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4 Nitrogen and Phosphorous Recovery from Municipal Wastewater …
Keywords Wastewater treatment · Biological nutrient removal · Wastewater
sludge · Nitrogen · Phosphorous · Resource recovery
Wastewater can be a valuable source of nutrients such as nitrogen and phosphorous.
Nutrient recovery from wastewater and sewage sludge is a sustainable approach for
wastewater management. In this chapter, principles of wastewater treatment, sludge
generation and treatment are briefly reviewed, and different technologies to recover
nutrients and their mechanisms are introduced in detail.
4.1 Wastewater Treatment
In typical wastewater treatment plants after eliminating large objects and grits,
suspended solids, colloidal particles, dissolved organics and nutrients are removed.
The effluent is then either discharged into the receiving water bodies or reused
for various purposes such as irrigation and recharging of groundwater. A typical
municipal wastewater treatment plant consists of three phases of treatment: primary,
secondary and tertiary. The core of all treatments is the secondary phase in which
the dissolved organics are degraded by different types of microorganisms [1].
4.1.1 Preliminary Treatment
Before entering the primary treatment, wastewater is subjected to several preliminary
treatments. The purpose of the preliminary treatment is to protect the equipment
and downstream processes. Preliminary treatments include screening, comminution,
grinding and grit removal and are designed to remove and reduce the size of the large,
suspended or floating solids, remove heavy inorganic solids such as sand, metal or
glass and remove excessive amounts of oils or greases [2, 3]. The screening system
removes the large debris from the influent, consisting of coarse screens for protection
of pumps and other equipment, fine screens for removal of smaller materials, and
microscreens for very fine particles. Comminutors and grinders include cutters and
shredders that provide an alternative to coarse screening [2]. And finally, grit removal
is performed by gravity or centrifugal processes through grit channels, detritus tanks,
aerated or vortex grit tanks, centrifugal type separators and stationary screens [3].
4.1.2 Primary Treatment
Primary treatments are performed in primary sedimentation tanks or clarifiers. Coagulants, such as alum (Al 2 (SO 4 ) 3 .14 H 2 O), are often used to facilitate sedimentation
4 Nitrogen and Phosphorous Recovery from Municipal Wastewater …
Keywords Wastewater treatment · Biological nutrient removal · Wastewater
sludge · Nitrogen · Phosphorous · Resource recovery
Wastewater can be a valuable source of nutrients such as nitrogen and phosphorous.
Nutrient recovery from wastewater and sewage sludge is a sustainable approach for
wastewater management. In this chapter, principles of wastewater treatment, sludge
generation and treatment are briefly reviewed, and different technologies to recover
nutrients and their mechanisms are introduced in detail.
4.1 Wastewater Treatment
In typical wastewater treatment plants after eliminating large objects and grits,
suspended solids, colloidal particles, dissolved organics and nutrients are removed.
The effluent is then either discharged into the receiving water bodies or reused
for various purposes such as irrigation and recharging of groundwater. A typical
municipal wastewater treatment plant consists of three phases of treatment: primary,
secondary and tertiary. The core of all treatments is the secondary phase in which
the dissolved organics are degraded by different types of microorganisms [1].
4.1.1 Preliminary Treatment
Before entering the primary treatment, wastewater is subjected to several preliminary
treatments. The purpose of the preliminary treatment is to protect the equipment
and downstream processes. Preliminary treatments include screening, comminution,
grinding and grit removal and are designed to remove and reduce the size of the large,
suspended or floating solids, remove heavy inorganic solids such as sand, metal or
glass and remove excessive amounts of oils or greases [2, 3]. The screening system
removes the large debris from the influent, consisting of coarse screens for protection
of pumps and other equipment, fine screens for removal of smaller materials, and
microscreens for very fine particles. Comminutors and grinders include cutters and
shredders that provide an alternative to coarse screening [2]. And finally, grit removal
is performed by gravity or centrifugal processes through grit channels, detritus tanks,
aerated or vortex grit tanks, centrifugal type separators and stationary screens [3].
4.1.2 Primary Treatment
Primary treatments are performed in primary sedimentation tanks or clarifiers. Coagulants, such as alum (Al 2 (SO 4 ) 3 .14 H 2 O), are often used to facilitate sedimentation