Induced Magnesium Ammonia Phosphate Precipitation to Prevent Incrustations and Measures for Phosphorus Recovery

2006 ◽  
Vol 1 (3) ◽  
Author(s):  
Bernd Heinzmann ◽  
Gerd Engel
Keyword(s):  
Carbon Dioxide ◽  
Ammonium Phosphate ◽  
Phosphorus Recovery ◽  
Anaerobic Sludge ◽  
Digested Sludge ◽  
Magnesium Ammonium Phosphate ◽  
Limit Values ◽  
Precipitation Product ◽  
Washing Process ◽  
Grass Growth

In 1994 for the first time massive incrustations in the centrifuges treating the digested sludge were detected in some wastewater treatment plants (WWTP’s) of the Berliner Wasserbetriebe, which were, as was found out later, mainly due to the precipitation of white MAP (magnesium ammonium phosphate = struvite) deposits with small portions of different calcium phosphate compounds. The reason for this was the over saturation of the digested sludge and the process water (from the separated centrate of the digested sludge) with carbon dioxide, the spontaneous release of or degassing of carbon dioxide, causing the pH to increase, thus altering the solubility equilibrium, and facilitating crystallisation, resulting in deposits (incrustations) on the walls. Obviously, the wastewater purification process used, with enhanced biological phosphorus removal and concentrated streams of digesting sludge, favours the formation of incrustations during sludge treatment. These incrustations were the cause of a lot of operational problems. To prevent incrustations, modifications in the process engineering technology have been applied after several studies and trials. Deliberate extraction of the CO2, e.g. by air injection through a fine-bubble surface aeration system at the bottom of the digested sludge storage tank just before the centrifuges, causes the pH to rise to approx. 8 and thus to cause induced struvite precipitation. This technology enables a precipitation product suitable for recycling to be generated and separated from the anaerobic sludge using a hydro-cyclone. A subsequent second hydro-cyclone stage allowed a further increase in the P-concentration to approx. 40 kg/m3, giving a yield of phosphorus of 20 %. This corresponds with P-load of approx. 316 kg/day and amounts to 18 % of the P inlet load in the WWTP Waßmannsdorf. It was shown that this experimental process is in principle suitable for the separation of the MAP precipitation product in the anaerobic sludge. A complete washing process for the raw MAP is not yet installed, and furthermore, to find the best sizes of nozzles in the hydro-cyclones and most effective pressures tests will have to be carried out soon at pilot level. A comparison with the minimum nutrients content for different kinds of fertiliser (super-phosphate, dicalcium-phosphate with magnesium, NP-fertiliser) defined by the German Fertiliser Regulations, shows that the precipitated MAP is within the range of other legally certified fertilisers. The MAP showed contaminant levels 5 times or more below the limit values of the German Sewage Sludge Ordinance. The MAP precipitation product is very soluble in different solvents (from ammonium chloride to hydrochloric acid). This implies that the precipitation product can be used as a long term fertilizer. In two test soils having a pH value of 6.6 and 7.1, the MAP precipitation solid was tested using standard ryegrass and showed good phosphorus availability from this material leading to a good grass growth.

Development of a process for the recovery of phosphorus resource from digested sludge by crystallization technology

2008 ◽  
Vol 57 (3) ◽  
pp. 451-456 ◽  
Author(s):  
K. Shimamura ◽  
H. Ishikawa ◽  
A. Mizuoka ◽  
I. Hirasawa
Keyword(s):  
Ammonium Phosphate ◽  
Recovery Process ◽  
Phosphorus Recovery ◽  
Test Material ◽  
Phosphorus Concentration ◽  
Digested Sludge ◽  
Magnesium Ammonium Phosphate ◽  
Magnesium Ammonium ◽  
Final Effluent

Removal and recovery of phosphorus from sewage in form of MAP (magnesium ammonium phosphate) have attracted attention from the viewpoint of eutrophication prevention and phosphorus resource recovery as well as scaling prevention inside digestion tanks. In this work, phosphorus recovery demonstration tests were conducted in a 50 m3/d facility having a complete mixing type reactor and a liquid cyclone. Digested sludge, having 690 mg/L T-P and 268 mg/L PO4-P, was used as test material. The T-P and PO4-P of treated sludge were 464 mg/L and 20 mg/L achieving a T-P recovery efficiency of 33% and a PO4-P crystallization ratio of 93%. The reacted phosphorus did not become fine crystals and the recovered MAP particles were found to be valuable as a fertilizer. A case study in applying this phosphorus recovery process for treatment of sludge from an anaerobic-aerobic process of a 21,000 m3/d sewage system, showed that 30% of phosphorus concentration can be reduced in the final effluent, recovering 315 kg/d as MAP.

scholarly journals Phosphorus Recovery from Excess Sludge with Subcritical Water Process and Magnesium Ammonium Phosphate Process

