Sulfide induced phosphate release from iron phosphates and its potential for phosphate recovery
Wilfert, P. ; Meerdink, J. ; Degaga, B. ; Temmink, H. ; Korving, L. ; Witkamp, G.J. ; Goubitz, K. ; Loosdrecht, M.C.M. van - \ 2020
Water Research 171 (2020). - ISSN 0043-1354
Iron - Phosphate recovery - Sewage sludge - Sulfide
Sulfide is frequently suggested as a tool to release and recover phosphate from iron phosphate rich waste streams, such as sewage sludge, although systematic studies on mechanisms and efficiencies are missing. Batch experiments were conducted with different synthetic iron phosphates (purchased Fe(III)P, Fe(III)P synthesized in the lab and vivianite, Fe(II)3(PO4)2*8H2O), various sewage sludges (with different molar Fe:P ratios) and sewage sludge ash. When sulfide was added to synthetic iron phosphates (molar Fe:S = 1), phosphate release was completed within 1 h with a maximum release of 92% (vivianite), 60% (purchased Fe(III)P) and 76% (synthesized Fe(III)P). In the latter experiment, rebinding of phosphate to Fe(II) decreased net phosphate release to 56%. Prior to the re-precipitation, phosphate release was very efficient (P released/S input) because it was driven by Fe(III) reduction and not by, more sulfide demanding, FeSx formation. This was confirmed in low dose sulfide experiments without significant FeSx formation. Phosphate release from vivianite was very efficient because sulfide reacts directly (1:1) with Fe(II) to form FeSx, without Fe(III) reduction. At the same time vivianite-Fe(II) is as efficient as Fe(III) in binding phosphate. From digested sewage sludge, sulfide dissolved maximally 30% of all phosphate, from the sludge with the highest iron content which was not as high as suggested in earlier studies. Sludge dewaterability (capillary suction test, 0.13 ± 0.015 g2(s2m4)−1) dropped significantly after sulfide addition (0.06 ± 0.004 g2(s2m4)−1). Insignificant net phosphate release (1.5%) was observed from sewage sludge ash. Overall, sulfide can be a useful tool to release and recover phosphate bound to iron from sewage sludge. Drawbacks -deterioration of the dewaterability and a net phosphate release that is lower than expected-need to be investigated.
Effect of pore size distribution and particle size of porous metal oxides on phosphate adsorption capacity and kinetics
Suresh Kumar, Prashanth ; Korving, Leon ; Keesman, Karel J. ; Loosdrecht, Mark C.M. van; Witkamp, Geert Jan - \ 2019
Chemical Engineering Journal 358 (2019). - ISSN 1385-8947 - p. 160 - 169.
Adsorption kinetics - Diffusion - Particle size - Phosphate adsorption - Pore size distribution - Porous metal oxide
Phosphate is a vital nutrient but its presence in surface waters even at very low concentrations can lead to eutrophication. Adsorption is often suggested as a step for reducing phosphate down to very low concentrations. Porous metal oxides can be used as granular adsorbents that have a high surface area and hence a high adsorption capacity. But from a practical point of view, these adsorbents also need to have good adsorption kinetics. The surface area of such adsorbents comes from pores of varying pore size and the pore size distribution (PSD) of the adsorbents can affect the phosphate adsorption kinetics. In this study, the PSD of 4 different adsorbents was correlated with their phosphate adsorption kinetics. The adsorbents based on iron and aluminium (hydr)oxide were grinded and the adsorption performance was studied as a function of their particle size. This was done to identify diffusion limitations due to the PSD of the adsorbents. The phosphate adsorption kinetics were similar for small particles of all the adsorbents. For larger particles, the adsorbents having pores larger than 10 nm (FSP and DD6) showed faster adsorption than adsorbents with smaller pores (GEH and CFH). Even though micropores (pores < 2 nm) contributed to a higher portion of the adsorbent surface area, pores bigger than 10 nm were needed to increase the rate of adsorption.
Understanding and improving the reusability of phosphate adsorbents for wastewater effluent polishing
Suresh Kumar, Prashanth ; Ejerssa, Wondesen Workneh ; Wegener, Carita Clarissa ; Korving, Leon ; Dugulan, Achim Iulian ; Temmink, Hardy ; Loosdrecht, Mark C.M. van; Witkamp, Geert-Jan - \ 2018
Water Research 145 (2018). - ISSN 0043-1354 - p. 365 - 374.
