Bacteriological Analysis of Water in Halls of Residence in University of Benin
Chapter One
AIM OF THE STUDY:
This study is aimed at the bacteriological analysis of the water from these tanks.
OBJECTIVES OF THE STUDY:
- To attain the total bacterial count of the water samples.
- To determine the coliform counts (Most Probable Number) of the water samples.
- To determine the species of bacteria present in the water.
CHAPTER TWO
LITERATURE REVIEW
Water, Water Wells, and Water Contamination
Understanding the Hydrologic Cycle
Water is constantly moving. As rain or snow (precipitation) falls to earth, some of it collects to form lakes, streams, and other bodies of water. The remaining water enters the soil in a process called infiltration. Some of this water evaporates back into the air and some is used by growing plants. The remainder seeps d o w n w a rd through the soil, until it accumulates at some depth and becomes groundwater (Wright et al., 2004). Downward movement of water thro u g h the soil is percolation. This water eventually makes its way into a zone of soil where the space around each soil particle is completely filled with water (saturated). Water in this space is called groundwater, and its upper boundary is called the water table. Groundwater is located in underground formations called aquifers at various depths beneath the ground surface, and is generally available for human use. It can move laterally as groundwater flow to replenish surface water supplies. Groundwater constantly moves through the soil and reappears on the lowland surface as lakes, streams, swamps, or springs (Ward, 1995). Although water is in constant motion, it seems to be stored in lakes, bays, oceans, and glaciers, as well as in underground supplies as discussed below, because the rate of movement in these vast bodies is relatively slow. Surface waters constantly evaporate into the air and produce clouds and later precipitation. Thus, water changes constantly from precipitation, to surface water, to groundwater, back to surface water, to atmospheric moisture, and back to rain or snow. This cycle of water movement is called the hydrologic cycle (Wright et al., 2004)
SURFACE AND GROUNDWATER SUPPLIES
What Is Surface Water? Surface supplies of water are quite familiar to most of us. They include rivers and streams, ponds and lakes (reservoirs), and cisterns or other controlled catchments. For purposes of this discussion, springs are also considered surface supplies although, strictly speaking, springs originate from groundwater and occur where the water table intersects the land surface. Each of these sources has different characteristics. Ponds and lakes occur where nature has created an obstruction to the normal flow of surface runoff or where a natural waterholding depression has formed. People can also create such supplies by building dams. Controlled catchments are areas from which nearly 100 percent of precipitation is collected as run off. Rooftops are the most easily recognized type of controlled catchment. However, larger areas of land can be manipulated to maximize run off and subsequent collection (for example, by paving with concrete or asphalt). Springs and seeps occur at the land surface where water from underground sources appears. Because springs appear at the ground surface, they must be treated differently than groundwater to adequately protect their quality (Clasen and Bastable, 2003).
What Is Groundwater? Groundwater, water that lies hidden beneath the earth‟s surface, is an important resource. Although it makes up only 4 percent of the total amount of water on earth, it constitutes 95 percent of the fresh water that is suitable for human consumption (Wright et al., 2004). Groundwater and the way it moves is not as easy to understand or visualize as surface water simply because we cannot see it. People often imagine that groundwater exists in vast buried lakes and rivers. However, only in certain soluble deposits, such as limestone, do waterfilled cavern s or channels resemble underground lakes and rivers. Unfortunately, the “hidden” nature of groundwater has resulted in a “out of sight, out of mind” sentiment and therefore contributed to its being considered out of danger. We now know that this is not so; too many cases of groundwater pollution are known. Groundwater occurs beneath the earth‟s surface in geologic formations called aquifers. In aquifers, all the spaces around individual soil particles and cracks within rocks are completely filled with water. Aquifers can be relatively small in area or they can stretch for several thousand Square miles. Aquifers vary in thickness from a few feet to several thousand feet. Unconfined aquifers have no impermeable layers overlaying them and usually are found close to the surface of the land. As shown in Figure 1.2, precipitation percolates through the soil until it reaches the unconfined aquifer‟s upper boundary, the water table. Only a very small portion of the water ever filters down to the confined aquifers. Unconfined aquifers, due to their proximity to people‟s activities on the soil surface, and the fact that the soil material above them transmits water readily, are especially susceptible to pollution. A confined aquifer is bounded on the top and bottom by relatively impermeable layers of clay or solid rock through which only very small amounts of water can pass. Precipitation can enter these deeper aquifers directly through regions called recharge areas where an aquifer is exposed to the earth‟s surface (Fig. 1.2). In the Coastal Plains especially, several aquifers might overlie each other (Wright et al., 2004). Only about 1 inch of this precipitation ever reaches the deeper aquifers. Most groundwater is later returned to the surface as base flow; that is, water discharged continuously into perennially flowing streams. Within an aquifer, groundwater travels along fractures in the rock, through the pores in sand and gravel, or along chananels carved out of soluble rock, such as limestone. The direction and rate of this movement are very diff e rent from that of surface water. Whereas surface water moves at the rate of tens or even hundreds of feet per minute, groundwater moves at the rate of inches per day or less. Once water enters an aquifer, it can remain there for centuries. Therefore, if contaminated, it might take aquifers just as long to cleanse themselves naturally. Though the soil above aquifers might filter some materials transported by percolating water, these substances can continue to be leached if they are not degraded in the soil by microbial and/or chemical processes. Natural water quality in the Coastal Plain aquifers is generally good, but varies with the type of aquifer material. Some elevation in dissolved mineral content (hardness) is always present, but is elevated in formations derived from fossilized material and limestone.
CHAPTER THREE
Materials and Methods
Study area
University of Benin is a research university located in Benin City, Edo State, Nigeria. It is among the universities owned by the Federal government of Nigeria and was founded in 1970. The study will cover the five hall of residence of the university of Benin, Benin, Edo state. The halls comprises of hall1,2,3,4,5 and it is been supply with water from an overhead borehole tap.
Samples collections, transport and storage
Water samples for analysis were collected in sterile containers and in the process, special care was taken to obtain fair samples. For samples collected from rivers and well, the sample bottles were filled from below the surface of the water to avoid sediments, while samples from the tap were taken after allowing the tap to run for about five minutes. Water samples were collected from five different sources namely; borehole water samples from hall 1, hall 2, hall 3, hall 4, and hall 5 respectively. The samples were majorly analyzed for microbial and biochemical analysis. However, all samples were transported to the laboratory in ice-bag and processed within 6 hours of collection.
CHAPTER FOUR
Results
The mean values and standard deviation of the bacteria counts of the various water samples at different locations are shown in Table 1.
Chapter five
Conclusion
The results obtained from this study show that the various water sources considered are contaminated with biological and agents of human and animal origins. However, the two borehole waters and two rain waters are comparatively better water than the two well waters and the two river waters. The high microbial load particularly in Borehole waterat Hall 1 and the two Borehole waters make them unsuitable for drinking purposes, although they can be used for washing purposes.
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