Full Report Exp 7

8/13/2019 Full Report Exp 7

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1.0 IntroductionWater quality is based on the physical, chemical and biological characteristics of water.

Therefore water quality analysis is the determination of the condition of water with regard to

human consumption, industrial and domestic use as well as environmental water quality.

Actually, water quality depends on the local geology and ecosystem, as well as human uses such

as sewage dispersion, industrial pollution. Apparently, the UTMslake seems to not be in a good

condition. The water is cloudy, indicating high turbidity and it also gives out unpleasant smell.

These current conditions seem to be a hindrance towards the students activities and need to be

taken care.

1.2 Objective of Experiment

To analyze the quality of lake water in UTM by conducting turbidity test, pH test,

conductivity test and biochemical oxygen demand (BOD) test in order to improve students

activities.

1.3 Scope of ExperimentThe four tests will be conducted with only on a small amount of water taken from UTMs

lake. However, the result will be representing the whole lake.

1.4 Significance of Experiment

To determine the lake water in UTM is considered as polluted as we compare the tests

result with the standard values.


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2.0 Literature review

Water quality is based on the physical, chemical and biological characteristics of water.

Therefore water quality analysis is the determination of the condition of water with regard to

human consumption, industrial and domestic use as well as environmental water quality. Water

quality depends on the local geology and ecosystem, as well as human uses such as sewage

dispersion, industrial pollution. It is often important to analyse the quality of water after natural

disaster because epidemics precede such calamities. This is usually carried out to ensure that

water is safe and free from contaminates that arise because of the disturbance in ecosystem.

We can measure quality of water through many ways such as conductivity, pH value, and

BOD, turbidity and total suspended solid (TSS). Conductivity is a measure of the ability of an

aqueous solution to carry an electric current. This ability depends on the presence of ions; ontheir total consentration, mobility and valence; and the temperature of measurement. Most

problems in obtaining good data in conductivity monitoring equipment are related to electode

fouling and to inadequated sample circulation. Conductivities grater than 10.000 to

50.000mhos/cm or less than about 10 mhos/cm may be difficult to measure with usual

measurement electronic and cell capacitance.

Measurement of pH is one of the most important and frequently used test in water

chemistry. Practically every phase of water supply and wastewater treatment e.g., acid-base

neutralization, water softening, precipitation, coagulation, disinfection, and corrosion control, is

pH dependent pH is used in alkalinity and carbon dioxide measurements and many other acid-

base equlibria. At a given temperature the intensity of the acidic or basic character of a solution

is indicated by pH or hydrogen ion activity.

The Biochemical Oxygen Demand (BOD) determination is an empirical test in which

standardized laboratory procedures are used to determine the relative oxygen requirements of

waste waters, effluents, and poluted waters. The test measures the molecular oxygen utilized

during specified incubation period for the biochemical degradation of organic material

(carbonaceous demand) and the oxygen used to oxidize inorganic material such as sulfides and

ferrous iron. The seeding and dilution procedures provide an estimate of the BOD at pH 6,5-7,5.


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Turbidity in lakes, reservoirs, channels, and the ocean can be measured using aSecchi

disk.This black and white disk is lowered into the water until it can no longer be seen; the depth

(Secchi depth) is then recorded as a measure of the transparency of the water (inversely related to

turbidity). The Secchi disk has the advantages of integrating turbidity over depth (where variable

turbidity layers are present), being quick and easy to use, and inexpensive. It can provide a rough

indication of the depth of theeuphotic zone with a 3-fold division of the Secchi depth, however

this cannot be used in shallow waters where the disk can still be seen on the bottom.

Total suspended solid (TSS) of a water sample is determined by pouring a carefully

measured volume of water (typically one litre; but less if the particulate density is high, or as

much as two or three litres for very clean water) through a pre-weighed filter of a specified pore

size, then weighing the filter again after drying to remove all water. Filters for TSS

measurements are typically composed of glass fibres. The gain in weight is a dry weight measure

of the particulates present in the water sample expressed in units derived or calculated from the

volume of water filtered (typically milligrams per litre or mg/L).
http://en.wikipedia.org/wiki/Secchi_diskhttp://en.wikipedia.org/wiki/Secchi_diskhttp://en.wikipedia.org/wiki/Euphotic_zonehttp://en.wikipedia.org/wiki/Euphotic_zonehttp://en.wikipedia.org/wiki/Secchi_diskhttp://en.wikipedia.org/wiki/Secchi_disk


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days in an incubator. All the steps was repeated after five days and the DO reading at day five

was recorded as D2. The result for BOD was calculated by using the formula.