Calcium adsorption - Phosphate adsorption - Regeneration - Reusability - Surface precipitation - Wastewater effluent
Phosphate is a vital nutrient for life but its discharge from wastewater effluents can lead to eutrophication. Adsorption can be used as effluent polishing step to reduce phosphate to very low concentrations. Adsorbent reusability is an important parameter to make the adsorption process economically feasible. This implies that the adsorbent can be regenerated and used over several cycles without appreciable performance decline. In the current study, we have studied the phosphate adsorption and reusability of commercial iron oxide based adsorbents for wastewater effluent. Effects of adsorbent properties like particle size, surface area, type of iron oxide, and effects of some competing ions were determined. Moreover the effects of regeneration methods, which include an alkaline desorption step and an acid wash step, were studied. It was found that reducing the adsorbent particle size increased the phosphate adsorption of porous adsorbents significantly. Amongst all the other parameters, calcium had the greatest influence on phosphate adsorption and adsorbent reusability. Phosphate adsorption was enhanced by co-adsorption of calcium, but calcium formed surface precipitates such as calcium carbonate. These surface precipitates affected the adsorbent reusability and needed to be removed by implementing an acid wash step. The insights from this study are useful in designing optimal regeneration procedures and improving the lifetime of phosphate adsorbents used for wastewater effluent polishing.
Effect of pore size distribution on iron oxide coated granular activated carbons for phosphate adsorption – Importance of mesopores
Suresh Kumar, Prashanth ; Prot, Thomas ; Korving, Leon ; Keesman, Karel J. ; Dugulan, Iulian ; Loosdrecht, Mark C.M. van; Witkamp, Geert Jan - \ 2017
Chemical Engineering Journal 326 (2017). - ISSN 1385-8947 - p. 231 - 239.
Adsorption affinity - Iron coating - Mesopores - Non Local Density Functional Theory (NLDFT) - Oxidized activated carbon
Adsorption is often suggested for to reach very low phosphate levels in municipal wastewater effluent and even to recover phosphate. Adsorbent performance is usually associated with surface area but the exact role of the pore size distribution (PSD) is unclear. Here, we show the effect of the PSD on phosphate adsorption. Granular activated carbons (GACs) with varying PSDs were treated with potassium permanganate followed by reaction with ferric chloride to form iron oxide coated GACs (Fe-GACs). Energy dispersive X-ray and kinetics experiments confirmed that manganese anchored on the GAC is important for subsequent iron attachment. Mössbauer spectroscopy showed presence of ferrihydrite in Fe-GAC. Transmission electron microscopy showed that the iron oxide particles are not present in the micropores of the GACs. Phosphate adsorption isotherms were performed with the Fe-GACs and adsorption at lower phosphate concentrations correlated with the porous area of >3 nm of the adsorbents, a high fraction of which is contributed by mesopores. These results show that high surface areas of GACs resulting from micropores do not contribute to adsorption at low phosphate concentrations. This can be explained by the micropores being difficult to coat with iron oxide nanoparticles, but in addition the diffusion of phosphate into these pores could also be hindered. It is therefore recommended to use backbones having high mesoporous areas. This information is useful for developing adsorbents particularly for applications treating low phosphate concentrations, for e.g. in municipal wastewater effluent polishing.
Vivianite as an important iron phosphate precipitate in sewage treatment plants
Wilfert, P. ; Mandalidis, A. ; Dugulan, A.I. ; Goubitz, K. ; Korving, L. ; Temmink, H. ; Witkamp, G.J. ; Loosdrecht, M.C.M. Van - \ 2016
Water Research 104 (2016). - ISSN 0043-1354 - p. 449 - 460.