2005 ◽  
Vol 16 (4) ◽  
pp. 309-317
Author(s):  
Mitsuhiro Arakane ◽  
Tsuyoshi Imai ◽  
Sadaaki Murakami ◽  
Masami Takeuchi ◽  
Masao Ukita ◽  
...  
Keyword(s):  
Subcritical Water ◽  
Ammonium Phosphate ◽  
Phosphorus Recovery ◽  
Excess Sludge ◽  
Magnesium Ammonium Phosphate ◽  
Magnesium Ammonium

Phosphorus recovery as struvite from eutropic waters by XDA-7 resin

2012 ◽  
Vol 65 (12) ◽  
pp. 2091-2097 ◽  
Author(s):  
Huanwen Li ◽  
Zhiping Ye ◽  
Ying Lin ◽  
Fengying Wang
Keyword(s):  
Ammonium Phosphate ◽  
Phosphorus Recovery ◽  
Phosphate Adsorption ◽  
Nacl Solution ◽  
Acid Dissolution ◽  
Magnesium Ammonium Phosphate ◽  
Magnesium Ammonium ◽  
Struvite Precipitation ◽  
Ph Range ◽  
Removal And Recovery

Phosphorus releases into aquatic environment and its subsequent contribution to eutrophication have resulted in a widespread global pollution issue. However, phosphorus is a non-renewable source. The potential supplies of phosphorus are decreasing worldwide. Therefore, removal and recovery of phosphorus from the eutropic waters is important, emergent and necessary. In this research, experiments for recovering phosphate from eutropic waters by anion exchange combined with struvite precipitation were conducted. The results indicated that the prepared XDA-7 resin was an effective adsorbent for phosphate. The adsorption isotherm of XDA-7 resin was found to be a modified Freundlich type. The maximum phosphate adsorption (20.9 mg/g) occurred in the pH range of 6.0–8.0. Phosphate adsorbed on the XDA-7 resin was effectively desorbed with 8% NaCl solution, and the resin was able to be regenerated with 3% NaClO and 4% NaOH solutions. Phosphate desorbed from the resin was recovered as magnesium ammonium phosphate (struvite). The obtained struvite was analyzed by acid dissolution method, scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The struvite precipitate was found to be 75.8% in purity, a high-value fertilizer.

Effects of organic and inorganic acids on phosphorus release from municipal sludge

2007 ◽  
Vol 56 (9) ◽  
pp. 87-94 ◽  
Author(s):  
N.B. Pakdil ◽  
A. Filibeli
Keyword(s):  
Nitric Acid ◽  
Organic Acids ◽  
Chemical Constituents ◽  
Ammonium Phosphate ◽  
Phosphorus Release ◽  
Major Elements ◽  
Phosphorus Recovery ◽  
Magnesium Ammonium Phosphate ◽  
Inorganic Acids ◽  
Oxalic Acids

This paper reports on the effects of inorganic acids (sulphuric acid, hydrochloric acid, nitric acid) and organic acids (citric acid, oxalic acids) for phosphorus recovery from sludge and struvite precipitation results. It was observed that both inorganic acid and organic acids were effective at phosphorus release. The studies on precipitation of released phosphorus from sludge as magnesium ammonium phosphate (struvite) were also done using nitric and oxalic acids. Phosphorus and heavy metals of leachate were analyzed before and after precipitation. It was observed that heavy metal concentrations in the extracted samples decrease after precipitation. Precipitation was accomplished by using extract derived with nitric acid; however, in oxalic acid applications, it was not achieved. When the chemical constituents of the dried material were examined oxygen, sodium and nitrogen were found to be the major elements.

Phosphorus recovery from anaerobic digester supernatant by struvite crystallization: model-based evaluation of a fluidized bed reactor

2008 ◽  
Vol 58 (6) ◽  
pp. 1321-1327 ◽  
Author(s):  
M. S. Rahaman ◽  
D. S. Mavinic ◽  
N. Ellis
Keyword(s):  
Fluidized Bed ◽  
Plug Flow ◽  
Ammonium Phosphate ◽  
Phosphorus Recovery ◽  
Reactor Performance ◽  
Magnesium Ammonium Phosphate ◽  
University Of British Columbia ◽  
Magnesium Ammonium ◽  
Struvite Crystallization ◽  
Anaerobic Digester Supernatant

This paper is an attempt to model the UBC (University of British Columbia) MAP (Magnesium Ammonium Phosphate) fluidized bed crystallizer. A mathematical model is developed based on the assumption of perfect size classification of struvitre crystals in the reactor and considering the movement of liquid phase as a plug flow pattern. The model predicts variation of species concentration of struvite along the crystal bed height. The species concentrations at two extreme ends (inlet and outlet) are then used to evaluate the reactor performance. The model predictions provide a reasonable good fit with the experimental results for both PO4—P and NH4—N removals. Another important aspect of this model is its capability of predicting the crystals size and the bed voidage at different height of the reactor. Those predictions also match fairly well with the experimental observations. Therefore, this model can be used as a tool for performance evaluation of the reactor and can also be extended to optimize the struvite crystallization process in the UBC MAP reactor.

