Favorable Operating Conditions for Obtaining High-Value Struvite Product from Sludge Dewatering Filtrate

Lew, Beni; Phalah, Somaya; Sheindorf, Chaim; Kummel, Mario; Rebhun, M.; Lahav, Ori

doi:10.1089/ees.2009.0279

Cited by 16 publications

(4 citation statements)

References 27 publications

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“…Third, the reaction time can affect the properties of the precipitate. A shorter reaction time may be beneficial − for purity; however, it may be adverse for the particle size . Based on the experiments on the laboratory scale, the reaction time for the mixed solution from the HTL byproducts of manure was reduced to 60 min and HTL byproducts of sewage sludge in the presence of CA increased to 600 min.…”

Section: Results and Discussionmentioning

confidence: 99%

Valorization of Byproducts from Hydrothermal Liquefaction of Sewage Sludge and Manure: the Development of a Struvite-Producing Unit for Nutrient Recovery

2021

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Hydrothermal liquefaction (HTL) presents a promising technology to recover energy from sewage sludge and manure as bio-crude oil. The liquid and solid phases after HTL are considered as byproducts; however, the latter is rich in nutrients, which offers a possibility for nutrient recovery and manufacturing of valuable products. This study focuses on the simultaneous recovery of phosphate and ammoniacal nitrogen as struvite by combining the liquid HTL byproduct and leachate from the solid HTL byproduct. To implement a flexible struvite-producing unit, the effect of an inlet-mixed solution composition on the struvite precipitation was investigated on a laboratory scale and preferable operating conditions were identified. These operating conditions were used afterward to evaluate and adapt an air-agitated system for struvite precipitation subsequent to the HTL production chain. Moreover, the precipitation process in the air-agitated system was evaluated using synthetic model solutions compared to real HTL byproducts to offer insight into the effect of impurities on the product quality. The product, which has a struvite content of more than 75 wt %, was manufactured from the HTL byproducts of manure and sewage sludge as well. It has potential for use as a fertilizer based on its elemental composition but the use of citric acid was found to be effective to improve the quality of the product, especially of sewage sludge. The results showed that the air-agitated system could be effectively implemented in the HTL production chain. It has the potential to enhance features of the product, leading to a ready-to-use fertilizer in shape (particle size) and quality (struvite content).

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Section: Results and Discussionmentioning

confidence: 99%

Valorization of Byproducts from Hydrothermal Liquefaction of Sewage Sludge and Manure: the Development of a Struvite-Producing Unit for Nutrient Recovery

2021

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“…Although pH 8.5 does not maximize P recovery as struvite, Hao et al [24] reported that struvite formation at pH~8.5 lessened the prospect of Ca and Mg co-precipitates. Lew et al [29] reported more Mg 2+ and PO 4 3− co-precipitates formed at higher pH (conditions that maximized struvite formation). Operating under conditions that promote mixed P precipitate formation may be allowable under some circumstances, but a business aimed at commercializing struvite fertilizer will likely desire a relatively pure product.…”

Section: Discussionmentioning

confidence: 98%

Struvite Phosphorus Recovery from Aerobically Digested Municipal Wastewater

Hallas¹,

Mackowiak

Wilkie

et al. 2019

Sustainability

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Small, municipal wastewater treatment plants (WWTPs) that use aerobic digestion treat approximately 40% of the discharged wastewater in the USA, and yet they are an overlooked source of recoverable P. There are no known reports of small, aerobic WWTPs recovering P through struvite (MgNH4PO4·6H2O) precipitation for repurposing as a mineral fertilizer, even though some large WWTPs with anaerobic digestion are. Four small WWTPs in north Florida, USA, with treatment capacities from 371 to 2650 m3 wastewater d−1 and incoming P loads from 2 to 14 kg d−1 were investigated for their potential to produce struvite from digester filtrates. A chemical equilibrium model was used to predict the feasibility of struvite production and the results compared with actual WWTP filtrate measurements. Filtrates from aerobic digesters were able to form struvite if solution pH was increased by ≤1 pH unit. Depending on the WWTP, P recovery in filtrates through struvite precipitation ranged from 27–57% by mass at pH 8.5, via NaOH additions or air sparging. Increasing filtrate Mg concentrations improved P recovery up to 97%. Based upon these results, small WWTPs using aerobic digestion will be able to lower their P waste output through recovery as struvite fertilizer.

