oxidation processes such as Fenton oxidation, ozonation, photolysis, and advanced
oxidation processes (AOPs) are commonly applied. Additionally, biological nitrogen removal techniques involving nitrification, denitrification, anammox, and
comammox processes have been found to be suitable (Li et al. 2018; Wang et al.
2018; Capodici et al. 2019; Yan et al. 2019; Cotto et al. 2020). However, there are
advantages and disadvantages for every treatment technology, as enlisted in
Table 7.1.
Until recently, not only nutrient (nitrogen, phosphorous, etc.) removal processes
but also removal of micropollutants, polyaromatic hydrocarbons, etc. have gained
much attention. Micropollutants are synthetic organic chemicals found in concentration range from few nanograms per liter to a few hundred micrograms per liter and
include pharmaceutical organic contaminants, personal care products, and
endocrine-disrupting compounds (Men et al. 2017). Biological treatment processes
used for removal of nitrogenous pollutants have a good correlation with removal of
these micropollutants and aromatic hydrocarbons (Fernandez-Fontaina et al. 2012;
Buitrón et al. 2015; Wang et al. 2019a; Zhou et al. 2019). Simultaneous removal of
NH
þ
4 À N with micropollutants and organic aromatic pollutants has been reported
by ammonia-oxidizing bacteria (AOB), which are responsible for nitrification. AOB
are involved in the first step of nitrification wherein it catalyzes the oxidation of NH
þ
4
into NO
À
2 which is further oxidized into NO
À
3 by nitrite-oxidizing bacteria. The first
step performed by AOB is regarded as the rate-limiting step of nitrification and, thus,
grabs considerable attention in treatment of nitrogenous waste.
This chapter henceforth summarizes various physical, chemical, and biological
treatment processes for removal of nitrogenous waste from wastewater. In addition,
AOB have been given emphasis on biological removal of nitrogen along with
removal of micropollutants and aromatics from wastewater. Apart from the
multifunctional role of AOB in wastewater treatment, they have been further recognized with their bio-valorization potential in biofuel production.
7.2 Sources of Nitrogenous Waste in Water
7.2.1 Organic Wastes
Wastewater from food processing industries primarily contributes toward organic
nitrogen wastes into wastewater. Fish processing industries mainly liberate proteins,
peptides, and volatile amines as nitrogenous wastes (Chowdhury et al. 2010).
Mushroom production industries release proteinaceous wastes, carbohydrates, and
fats and generate spent mushroom substrate as a byproduct, which is also rich in
protein, carbohydrate, and fat (Lou et al. 2017; Meng et al. 2017). In addition,
organic nitrogenous wastes are also generated from beverage industries such as dairy
processing units and corn steep liquor manufacturing industries. Corn steep liquor
contains only 2% protein, but corn gluten water obtained from separation of corn
148
P. Chawley et al.
oxidation processes (AOPs) are commonly applied. Additionally, biological nitrogen removal techniques involving nitrification, denitrification, anammox, and
comammox processes have been found to be suitable (Li et al. 2018; Wang et al.
2018; Capodici et al. 2019; Yan et al. 2019; Cotto et al. 2020). However, there are
advantages and disadvantages for every treatment technology, as enlisted in
Table 7.1.
Until recently, not only nutrient (nitrogen, phosphorous, etc.) removal processes
but also removal of micropollutants, polyaromatic hydrocarbons, etc. have gained
much attention. Micropollutants are synthetic organic chemicals found in concentration range from few nanograms per liter to a few hundred micrograms per liter and
include pharmaceutical organic contaminants, personal care products, and
endocrine-disrupting compounds (Men et al. 2017). Biological treatment processes
used for removal of nitrogenous pollutants have a good correlation with removal of
these micropollutants and aromatic hydrocarbons (Fernandez-Fontaina et al. 2012;
Buitrón et al. 2015; Wang et al. 2019a; Zhou et al. 2019). Simultaneous removal of
NH
þ
4 À N with micropollutants and organic aromatic pollutants has been reported
by ammonia-oxidizing bacteria (AOB), which are responsible for nitrification. AOB
are involved in the first step of nitrification wherein it catalyzes the oxidation of NH
þ
4
into NO
À
2 which is further oxidized into NO
À
3 by nitrite-oxidizing bacteria. The first
step performed by AOB is regarded as the rate-limiting step of nitrification and, thus,
grabs considerable attention in treatment of nitrogenous waste.
This chapter henceforth summarizes various physical, chemical, and biological
treatment processes for removal of nitrogenous waste from wastewater. In addition,
AOB have been given emphasis on biological removal of nitrogen along with
removal of micropollutants and aromatics from wastewater. Apart from the
multifunctional role of AOB in wastewater treatment, they have been further recognized with their bio-valorization potential in biofuel production.
7.2 Sources of Nitrogenous Waste in Water
7.2.1 Organic Wastes
Wastewater from food processing industries primarily contributes toward organic
nitrogen wastes into wastewater. Fish processing industries mainly liberate proteins,
peptides, and volatile amines as nitrogenous wastes (Chowdhury et al. 2010).
Mushroom production industries release proteinaceous wastes, carbohydrates, and
fats and generate spent mushroom substrate as a byproduct, which is also rich in
protein, carbohydrate, and fat (Lou et al. 2017; Meng et al. 2017). In addition,
organic nitrogenous wastes are also generated from beverage industries such as dairy
processing units and corn steep liquor manufacturing industries. Corn steep liquor
contains only 2% protein, but corn gluten water obtained from separation of corn
148
P. Chawley et al.