Integrated chemicalâphysical processes modellingâII. simulating aeration treatment of anaerobic digester supernatants

Musvoto, E. V.; Wentzel, M. C.; Ekama, G. A.

doi:10.1016/s0043-1354(99)00335-8

Cited by 143 publications

(121 citation statements)

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“…It can be observed that the precipitate is composed of a mixture of hydroxyapatite [hydroxide calcium phosphate, Ca5(PO4)3(OH)] and a calcium-deficient hydroxyapatite [hydroxide calcium hydrogen phosphate Ca9HPO4(PO4)5OH] which is a non-stoichiometric hydroxyapatite. According to some authors (Abbona et al, 1986;Musvoto et al, 2000;Liu et al, 2009), hydroxyapatite precipitation starts at pH> 5; however, the precipitation reaction kinetics is not favored and other species, such as amorphous calcium phosphate, octacalcium phosphate and brushite, act as precursors of the hydroxyapatite precipitation. Gray and Schwab (1993) reported that calcium phosphate precipitation is almost complete at pH values higher than 9.8.…”

Section: Precipitate Characterizationmentioning

confidence: 99%

Electroflotation of precipitated phosphate from synthetic solution

Cruz

Monte

Dutra

2017

Braz. J. Chem. Eng.

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-The phosphate recovery from a 20 mg L -1 Na2HPO4 solution through precipitation with Ca(OH)2 followed by electroflotation was evaluated. X-ray diffraction and particle size measurements indicated that the precipitates were a mixture of hydroxyapatite and calcium-deficient hydroxyapatite, with size ranging from 3 to 10 mm. Electroflotation with Na-oleate as surfactant was used to recover the precipitates. The surfactant adsorption was evaluated through zeta potential measurements. The influence of Na-oleate concentration, pH and bubble size on phosphate recovery was investigated. In the absence of Na-oleate, a phosphate recovery of 50% was achieved, while in the presence of 20 mg L -1 of Na-oleate it was increased to 90%, at pH 11. The phosphate recovery also increased with Ca(OH)2 concentration increase and bubble size decrease, reaching 100% at 300 mg L -1 Ca(OH)2 and bubble size around 39 µm.

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Section: Precipitate Characterizationmentioning

confidence: 99%

Electroflotation of precipitated phosphate from synthetic solution

Cruz

Monte

Dutra

2017

Braz. J. Chem. Eng.

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“…Figure 2b shows that remaining ammonium concentrations reached between 235 and 309 mg/L after 12 h, excluding the experiment performed with 23.2 g/L. In addition, it was observed that for S/L ratios over 39.2 g/L the concentration of remaining ammonium rapidly reached close to a minimum value after 0.5 h. When wastewater was treated with 23.2 g/L, the remaining ammonium concentration decreased within 2 h, and increased slightly between 2 and 8 h, and then decreased again after 8 h. This could be because newberyite (MgHPO 4 ?3H 2 O) could precipitate significantly in solution media of lower pH values (o6) containing high concentrations of magnesium and phosphate (Musvoto et al 2000), and its formation might result in undersaturation with respect to struvite, which led to the dissolving of struvite to restore saturation (Bhuiyan et al 2008). Nevertheless, as the solution pH increased (5.35-5.6), the predominant solid species might gradually change from newberyite to struvite.…”

Section: Effect Of Solid Brucite Acting As a Dual Function Chemicalmentioning

confidence: 99%

Removal of ammonium from rare-earth wastewater using natural brucite as a magnesium source of struvite precipitation

Huang

Xiao

Yang

et al. 2011

Water Science and Technology

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This paper presents a study regarding ammonium removal from rare-earth wastewater by struvite precipitation with natural brucite mineral as a source of magnesium. Experimental results indicated that a pH ranging from 8.5 to 9.5 was the optimum for the removal of ammonium using the soluble form of brucite as a magnesium source. Additionally, when solid brucite was used as a magnesium source as well as an alkali reagent, the initial ammonium concentration of 4,535 mg/L decreased to 239-317 mg/L after an reaction time of 12 h in wastewater treated with the S/L (solid brucite/liquid wastewater) ratios ranging from 31.2 to 63.2 g/L. Furthermore, as some non-reacted brucite still remained in the precipitates obtained at the end of reaction, the precipitates were subjected to reuse. The reuse results demonstrated that the reuse of the precipitates obtained with 63.2 g/L was feasible, and almost half of the brucite dose could be saved.Key words 9 9 9 9 ammonium, brucite mineral, phosphorus, rare-earth, struvite precipitation

