66
Figure 3. 7 Experimental set up of biodegradability test.
Therefore, no special or adapted bacteria are needed to reproduce the results. The chemical oxygen demand COD was measured by using COD TestNTube HACH
and the value of COD was measured using spectrophotometer DR 5000. Furthermore, the biodegradability of partially degraded MDEA was determined from
the ratio of BOD
5
COD. The compound is considered readily biodegradable when the ratio of BOD
5
COD is greater than 0.5 [118 – 119].
3.3 Analytical Methods
3.3.1 Total Organic Carbon TOC Determination
The determination of total organic carbon TOC was conducted using TOC analyzer Shimadzu
– Model TOC-V
CSH
, S. No. H 51104600672, Japan. The collected sample 1 ml was diluted to obtain 20 ml of sample as required for TOC measurement.
67 The actual reading of TOC value was calculated from the TOC reading from the
analyzer multiplied by dilution factor. This measurement was used to monitor the degradation of organic compound during UVH
2
O
2
process. The percentage of TOC removal at time “t” was calculated as follows Equation 3.4:
x100 TOC
TOC TOC
removal TOC
t t
3.4
where:
t
removal TOC
= percentage of TOC removal at t, TOC
= TOC value at 0 minute, and TOC
t
= TOC value at t.
3.3.2 Chemical Oxygen Demand COD Determination
Chemical oxygen demand COD is a measure of oxygen required for oxidizing oxidizable organic content in the water sample. COD
is defined as mg of O
2
consumed per liter of sample
. The measurement of COD value was performed using COD analytical equipment HACH according to Method 8000. Method 8000 was USEPA
approved 5220 D for wastewater analysis [125 – 126]. Two ml of sample was
oxidized using the standard chemicals supplied by HACH and digested at 150 ⁰C for
two hours on the DRB HACH digester. The COD reading was obtained by using HACH DR 5000 spectrophotometer.
3.3.3 BOD
5
Determination
The measurement of BOD
5
was performed by using HACH method for BOD
5
determination HACH-BODTrak
TM
, Figure 3.7. A total sample of 95 ml was used for the BOD
5
test.
68 Activated sludge was used as seed and was collected from WWTP Universiti
Teknologi PETRONAS Malaysia. Incubation was conducted for 5 days in the incubator at a temperature of 20 + 1
⁰C. The BOD
5
value was estimated as follows Equation 3.5:
v.t v.tc
control DO
v.t v.s
sample DO
BOD
5 5
5
3.5
where: BOD
5
= BOD
5
of test compound, DO
5
sample = DO
5
of test compound + DO
5
of seed, DO
5
control = DO
5
of seed v.s = volume of seed = 30 ml,
v.tc = volume of test compound = 65 ml, and v.t = total volume = 95 ml.
3.3.4 Identification of UV Absorption Spectra of MDEA
