1. Dr. Bajnóczy Gábor Tonkó Csilla HIGH OXYGEN DEMANDING TOXIC WASTEWATER BUDAPEST UNIVERSITY OF TECHNOLOGY AND ECONOMICS DEPARTMENT OF CHEMICAL AND ENVIRONMENTAL PROCESS ENGINEERING FACULTY OF CHEMICAL AND BIOCHEMICAL ENGINEERING

2. HIGH OXYGEN DEMANDING TOXIC WASTE WATER Significant amount of biological degradable organic compounds and compounds toxic on aquatic life. Main sources: petroleum refining ship disaster oil tanker operation (release of ballast water) oil mining

3. VISIBILITY OF OIL SPILL IN NATURAL WATER Oil spill → fast spreading on the surface of water Characteristics of floating oil thickness [μm] Volume of oil slick [dm 3 /km 2 ] Visibility 0,04 0,08 0,15 0,3 1 2 1000 (1mm) 40 80 150 300 1000 2000 1 000 000 detection limit coloured area silvery, continuous slick rainbow colours dark oil area Layer-thickness, if large amount of oil spilled.

4. VISIBILITY OF OIL SPILL IN NATURAL WATER

5. PROCESSES AFTER OIL SPILL oil spill in natural water effect of wave → formation of stable emulsion upper phase: water in oil lower phase: oil in water dissolution of oil in water petrol: 50-500 mg/dm 3 diesel oil: 10-50 mg/dm 3 petroleum: 0,1-5 mg/dm 3 toxic effect of dissolved aromatic compounds biodegradation of organic matter reduction of dissolved oxygen content non-biodegradable residue: „tarballs” content: long- and branched- carbon-chain compounds, highly condensed aromatic compounds about 3 – 6 month

6. SOIL POLLUTION WITH MINERAL OIL oil The slick can be thicker in observation well due to pressure drop. Oil retention capacity of soil [dm 3 oil/m 3 soil] Gravel 5 Sand 15-30 Silt 40 observation well capillary capillary action action gravitation capillary action groundwater groundwater flow-direction oily soil oil lens impervious stratum

7. DEOILING PROCESSES floating dam oil separator on-site burning (not the best solution) manual clearance

8. - The most common technology: oil adsorbents eg. hydrophobic perlite stuffed tube with adsorbents and oil traps used oil straps will normally be sent for incineration DEOILING PROCESSES oil traps on stream

9. LIMITED USE OR PROHIBITED DEOILING PROCESSES Dispersion of oil drops results in faster biodegradation. detergent spraying on oil spill Quick decrease of dissolved oxygen concentration in water → possible application far from the coastal area, high sea is preferred. The use in rivers is prohibited. The treatment of oil spills by lowering agents e.g. brick and cement dust is prohibited! Brick / cement Oil+brick/cement in sludge Oil in water long-term toxic effect of hydrocarbons little dissolved oxygen in sludge