Page 32 - Materials Chemistry, Second Edition

Environmental and Health Effects Due to the Usage of Wastewater 13

1.5.3 bioaccuMulaTion
Bioaccumulation is the process by which certain substances such as heavy metals,
pesticides, and toxic chemicals that are in low concentrations in water can be found
in high concentrations in the tissues of plants and animals. Substances that bioaccu-
mulate are stable, possess a long half-life period, and are not processed by the human
digestive system. Bioaccumulated substances are further magnified by entering the
food chain (Okereke et al., 2016). Discharge of effluents and domestic waste is the
main source of deposits of bioaccumulatives in wastewater. This alters the quality
of the fresh water bodies and transfers the toxic substance into the receiving water
bodies (Akpor and Muchie, 2011). Bioaccumulation with the support of supplements
and vitality takes place within the sight of living cells. There are two phases in the
expulsion of substantial metals from the condition. The first is the maintenance of
the metal particles on the cell surface, and the second is the transportation of the
particles of metal into the cell (Alqadami et al., 2017).

1.5.4 euTropHicaTion
Nitrogen and phosphorus are the nutrients responsible for the growth of plants, and
when these nutrients are released from agricultural runoff into the nearby water bod-
ies, it causes eutrophication. These nutrients also boost the development of aquatic
vegetation, but when they exceed an optimum level, they may cause the develop-
ment of unnecessary weeds and algal bloom. This gives a bad odor and taste to
the water, which make it unfit for drinking (Owa, 2013). Eutrophication causes a
deficiency of dissolved oxygen. Eutrophication of water sources may likewise create
natural conditions that support the development of toxin-producing cyanobacteria.
Eutrophication leads to the depletion of dissolved oxygen in water bodies, which
kills fish and other aquatic organisms (Okereke et al., 2016). The pernicious effects
caused by the eutrophication of wastewater are

• Reduced quality of receiving water bodies, with bad odor and formation of
algal blooms
• Increased depletion of dissolved oxygen
• Undesirable growth of phytoplankton
• Inhibition of aeration of aquatic plants, leading to the death of the plants
• Decreased wastewater treatment efficiency

Effects may also include the expansion of growth of new varieties of plants and
also the extinction of rare species of other plants and animals in our habitat (Akpor
and Muchie, 2011).

1.5.5 DecreMenT of DissolveD oxygen
During the degradation of organic compounds and complex chemical compounds
by bacteria, dissolved oxygen is consumed as a substrate for the decomposition reac-
tion. This further leads to deficiency of dissolved oxygen in the receiving fresh water