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Nutrient recovery from waste streams through struvite formation

Latifian, Maryam LU (2015)
Abstract (Swedish)
Popular Abstract in English

These days we hear a lot about sustainability and most of us try to live in a more

sustainable way. We use less water and energy, we sort our household waste and we

prefer to consume products that are produced with less negative human impact.

However, when it comes to our own excreta we definitely think of it as waste. And we

are glad enough that wastewater treatment systems are there to take care of it! But the

question is: how sustainable are our wastewater treatment systems?

Today’s wastewater treatment systems are mainly built on the concept of removing

substances that can be harmful to humans and the environment. The problem... (More)
Popular Abstract in English

These days we hear a lot about sustainability and most of us try to live in a more

sustainable way. We use less water and energy, we sort our household waste and we

prefer to consume products that are produced with less negative human impact.

However, when it comes to our own excreta we definitely think of it as waste. And we

are glad enough that wastewater treatment systems are there to take care of it! But the

question is: how sustainable are our wastewater treatment systems?

Today’s wastewater treatment systems are mainly built on the concept of removing

substances that can be harmful to humans and the environment. The problem still

remains; we are left with substances that we do not really know how to dispose of.

However, considering the principles of sustainability recovering and reusing resources

is a far superior approach than removing them.

One good example of this is today’s unsustainable phosphorus flow; from its starting

point in mining to its end point in discharging it to the environment. Phosphorus,

which is mainly used as a fertilizer, is obtained by mining of phosphorus rock and

deterioration of land is its obvious consequence. A lot of this phosphorus ends up on

our plate and eventually in our excreta. But from this point on, this valuable element

becomes waste. Phosphorus is a non-renewable resource and with its ever-increasing

consumption, it is predicted to be depleted within 50 to 100 years.

The goal of this thesis is to capture and reuse the phosphorus lost in our wastewater.

For this purpose, magnesium is added to a process that, together with phosphorus

and nitrogen, forms a crystal compound called struvite. Struvite can be separated

from wastewater and can be used as a high-quality fertilizer. Currently, there are only

a few full-scale struvite crystallization processes in use around the world. Several

technical and economical limitations hinder wide application of this process. One of

the main objectives of this study was to improve the process by either coagulation or

aggregation of struvite crystals. It was also possible to efficiently capture both nitrogen

and phosphorus from urine. This is an important finding for better use of potential

future decentralized sanitation systems.

The work throughout this thesis is a step towards a more sustainable waste

management. It is an effort to further highlight the notion that “waste is a valuable

resource”. (Less)
Abstract
Eutrophication or the nutrient enrichment of water bodies, typically by nitrogen and phosphorus has adversely

affected the aquatic life and the quality of water. Governments have been forced to take actions in order to reduce

the release of these nutrients into the environment.

To date the main global effort has been to remove such nutrients at source. However, with an increase in awareness

of the importance of phosphorus as a non-renewable resource, more studies are being carried out to find methods to

prevent loss of phosphorus and to recover it instead. The struvite crystallization process has been shown to be a

promising technology to efficiently recover phosphorus from point... (More)
Eutrophication or the nutrient enrichment of water bodies, typically by nitrogen and phosphorus has adversely

affected the aquatic life and the quality of water. Governments have been forced to take actions in order to reduce

the release of these nutrients into the environment.

To date the main global effort has been to remove such nutrients at source. However, with an increase in awareness

of the importance of phosphorus as a non-renewable resource, more studies are being carried out to find methods to

prevent loss of phosphorus and to recover it instead. The struvite crystallization process has been shown to be a

promising technology to efficiently recover phosphorus from point sources such as municipal, agricultural and

industrial wastewater.

The work throughout this thesis deals with the use of the struvite crystallization process as a mean to recover

nitrogen and phosphorus from waste streams. To prevent the formation of struvite fine crystals, which are difficult to

harvest; aggregation of struvite crystals was promoted using a fluidized bed reactor. Further analysis of the

precipitates using X-ray diffraction proved that these precipitated aggregates were in fact struvite. In cases where

crystal aggregation cannot be performed, it has been suggested that harvesting of struvite fine crystals can be

improved by the addition of coagulants and coagulating aids such as chitosan and bentonite, which have been shown

to be efficient in increasing the setting velocity of the crystals. Furthermore, struvite crystals were formulated into

granules to create a product with a higher commercial value. The quality of this product as a fertilizer was

investigated in terms of its physical and chemical properties. Finally, the use of struvite crystallization followed by a

struvite recycling process to recover nutrients from urine was investigated. Using this process, it was possible to

recover 90% of both nitrogen and phosphorus from urine. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Gustafsson, Jon Petter, SLU, Uppsala
organization
publishing date
type
Thesis
publication status
published
subject
keywords
struvite, nutrient, phosphorus, nitrogen, wastewater treatment, anaerobic digestion, urine
defense location
Kemicentrum Lecture Hall B, Getingevägen 60, Lund University, Faculty of Engineering, (LTH)
defense date
2015-02-12 10:30
ISBN
978-91-7422-383-5
language
English
LU publication?
yes
id
ebf95620-b938-4d3d-8a81-7f4501d1f7e0 (old id 4936528)
date added to LUP
2015-01-19 11:37:56
date last changed
2016-09-19 08:45:16
@phdthesis{ebf95620-b938-4d3d-8a81-7f4501d1f7e0,
  abstract     = {Eutrophication or the nutrient enrichment of water bodies, typically by nitrogen and phosphorus has adversely<br/><br>
affected the aquatic life and the quality of water. Governments have been forced to take actions in order to reduce<br/><br>
the release of these nutrients into the environment.<br/><br>
To date the main global effort has been to remove such nutrients at source. However, with an increase in awareness<br/><br>
of the importance of phosphorus as a non-renewable resource, more studies are being carried out to find methods to<br/><br>
prevent loss of phosphorus and to recover it instead. The struvite crystallization process has been shown to be a<br/><br>
promising technology to efficiently recover phosphorus from point sources such as municipal, agricultural and<br/><br>
industrial wastewater.<br/><br>
The work throughout this thesis deals with the use of the struvite crystallization process as a mean to recover<br/><br>
nitrogen and phosphorus from waste streams. To prevent the formation of struvite fine crystals, which are difficult to<br/><br>
harvest; aggregation of struvite crystals was promoted using a fluidized bed reactor. Further analysis of the<br/><br>
precipitates using X-ray diffraction proved that these precipitated aggregates were in fact struvite. In cases where<br/><br>
crystal aggregation cannot be performed, it has been suggested that harvesting of struvite fine crystals can be<br/><br>
improved by the addition of coagulants and coagulating aids such as chitosan and bentonite, which have been shown<br/><br>
to be efficient in increasing the setting velocity of the crystals. Furthermore, struvite crystals were formulated into<br/><br>
granules to create a product with a higher commercial value. The quality of this product as a fertilizer was<br/><br>
investigated in terms of its physical and chemical properties. Finally, the use of struvite crystallization followed by a<br/><br>
struvite recycling process to recover nutrients from urine was investigated. Using this process, it was possible to<br/><br>
recover 90% of both nitrogen and phosphorus from urine.},
  author       = {Latifian, Maryam},
  isbn         = {978-91-7422-383-5},
  keyword      = {struvite,nutrient,phosphorus,nitrogen,wastewater treatment,anaerobic digestion,urine},
  language     = {eng},
  school       = {Lund University},
  title        = {Nutrient recovery from waste streams through struvite formation},
  year         = {2015},
}