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233 results on '"SIEGRIST, HANSRUEDI"'

14. (NH4)2SO4 recovery from liquid side streams

Author

Boehler, Marc, Heisele, Alexander, Seyfried, Alexander, Grömping, Markus, Siegrist, Hansruedi, Boehler, Marc, Heisele, Alexander, Seyfried, Alexander, Grömping, Markus, and Siegrist, Hansruedi

Abstract

Two methods of recovering nitrogen from liquid side streams are presented in this paper. The first method was demonstrated at an ammonia stripping plant treating 5-7m3/h sludge water at the wastewater treatment plant (WWTP) Kloten-Opfikon (CH). In addition to the usual stripping and scrubbing columns, a third column had been added in order strip CO2, thus reducing the NaOH-demand of the subsequent ammonia stripping. At first, just the stripping plant was put into operation and optimized without any pre-treatment of the supernatant. Next, the CO2-stripper column was activated and optimized by gas measurements to minimize free ammonia losses, heat losses, and energy consumption. Key operational aspects of the plant were evaluated. Finally, up to 1.4m3/h source-separated urine was successfully fed into the stripping facility. The second ammonia removal method using hydrophobic hollow fiber membranes was tested in two small pilot systems by different manufacturers in 2012 and 2013 at WWTP Neugut. In this technology, free ammonia gas in the sludge liquid diffuses at pH >9.3 from the sludge liquid through the air-filled pores of the microporous hydrophobic membrane into concentrated sulfuric acid flowing through the hollow fibers, forming ammonium sulfate. The small pore size and the hydrophobic nature of the membrane prevent the liquid phase from entering into the pores due to the surface tension effect. Practical experience regarding operational parameters like wastewater flow rate, pH, temperature, ammonia concentration, fouling and precipitations processes, optimal flow schemes, and process configurations was collected.

Published
2021

35. Recovery of N and P from urine by struvite precipitation followed by combined stripping with digester sludge liquid at full scale

Author

Universidade de Santiago de Compostela. Departamento de Enxeñaría Química, Morales Pereira, Nicolás, Boehler, Marc Anton, Buettner, Sandra, Liebi, Christoph, Siegrist, Hansruedi, Universidade de Santiago de Compostela. Departamento de Enxeñaría Química, Morales Pereira, Nicolás, Boehler, Marc Anton, Buettner, Sandra, Liebi, Christoph, and Siegrist, Hansruedi

Abstract

A novel ammonia stripping method, including a CO2 pre-stripper was used to treat a mix of supernatant liquor from an anaerobic digester and urine in order to recycle nitrogen as ammonium sulfate at full-scale in the WWTP Kloten/Opfikon. Waste streams were not generated, since the ammonia was recovered as a marketable nitrogen fertilizer, turning a waste product into a valuable product. The efficiency of this system was increased by means of the addition of pre-treated urine collected separately at EAWAG building. The separation step was performed by the use of water free urinals and urine diversion flush toilets. An increase of 10% in the liquid flux with the addition of the urine translated into a 40% increase of the ammonia concentration in the inlet of the stripping unit. The achievement of these percentages generated a proportional increase in the fertilizer production. The urine pre-treatment was carried out by adding magnesium to produce a precipitate of struvite. The first experiments with the combined treatment showed the feasibility of the combination of the separation and pre-treatment steps

Published
2013

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