Iron - Mössbauer spectroscopy - Phosphorus - Sewage - Sewage sludge - Vivianite
Iron is an important element for modern sewage treatment, inter alia to remove phosphorus from sewage. However, phosphorus recovery from iron phosphorus containing sewage sludge, without incineration, is not yet economical. We believe, increasing the knowledge about iron-phosphorus speciation in sewage sludge can help to identify new routes for phosphorus recovery. Surplus and digested sludge of two sewage treatment plants was investigated. The plants relied either solely on iron based phosphorus removal or on biological phosphorus removal supported by iron dosing. Mössbauer spectroscopy showed that vivianite and pyrite were the dominating iron compounds in the surplus and anaerobically digested sludge solids in both plants. Mössbauer spectroscopy and XRD suggested that vivianite bound phosphorus made up between 10 and 30% (in the plant relying mainly on biological removal) and between 40 and 50% of total phosphorus (in the plant that relies on iron based phosphorus removal). Furthermore, Mössbauer spectroscopy indicated that none of the samples contained a significant amount of Fe(III), even though aerated treatment stages existed and although besides Fe(II) also Fe(III) was dosed. We hypothesize that chemical/microbial Fe(III) reduction in the treatment lines is relatively quick and triggers vivianite formation. Once formed, vivianite may endure oxygenated treatment zones due to slow oxidation kinetics and due to oxygen diffusion limitations into sludge flocs. These results indicate that vivianite is the major iron phosphorus compound in sewage treatment plants with moderate iron dosing. We hypothesize that vivianite is dominating in most plants where iron is dosed for phosphorus removal which could offer new routes for phosphorus recovery.
Buisman, C.J.N. ; korving, L. - \ 2014
In: Clean Tech, Clean Profits : Using Effective Innovation and Sustainable Business Practices to Win in the New Low-Carbon Economy / Jolly, A., London, UK : Kogan Page - ISBN 9780749470418 - p. 187 - 198.
Verwerking van mest en zuiveringsslib: kansen voor synergie
korving, L. ; Verdoes, N. ; Wilt, J. de - \ 2013
H2O online 2013 (2013)17 mei.
mestverwerking - waterzuivering - terugwinning - fosfor - stikstof - innovaties - samenwerking - biobased economy - slib - pyrolyse - manure treatment - water treatment - recovery - phosphorus - nitrogen - innovations - cooperation - biobased economy - sludges - pyrolysis
Bij de verwerking van menselijke en dierlijke mest kunnen meer nutriënten en energie worden teruggewonnen. Waterzuiveraars en mestverwerkers kunnen elkaar versterken door samen in onderzoek en praktijk te werken aan nieuwe verwerkingsmethoden.
VIP project: Passieve Visserij Ontwikkeling
Marlen, B. van; Vandenberghe, C. ; Craeynest, N. ; Korving, A. ; Cramer, R. ; Reker, E. - \ 2011
IJmuiden : IMARES Wageningen UR (Rapport / IMARES Wageningen UR C117/11)
visserij - vistuig - vismethoden - alternatieve methoden - netten - fisheries - fishing gear - fishing methods - alternative methods - nets
De introductie van passieve vistechnieken vormt een onderdeel van duurzame visserij ontwikkeling. Drie vaartuigen (KW-2, SCH-61 en IJM-27) beoefenen al geruime tijd passieve technieken. In het kader van dit project werd kennisoverdracht gedaan, vooral vanuit ILVO-Vlaanderen (Visserij Oostende, België), waar recent ervaring is opgedaan met schakels en potten, maar ook vanuit Denemarken, Frankrijk en Groot Brittannië. Na deze fase zijn de drie schippers gaan werken met verschillende passieve technieken (staand want, jiggen en potten) en hebben hiermee praktijkervaring opgedaan. Vervolgens werden vangsten en bijvangsten bemonsterd door onderzoekers van het ILVO en zijn er een tijd lang vangstgegevens bijgehouden door de schippers en opgeleverd aan IMARES en statistisch bewerkt. Een economische analyse laat zien, dat investeringen binnen redelijke korte tijd (1-3 jaren) zijn terug te verdienen. Hoewel de aanlandingen vergeleken met de boomkor relatief laag zijn, zijn de discards ook veel geringer. Met het lage brandstofverbruik zouden passieve vistuigen voor een beperkt deel van de vloot een alternatief kunnen zijn.
Radar en neerslagmeting, samen een sterker beeld
Uijlenhoet, R. ; Korving, H. ; Rameckers, G. - \ 2010
RIONED nieuws 2 (2010)maart. - p. 6 - 7.
|Organische polymeren: doorbraak in de fysich-chemische voorzuivering
Nieuwenhuizen, A.F. van; Mels, A.R. - \ 1999
In: Voordrachtenbundel 18e vakantiecursus in riolering en afvalwaterbehandeling, Delft 7 januari, 1999 / H. Korving, J.G. Langeveld (eds.). - Delft : Technische Universiteit, 1999 - p. 29 - 40.