Upload
abu-khairul-bashar
View
221
Download
4
Tags:
Embed Size (px)
DESCRIPTION
Hydrochemistry is the process of measuring the condition of water according to the requirements of more than one biotic species or any human purpose. It is most commonly used to refer to a set of standards which compliance is tested against. Hydrochemistry is the subdivision of hydrogeology that deals with the chemical characteristics of water. In Hydrochemistry, there are needed so many parameters.
Citation preview
Department of Environmental Sciences
Jahangirnagar University
Savar, Dhaka-1342
Descriptions on Some Parameters
of Hydrochemistry
Submitted By
Abu Khairul Bashar
Class Roll: 584
Session 2011-12
Submitted To
Dr. Syed Hafizur Rahman
Professor
Department of
Environmental Sciences
Hydrochemistry is the process of measuring the
condition of water according to the requirements of
more than one biotic species or any human purpose. It
is most commonly used to refer to a set of standards
which compliance is tested against. Hydrochemistry is
the subdivision of hydrogeology that deals with the
chemical characteristics of water. In Hydrochemistry,
there are needed so many parameters. Such as-
DO
BOD
COD
TDS
TSS
TOC
Iron(Fe)
Heavy Metal
Trace Element
Microorganism
Chlorination
Hardness
Dissolved Oxygen refers to the volume of oxygen that
is contained in water. Oxygen enters the water by
photosynthesis of aquatic biota and by the transfer of
oxygen across the air-water interface. The amount of
DO in water is dependent on the water temperature. DO
is a very important indicator of a water body’s ability to
support aquatic life. Oxygen is more easily dissolved
into water at low altitudes than high altitudes because of
higher atmospheric pressure. DO concentrations are
higher in the winter than in the summer. The colder the
water, the more oxygen can be dissolved water.
Biochemical oxygen demand is a measure of the
oxygen used by microorganisms to decompose the
organic matter. When BOD levels are high, DO levels
decrease because the oxygen that is available in the
water is being consumed by the bacteria. Since less DO
is available in the water, fish and other aquatic
organisms may not survive. The BOD test takes 5days
to complete and is performed using a DO test kit.
The amount of oxygen needed to consume the organic
and inorganic materials is called chemical oxygen
demand (COD). COD has the advantage over BOD in
that the analysis can be completed within a few hours
whereas BOD requires 5 days. The major drawback of
the COD test is the presence of hazardous chemicals
toxic waste disposal. The UV absorption can be
considered as an alternative method for COD. The COD
is a rapid and precise method for determination of
aggregate organic matter. COD value can be related to
TOC value also which is a measure of organic carbon
atoms in a sample.
BOD level(in ppm) Water Quality
1-2 Very good
3-5 Fair: Moderately clean
6-9 Poor: somewhat polluted
100 or greater Very poor: very polluted
The expression of ‘’total dissolved solid’’ (TDS) refers
to the total amount of all inorganic and organic
substances including minerals, salts, cat ions, anions,
metals that are dispersed within a volume of water. TDS
concentrations are the cat ions and anions in water.
Sources for TDS include agricultural run-off, urban run-
off, industrial wastewater, sewage and natural sources
such as leaves, silt, plankton and rocks. Piping and
plumbing also release metals in water.
Total Suspended Solids (TSS) are solids in water that
can be trapped by a filter. TSS can include a wide
variety of material, such as silt, decaying plant and
animal matter, industrial wastes, and sewage. High
concentrations of suspended solids can cause many
problems for stream health and aquatic life. High TSS
can block light from reaching submerged vegetation. As
the amount of light passing through the water is
reduced, photosynthesis slows down. Reduced rates of
photosynthesis causes less dissolved oxygen to be
released into the water by plants. If light is completely
blocked from bottom dwelling plants, the plants will
stop producing oxygen and will die. As the plants are
decomposed, bacteria will use up even more oxygen
from the water. Low dissolved oxygen can lead to fish
kills. High TSS can also cause an increase in surface
water temperature, because the suspended particles
absorb heat from sunlight. This can cause dissolved
oxygen levels to fall even further (because warmer
waters can hold less DO), and can harm aquatic life in
many other ways, as discussed in the temperature
section.
Total organic carbon (TOC) is the amount of carbon
bound in an organic compound and is often used as a
non-specific indicator of water quality or cleanliness of
pharmaceutical manufacturing equipment. A typical
analysis for TOC measures both the total carbon present
and the so-called "inorganic carbon" (IC), the latter
representing the content of dissolved carbon dioxide
and carbonic acid salts. Subtracting the inorganic
carbon from the total carbon yields TOC. Another
common variant of TOC analysis involves removing the
IC portion first and then measuring the leftover carbon.
