Four different sachet water (Uniben water, Faith Mark water, Coheads water and Enaho water) were collected and their physico chemical properties analysed. The parameters analysed were pH, alkalinity, chloride, nitrate, sulphate, phosphate, hardness, total dissolved solidsTDS, turbidity, electrical conductivity and heavy metals.
The nitrate, sulphate and phosphate were determined spectrophotmetrically while hardness, chloride, TDS, chloride were determined titrimetrically. The result showed that pH ranges from (4.45 to 6.02), Electrical conductivity (6.00 to 115.00) uS/cm, Total dissolved solids (3.00 to 58.00)mg/l, Temperature of 26.500C, Turbidity (<0.001) NTU, chloride (1.86 to 35.65)mg/l, alkalinity (2.51 to 37.10) mg/l, sulphate (0.02 to 0.29)mg/l, phosphate (<0.001) mg/l, Nitrate (0.02 to 0.41)mg/l, Hardness (0.56 to10.67)mg/l , Heavy metals determined are Fe3+ , Zn2+ and Pb2+ (<0.001) were below detection limits.
The results of the analysis reveal that Enaho sachet water had the best quality because the values obtained for all the parameters were within acceptable limits given by the Nigerian Industrial standard (NIS) and the (WHO) standards too, except for the pH value of (6.02).
Uniben water had the least quality of all the sachet water determined, it had the lowest pH of (4.45), highest values in parameter such as chloride (35.65)mg/l,Electrical conductivity (115.00)uS/cm, TDS (58.00)mg/L,Alkalinity (37.10)mg/l and Nitrate (0.41)mg/l.
Water is an odourless, tasteless, transparent compound or liquid that is quite colourless but exhibits a bluish tinge in large quantities. It is the most abundant liquid on earth at it covers three quarters of the earth’s surface. Water is one of the most physical elements of the earth’s system. In addition, Most of the living tissues in human beings is made up of water as it constitutes about 92% of blood plasma, about 80% of muscle tissues, about 60% of red blood cells and over half of most others tissues.
Water is very important to the sustainance of life and satisfactory supply must be made available for consumers. Every effort should be made to achieve a good drinking water quality as high as possible,protection of water supplies from contaminants is the first line of defence. Source protection is almost invariably the best method of ensuring safe and portable drinking water.
Once a potentially hazardous situation has been recognized, the availability of alternative sources and the availability of suitable remedial measures must be considered so that a decision can be made about the acceptability of the supply (WHO, 1984).
It should be noted that the use of chemical disinfectant in water treatment usually results in the formation of chemical by products, some of which are potentially hazardous. However, the risk to health from these by product are extremely small in comparism with the risk associated with inadequate disinfection.It is important that disinfection should not be compromised in attempting to control such by products (WHO, 1984). Furthermore, taste, odour and colour may be the first indication of potential hazards (WHO, 1984b).
Many parameters must be taken into consideration in the assessment of water quality, such as source protection, treatment efficiency, and reliability guideline values have been set for assessing portable water quality and the recommended guideline values are set at a level to protect human health which may not be suitable for aquatic life (WHO, 1984). Water intended for human consumption must be free from local contamination since it can lead to the spread of microbial infections.
Moreso, safety should be achieved before the treatment step, so that the failure of any of the treatment process will not result to water borne disease. The protection of the source from pollution of any set and the provision of adequate and properly operated system of treatment constitute essential barriers to the transmission of disease on which the supply of portable and a wholesome water depends (WHO, 1984).
1.1 WATER SOURCES
For most urban residents relying on municipal water systems, drinking water comes from two major sources. Ground water and surface water.
1.2 GROUND WATER
This refers to water below the earth’s surface, it is an important component of the hydrologic cycle, which includes bore hole water, wells and spring water contains a considerable amount of salt but very little suspended impurities such as dust and bacteria. It is a good source of drinking water.
Well water contains a lot of clay and other mineral salts. A well that is used as source of drinking water contains alot of clay and other mineral salts. A well that is used as a source of drinking water should be sited away from sources of underground water pollution such as pit latrines and other sources of underground contamination. Moreover, water from deep wells tends to be less polluted than water from a shallow well.
Rain water is the purest form of natural water because it is formed as a result of condensation of water vapour in the atmosphere. It is a natural form of distilled water free from most impurities but contains some dissolved gases which are absorbed as it falls into the atmosphere.Examples of these dissolved gases are nitrogen(IV)oxide, sulphur(iv)oxide, hydrogen sulphide and carbon iv oxide. These gases sometime react with water forming acid which are generally referred to as “ACID RAIN” scientist estimate that ground water makes up 95% of all fresh water available for drinking.
1.3 SURFACE WATER
This class of water occurs on land surface, examples are seas, oceans, lakes etc.Surface water is a natural habitat for aquatic animals and many micro organism because of this, surface water may be salty due to the presence of sodium chloride, a bitter taste due to the presence of magnesium sulphate and acid taste as a result of carbon dioxide.
1.4 UNDERGROUND WATER
Underground water exists beneath the earth’s surface, the earth contains about 8.33million cubic kilometer of ground water. There are three main types of underground water namely. Meteoric, cognets and juvenile.