Phosphate release of sludges from enhanced biological p-removal during digestion

1994 ◽  
Vol 30 (6) ◽  
pp. 281-292 ◽  
Author(s):  
Norbert Jardin ◽  
H. Johannes Pöpel
Keyword(s):  
Total Phosphorus ◽  
Phosphorus Removal ◽  
Ammonium Phosphate ◽  
Soluble Form ◽  
Anaerobic Sludge ◽  
Minor Role ◽  
Soluble Phosphate ◽  
Magnesium Ammonium Phosphate ◽  
Sludge Digestion ◽  
Anaerobic Sludge Digestion

During the start-up phase of an enhanced biological phosphorus removal (EBPR) plant, the amount of eliminated phosphorus during wastewater treatment and the subsequent release during anaerobic sludge digestion was investigated. Different approaches were used to determine the mechanisms of enhanced phosphorus removal. From a comparison of the EBPR plant with a control, a strong correlation between the potassium, the magnesium and the phosphorus content of the sludge and the results gained from phosphorus fractionations we conclude that the major part of the eliminated phosphorus was stored in form of polyphosphate. During digestion of excess and a mixture of excess and primary sludge a complete release of the stored polyphosphate was found. The release of phosphorus was accompanied by a release of potassium and magnesium ions, from which only potassium remains in soluble form. Therefore, the soluble potassium concentration seems to be a good measure for the amount of phosphate released. Only a part of the released phosphate remains in soluble form. When digesting excess and mixed sludge this accounts for approximately 40% of the total phosphorus brought into the digester. The difference between the measured soluble phosphate concentration and the amount of released phosphorus was fixed, mainly due to chemical precipitation. It was found that a fixation in the form of magnesium ammonium phosphate (struvite) was likely to occur under the conditions of anaerobic sludge digestion. The amount of phosphate precipitation as struvite could be estimated using theoretical calculations at approximately 20% of the total phosphorus in the digester. Calcium dosing experiments show that calcium-phosphate precipitation plays only a minor role in phosphate fixation.

Struvite precipitation from anaerobically treated municipal and landfill wastewaters

2002 ◽  
Vol 46 (9) ◽  
pp. 271-278 ◽  
Author(s):  
M. Altinbaş ◽  
C. Yangin ◽  
I. Ozturk
Keyword(s):  
Ammonium Phosphate ◽  
Domestic Wastewater ◽  
Treatment System ◽  
Upflow Anaerobic Sludge Blanket ◽  
Anaerobic Sludge ◽  
Stoichiometric Ratio ◽  
Magnesium Ammonium Phosphate ◽  
N Removal ◽  
Fenton’S Oxidation ◽  
Fenton's Oxidation

A two-stage treatment system including upflow anaerobic sludge blanket reactor pre-treatment combined with a chemical post treatment system such as magnesium ammonium phosphate (MAP) precipitation was proposed as a comparable alternative to conventional biological treatment. In this study, anaerobically pre-treated domestic wastewater, domestic wastewater mixed with 2% and 3% of leachate by volume and raw leachate were further treated chemically with MAP precipitation. MAP precipitation was both applied at the stoichiometric ratio (Mg:NH4 = PO4; 1:1:1) and above the stoichiometric ratio (1.1:1:1 and 1.1:1:1.1) on domestic wastewater +3% leachate mixture. Maximum NH4-N removal of 68% was achieved at the pH of 9.2 at the stoichiometric ratio, whereas at the same pH value 70 to 72% NH4-N removal was obtained above the stoichiometric ratio. Additional ammonia recovery studies were conducted on Fenton's oxidation applied effluents before MAP precipitation and no significant additional ammonium removal was achieved. However, by the application of Fenton's oxidation high additional COD removals were obtained. Consequently, chemical treatment by MAP precipitation and/or Fenton's oxidation after anaerobic treatment yielded very effective removals for COD and NH4-N in domestic wastewaters + leachate mixtures.

Phosphorus recovery using a crystallization process for Sewage Treatment Plant

2011 ◽  
Vol 6 (4) ◽  
Author(s):  
Kazuaki Shimamura ◽  
Tateki Kurosawa
Keyword(s):  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Ammonium Phosphate ◽  
Recovery Process ◽  
Phosphorus Recovery ◽  
Phosphorus Concentration ◽  
Magnesium Ammonium Phosphate ◽  
Magnesium Ammonium ◽  
Verification Test

A novel phosphorus recovery process enabling an effective reuse of recovered phosphorus as a resource has been developed. Three processes, which match the characteristics (sewage component, concentration and flow rate, etc.) of the waste water or the sludge generated form sewage treatment, are introduced here. Verification tests carried out using a crystallization of magnesium ammonium phosphate revealed a phosphorus crystallization exceeding 85%. Moreover, these tests show that the recovered phosphorus can be reused as a fertilizer. Another verification test carried out using a crystallization of hydroxylapatite revealed that the phosphorus concentration is reduced to a few milligrams per liter. In addition it is found that the recovered hydroxylapatite can be reused as a phosphorus ore. Each of the three processes is revealed to contribute to prevention of water contamination, as well as the recovery of phosphorus as a resource.

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