Dr. Bajnóczy GáborTonkó 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

HIGH OXYGEN DEMANDING TOXIC WASTE WATER

Significant amount of biological degradable organic compounds and compounds toxic on aquatic life.

Main sources:

petroleum refining

ship disasteroil tanker operation

(release of ballast water)

oil mining

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

[dm3/km2]

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 areaLayer-thickness, if large

amount of oil spilled.

VISIBILITY OF OIL SPILL IN NATURAL WATER

PROCESSES AFTER OIL SPILL

oil spill innatural water

effect of wave → formation of stable emulsion

upper phase: water in oillower phase: oil in water

dissolution of oil in waterpetrol: 50-500 mg/dm3

diesel oil: 10-50 mg/dm3

petroleum: 0,1-5 mg/dm3

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

SOIL POLLUTION WITH MINERAL OIL

oil

The slick can be thicker in observation well due to pressure drop.

Oil retention capacity of soil

[dm3 oil/m3 soil]

Gravel 5Sand 15-30Silt 40

observation well

capillary

capillary action

action

gravitation

capillary action

groundwater

groundwater flow-direction

oily soil

oil lens

impervious stratum

DEOILING PROCESSES

floating dam oil separator

on-site burning(not the best solution) manual clearance

- 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

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