Midterm Lesson 1 - Sources of Water PDF

SOURCES , QUALITY OF WATER AND TREATMENT  Learning Content A. Sources of Water B. Water Quality Parameters C. Water Testing and Impurities D. Water Treatment Process E. Water Conservation  Sources of Water 1. Surface Water - Is the rain that ru...

SOURCES , QUALITY OF WATER AND TREATMENT  Learning Content A. Sources of Water B. Water Quality Parameters C. Water Testing and Impurities D. Water Treatment Process E. Water Conservation  Sources of Water 1. Surface Water - Is the rain that runs off the surface of the ground into streams, rivers, and lakes 2. Groundwater - Is water found below the surface of the earth. It is water that has percolated through porous soil until it reaches an impervious stratum, upon which it collects.  Water Potability Potable Water - is clean water that is suitable for human drinking. It must be available for drinking, cooking, and cleaning. Non – Potable Water - Nonpotable water may be used for flushing water closets (toilets), irrigating grass and gardens, washing cars, and for any use other than drinking, cooking, or cleaning. An abundant supply of potable water that is easily distributed is vital to a prosperous economy.  SURFACE WATER Readily provides much of the water needed by cities, counties, large industry, and others. However, this source is dependent on recurring rain. During a long period of drought, the flow of water may be significantly reduced Reservoirs hold surface water during periods of high run-off and release water during periods of low runoff. Surface water is typically treated to provide the potable water required. Where nonpotable water may be used, no treatment of the water is necessary.  Cisterns Surface water can be collected in a storage tank called a cistern. A cistern can fill with rainwater as it drains from the roof of a building or a more elaborate collection system. Collected water is then pumped into the supply line of the building for use. The need for water is so important on certain islands that the government has covered part of the land surface (usually the side of a mountain or a hill facing the direction from which the rains usually come) with a plastic film so rain can be collected and stored for later use. Lay-out of a Cistern  Groundwater Groundwater seeps through the soil and is trapped on impervious stratum, a layer of soil or rock that water cannot pass through. The water collects in pores of permeable stratum; a layer of porous earth that water can pass through such as sands, gravels, limestone, or basalt. Saturated permeable stratum capable of providing a usable supply of water is known as an aquifer.  GROUNDWATER Groundwater can be captured at many layers below a building site—that is, there may be several aquifers at different depths. Very deep-lying groundwater can remain undisturbed for thousands or millions of years. However, most groundwater lies at shallower depths. An aquifer can serve as an underground reservoir with almost unlimited capacity. However, if water is removed from the aquifer at too rapid a rate, the water level may drop so drastically that groundwater can no longer be reached.  Water Table The level of groundwater is referred to as the water table. The distance from the ground surface to the water table is referred to as the water table depth. Depth of a shallow water table can vary considerably. Generally, shallow water table depth will vary with amount of rain. During a long dry spell, the water table depth will usually drop and during the rainy season it will likely rise. Depth of a water table can also change artificially by seepage from a nearby stream, lake, reservoir, or irrigation ditch.  Groundwater Potability Groundwater may require treatment to be potable, but often it does not. When treatment is required, it is generally less treatment than is required when making surface water potable. Water Quality  Chemical Quality pH, hardness, presence of a selected group of chemical parameters, biocides, highly toxic chemicals, and B.O.D are estimated. pH is a measure of hydrogen ion concentration. It is an indicator of relative acidity or alkalinity of water.  Physical Quality The physical parameters include color, taste, odor, temperature, turbidity, solids, and electrical conductivity. On the other hand, chemical parameters can include pH, acidity, alkalinity, chlorine, hardness, dissolved oxygen, and biological oxygen demand.  Biological Quality Bacteria , Viruses , Protozoans , Phytoplanktons , zooplankton , insects, plants and fish  Common Water borne - infections Amoebiasis - Gastroenteritis (gastro) can be a problem for travellers to countries with poor sanitation. Amoebiasis, a type of gastro, is a cause of diarrhoea among travellers to developing countries. It is caused by a parasite known as Entamoeba histolytica that infects the bowel. Amoebiasis most commonly affects young to middle-aged adults. Proper handwashing helps prevent the spread of amoebiasis. When travelling overseas, especially to developing countries, remember to ‘cook it, peel it or leave it’.  IMPURITIES IN WATER Chemicals and toxins can contaminate the water source: 1. Agricultural runoff – pesticides and herbicides 2. Industrial runoff – metals and mine tailings  IMPURITIES IN WATER Surface water generally contains larger quantities of turbidity (cloudiness) and bacteria than groundwater. As surface water runs over the ground, it may pick up various organic substances - algae, fungi, bacteria, vegetable matter, animal decay and wastes, fertilizer, garbage wastes, and sewage. Groundwater generally contains higher concentrations of dissolved chemicals. As groundwater percolates down through the soil, it dissolves minerals such as calcium, iron, silica, sulfates, fluorides, and nitrates, and may also entrap gases such as sulfide, sulfur dioxide, and carbon dioxide Seawater contains high concentrations of dissolved chemicals and some microscopic organisms.  WATER TESTING Chemical analysis of the water - indicates the parts per million (ppm) of each chemical found in the water. Bacteriological quality of the water - provides an estimate of the density of bacteria in the water supply. The presence of any coliform organisms indicates that the water supply may be contaminated with human or animal wastes (perhaps seepage from a nearby septic tank field or animal pasture).  WATER TREATMENT FUN FACT: Potable water can have an objectionable odor and taste and even be cloudy and slightly muddied or colored in appearance. Although the odor, taste, or appearance of potable water may not mean you want to drink it, it is still safe to drink.  Methods to Improve Water Quality 1. Problems with undesirable taste and odor are overcome by use of filtration equipment or by aeration of the water. 2. Bacteria are destroyed by the addition of a few parts per million of chlorine. The taste of chlorine is then removed with sodium sulfite. 3. Suspended organic matter that supports bacterial life and suspended mineral matter are removed by the addition of a flocculating and precipitating agent, such as alum, before settling or filtration. 4. Excessive hardness, which renders the water unsuitable for many industrial purposes, is reduced by the addition of slaked, or hydrated, lime or by an ion exchange process.  Fluoridation and Desalination Fluoridation of public water - is an established method of reducing tooth decay in children. Desalination process - saline (salt) is removed from water (e.g., seawater) thereby making the water potable. This process is used in areas where seawater is the only source of water available or where groundwater is high in saline. Desalination plants provide much of the potable water in arid countries such as Kuwait, United Arab Emirates, and Qatar.  Water Conservation Potable water is not an infinite resource. As population and demand for water grows, it is in short supply and is becoming more expensive, particularly in arid and semiarid climates and in all regions during periods of long drought.  Conservation Techniques Flow Restrictors - on all water outlets (such as sinks and showers), can reduce the amount of water used by 50%, depending on the type installed Water Saving Toilets - Originally, the water tank used to flush a toilet bowl was mounted high on the wall so the water would gain enough velocity to flush away the waste. This could be accomplished with between 1 and 1½ gal (3.8 to 5.7 L) of water Gray Water System - involves the processing of household wastewater for reuse. In the design of the gray-water system, the water from the bathtub or shower and the washing machine is run into a collection tank instead of going into the sewer lines. From the collection tank, the water is filtered and chlorinated and then reused as water to flush the toilets. This water reuse system cuts water consumption by about one-half.