Emerging Water Pollutants and Wastewater Treatments
17
is found associated with more than 300 minerals. The great use of these arseniccontaining minerals in metallurgical processes has made arsenic a common water
pollutant [22]. Arsenic carcinogenic activities depend on duration and dosage; it as
well focuses on different tissues and organs of the body including the lungs, skin and
bladder. Arsenic has been reported in varying concentrations in drinking water in the
United State [23]. Physicochemical processes, such as adsorption and ion exchange as
well as bioremediation have been used for arsenic removal from the environment [24].
(b) Cadmium
Cadmium enters the environment through natural sources, such as phosphate rocks
while numerous anthropogenic activities basically release cadmium into water
bodies. They are highly toxic, persist in the environment and are referred to as
probable human carcinogens [25]. Cadmium attacks the bones, liver, renal systems
and lungs, causing shortness of breath and hypertension amidst other diseases. Major
human exposure route to cadmium has been traced to food irrigated with wastewater followed by a nonfood material (tobacco). Cadmium accumulation is higher in
women than in men, this is closely associated with hemoglobin deficiency [26]. The
concentration of cadmium has been set to be less than or equal to 3.0 μg/L in water
and less than or equal to 5.0 μg/L in wastewater to be discharged in the environment
[27, 28]. Various conventional methods, such as precipitation, ion exchange, coagulation, filtration, solvent extraction and adsorption have been used for cadmium
removal from water. Adsorption is a preferred technique because of its simplicity of
operation.
(c) Lead
The major exposure route to lead has been from leaded paints, although leaded gasoline and industrial release of lead are also prominent. Danger associated with lead
exposure is enormous; this is aggravated in children as it damages cognitive and
behavioral development [29]. High levels of lead exposure experienced in children
have been recently traced to lead presence in water. This is attributed to water distribution channel lines constructed with leaded materials [30]. Lead poisoning may
result in diverse neurological disorders, and long-term exposure can form a basis for
brain tumor. Adsorption has been reported as a preferred method of lead removal
compared with other conventional water treatment techniques [31].
(d) Mercury
Mercury does not exist with gold in the raw ore, but that is extensively used in
gold extraction. The highest level of mercury pollution has been reported to emanate
from artisanal gold mining [32, 33]. Other sources of mercury pollution are cement
production, waste disposal, coal combustion, chemical synthesis, ferrous and nonferrous metal manufacturing as well as chlor-alkali industries [34]. Mercury is known
to affect the cardiovascular system, renal system as well as causes damage to the
central nervous system. Children and pregnant women are highly prone to the effects
17
is found associated with more than 300 minerals. The great use of these arseniccontaining minerals in metallurgical processes has made arsenic a common water
pollutant [22]. Arsenic carcinogenic activities depend on duration and dosage; it as
well focuses on different tissues and organs of the body including the lungs, skin and
bladder. Arsenic has been reported in varying concentrations in drinking water in the
United State [23]. Physicochemical processes, such as adsorption and ion exchange as
well as bioremediation have been used for arsenic removal from the environment [24].
(b) Cadmium
Cadmium enters the environment through natural sources, such as phosphate rocks
while numerous anthropogenic activities basically release cadmium into water
bodies. They are highly toxic, persist in the environment and are referred to as
probable human carcinogens [25]. Cadmium attacks the bones, liver, renal systems
and lungs, causing shortness of breath and hypertension amidst other diseases. Major
human exposure route to cadmium has been traced to food irrigated with wastewater followed by a nonfood material (tobacco). Cadmium accumulation is higher in
women than in men, this is closely associated with hemoglobin deficiency [26]. The
concentration of cadmium has been set to be less than or equal to 3.0 μg/L in water
and less than or equal to 5.0 μg/L in wastewater to be discharged in the environment
[27, 28]. Various conventional methods, such as precipitation, ion exchange, coagulation, filtration, solvent extraction and adsorption have been used for cadmium
removal from water. Adsorption is a preferred technique because of its simplicity of
operation.
(c) Lead
The major exposure route to lead has been from leaded paints, although leaded gasoline and industrial release of lead are also prominent. Danger associated with lead
exposure is enormous; this is aggravated in children as it damages cognitive and
behavioral development [29]. High levels of lead exposure experienced in children
have been recently traced to lead presence in water. This is attributed to water distribution channel lines constructed with leaded materials [30]. Lead poisoning may
result in diverse neurological disorders, and long-term exposure can form a basis for
brain tumor. Adsorption has been reported as a preferred method of lead removal
compared with other conventional water treatment techniques [31].
(d) Mercury
Mercury does not exist with gold in the raw ore, but that is extensively used in
gold extraction. The highest level of mercury pollution has been reported to emanate
from artisanal gold mining [32, 33]. Other sources of mercury pollution are cement
production, waste disposal, coal combustion, chemical synthesis, ferrous and nonferrous metal manufacturing as well as chlor-alkali industries [34]. Mercury is known
to affect the cardiovascular system, renal system as well as causes damage to the
central nervous system. Children and pregnant women are highly prone to the effects