Thursday, 22 September 2016

GROUNDWATER POLLUTION (vis-à-vis Groundwater Quality) AND CAUSES


Groundwater in it’s natural state is made up of dissolved substances including gases. These contribute greatly to it’s quality. The surrounding environment (Formations), anthropological and bacterial activities influence it’s quality as well.


Below is a rundown of factors that determine the quality of any groundwater:


They can be categorised into:

1.   Physical factors;

2.   Bacterial factors;

3.   Chemical factors;

4.   Anthropological factors.


Physical factors can be easily seen with the eyes without first being analysed in the laboratory. They are apparent to the physical senses of sight, smell, taste and in some cases, touch. It can be known physically if a groundwater is polluted or not by Colour changes, Odour, presence of suspended materials. The presence of suspended materials make the water appear cloudy. Commonsensically, no sane person will like to consume anything, let alone, water that is not appealing to the eyes.


Chemical pollutants are determined by the mineral composition of the underlying and surrounding Formations. It varies in concentrations and proportions. Some are localized, while some are regional. For instance, regions where limestone is predominant tend to  have hard water which is of no economic use due to the high percentage of Calcium and Magnesium ions prevalent in the groundwater. Likewise, places rich in Coal deposits, Hydrocarbon deposits such as Crude oil, Tarsands have Sulphur and other harmful compounds prevalent in their groundwater. Chemical pollutants are determining factors on the pH of the groundwater. These pollutants include, but not limited to, Calcium, Magnesium, Chlorine, Lead, Iron, Copper, Phenols, Zinc and Sulphur.


Bacterial factors: Bacteria thrive well mostly in places where oxygen is available. So the amount of Dissolved Oxygen Concentration (DOC) in the groundwater may determine whether bacteria will be in it and the amount or not. Deeper boreholes usually have no bacterial activities in them because no bacteria can thrive at such depth. Temperature increases with depth while Dissolved Oxygen Concentration reduces with depth. Unsanitary sewage disposal methods, defecation in open water bodies and water channels and dump sites  are main sources of bacterial contaminations to groundwater. The predominant bacterial pollutant in groundwater is Escherichia coli, commonly known as E. coli .
Anthropological factors: Industrialization and urbanization has posed great danger to the ecosystem. While trying to better lives by industrialization, mankind has ended up releasing toxic wastes into the surroundings. Some of these wastes like Brine, Metals, Ammonia, Sulphates, Plastics and Rubber by-products cannot be safely disposed off, hence, hole is bored into the ground and is discharged directly into the ground thereby polluting the nearby aquifer. Wastes discharged through this means cannot be effectively controlled as at seeps across the underlying and surrounding Formations. Brewing companies and Oil companies release most of their wastes directly into the ground. Mining activities, tank and pipeline leakages also pollute the groundwater.

However, the baby cannot be throw away with the bath water merely because it soiled the bath water. Polluted groundwater can still be remedied depending on the degree of contamination and the nature of the pollutant. 

The treatment includes:
          Disinfection: This involves using Chlorine, Ozone, and Flourine in a calculated proportion.

          Coagulation: this involves adding of alum to make the dirts to form larger clumps and facilitate sedimentation.
          Sedimentation: Here, heavier particles are allowed to settle under gravitational effect and then decantation takes effect.

          Aeration: In this case, the water is exposed to air so that encourage precipitation. This  is for water polluted with Iron and Manganese. Once precipitation is over, it can be decanted easily.


          Filtration: This helps to remove bacteria and other pollutants like organic matter. This is the most common of all techniques.


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