- The meteoric underground water composes the largest percentage of underground water. The water does percolate underground from rainfall or from the bottom of lakes and rivers due to the downward percolction of a proportion of rain water
- The cognate water is all like salt water which is from rocks that lay beneath ancient seas.
- The juvenile water is formed by the chemical processes that occurs in rocks of beneath the earth’s surface.
1.5 PROPERTIES AND STRUCTURE OF WATER
Water exist in three different states which are solid, liquid and gas/vapour states. It is a universal solvent and acts as catalyst in nearly all chemical reactions occuring in the environment. Water has chemical formula of H2O, which consists of two atoms of hydrogen and one atom of oxygen which are joined by covalent bond. The oxygen atom has a partial negative charge while the hydrogen atoms have a partial positive charge. Hydrogen bonding occurs between water molecules i.e association of the hydrogen of one molecule and the lone pair of another molecule, this is prevalent in liquid water and ice as it explains some of the extraordinary physical properties of water. (Tebbult 1973), examples are high boiling point and melting point,low density and are dependent on temperature and pressure.
The hydrogen bonds holds water molecules together, the large amount of energy required to break hydrogen bonds makes water an excellent energy absorber. Water absorbs considerable energy when heated to vapour. This requires that all hydrogen bonds must be broken when the vapour condense to liquid and cools, energy is released as hydrogen bonds formed again. The energy is exactly equal to the amount in the reverse process (Richard, 1980).
1.6 WATER CYCLE
The water cycle also known as the hydrological cycle, describes the continuous movement of water on, above, and below the surface of the earth.Water can change states among liquid, vapour and ice at various place in the water cycle. The water moves from one place to the other, such as from river the ocean, or from ocean to the atmosphere by the physical process such as evaporation, condensation, precipitation, infiltration runoff and sub surface flow. During these processes,water goes through different phases.
The hydrologic cycle involves, the exchange of heat energy, which leads to temperature change. For example during the process of condensation , water takes up energy from the surroundings and cools the environment. The sun which drives the water cycle heats up the oceans and seas. Water evaporates as water vapour into the ice and snow can sublime to water vapour. Evapotranspiration is water transported by plants and evaporated from the soil. Rising air currents takes the vapour up into the atmosphere where cooler temperature causes it to condense into clouds. Air current moves water vapour around the globe, cloud particles collides and fall as out of the sky. Most water falls back into the ocean or onto land as rain where water flows over the ground as surface runoff. A portion of runoff flows into rivers or valleys in the landscape, with streams flowing into oceans. Runoff and ground waters are stored as fresh water in lakes. Not all runoff flows into river, much of its soaks into the ground as infiltration some water infiltrate deep into the ground and replenishes the aquifers which store fresh water for long period of time. Some infiltrate stay close to the land surface and can seep into surface water bodies (and the ocean) as groundwater .
Some human activities which affects water cycle includes:
Deforestation and afforestation
The different processes in the water cycle are :
- Precipitation: This is condensed water vapour that falls to the earth surface. Most precipitation occurs as rain. But also include snow , fog, drip and sleet (King, 2006). Approximately 305,000km3 of rain water falls as precipitate each year (Arts, 2006).
- Runoff: The variety of ways by which water moves across the land. This includes both surface runoff and channel runoff. As it flows, the water may seep into the ground, evaporate into the air, becomes stored in lakes or reservoirs.
- Infiltration: This is the flow of water from the ground surface into the ground. Once infiltrated the water becomes soil moisture or ground water.
- Evaporation: This is the transformation of water from liquid to gas phases as it moves from the ground or bodies of water into the overlying atmosphere (King 2006). The source of energy for evaporation is primarily solar radiation. Evaporation often include transpiration from plants which can be referred to as evapotranspiration (Arts, 2006).
- Sublimation: This occurs when there is a direct change of state from to water vapour (King 2006).
- Advection: This is the movement of water in solid, liquid or vapour states, through the atmosphere. Without advection water evaporated over the oceans cannot precipitate over land (King, 2006).
- Condensation: This is the transformation of water vapour to liquid droplets in the air, creating clouds and fog (King 2006).
- Transpiration: This is the release of water vapour from plants into the air
1.7 USES OF WATER
The utilization of water can be divided into two general types
withdrawal and non withdrawal
Withdrawal use lend themselves to evaluation in terms of quantity, as they require the water to be removed from the ground, streams, lakes or ponds. The important withdrawal uses are:
- Rural, domestic and stock
NON WITHDRAWAL USES
In contrast to withdrawal uses,non withdrawal uses do not lend themselves to evaluation in terms of quantity of water used. These uses do however have a very large economic value. The most important non withdrawal uses are
- Waste disposal
- Conservation of wild life
HOUSE HOLD USES
It is estimated that 80% of the water used world wide is used for domestic purposes. These includes drinking water, bathing, cooking, sanitation gardening etc (Gleick, 1974). Basic household requirements have been estimated at about 50 litres per person daily,excluding gardening (Gleick 1974. Drinking water is a water that is of sufficiently high quality so that it can be consumed without risk of immediate or long term harm. Such water is often called portable water. Water can also be classified into consumptive and non consumptive water use.
