Assignment 1

Biological characteristic of water

Name : NurulAin bt Mohd Shokri

ID : 2014466332

Class : AS 2293A

Subject : Water Resource Technology

(EVT 525)

Prepared for : Dr Nik Azlin Nik Ariffin

INTRODUCTION

All living things, from the smallest incest need water to live. Expert predicts that by 2025, 1/3 of the world’s populations will not have water due to the increase in population and water contamination. Each person discharge about 200,000,000,000 coliforms per day. Coliform bacteria are therefore very numerous and the most common and widespread health risk associated with drinking water is microbial contamination, the consequence of which mean that it’s control must always be of paramount importance. Earth currently has estimated 6.9 billion populations as of July 1, 2011 by the United States census bureau.

Water quality is determined by physical, chemical and biological properties of water. These water quality characteristics throughout the world are characterized with wide variability. Therefore the quality of natural water sources used for different purposes should be established in terms of the specific water-quality parameters that most affect the possible use of water.

Biological water characteristics are used to describe the presence of microbiological organisms and water-borne pathogens. Many organisms can cause illness when consumed by humans and animals. Micro-organisms and waterborne pathogens enter rivers and lakes either naturally or via the release of untreated or partially treated sewage.

Today we know that disease-causing microorganism can be carried in water and that their presence in drinking water is a serious hazard to human health. But the knowledge is relatively new. In 1676 a Dutch scientist was able to see bacteria using a very primitive microscope, but it wasn’t until the mid and late 1800s that we began to understand that bacteria caused disease and that they can be carried in water. Microorganisms that caused disease by transmission through contaminated water are called waterborne pathogens.

Objective

To study the structure and characteristics of the microorganisms. To look at their size, shape, types, nutritional needs, and control of each of the major groups of microorganism and to discuss some of the specific waterborne pathogens.

Content

Microbiology is the study of the microorganisms, of small living things. Although some forms of the organisms studied by microbiologists can be seen with naked eye, most of the things that microbiologists are interested in require the use of a microscope to see clearly. Microorganisms of interest to the water industry include the following;

Bacteria Fungi Viruses Protozoa Algae

Content

i. Bacteria

Bacteria are among the most common microorganisms in water. Bacteria are primitive, single-celled organisms with a variety of shapes and nutritional needs. Bacteria are microscopic organism ranging from approximately 0.2 to 10 µm in length. Another way to visualize the size of bacteria is to consider that it will take 1 000 bacteria lying side-by-side, to reach across the head of a straight pin. Bacteria is the smallest living thing and very efficient. 1 bacterium could multiply and cover the earth in 36 hours if the conditions were correct.

There are three general groups of bacteria based on their physical shape which is bacilli, cocci and spirillus. Bacilli are the bacteria which have the rod-shaped, cocci for bacteria in spherical shaped and spirillus for spriral shaped bacteria. Within these three groups, there are many different arrangements. Some exist as single cells, pair, packets of four or eight, chains and clumps.

Bacteria are distributed ubiquitously in nature and have a wide variety of nutritional requirements. Most bacteria require organic food to survive and multiply. This food comes from plants and animal material that gets into the water where the bacteria exist. The bacteria convert the food into energy and use the energy to make new cells. Some bacteria can exist and multiply even when organic pollution is not present. Temperature affects the rate at which bacteria grow. The warmer the environment, the faster the rate of growth. Typically, for each increase of 10°C, the growth rate doubles. This means that bacteria will multiply more quickly when it is warm, and more chlorine may be required to obtain proper disinfection.

pH affect the growth of bacteria. Most bacteria grow best at a neutral pH. Extreme acidic or basic condition will inhibit growth. Other materials, such as metal ions (Cu, Pb, Ag) and some organics, such as pesticide and herbicide, are toxic and will inhibits bacterial growth. Many bacteria are aerobic. They require free or dissolve oxygen in their aquatic environment. Only a few bacteria are anaerobic. They can exist and multiply in an environment that lacks dissolved oxygen. Some bacteria that are normally aerobic can switch to anaerobic, which are called as facultative. One of the most troublesome bacteria in the water business is the iron bacteria, which is a facultative organism. The bacteria for the most of the biological treatment of wastewater are aerobic.