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4.0 Results

Table 4.1: Data for BOD Test (21stNovember 13 until 26

thNovember 13)

No Sample size (mL)Initial DO reading

(D1)

Final DO reading

(D2)BOD (mg/L)

1 300 8.89 4.02 4.87

2 100 8.46 7.41 2.31

3 50 8.30 7.53 6.29

Table 4.2: Overall data for water quality parameters

Parameter Reading

pH6.43

Salinity (%) 0.2

Conductivity (S/cm)100

Temperature (C)26

Turbidity (NTU)20.8


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Sample Calculations

P=

BOD =

i. 300 mL water sample

P=

= 1, BOD =

= 4.870 mg/L

ii. 100 mL water sample

P=

= 0.333, BOD =

= 3.153 mg/L

iii. 50 mL water sample

P=

= 0.167, BOD =

= 4.61 mg/L


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5.0 Discussion

For the water samplein the experiment based upon the temperature of the turbidity

(NTU) was about 20.8 at the range of 200. The turbidity is basically to measure the clarity of

water. High turbidity meaning that the water is more cloudy and low turbidity is vice versa. For

the turbidity test, the level of turbidity obtained and compared according to the National Water

Quality Standards for Malaysia, shown that it will be classified into first class to second class A.

Literally meaning, first class to the second class will indicate that, water in the experiment was

coming from the conservation of natural environment, in case for supplying the water; treatment

is necessary though. In addition the range of NTU of 20.8 is in between the two class also shows

that the water resources which came from the lake is quite dangerous and sensitive towards

aquatic species but it still can be considered as safe since it is in between this two classes. As

conclusion for turbidity, it is preferred if the NTU of the water is in between 0.1 and 5.

For the pH measurement of water quality, we found that the pH of the water sample that

we took from the UTMs lakewas about 6.43. This value has proved that the water sample was

almost reaching the neutral level of pH 7. This value also remarks the condition of water sample

from the lake. The close value of pH towards alkalinity in result as the region is quite rich in

mineral. In assumption for the condition of the pH, the existence of high concentration of

carbonates, bicarbonate and hydroxide ions from limestone provided enough of natural buffering

capacity to neutralize the ions from the acid. As summary, pH of 6.43 is characterized in

second class in water quality index in Malaysia. This water sample need conventional treatment

as it is also quite sensitive towards aquatic life. Water Quality Index also agree that the water

from the lake is slightly polluted. The best pH value for domestic water usage is 7 and above

(alkaline).

From the experiment, the conductivity of the water sample used is quite high and it

means that there is high amount of mobility ions. It shows that the water sample has high ability

to conduct an electric current based on high amount of mobility ions. Basically, conductivity is

an indirect measure of the presence of dissolved solids such as chloride, nitrate, sulfate, and also

been used as an indicator of water pollution. Since only conductivity value being measured in

this experiment, it can only shows the level amount of the mobility ions. Total dissolved solid

test can be used in future as the extension for conductivity test.


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Based on the BOD test conducted, the BOD value calculated for 100% water sample is

higher compared to the sample that being diluted and according to National Standard Water

Quality, for the BOD5 of 4.87 mg/L can be categorized into class III. The water under this

category can be defined on protecting common and moderately tolerant aquatic species of

economic value. It means that the water from UTMs lake is not highly polluted and safe for

aquatic life. The BOD for 100 mL sample should be higher than BOD for 50 mL sample. From

the experiment, the result was not the same as expected. This might happen due to some errors

that take place during conducting this experiment.

There are significant different in the BOD value obtained in this experiment due to

several errors. Firstly, there are bubbles present without noticing in the water sample that caused

an error in Dissolved Oxygen (DO) reading. Next, the water sample in the bottle was left opened

to air without the cover that allowed more oxygen dissolved and affected the results. More than

that, the dilution sample was not well mixed and thus gave an incorrect value for the DO reading.

The device to measure the DO reading was not correctly handled or used is also one of obvious

error in BOD test.

Finally, some precautions should be taken in order to reduce errors in this experiment.

Seal the sample to prevent further oxygen dissolving in. Then, it is necessarily to shake the water

sample before running the tests to ensure that the components in the water are well-mixed. Next,

do not let the BOD bottle left opened to air without cover. Make sure that the apparatus is clean

prior to use to avoid error. Understand the procedure on how to use the device related to the

experiment is the most important step in order to get precise results.


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Conclusion

Based on the result obtained from the test conducted it can be stated that UTMs lake is

not highly polluted. By referring to the National Standard Water Quality UTMs lake can be

classified into class III that supported by the result obtained from turbidity and BOD tests. The

water may be used for water supply with extensive treatment and it also suit livestock drinking

needs.


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References

1. Water quality analysis, retrieved on 28thOctober 2013, retrieved fromhttp://putrowaterquality.blogspot.com/

2. Water quality tests, retrieved on 28thOctober 2013, retrieved fromhttp://www.sasta.asn.au/may08/adc/datalogging/DataSinglePagePDFs/ADCBookDatalog

13-23.pdf

3. WEPA, National Water Quality Standard for Malaysia, retrieved on 29 thOctober 2013,retrieved from http://www.wepa-db.net/policies/law/malaysia/eq_surface.htm

4. Water online, retrieved on 29thOctober 2013, retrieved fromhttp://www.wateronline.com/industrysegment/water-quality-analysis

5. Water sampling and analysis, retrieved on 29thOctober 2013, retrieved fromhttp://www.who.int/water_sanitation_health/dwq/2edvol3d.pdf


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Appendices

Turbidity Meter


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pH meter

Conductivity Measure

BOD Meter


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Documents

Full Report Exp 7