7.6 Quaternary Wastewater Treatment
159
removing pathogens, ensuring that water becomes safe for drinking. Tertiary
treatment involves various more steps after secondary treatment to further minimize
nitrogen, pathogens, turbidity, metals, as well as organics. Many of these processes
entail some form of physicochemical treatment like filtration, reverse osmosis, more
disinfection, coagulation, and adsorption of organics. It is carried out when the
wastewater is to be redeployed for irrigation, recreational purposes, or drinking
water.
Tertiary processes can eliminate not less than 99% of the impurities found in
sewage, leading to the production of an effluent that is safe for drinking (Hamoda
et al. 2004). However, tertiary treatment could be quite costly, usually twice more
than the secondary treatment cost. This form of treatment is usually utilized under
particular circumstances. This stage also removes parasites, viruses, and bacteria
which harm the public health. The process involves wastewater flowing from the
biological reactor into a pumping station where they meet within the flash mixer.
Alum is then used for the removal of extra phosphorous particles and grouping the
remaining solids to easily remove them from the filters. Through gravity, wastewater
emanating from flash mixers goes through sand filters. Due to alum being added,
tiny particles cluster in masses known as floc. Sand traps the floc, whereas the clear
water is often gravity-fed to the chlorine tank. Backwashing of the filters is done
every 24 h to get rid of the accumulating floc. The backwash water is taken back
to the primary treatment stage to traverse the full treatment (Hamoda et al. 2004).
The tertiary treated wastewater is disinfected by the chlorine contact tank. Chlorine
eliminates microorganisms within treated wastewater, such as parasites, bacteria,
and viruses like Cryptosporidium and Giardia. Any of the remaining chlorine is
then eliminated through the addition of sodium bisulfite prior to it being discharged.
Chlorine is eliminated from the water because it could harm the water quality.
7.6 Quaternary Wastewater Treatment
The purpose of quaternary treatment is to lower the dissemination of pollutants
whose presence within surface waters rises regularly, involving issues for people’s
health as well as the aquatic environments’ biodiversity. The process is vital for
eliminating micropollutants in sewer water. Adsorption and oxidation are used
for eliminating micropollutants. The method recognizes that the increased use of
industrial chemicals, hormones, and pharmaceuticals results in rising volumes of
pollution in waters (Costa-Pierce 1998). Since the substances manifest in surface
waters, they are called micropollutants or trace substances. Various substances
are initiated into the sewer system at various points. The concentration of the
substances increase to the sewage treatment plant until the optimal micropollutant
concentration is reached. One of the elimination methods is the use of active carbon
powder as granulate.
159
removing pathogens, ensuring that water becomes safe for drinking. Tertiary
treatment involves various more steps after secondary treatment to further minimize
nitrogen, pathogens, turbidity, metals, as well as organics. Many of these processes
entail some form of physicochemical treatment like filtration, reverse osmosis, more
disinfection, coagulation, and adsorption of organics. It is carried out when the
wastewater is to be redeployed for irrigation, recreational purposes, or drinking
water.
Tertiary processes can eliminate not less than 99% of the impurities found in
sewage, leading to the production of an effluent that is safe for drinking (Hamoda
et al. 2004). However, tertiary treatment could be quite costly, usually twice more
than the secondary treatment cost. This form of treatment is usually utilized under
particular circumstances. This stage also removes parasites, viruses, and bacteria
which harm the public health. The process involves wastewater flowing from the
biological reactor into a pumping station where they meet within the flash mixer.
Alum is then used for the removal of extra phosphorous particles and grouping the
remaining solids to easily remove them from the filters. Through gravity, wastewater
emanating from flash mixers goes through sand filters. Due to alum being added,
tiny particles cluster in masses known as floc. Sand traps the floc, whereas the clear
water is often gravity-fed to the chlorine tank. Backwashing of the filters is done
every 24 h to get rid of the accumulating floc. The backwash water is taken back
to the primary treatment stage to traverse the full treatment (Hamoda et al. 2004).
The tertiary treated wastewater is disinfected by the chlorine contact tank. Chlorine
eliminates microorganisms within treated wastewater, such as parasites, bacteria,
and viruses like Cryptosporidium and Giardia. Any of the remaining chlorine is
then eliminated through the addition of sodium bisulfite prior to it being discharged.
Chlorine is eliminated from the water because it could harm the water quality.
7.6 Quaternary Wastewater Treatment
The purpose of quaternary treatment is to lower the dissemination of pollutants
whose presence within surface waters rises regularly, involving issues for people’s
health as well as the aquatic environments’ biodiversity. The process is vital for
eliminating micropollutants in sewer water. Adsorption and oxidation are used
for eliminating micropollutants. The method recognizes that the increased use of
industrial chemicals, hormones, and pharmaceuticals results in rising volumes of
pollution in waters (Costa-Pierce 1998). Since the substances manifest in surface
waters, they are called micropollutants or trace substances. Various substances
are initiated into the sewer system at various points. The concentration of the
substances increase to the sewage treatment plant until the optimal micropollutant
concentration is reached. One of the elimination methods is the use of active carbon
powder as granulate.