Under optimum conditions, bacteria grow very rapidly. They multiply by a simple dividing process referred as binary fission. Each cells splits into two identical new cells. Bacteria growing under optimal condition can double their number about every 20 to 30 minutes. This means that as long as the nutrients hold out, even the smallest contamination can result in a sizable growth in a very short time. The destruction of pathogenic microorganism is called disinfection. Disinfection does not mean that all microbial forms are killed. Rather that is sterilization. However, disinfection does destroy the most disease-causing organism and reduce the total number to an acceptable level. Growing bacteria are fairly easy to control by disinfection. Some bacteria, however, form spores, which are more difficult to destroy. Spores are survival structural formed by some bacteria to resists harsh, threatening environments.

Bacteria are responsible for a number of the most infamous epidemic diseases. The bacterial pathogens responsible for these diseases enter potential drinking water supplies through fecal contamination and are ingested by human if the water not properly treated and disinfected.

ii. Protozoa

Protozoa are single-celled organisms that lack a cell wall, but do possess a flexibility covering called a pellicle. Typically they are larger than bacteria which range from 4 to 500 microns and unlike algae, cannot photosynthesize. Protozoa are common in fresh and marine water, and sometime can grow in soil and other location.

There are five major groups of protozoa are based on their method of locomotion or movement, which are amoebas, ciliates, flagellates, suctoria and sporozoa. Amoebas move by streaming or gliding action. The shape of an amoeba changes as they sort of ooze from place to place. Ciliates are covered with short hair-like projections, called cilia, which beat rapidly and propel the ciliate through the water. Most ciliates are free-swimming, although some are attached to floating material or basin walls. While flagellates have one or more long whip-like projections, called flagella, which propel the free-swimming organisms. Suctoria are attached organisms, similar to attached ciliates, but have tentacles rather than cilia. Last but not least, sporozoa that are non-mobile and are simply swept along with the current of the water.

Protozoa use organics for food. In fact, bacteria are among their favourite prey. Protozoa are mostly aerobic or facultative in regards to oxygen requirements. In the same manner as bacteria, pH, toxic material, and temperature affect their rate of growth. Most protozoa have a complex life cycle in which they are alternate between an active growth phase, when they are called trophozoites, and a resting stage, called cysts. Cysts are extremely resistant structures that protect the organism from destruction when it encounters harsh environmental conditions.

Because of their relative complexity and ability to form the extremely resistant cysts, protozoa require higher disinfectant concentration and longer contact time to control them. In fact, some types of protozoa may be almost completely resistant to disinfection by chlorination.

iii. Viruses

Viruses are obligate intracellular parasites able to multiply only within a host cell and are host-specific. Viruses occur in various shapes and range of size from 0.01 to 0.03 µm in cross-section and are composed of a nucleic acid core surrounded by an outer coat of protein. Enteric viruses are obligate human pathogens, which mean they replicate only in human host. Their simple structure, a protein coat surrounding a core genetic material (DNA or RNA), allows to prolonged survival in the environment. There are more than 120 identified human enteric viruses. Some of the better understood viruses include the enteroviruses, hepatitis A virus, rotavirus, and human caliviciviruses.

Viruses occur in many shapes, for examples; geometric polyhedrals, long slander roads and elaborate irregular shapes.

There are almost as many kinds of viruses as there are types of other living organisms. Viruses can exist that can be invade virtually every kind of living cells; animal, plants, insects, fish, and event bacteria. After they invade their specific host, they take over the machinery of the host and force it to make more viruses. The host cell is then destroyed, and hundreds of new viruses are released into the environment. Because they lack sensitive cellular machinery and because they have relatively tough capsids and envelops, viruses are hard to destroy by normal disinfection practice. Increased disinfectant concentration and contact time must be used to effectively destroy viruses by chlorine disinfection.

iv. Algae

Algae are a form of aquatic plants. Although in mass they are easily seen by the naked eye, many are microscopic as single cells. They exist as microscopic, single celled forms and also as huge, multicellular forms, such as marine kelp. They occur in fresh and polluted water, as well as in salt water. Since they are plants, they are capable of using energy from the sun in the process called photosynthesis. They grow only where there only light, and grow better where there is bright sunlight, as opposed to cloudy weather. They usually grow near the surface of the water because light cannot penetrate very far through the water.

