Bianchi, Lavinia (2019) New prospects on ammonia recovery technologies from wastewater. EngD thesis, University of Warwick.

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Abstract

Water pollution is rising due to the increase in human population. This represents a serious danger for the environment and human health. The wastewater sector is facing stricter regulations on environmental discharge limits, which result in higher energy and costs to remove contaminants. Thus, there is the need to develop more sustainable technologies that promote circularity by recovering valuable products and reusing resources. Amongst them, ammonia is a valuable resource widely used as a fertiliser, which can be recovered and exploited from wastewater.

This innovative research project focuses on two different ammonia recovery technologies that can be applied in different ranges of concentrations. The first contribution regards the optimisation of the chemical precipitation technique, which is commonly applied in ammonium-rich streams. In particular, optimal conditions are defined to: (i) thermally decompose the precipitate (struvite) and recover higher quality products; (ii) recover the chemical employed for the precipitation. A kinetic mechanism of the thermal decomposition is also developed, which is key for a thorough understanding of the chemical process and to design the technology.

The second contribution focuses on lower concentration streams with the development of a new material for the adsorption technology. In this regard, innovation is needed due to high operational costs of conventional adsorbents. In this work, the Metal-Organic Framework ZIF-67 is used for the first time for this application. ZIF-67 demonstrates to: (i) successfully remove ammonium with an adsorption capacity comparable to natural zeolites; (ii) achieve 85 % removal efficiency at 35 °C; (iii) be effectively used in a continuous system; and (iv) be used in a composite configuration with recycled carbon fibres, which will facilitate the use of this material at large scale. ZIF-67 removes ammonia upon heating, thus reducing the need of chemicals required for zeolites regeneration. A cost analysis is also presented to discuss the conditions to make this material competitive for industrial application.

Item Type:	Thesis (EngD)
Subjects:	T Technology > TD Environmental technology. Sanitary engineering T Technology > TP Chemical technology
Library of Congress Subject Headings (LCSH):	Sewage -- Purification, Ammonia -- Absorption and adsorption
Official Date:	December 2019
Dates:	Date Event December 2019 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Warwick Manufacturing Group
Thesis Type:	EngD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Coles, Stuart R. ; Kirwan, Kerry
Sponsors:	Engineering and Physical Sciences Research Council ; Severn Trent Water (Firm)
Format of File:	pdf
Extent:	xiv, 126 leaves : illustrations (some colour)
Language:	eng

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