Abstract
Water is the most important resource for all kinds of life on this earth. Water pollution is the contamination of water bodies (i.e. rivers, oceans, lakes, and ground water). Water pollution occurs when pollutants are directly or indirectly discharged into water bodies without treatment to remove harmful compounds. Water pollution and its treatment are interconnected to each other so it is not possible to explore one topic without the other. Today, all over world, people suffer from this problem so scientists and researchers are trying to solve these problems by different ways. There are many chemical and biological methods for water pollution treatment. This chapter deals with a brief introduction about water pollution, its types, main reasons that cause water pollution, and their effects on human health and environment, and it is mainly focused on the waste water treatment processes by bioremediation and chemical methods for removing heavy metals, pesticides, organic compounds, and dyes, which are mainly found in industrial and domestic waste water.
TopBackground
Water can be divided into two categories: surface water (rivers, natural lakes, reservoirs, ponds) and subterranean water (springs and ground water). The composition of natural water is determined by a sequence of physical, chemical and bio-chemical processes which occur during different stages in hydrologic cycle. Atmospheric agents play an active role in these processes. So the quality of natural water is greatly influenced by atmospheric conditions and seasonal variations in temperature. The contamination of soil and water resources with environmentally harmful chemicals represents a problem of great concern not only in relation to the biota in the receiving environment, but also to humans. The continuing growth in industrialization and urbanization has led to the natural environment being exposed to ever increasing levels of toxic elements, such as heavy metals. Some standards parameters for water characterization are available which justify the water quality i.e. water is polluted or not. Table 1 and 2 show these standard parameters. So the water must follow these parameters, if the water does not follow these parameters then it is called as polluted water.
Table 1. According to Indian Standard Institute (ISI), World Health Organization (WHO) and National Interim Primary Drinking Water Standards (NIPDWS), Parameters for water characterization (Jayasree, 2002;BIS, 1991)
| S. No. | Parameter | Standard Values |
| ISI | WHO | NIPDWS |
| 1 | pH | 6-9 | 6.5-8.5 | 6.5-8 |
| 2 | Specific Conductance (mho, cm) | - - | - | - |
| 3 | Total solid (mg/L) | 3 | - | - |
| 4 | Total dissolved solids (mg/ L) | - - | 500-100 | - |
| 5 | Dissolved oxygen | - - | - | - |
| 6 | Biological Oxygen demand (mg/L) | - | - | |
| 7 | Total alkalinity (mg/L) | 1,000 | 120-250 | |
| 8 | Total hardness (mg/L) | 600 | 100-500 | |
| 9 | Calcium hardness (mg/L) Magnesium | - | 75-200 | |
| 10 | Hardness (mg/L) | | 30-150 | |
| 11 | Sulphate (mg/L) | | 400 | |
| 12 | Chloride | | 250 | |
| 13 | Turbidity (NTU) | | - | |
Key Terms in this Chapter
Bioremediation: The use of biological agents (bacteria/ plants) to remove pollutants from the polluted soil/water.
Non-Point Source Pollution: Pollution that comes from a multiple source.
Adsorbent: It is a substance that has the ability to adsorb other substance.
Trans- Boundary Pollution: Pollution, which originates from a one region but by crossing the border through pathways of air or water, is able to cause damage to the environment in another region e.g. nuclear waste pollution.
OSMOSIS: It is a process by which molecules of a solvent tend to pass through a semi-permeable membrane from less concentrated solution to a more concentrated one.
Flocculation: It is the process wherein colloids come out of suspension in the form of flocs.
Adsorption: Adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface of adsorbent.
Adsorbate: It is a substance which is adsorbed on the surface of adsorbent.
Heavy Metal: A metal with a specific gravity greater than about 5 or have relatively high atomic weight.
Point-Source Pollution: Pollution that comes from a single source.