nitrogenous wastes, and allows the pollutant or material to be recovered (Sohni et al.
2018).
7.3.1.1 Reverse Osmosis
To meet the increasing demands of water supply, people all around the world are
looking for utilization of wastewater by improving the quality of water through
reverse osmosis (RO). Reverse osmosis offers a great capacity to remove organic
nitrogen (Merlo et al. 2012), proteins, and ions from brackish water and seawater
(Afonso et al. 2004). However, this process produces RO concentrate (ROC),
containing several contaminants and nutrients. Nearly, 30–50% of RO input is left
as ROC in municipal reclamation system (Dialynas et al. 2008), since ROC derived
from municipal wastewater contains nitrogen as the primary nutrient. In spite of
direct disposal of ROC, zero liquid discharge (recovery of feed water up to 95–98%)
could be one suitable approach to reduce volume of wastewater. A typical ROC with
high amount of total nitrogen (TN) and low C/N ratio was utilized in membraneaerated reactor to check the nitrogen removal efficiency. Results showed that TN
removal percentage was 79.2 with 5.8 C/N ratio, 24-h retention time, and 0.02 MPa
aeration pressure (Quan et al. 2018).
RO was performed for removal of nitrogen (TN) from domestic wastewater and
in combination with industrial wastewater by tubular and spiral-wound membrane
elements. The separation efficiency of total nitrogen from domestic wastewater
through RO approach (tubular membrane) was found to be 95% (Bilstad 1995).
Tubular membrane did not require any pretreatment, while spiral membrane element
necessitated an additional 25–200 micrometer cartridge filter as pretreatment
(Bilstad 1995). In another study, higher concentration of nitrate-nitrogen
(35–75 mg/L) in water was reduced to level of potable water having concentration
less than 10 mg/L with the help of reverse osmosis. In this study, two sets of initial
concentration of nitrate-nitrogen were investigated: (i) low to medium (35–43 mg/L)
and (ii) medium to high (54–72 mg/L). Better removal was reported in the first
condition with initial concentration of nitrate-nitrogen reduced to 1.4–5.5 mg/L,
while in the second case, it was found to be 12–17 mg/L in treated water (Schoeman
2009).
The intrinsic properties such as high efficiency of membrane in selective mineral
rejection, permeability to water, and ease of operation at room temperature make it a
suitable choice for WWT (López-Ramírez et al. 2006). However, the operational
cost for reverse osmosis is found to be high owing to its high energy consumption for
huge project. This problem can be resolved by introducing renewable energy sources
such as solar, wind, and wave energy (Liu et al. 2002, 2007). Studies have reported
wind-driven reverse osmosis system to be capable of removing nitrogen from
aquaculture wastewater (Liu et al. 2007). The nitrate removed by such process
however gets accumulated in the brine system, thus defeating the purpose for
installation of such a hybrid process (Matos et al. 2009). In addition, permeability
7 Nitrogenous Wastes and Its Efficient Treatment in Wastewater
151
2018).
7.3.1.1 Reverse Osmosis
To meet the increasing demands of water supply, people all around the world are
looking for utilization of wastewater by improving the quality of water through
reverse osmosis (RO). Reverse osmosis offers a great capacity to remove organic
nitrogen (Merlo et al. 2012), proteins, and ions from brackish water and seawater
(Afonso et al. 2004). However, this process produces RO concentrate (ROC),
containing several contaminants and nutrients. Nearly, 30–50% of RO input is left
as ROC in municipal reclamation system (Dialynas et al. 2008), since ROC derived
from municipal wastewater contains nitrogen as the primary nutrient. In spite of
direct disposal of ROC, zero liquid discharge (recovery of feed water up to 95–98%)
could be one suitable approach to reduce volume of wastewater. A typical ROC with
high amount of total nitrogen (TN) and low C/N ratio was utilized in membraneaerated reactor to check the nitrogen removal efficiency. Results showed that TN
removal percentage was 79.2 with 5.8 C/N ratio, 24-h retention time, and 0.02 MPa
aeration pressure (Quan et al. 2018).
RO was performed for removal of nitrogen (TN) from domestic wastewater and
in combination with industrial wastewater by tubular and spiral-wound membrane
elements. The separation efficiency of total nitrogen from domestic wastewater
through RO approach (tubular membrane) was found to be 95% (Bilstad 1995).
Tubular membrane did not require any pretreatment, while spiral membrane element
necessitated an additional 25–200 micrometer cartridge filter as pretreatment
(Bilstad 1995). In another study, higher concentration of nitrate-nitrogen
(35–75 mg/L) in water was reduced to level of potable water having concentration
less than 10 mg/L with the help of reverse osmosis. In this study, two sets of initial
concentration of nitrate-nitrogen were investigated: (i) low to medium (35–43 mg/L)
and (ii) medium to high (54–72 mg/L). Better removal was reported in the first
condition with initial concentration of nitrate-nitrogen reduced to 1.4–5.5 mg/L,
while in the second case, it was found to be 12–17 mg/L in treated water (Schoeman
2009).
The intrinsic properties such as high efficiency of membrane in selective mineral
rejection, permeability to water, and ease of operation at room temperature make it a
suitable choice for WWT (López-Ramírez et al. 2006). However, the operational
cost for reverse osmosis is found to be high owing to its high energy consumption for
huge project. This problem can be resolved by introducing renewable energy sources
such as solar, wind, and wave energy (Liu et al. 2002, 2007). Studies have reported
wind-driven reverse osmosis system to be capable of removing nitrogen from
aquaculture wastewater (Liu et al. 2007). The nitrate removed by such process
however gets accumulated in the brine system, thus defeating the purpose for
installation of such a hybrid process (Matos et al. 2009). In addition, permeability
7 Nitrogenous Wastes and Its Efficient Treatment in Wastewater
151