Optimisation of nutrients and metals release from municipal sewage sludge by chemical extraction using Box-Behnken design
by Ayla Uysal; Dilara Tuncer
International Journal of Global Warming (IJGW), Vol. 11, No. 3, 2017

Abstract: In this study, H₂SO₄ and citric acid using Box-Behnken design were utilised in order to release the nutrients and metals fixed in the anaerobic digested and dewatered sludge. For the dewatered sludge, release of 16.27 mg/L P and 120.74 mg/L NH₄⁺ were obtained at optimised conditions with citric acid 0.3 M, H₂SO₄ 6% and reaction time 105 min, respectively. For the digested sludge, release of 764.1 mg/L P and 388.3 mg/L NH₄⁺ were achieved at optimised conditions with citric acid 0.1 M, H₂SO₄ 6% and reaction time 180 min, respectively. In all experimental conditions, Fe and Zn were released together with nutrients. For digested sludge, a minimum Fe and Zn release was achieved at optimised conditions with citric acid 0.5 M, H₂SO₄ 2% and reaction time 105 min, respectively. Thus, this test conditions are thought to be more appropriate for the nutrients recovery from digested sludge.

Online publication date: Sun, 12-Mar-2017

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