Transcript 11. high oxygen demand, toxic wastewater.ppt

BUDAPEST UNIVERSITY OF TECHNOLOGY AND ECONOMICS
FACULTY OF CHEMICAL AND
BIOCHEMICAL ENGINEERING
DEPARTMENT OF CHEMICAL AND
ENVIRONMENTAL PROCESS
ENGINEERING
HIGH OXYGEN DEMANDING
TOXIC WASTEWATER
Dr. Bajnóczy Gábor
Tonkó Csilla
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
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 area
Layer-thickness, if large
amount of oil spilled.
VISIBILITY OF OIL SPILL IN NATURAL WATER
PROCESSES AFTER OIL SPILL
oil spill in
natural water
effect of wave →
formation of stable emulsion
toxic effect
of dissolved
aromatic
compounds
biodegradation
of organic matter
reduction of
dissolved
oxygen
content
about 3 – 6 month
upper phase: water in oil
lower phase: oil in water
dissolution of oil in water
petrol: 50-500 mg/dm3
diesel oil: 10-50 mg/dm3
petroleum: 0,1-5 mg/dm3
non-biodegradable residue: „tarballs”
content: long- and branched- carbon-chain compounds,
highly condensed aromatic compounds
SOIL POLLUTION WITH MINERAL OIL
The slick can be thicker in observation well
due to pressure drop.
oil
observation
well
gravitation
Gravel
5
Sand 15-30
Silt
40
capillary action
capillary action
Oil retention capacity of
soil
[dm3 oil/m3 soil]
oily soil
capillary
action
oil lens
groundwater
groundwater flow-direction
impervious stratum
DEOILING PROCESSES
floating dam
on-site burning
(not the best solution)
oil separator
manual clearance
DEOILING PROCESSES
- The most common technology: oil adsorbents eg. hydrophobic perlite
stuffed tube with adsorbents and oil traps
oil traps on stream
used oil straps will normally be sent for incineration
LIMITED USE OR PROHIBITED
DEOILING PROCESSES
Dispersion of oil drops results in faster biodegradation.
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.
detergent spraying on oil spill
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
little
dissolved
oxygen in
sludge
long-term toxic effect
of hydrocarbons