Understanding Water Quality and Its Impact on Health

water quality

Water quality constituents Natural water may contain suspended and dissolved inorganic and organic compounds and microorganisms. The inorganic compounds originate from weathering of rocks, solid and sediments. The organic compounds originate from decaying plants and animals matters. Municipal and industrial waste contribute to a wide spectrum of both organic and inorganic impurities.

Inorganic constituents: Including the following principal chemical constituents in addition to trace constituents. Magnesium Calcium Sodium Chloride Potassium Inorganic constituents Fluoride Iron Manganese Phosphate Sulfate Nitrate Bicarbonate - carbonate

Inorganic water quality indicators Several water quality parameters are used to describe properties of water. Alkalinity: alkalinity in natural water is due to primarily the presence of bicarbonate and carbonate ions. Alkalinity of water varies in concentration with geographical location depending particularly upon the characters of the rocks and soils in the area. For healthy fresh water, the desirable bicarbonate alkalinity range is 30 130 mg/L as caco3. The pH is well maintained of 6.5 8.2.

Hardness: hard water is generally associated with formation of scales in boiler, heaters and hot water pipes. Hard water also prevents formation of leather until excessive soap is consumed. Hardness in natural water is due primarily to calcium and magnesium ions. Area that have limestone formations generally have hard water. Total hardness mg/L as caco3 0-40 Classification Soft 40-100 Moderately hard 100-300 Hard 300 500 Very hard Greater than 500 Extremely hard

Hard water have had no harmful effects upon the health of people. Hardness over 100 mg/L in municipal water supplies has been found inconvenient by reason of excessive soap consumption. Recent studies relate soft water to heart disease, simply because the soft water is corrosive and dissolves potentially harmful substances from the piping and plumbing. Total dissolved solids (TDS): total dissolved solids in natural water are due to inorganic salts. In river and lakes, the concentration of TDS in water will vary depend on the time of the year, local geological condition, climate and waste discharge.

The EPA recommends a maximum of 500 mg/L TDS in drinking water supply. Above this level, the water may have a salty test. Conductivity : the electrical conductivity (EC) is related to TDS. It is a measure of the ability of the water to conduct an electrical current. It is reported in micro siemens per centimetre. Because the electrical current is transported by the ions in solution, the conductivity increases as TDS increases.

Dissolved oxygen (DO): In nature clean water is saturated with DO or nearly so. The level of DO in natural water is an indication of pollution. Low DO concentrations are likely to be associated with low quality water. If organic wastes are discharged into the natural water, microorganism decompose these wastes and utilize the DO. Turbidity: turbidity in water is caused by the presence of such suspended matter as clay, finely divided organic and inorganic matter, and microorganisms. Turbidity represents the optical property of water which causes light to be scattered and absorbed rather than transmitted.

Attempts to correlate turbidity with suspended solids concentration are impractical because the size and shape of particles are important optically but have little direct relationship to the suspended matter. concentration of the Nephelometers are now the standard instrument for measurement of law turbidities and give results in terms of the Nephelometric turbidity units NTU.

Organic constituents: The organic compounds in natural water are derived from natural decomposition of plants and animals materials. Organic compounds may also reach surface water from municipal and industrial discharge. Organic compounds could be divided to natural organic matters which originates from plant and animal residues and synthetic organic compounds such as surfactant, pesticides, cleaning solvents etc. The concentrations of organic matters in natural water is generally small. The most common measurements include BOD5 ,COD and TOC.

Microorganisms: Bacteria: their importance in water supply is great because they may cause disease. Most bacteria are harmless and many are actually beneficial. Some bacteria produce by products that inhibit growth of many pathogens. Other types of bacteria are pathogens Viruses: they are the smallest of infectious agents. Viruses are more resistant to disinfection than bacteria, but in a natural water they are present in far fewer numbers than bacterial pathogens Other microorganisms such as fungi, Algae and Protozoa.

Indicator organisms: Coliform organisms, these are non-pathogenic bacteria whose origin is in faecal matter. The presence of these bacteria in water is an indication of faecal contamination and probably unsafe water. organisms currently used as indicator The results is reported as most probable number per 100 ml (MPN / 100 ml).

Water treatment plants The principal objective of a water treatment plant is to produce water that satisfies a set of drinking water quality standards to the consumer at a reasonable price. A water treatment plant utilizes many treatment processes to produce water of a desired equality. The most common processes in conventional treatment plants are: screening, sedimentation, filtration, disinfection .etc. coagulation, flocculation,

Other processes that might be used in treatment plants are: aeration, chemical precipitation, activated carbon adsorption, fluoridation, membrane ..etc. Many factors should be considered in determination of the required processes in a certain treatment plant such as: characteristics and seasonal variation In the raw water quality, site condition, Plant economics, required effluent characteristics etc.