TOC detection is an important measurement because of
the effects it may have on the environment, human
health, and manufacturing processes. TOC is a highly
sensitive, non-specific measurement of all organics
present in a sample. It, therefore, can be used to
regulate the organic chemical discharge to the
environment in a manufacturing plant. In addition, low
TOC can confirm the absence of potentially harmful
organic chemicals in water used to manufacture
pharmaceutical products. TOC is also of interest in the
field of potable water purification due to disinfection of
byproducts. Inorganic carbon poses little to no threat.
Typically, iron exists in water in two different forms,
soluble ferrous or insoluble ferric. Soluble ferrous iron
is dissolved in the water and thus clears, while insoluble
ferric iron will be very visible. Excessive amounts of
iron in water (more than ten parts per million) will give
food and drink a very unpleasant, metallic flavor.
Additionally, water with too much iron could stain
clothing and appliances if spilled. Iron is not a hazard to
health, so there are no health-related risks involved
when water contains too much iron. After doing a water
test to determine that there is a problem with iron, there
are many treatment options available, such as aeration,
filtration, softening and zonation.
A heavy metal is any one of a number of elements that
exhibit metallic properties, which includes transition
metals lanthanides actinides as well as the metalloids
Arsenic and Antimony. Typically the term refers to
elements of atomic number 21 or higher (e.g. Scandium
or above) the term heavy metal chiefly arose with
discussions of pollutants discharged to the environment
in the form of air, water or soil contaminants. While
many heavy metals have considerable toxicity, others
are considered not deemed to possess significant toxic
properties, and, in fact, several of these elements
including zinc, iron, copper, chromium and cobalt are
necessary for metabolic function for a large class of
organisms.
A trace element is a chemical element whose
concentration is less than 1000 ppm or 0.1% of a rock's
composition. The term is used mainly in igneous
petrology. Trace elements will either prefer liquid or
solid phase. If compatible with a mineral, it will prefer a
solid phase (e.g., Ni compatible with Olivine). If it is
incompatible with an element it will prefer a liquid
phase. The measurement of this ratio is known as the
partition coefficient. Trace elements can be substituted
for network-forming captions in mineral structures.
Minerals do not have to contain trace elements, i.e.,
they do not have to appear in the mineral's chemical
formula. When practicing biodynamic farming it is
important to utilize the trace elements of the soil, in
order to give strength to the roots. Hydroponic practices
however are decreasing the seed germination rate,
causing an increase in pollution and waste. Trace
element analysis is a technique that measures very small
concentrations of specific elements present in a sample
to understand alteration of the host rocks under
investigation, with the greater purpose of reconstructing
fluid circulation of a hydrothermal system.
Microorganisms are vital to humans and the
environment, as they participate in the Earth's element
cycles such as the carbon cycle and nitrogen cycle, as
well as fulfilling other vital roles in virtually all
ecosystems, such as recycling other organisms' dead
remains and waste products through decomposition.
The majority of all oxidative sewage treatment
processes rely on a large range of microorganisms to
oxidize organic constituents which are not amenable to
sedimentation or flotation. Anaerobic microorganisms
are also used to reduce sludge solids producing methane
gas (amongst other gases) and a sterile mineralized
residue. In potable water treatment, one method, the
slow sand filter, employs a complex gelatinous layer
composed of a wide range of microorganisms to remove
both dissolved and particulate material from raw water.
Water chlorination is the process of adding chlorine to
water as a method of water purification to make it fit for
human consumption as drinking water. Water that has
been treated with chlorine is effective in preventing the
spread of waterborne disease. Chlorides are present
both in fresh and salt water and are essential elements
for life. A normal adult human body contains
approximately 81.7g chloride. Chloride increases the
electrical conductivity of water.
As a halogen, chlorine is a highly efficient disinfectant,
and is added to public water supplies to kill disease-
causing pathogens, such as bacteria, viruses and
protozoans, that commonly grow in water supply
reservoirs, on the walls of water mains and in storage
tanks.[1] The microscopic agents of many diseases such
as cholera, typhoid fever, and dysentery killed countless
people annually before disinfection methods were
employed routinely. Chlorine is obtained from salt
(NaCl). It is a gas at atmospheric pressures but liquefies
under pressure. The liquefied gas is transported and
used as such. As a strong oxidizing agent, chlorine kills
via the oxidation of organic molecules. Chlorine and its
hydrolysis product hypochlorous acid are neutrally
charged and therefore easily penetrate the negatively
charged surface of pathogens. It is able to disintegrate
the lipids that compose the cell wall and react with
intracellular enzymes and proteins, making them
nonfunctional. Microorganisms then either die or are no
longer able to multiply.
Water hardness is a natural feature and is a result of the
geology of the area, being primarily limestone.
Minerals such as calcium and magnesium dissolve into
the water as moves over and through the ground. The
level of these minerals in the water determines the
water hardness. The information in the table below
provides a general rule for classifying water hardness.
Hardness description Total Hardness in mg/l
Calcium carbonate
Soft < 150
Hard 150 – 300
Very Hard > 300