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“…gap at the base of their shared wall (Figure ). Most struvite reactors are either plug-flow or CSTR with separate FBRs. ,, Thus, the combination of the CSTR and FBR into a single compact unit is a novel design . For CO 2 (g) purging, air flow is applied to the CSTR at 42 L air L –1 reactor volume h –1 to maximize CO 2 (g) stripping while minimizing NH 4 –N volatilization, and a vacuum tube removes foam formed by aeration.…”

Section: Materials and Methodsmentioning

confidence: 99%

“…Agricultural wastewater can be treated for nutrient recovery by an aerated fluidized bed reactor (aerated-FBR) method that precipitates PO 4 –P and NH 4 –N as struvite (MgNH 4 PO 4 ·6H 2 O), a viable slow release fertilizer. − Struvite precipitation is predicted from its saturation index (SI), which is influenced by Mg 2+ , NH 4 –N, and PO 4 –P concentrations (eqs S1–S2), and is optimized at pH 9–10 − (Figure S1). For aerated-FBR treatment, struvite precipitation can be induced by raising the wastewater pH from a typical value of pH 6–8 to pH 8–9 by carbon dioxide [CO 2 (g)] stripping with aeration and sodium hydroxide (NaOH) titration .…”

Section: Introductionmentioning

confidence: 99%

Aerated Fluidized Bed Treatment for Phosphate Recovery from Dairy and Swine Wastewater

Rabinovich

Rouff

Lew

et al. 2017

ACS Sustainable Chem. Eng.

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An aerated fluidized bed reactor (aerated-FBR) was used for recovery of orthophosphate (PO 4 −P) from dairy wastewater (D-WW) and swine wastewater (S-WW) by struvite (MgNH 4 PO 4 •6H 2 O) precipitation. Model wastewater solutions (S-model, D-model) free of organic material were also treated. The maximum PO 4 −P recovery for treated livestock wastes was 94% for S-WW and 63% for D-WW. The PO 4 −P recovery did not improve for S-model compared to S-WW, but increased to 81% for D-model relative to D-WW, suggesting that the high organic content of D-WW may hinder the recovery process. X-ray diffraction (XRD) analysis of recovered solids revealed that treated S-WW produced mostly struvite (95−98%) while D-WW yielded a mixture of struvite (28−33%), calcite (CaCO 3 ; 17−55%), and monohydrocalcite (CaCO 3 •H 2 O; 13−42%). The Fourier transform infrared (FTIR) spectra of the solids confirm the presence of vibrational bands associated with these minerals. Simultaneous thermal analysis (STA) indicated that all solids, except for D-WW, show thermogravimetric (TG) trends consistent with the struvite and calcium carbonate content. The D-WW solids had additional TG steps, possibly due to high organic and colloidal content, and slightly improved ammonium stability. The aerated-FBR treatment is an effective method to reduce PO 4 −P from livestock wastewater through precipitation of pure struvite and struvite/calcium carbonate mixtures.

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Favorable Operating Conditions for Obtaining High-Value Struvite Product from Sludge Dewatering Filtrate

Cited by 16 publications

References 27 publications

Valorization of Byproducts from Hydrothermal Liquefaction of Sewage Sludge and Manure: the Development of a Struvite-Producing Unit for Nutrient Recovery

Valorization of Byproducts from Hydrothermal Liquefaction of Sewage Sludge and Manure: the Development of a Struvite-Producing Unit for Nutrient Recovery

Struvite Phosphorus Recovery from Aerobically Digested Municipal Wastewater

Aerated Fluidized Bed Treatment for Phosphate Recovery from Dairy and Swine Wastewater

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