement of the P component from Ca–P to Al–P. That such a rearrangement of P occurs indeed was confirmed through a combination of XRD, ICP and XRF analyses together with mass balance calculations. The present investigation proves that the process works for very different types of SSAs: For Al-rich SSAs that come from WWTPs where Al-salt is used for chemical P-removal the described sequential treatment process works best and yields P-recovery rates as high as 70–77. But even for SSAs from WWTPs where only iron salt is used for chemical P-removal, a considerable amount of the reactive Al necessary for the described P-rearrangement is supplied by decay products of detergent zeolites, a hidden Al-source present in most SSAs produced in Europe.

Item Type: Article
Erschienen: 2012
Creators: Petzet, Sebastian and Peplinski, Burkhard and Cornel, Peter
Title: On wet chemical phosphorus recovery from sewage sludge ash by acidic or alkaline leaching and an optimized combination of both
Language: English
Abstract:

The advantages and drawbacks of existing wet chemical phosphorus (P) recovery technologies, their applicability to different types of sewage sludge ash (SSA) and the role of the decay products of detergent zeolites as a source of reactive Al in SSA are analyzed. Since neither a purely acidic nor a purely alkaline treatment are able to provide satisfactory technical solutions a wet chemical phosphorus (P) recovery process for sewage sludge ashes (SSAs) is investigated in detail that is based on a sequential treatment of SSA with an acid and a base. As a result of an acidic pre-treatment, the P fraction of the raw SSA that was bound as – alkaline-insoluble – calcium phosphate (Ca–P) is converted into aluminum phosphate (Al–P). This newly formed Al–P can be easily dissolved via alkaline treatment and then easily separated from the alkaline leachate via precipitation of Ca–P. The Al-component can be reused as precipitant for P-removal in waste water treatment plants (WWTPs). The investigated process requires fewer chemicals than the direct acidic dissolution of all P-compounds contained in the SSA. This is due to the described rearrangement of the P component from Ca–P to Al–P. That such a rearrangement of P occurs indeed was confirmed through a combination of XRD, ICP and XRF analyses together with mass balance calculations. The present investigation proves that the process works for very different types of SSAs: For Al-rich SSAs that come from WWTPs where Al-salt is used for chemical P-removal the described sequential treatment process works best and yields P-recovery rates as high as 70–77. But even for SSAs from WWTPs where only iron salt is used for chemical P-removal, a considerable amount of the reactive Al necessary for the described P-rearrangement is supplied by decay products of detergent zeolites, a hidden Al-source present in most SSAs produced in Europe.

Journal or Publication Title: Water Research
Volume: 46
Number: 12
Uncontrolled Keywords: XRD analysis, Phosphorus recovery, Sewage sludge ash, Alkaline and acidic leaching, Calcium phosphate, Aluminum phosphate, Detergent zeolites
Divisions: 13 Department of Civil and Environmental Engineering Sciences > Institute IWAR
13 Department of Civil and Environmental Engineering Sciences > Institute IWAR > Wastewater Technology
13 Department of Civil and Environmental Engineering Sciences
Date Deposited: 13 Jul 2017 06:57
DOI: 10.1016/j.watres.2012.03.068
Official URL: http://www.sciencedirect.com/science/article/pii/S0043135412...
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