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Water (Sampling storage
[sample preservations: to maintain the integrity…
Water
Physical properties
- Colour
- Turbidity
- Conductivity
Colour
- Factors that affect th col. of water
(Light source, suspended materials in the water, absorption and scattering of light)
- Colour measurements
(Visual comparison method & spectrophotometric)
Turbidity
(how cloudy)
- Material cause water to be turbid
(Plankton, waste discharge, sediments from erosion, soluble organic compound)
- Effects
(cause the concentration of oxygen to be reduced, cause the attachment of heavy metals and other toxic organic compounds)
- Turbidity measurement
(Nephelometric turbidity meter)
Chlorine in water
- Chlorine demand: the amt. of chlorine needed for chlorination
- Residual chlorine: refers to excess chlorine
[Range 0.2 to 0.5mg/g]
How to test for residual chlorine?
- Dpd (diethyl paraphenlyene diamine) using a comparator
[add the tablet, more red = more chlorine]
Water sampling
[is the process of collecting water from different locations, using set procedures and equipment and following safety requirements]
Importance:
- ensure that drinking water is safe
- help determine the effectiveness of the water treatment
- ensure water being used are compatible and suitable quality
Techniques
- Grab sampling
- Composite sampling
Grab sampling
- sample take in one go
- collect samples from river, lakes and surface water
How to do it?
- Hold sampling bottle near the bottom and submerge it at 20cm
- Mouth of bottle should be facing towards the current
- Turn bottle right up to fill it
- Cap the bottle and pack it in a cooler box with ice
Parameters
(unstable)
- pH
- dissolved oxygen
- chlorine residual
- nitrites
- temperature
Composite sampling
- collect samples from different area over a period of time
- then are combined to reflect the overall condition of a water body
Parameters
- Total suspended solids (TSS)
- Total nitrogen
(TN)
Sampling location
- goundwater
- surface water
- water distribution systems
- water treatment system
- wastewater treatment system
How can I treat water before discharge?
- Reed bed
- Chemical Chlorine
Microbiological test
Heterophic Plate Count(HPC)
know as: - total plate count , - total bacterial count
Test is performed via:
- pour plate, spread plate
- membrane filtration
Plates are incubated at 35 degree for 45 hours
Unit: CFU/ml
-
Sampling equipment
- sampling iorn
- sampling tube
- dissolved oxygen sampler
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