potential human exposure to DEHP are inhalation, ingestion, and dermal contact in
occupational settings and from air pollution, water pollution, food consumption, and
food wrapped in PVC. It is easily dissolved in body fluids such as saliva and plasma.
DEHP is biodegradable, but it tends to partition into sediment where it is relatively
persistent. It also tends to bioconcentrate in aquatic organisms. Because of its low
vapor pressure, human exposure to DEHP in either water or air appears to be
minimal.
DEHP has been detected frequently in surface water, groundwater, and finished
drinking water in the USA at concentrations in the low μg/L range. Groundwater in
the vicinity of hazardous waste sites may be contaminated with DEHP. EPA
regulates DEHP under the CWA and the SDWAA. DEHP is included on lists of
chemicals for which water quality criteria have been established under the CWA.
EPA [9] classifies DEHP as a water priority pollutant and has set the MCL Goal at
zero. EPA has set the MCL at six parts DEHP per billion parts of drinking water
(6μg/L).
4 Water Treatments for EDC Removal
Water suppliers use a variety of treatment processes to remove contaminants from
drinking water. Individual processes may be arranged as series of processes applied
in a sequence. Water utilities select a treatment train that is most appropriate for the
contaminants found in the source water [31–35]. The most commonly used physicochemical processes include coagulation and flocculation, sedimentation, filtration,
and disinfection for surface water [36]. Some treatment trains also include ion
exchange and adsorption [37]. These conventional processes are inefficient for
substantially reducing certain pesticide concentrations and other EDCs.
The processes described below and in the following sections can be used for
removal of EDCs as specified either individually or as a class of compounds. The
feasibility of using the various techniques will depend on the size of the system and
the cost effectiveness. The two major concerns regarding technologies for small
systems are affordability and technical complexity (which determine the needed
skills for the system operators).
4.1 Granular Activated Carbon (GAC)
Activated carbon is similar to charcoal in composition, but its surface has been
altered to enhance its sorption properties. Activated carbon is made from a variety of
materials including wood, coal, peat, sawdust, bone, and petroleum distillates.
Activated carbon produced from wood and coal is the most commonly used variety
in drinking water treatment plants. The base carbon material is dehydrated then
carbonized through slow heating in the absence of air. It is then activated by
oxidation at high temperatures (200–1000
C), resulting in a highly porous, high
184
N. K. Shammas et al.
occupational settings and from air pollution, water pollution, food consumption, and
food wrapped in PVC. It is easily dissolved in body fluids such as saliva and plasma.
DEHP is biodegradable, but it tends to partition into sediment where it is relatively
persistent. It also tends to bioconcentrate in aquatic organisms. Because of its low
vapor pressure, human exposure to DEHP in either water or air appears to be
minimal.
DEHP has been detected frequently in surface water, groundwater, and finished
drinking water in the USA at concentrations in the low μg/L range. Groundwater in
the vicinity of hazardous waste sites may be contaminated with DEHP. EPA
regulates DEHP under the CWA and the SDWAA. DEHP is included on lists of
chemicals for which water quality criteria have been established under the CWA.
EPA [9] classifies DEHP as a water priority pollutant and has set the MCL Goal at
zero. EPA has set the MCL at six parts DEHP per billion parts of drinking water
(6μg/L).
4 Water Treatments for EDC Removal
Water suppliers use a variety of treatment processes to remove contaminants from
drinking water. Individual processes may be arranged as series of processes applied
in a sequence. Water utilities select a treatment train that is most appropriate for the
contaminants found in the source water [31–35]. The most commonly used physicochemical processes include coagulation and flocculation, sedimentation, filtration,
and disinfection for surface water [36]. Some treatment trains also include ion
exchange and adsorption [37]. These conventional processes are inefficient for
substantially reducing certain pesticide concentrations and other EDCs.
The processes described below and in the following sections can be used for
removal of EDCs as specified either individually or as a class of compounds. The
feasibility of using the various techniques will depend on the size of the system and
the cost effectiveness. The two major concerns regarding technologies for small
systems are affordability and technical complexity (which determine the needed
skills for the system operators).
4.1 Granular Activated Carbon (GAC)
Activated carbon is similar to charcoal in composition, but its surface has been
altered to enhance its sorption properties. Activated carbon is made from a variety of
materials including wood, coal, peat, sawdust, bone, and petroleum distillates.
Activated carbon produced from wood and coal is the most commonly used variety
in drinking water treatment plants. The base carbon material is dehydrated then
carbonized through slow heating in the absence of air. It is then activated by
oxidation at high temperatures (200–1000
C), resulting in a highly porous, high
184
N. K. Shammas et al.