Technical Committee Storage, Transportation and Distribution

Separator Systems for Light Liquids and Bioethanol

Within the scope of short term static tests, separator systems for light liquids were charged with tap water and a mixture of premium gasoline (with ethyl tertiary butyl ether - ETBE) and (bio)ethanol (C2H5OH) on a laboratory scale and examined over a period of 5 days. For these tests, ethanol additions of 0 % (zero value), 5 % (permitted admixture of ethanol to conventional gasoline), 10 %, 20 %, 85 % to the conventional premium gasoline and pure ethanol were used. Within the framework of the static tests, it could be determined, that the bulk of the ethanol expectedly passes into the water phase, thus increasing the chemical oxygen demand (COD) of the water phase considerably (from 350 mg/l to 85,000 mg/l). However, the COD caused by the ethanol content is an easily degradable COD, which poses no problem in a waste water treatment plant. With regard to the influence of ethanol on the hydrocarbon index (HC index) of the water phase, it could be shown, that the HC index, measured according to DIN EN ISO 9377-2 (H 53) is increased slightly by a raised ethanol content, both with and without clean-up. However, the limit value of 20 mg/l according to attachment 49 (mineral oil containing waste water) of the waste water ordinance was never reached nor exceeded. Evaporation tests, which were run, showed that fuel blends with a greater share of mineral oil based gasoline evaporated faster than mixtures with higher ethanol content.