Page 18 - Shaping A Sustainable Future

Refer to Table 3 for the conductivity of the water before The lack of reaction from the oil control film indicated
and after soaking the rinsed dishes. Values were 128.0 the absence of oil on the cleaned dishes. Hence, it is
µS/cm and 128.8 µS/cm, respectively, with a difference shown that it is unnecessary to use more than the CMC
of 0.8 µS/cm. This result showed negligible detergent value of 12.5 ml/l of detergent to clean and degrease
residue left on the plates and was effectively rinsed the dishes. Usage of additional detergent will increase
using only 50 % of the commonly used water. the volume of water required to rinse off detergent on
the plates and release more chemical wastewater into
The Conductivity of Water The Conductivity of Water the environment.
Before Rinsing After Rinsing
128.0 µS/cm 128.8 µS/cm
Analysis of Experimental Data
Difference 0.8 µS/cm

Table 3: Using dishwashing method based on CMC value of Based on our statistical analysis, the coffee shop can
12.5 ml/l conserve about 401.5 litres of detergent and 36,500
litres of water every year using the recommended
Oil Removal Efficiency dishwashing method, based on the optimum CMC value.
This translates to a cost-saving of $461 in detergent
Having identified the optimal amount of detergent for
rinsing the dishes, we moved on to test the oil removal and water every year. It also reduces the discharge of
efficacy of our dishwashing method. The testing for wastewater by over 36,500 litres per annum.
residual oil on the cleaned plates after washing was
done using Clean & Clear® oil control film. This film is A correlation of water usage to CO emission was also
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highly absorbent and sensitive to oil. The blue-coloured analysed. According to the Public Utilities Board of
film will change to a darker shade of blue even in minute Singapore (PUB) data, the desalination and NEWater
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amounts of fat. Refer to Figure 6 for the result of the oil process energy consumption is around 3.5 kWh/m and
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removal efficacy experiment. 0.4 kWh/m of water, respectively, with an average of
1.95 kWh/m . According to the PUB, energy consumption
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for wastewater treatment is around 0.5 kWh/m . Hence,
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by conserving 36,500 litres of water and 401.5 litres of
detergent, we can reduce the total CO emission to the
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environment by 36.6 kgCO every year.
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50 % Less water used in Positive control (With oil)
dishwashing method
based on CMC
Figure 6: Testing the presence of oil on plates by
using Clean & Clear oil control film

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