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“…Because the pH of the black water used in this research attained values of 8.6 -8.8 (table 1), struvite and hydroxyapatite will likely precipitate during storage and transport. It should be mentioned that kinetics are not taken into account in the simulation, which will have an effect on the type of precipitates formed (Musvoto et al, 2000). Therefore, the results from the simulation are indicative, showing the possible effect of the amount of flushing water and pH.…”

Section: Simulation Of Chemical Precipitation In Black Watermentioning

confidence: 99%

Energy and phosphorus recovery from black water

Graaff

Temmink

Zeeman

et al. 2011

Water Science and Technology

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Source-separated black water (toilet water) containing 38% of the organic material and 68% of the phosphorus in the total household waste(water) stream including kitchen waste, is a potential source for energy and phosphorus recovery. The energy recovered, in the form of electricity and heat, is more than sufficient for anaerobic treatment, nitrogen removal and phosphorus recovery. The phosphorus balance of a UASB reactor treating concentrated black water showed a phosphorus conservation of 61% in the anaerobic effluent. Precipitation of phosphate as struvite from this stream resulted in a recovery of 0.22 kgP/p/y, representing 10% of the artificial phosphorus fertilizer production in the world. The remaining part of the phosphorus ended up in the anaerobic sludge, mainly due to precipitation (39%). Low dilution and a high pH favour the accumulation of phosphorus in the anaerobic sludge and this sludge could be used as a phosphorus-enriched organic fertilizer, provided that it is safe regarding heavy metals, pathogens and micro-pollutants. Keywords anaerobic treatment, black water, biogas production, phosphorus recovery, separation at source, struvite INTRODUCTIONNew sanitation concepts are based on separation at source of household wastewater streams into grey water and black water (faeces and urine) or into grey water, urine and brown water (faeces), and have a large potential to recover the important resources energy, nutrients and water. Anaerobic treatment is regarded as the core technology for energy and nutrient recovery from source separated domestic wastewater (Otterpohl et al., 1999;Kujawa-Roeleveld and Zeeman, 2006). Previous research showed that concentrated black water (faeces and urine collected in a vacuum toilet) can be efficiently treated in a UASB (Upflow anaerobic sludge blanket) reactor at a relatively short hydraulic retention time (HRT) of 9.1 days (de Graaff et al., 2010), in a UASB septic tank at a longer HRT of 29 days (Kujawa-Roeleveld et al., 2005) or in a CSTR at an HRT of 20 days (Wendland et al., 2007). A methane production of 1.8 m 3 CH 4 per m 3 of black water can be achieved, which can be converted to 56 MJ/p/y as electricity and 84 MJ/p/y as heat by combined heat and power (CHP) (de Graaff et al., 2010). The nutrients are largely conserved in the effluent of the anaerobic treatment step. Van Voorthuizen et al. (2008) reported a phosphorus removal of only 5% during anaerobic treatment of black water collected with conventional flush toilets (6L per flush), i.e. 95% was conserved in the effluent. However, for more concentrated black water, collected with vacuum toilets (1L per flush), 40% of the phosphorus was removed when applying UASB-septic tank (Kujawa-Roeleveld et al., 2005).

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Integrated chemicalâphysical processes modellingâII. simulating aeration treatment of anaerobic digester supernatants

Cited by 143 publications

References 18 publications

Electroflotation of precipitated phosphate from synthetic solution

Electroflotation of precipitated phosphate from synthetic solution

Removal of ammonium from rare-earth wastewater using natural brucite as a magnesium source of struvite precipitation

Energy and phosphorus recovery from black water

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Integrated chemicalâphysical processes modellingâII. simulating aeration treatment of anaerobic digester supernatants

Cited by 143 publications

References 18 publications

Electroflotation of precipitated phosphate from synthetic solution

Electroflotation of precipitated phosphate from synthetic solution

Removal of ammonium from rare-earth wastewater using natural brucite as a magnesium source of struvite precipitation

Energy and phosphorus recovery from black water

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Product

Resources

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Integrated chemicalâphysical processes modellingâII. simulating aeration treatment of anaerobic digester supernatants