Phosphate recovery from sewage sludge in combination with supercritical water oxidation

2003 ◽  
Vol 48 (1) ◽  
pp. 185-190 ◽  
Author(s):  
K. Stendahl ◽  
S. Jäfverström
Keyword(s):  
Sewage Sludge ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Organic Contaminants ◽  
Sodium Phosphate ◽  
Pure Water ◽  
Phosphate Solution ◽  
Supercritical Water Oxidation ◽  
Digested Sludge ◽  
Sodium Phosphate Solution

Supercritical Water Oxidation (SCWO) is an innovative and effective destruction method for organics in sewage sludge. The SCWO process leaves a slurry of inorganic ash in a pure water phase free from organic contaminants, which opens possibilities for a simple process to recover components like phosphates from the sewage sludge. In a continuous pilot plant for the SCWO process digested sludge has been treated. The ash has been extracted in lab scale with both caustic and acids in order to recover phosphates. By leaching the ash with caustic, 90% of the phosphorus could be separated as a sodium phosphate solution. By treating the sodium phosphate solution with lime, calcium phosphate was precipitated and caustic recovered and circulated back to the leaching process.

Simulation of Supercritical Water Oxidation with Air at Pilot Plant Scale

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Belén García Jarana ◽  
Jezabel Sánchez Oneto ◽  
Juan Ramón Portela Miguélez ◽  
Enrique Nebot Sanz ◽  
Enrique J. Martínez de la Ossa
Keyword(s):  
Kinetic Parameters ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Pilot Plant ◽  
Reaction Kinetic ◽  
Pure Water ◽  
Kinetic Equations ◽  
Pilot Scale ◽  
Laboratory Scale ◽  
Supercritical Water Oxidation

Supercritical Water Oxidation (SCWO) processes have been studied by numerous researchers. The effectiveness of this approach to treat a wide variety of wastes has been proved and the kinetics involved in some cases have been described. Phenol is commonly present in industrial wastewaters and it is extremely toxic. Hence, phenol is a model pollutant that has been the subject of numerous studies by SCWO on a laboratory scale. In this work, a pilot-scale SCWO system has been used to compare experimental and predicted conversions in the SCWO of phenol, using the reaction kinetic equations obtained at the laboratory scale. In this context, “PROSIM PLUS” software was employed to develop a simulator for the pilot plant facility, with the reaction kinetic parameters adjusted to represent the experimental data. In this study it was necessary to determine the thermal losses between the experimental reactor and its surroundings. These thermal losses were obtained from tests with pure water and oxidant streams in the absence of chemical reaction. An equation that predicted the effect of flow rate and temperature on the thermal losses was used. Experimental oxidation tests were conducted with initial temperature in the range 380 to 425 ºC, at 250 bar and phenol concentrations ranging from 1 to 12 g/l. Good agreement in the simulation was obtained by adjusting the kinetic parameters within their confidence range. This simulator was used to optimize the SCWO of phenol solutions in the pilot plant facility.

Design of the first pilot scale plant of China for supercritical water oxidation of sewage sludge

2012 ◽  
Vol 90 (2) ◽  
pp. 288-297 ◽  
Author(s):  
Donghai Xu ◽  
Shuzhong Wang ◽  
Xingying Tang ◽  
Yanmeng Gong ◽  
Yang Guo ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Pilot Scale ◽  
Supercritical Water Oxidation

Application of red mud as both neutralizer and catalyst in supercritical water oxidation (SCWO) disposal of sewage sludge

RSC Advances ◽  
2016 ◽  
Vol 6 (59) ◽  
pp. 54202-54214 ◽  
Author(s):  
Hongzhen Chen ◽  
Guangwei Wang ◽  
Yuanjian Xu ◽  
Zhong Chen ◽  
Fengjun Yin
Keyword(s):  
Sewage Sludge ◽  
Supercritical Water ◽  
Red Mud ◽  
Water Oxidation ◽  
Supercritical Water Oxidation

Red mud was used in the supercritical water oxidation (SCWO) disposal of sewage sludge, not only as a neutralizer for acidic substances produced in situ, but also as a catalyst for decomposition of pollutants.

Green process for supercritical water oxidation of sewage sludge with red mud as CO2 absorbent

2016 ◽  
Vol 4 (3) ◽  
pp. 3065-3074 ◽  
Author(s):  
Hongzhen Chen ◽  
Guangwei Wang ◽  
Yuanjian Xu ◽  
Zhong Chen ◽  
Fengjun Yin
Keyword(s):  
Sewage Sludge ◽  
Supercritical Water ◽  
Red Mud ◽  
Water Oxidation ◽  
Supercritical Water Oxidation ◽  
Green Process ◽  
Co2 Absorbent

Recycling of sludge with the Aqua Reci process

2004 ◽  
Vol 49 (10) ◽  
pp. 233-240 ◽  
Author(s):  
K. Stendahl ◽  
S. Jäfverström
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Water Oxidation ◽  
Organic Contaminants ◽  
Iron Hydroxide ◽  
Pure Water ◽  
Calcium Content ◽  
Iron Phosphate ◽  
Extraction Process ◽  
High Calcium

Supercritical Water Oxidation (SCWO) is an innovative and effective destruction method for organics in sewage sludge. The SCWO process leaves a slurry of inorganic ash in a pure water phase free from organic contaminants, which opens possibilities for a simple process to recover components like phosphates and/or coagulants from the sewage sludge, a process marketed as the Aqua Reci. In a continuous pilot plant for the SCWO process digested sludge has been treated. The ash has been extracted in lab- and pilot scale with both caustic and acids in order to recover phosphates and coagulants. The particle size of the inorganic contaminants in the water after the SCWO process is between 1-10 μm, which means that it is very reactive. The phosphate, and partly the aluminium, can be extracted with caustic as iron and heavy metals are completely insoluble in caustic. This is a method to separate the phosphates from the rest of the contaminants. However, high calcium content will bind the phosphate as calcium phosphate insoluble in caustic. In most cases the calcium content is too high and the best solution is to dissolve phosphates and all metals with sulphuric acid. From this solution first iron phosphate can be separated and thereafter in a second step aluminium and finally heavy metals in a third step. Iron can be separated from the phosphate, either by leaching the phosphate with caustic off to sodium phosphate leaving a precipitate consisting of iron hydroxide, or the iron phosphate can be dissolved in hydrochloric acid followed by a liquid extraction process where ferric chloride can be separated leaving a phosphoric acid. By the acid dissolving process it is possible to recover phosphate, iron, aluminium, and heavy metals from the inorganic since the Aqua Reci process only leaves a silica residue representing about 10% of the DS content in the original sludge.

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