While the cost of water and sewerage in the city where the food processing factory located was 0.2 JPY/L, the
oil-removed wastewater was hot and can be used for melting snow around the factory and its price was determined
as 0.6 JPY/L. The wastewater standard of normal hexane (n-Hex) was 30 mg/L (Noguchi, 2012), so that wastewater
below 30 mg/L of n-Hex was treated as non-drinking water resource at 0.6 JPY/L and above 30 mg/L of n-Hex need
to be purified. The food processing factory had its own wastewater treatment facilities but it treated not only
wastewater from chicken boiling line but also from another line. So it was difficult to reveal the price of purified
water from the initial cost and running cost of wastewater treatment facilities. Therefore, the wastewater above 30
mg/L of n-Hex was assumed to treat as industrial waste at 0.2 JPY/L. However, another confectionary maker pays
30 JPY/L for wastewater, and it seems to differ among each case.
Using VF, SWU was calculated with the decrease of the separation ability of the oil-water separation technology
from 100% by 0.01% (Fig. 5). In the case of 0% and 100% of the oil mixing ratio, regardless of the separation
ability, SWU always indicated 0 USD/L because SWU shows the value produced before and after separation and the
oil mixing ratio 0% and 100% was pure and no need to separate. It shows that below 99.70% of the separation
Mixing ratio of oil [%]
Price [JPY/L]
100
Oil as fuel
0
Waste fluid
as industrial waste
Hot water
for non-drinking
0.003 99.70 1
0.6
125
-2
0 0.
72 Eriko Ankyu and Ryozo Noguchi / Agriculture and Agricultural Science Procedia 2 ( 2014 ) 67 – 73
ability decreases SWU sharply and approaches to 0. Then, it was indicated that the oil-water separation technology
with the separation ability over 99.70% was required to produce value. This is because the oil as valuable resource
needs to be 99.70% of purity according to the hearing investigation and below 99.69% is treated as wastewater not
as oil.