Algae are classified by their colour which is green algae, euglenoids, diatoms, and cynobacterium. Green algae contain green chlorophyll and are found mostly in fresh water. This form is the green roadside ditch algae, and the type that grows on clarifier and basin walls. Euglenoids are single-celled, green-pigmented algae that resemble protozoa. They have flagella, but are considered algae because they carry out photosynthesis. While diatoms are golden-brown, single cell forms that have hard silica shell. The shells of millions of dead diatoms are mined commercially and known as diatomaceous earth. Cyanobacterium is bluish-green in colour and undergoes photosynthesis. It was formerly called blue-green algae, but is now classified as a type of bacteria.

Although algae are not considered to be waterborne pathogens, they do cause some problems with water operations. They grow easily on the walls of basins and troughs, and heavy growth can caused plugging of screens and intakes. Algae release chemicals that can cause taste and odour problem in drinking water. Algae in raw water supplies can be controlled with chlorine and potassium permanganate. In raw water reservoirs, algae blooms are often controlled with copper sulphate.

v. Fungi

Fungi are relatively minor importance to the water business. Fungi are non-photosynthetic organisms that grow as aerobic multicellular, filamentous, mold-like forms or as single-celled, yeast-like organisms and heterotrophic. Fungi must have organic material as a food source and most fungi are saprophytes, obtaining food from dead organic matter. Fungi like to growth in damp material such as drying or compositing sludge.

As part of their reproduction cycle, they produce spores that are so small; they can easily be carried by dust or wind. When inhale, some of these spores can caused respiratory infection. They are principle micro-organism along with bacteria that decomposes carbon. Without fungi, the carbon cycle would cease and organic matter would build up. Ideal conditions for fungi are high moisture and low pH. Fungi are not considered to be waterborne pathogens.

Group Pathogen DiseaseBacteria Salmonella typhi Typhoid Fever

Shigella spp. GastroenteritisVibrio cholera CholeraCampylobacter spp. GastroenteritisEnteropathogenic E. coli GastroenteritisLeptospira spp. Leptospirosis

Protozoa Entamoeba histolytica Amoebic dysenteryGiardia lamblia (5 to 21 µ in size) GiardiasisCryptosporidia (4 to 6 µ in size) Cryptosporidiosis

Viruses Enteroviruses Meningitis, myocarditisHepatitis A Infectious hepatitisRotavirus DiarrheaNoroviruses Gastroenteritis

Algae Microcystis Diarrhea

Anabaena Liver damageAphantiomenon

Conclusion

Many bacteria, viruses and protozoa are causative organisms for some of the more virulent diseases transmitted to humans directly through water and indirectly through contaminated food. This is because they are waterborne pathogens that cause disease and are carried by water. Although algae and fungi are not waterborne pathogens, but they also bring harms as they can interrupt the water operations. Assay and confirmation of the presence of the causative agent of waterborne diseases are lengthy and time consuming. Instead of specific analyses, coliform organisms have been used to determine the biological characteristics of natural waters. The coliform group of bacteria are aerobic and/or facultative gram-negative, nonspore-forming, rod-shaped bacteria that ferment lactose to gas. Escherichia coli is commonly used as an indicator organism. This organism is present in the intestine of warm-blooded animals, including humans. Therefore the presence of Escherichia coli in water samples indicates the presence of fecal matter and then the possible presence of pathogenic organisms of human origin. The concentration of indicator organisms is reported in MPN/100 mL (MPN = most probable number) or in CFU/100 mL (CFU = colony forming units).

Reference

1) Takashi Asano. (2007). Water Reuse. United States, America: McGraw Hill2) https://dec.alaska.gov/water/opcert/Docs/Chapter2-BiologicalCharacteristicsofWater.pdf 3) http://www.soe.uoguelph.ca/webfiles/rzytner/WQ/biological.pdf 4) http://echo2.epfl.ch/VICAIRE/mod_2/chapt_2/main.htm