Consumptive water use causes diminishment of the source at the point of appropriation. Diminishment is used to describe how smaller or less in quality, quantity, flow rate,and availability. Water used consumptively diminishes the source and is not available for other uses.
Non- consumptive water use does not diminish source or impair future water use. Surface water use is non-consumptive when there is no deviation from the water source or diminishment of the source. Ground water use is non consumptive when there is no diminishment of the source. In order not to diminish the source, the water is injected or infiltrated immediately back to the aquifer.
1.8 WATER TREATMENTS
Water treatment describes the processes used to make water more acceptable for a desired end use. These includes the use of water as drinking water, industrial process, medical and many other uses. The goal of all water or reduce the concentration of such contaminants so that the water becomes fit for its desired purpose.
The process involved in treating water for drinking purpose may be by solid separation by physical process such as filtration and settling and chemical processes such as disinfection and coagulation. Biological processes are also employed in the treatment of waste water and these process may include aerated lagoons, activated sludge or slow sand filters.
Water purification is the removal of contaminants from untreated water to produce drinking water that is pure enough for the most critical of its intended uses, usually for human consumption. Substance that are removed during the process of drinking water treatment includes suspended solids, bacteria, algae, fungi, mineral such as iron, manganese, sulphur etc. and other chemical pollutants.
Measures taken to ensure water quality not only relate to the treatment of the water, but to its conveyance and distribution after treatment as well. It is therefore a common practice to have residual disinfectant in the treated water in order to kill any bacteriological contamination during distribution.
World Health Organization (WHO) standards and guidelines are generally followed throughout the world for drinking water quality requirements.Inaddition to the (WHO) guidelines,each country have their own guidelines in order for consumers to have access to a safe drinking water.
1.9 Physicals And Chemical Characteristics Of Water
Some of the major physical and chemical characteristics of water includes:
Water is a liquid at room temperature and pressure
Water is transparent in the visible electromagnetic spectrum, thus aquatic plants can live in water because sunlight can reach them through ultraviolet and infrared light which is strongly absorbed.
It is tasteless and odourless. The intrinsic colour of water is a very slight blue although appears colourless in small quantities.
Water is a good solvent and it is often referred to as universal solvent. Substances that dissolve in water (e.g salts, sugar, acids, alkali etc) are known as hydrophile (water loving substances), while those that do not dissolve well in water (e.g fats and oil) are known as hydrophobic (water fearing substances).
Pure water has a low electrical conductivity, but this increase significantly with the dissolution of small amount of ionic material such as sodium chloride.
The boiling point of pure water varies,which is dependent upon barometric pressure. For example, on mountain Everest water boils at 680C compared to 1000C at sea level.
Its density is 10,000 kg/m3 in liquid and weigh 62.4ibft3
Water forms an azetrope with many other solvents
Water is miscible with many liquids such as ethanol, in all proportion forming a single homogenous liquid.
1.10 THE PHYSIOCHEMICAL PROPERTIES OF SACHET WATERS
Physical properties are:
Taste and odour
Turbidity: This represent the optical property of water which causes light to be scattered and absorbed rather than transmitted. Turbidity in water is caused by the presence of some suspended matter such as clay, finely divided organic and inorganic matter, and microorganisms (ASCE and AWWA, 1990) It can be measured using a turbidimeter in NTU(Nephelometric turbidity unit) or in FAU (Formazin Attenuation Units). Water turbidity can also be measured using photoelectric calorimeter.Turbidity should not exceed 1.5mg/l in sachet.High turbidity in drinking water or pure water is usually as a result of inadequate treatment facilities or improper operations.
Colour: Sachet water should be colourless, the presence of colour indicates that it contains dissolved colloidal substances. Pure water has a pale blue green tint in large volume .Most consumers object to taste and colour in water rather than its safety. At 15 units or a threshold odour of 3, water becomes objectionable to many people (Gordon and Williams, 1986).
Conductivity: As it applies to water analysis, it is an indication of the concentration of dissolved ionized solutes. Conductivity can also be said to be the measurement of water capacity for conveying electrical current and it is directly related to the concentration of ionized substance in the water.
Conductivity can be measured by the means of an a.c wheat stone bridge circuit or a conductivity meter. The units is expressed in microsiemers /cm (Patterson et al 1979).
Temperature: This is the degree of hotness and coldness of a substance, temperature also has an influence on taste since warm water taste flat and insipid because of the decreased solubility of oxygen and carbondioxide at evaluated temperature. The temperature should be measured immediately the sample is taken. It is measured by the use of thermometer. It is expressed in degree centrigrade or celcius or in degree Fahrenheit.
Taste and odour: Dissolved impurities which are organic in nature causes taste and odour which are objectionable in water. They are difficult to measure and differ according to individual feeling. Ideally pure water should not have a bad taste and odour.Certain organics and inorganic impurities when present in slight amount make the water unpalatable e.g phenol odour is also objectionable in water. Ozone is one of the most efficient agents in removing taste and odour because it leads to the formation of intermediate products.