Industrial Pollution Control
Prof. R. Shanthini
Dept of Chemical & Process Engineering
University of Peradeniya
September 05, 2010
Biodegradable Industrial Waste
Wastewater from many industries using biomass
as raw materials contains mostly carbohydrates
(sugars, starch, cellulose and lignin) and fats and
proteins.
These organics are biodegradable, that is,
decomposed to simple end products by the biliions
and billions of microorganisms found nature.
Some organics are aerobically biodegraded (by
aerobic microbes) and others are anaerobically
biodegraded (by anaerobic microbes).
Biochemical Oxygen Demand (BOD)
• Concentration of aerobically biodegradable organic
matter (such as sugars, starch and other simple organics)
is quantified by the amount of oxygen consumed during
the aerobic microbial (mostly bacterial) degradation of the
waste under controlled conditions.
• This measurement is known as the biochemical oxygen
demand (BOD) of the wastewater concerned.
• To be precise, BOD is written as BOD5 at 20oC, which
means the biochemical oxygen demand of the
wastewater for 5 days of microbial degradation at 20oC.
BOD (continued)
• The water body is considered to be very clean if its
BOD5 at 20oC is less than 1 mg/litre (i.e. ppm).
• The cleanliness of the waterbody is considered poor if
its BOD5 at 20oC is more than 5 mg/litre.
• The BOD5 estimate however excludes complex
organics such as cellulose, lignin, chitin, and proteins,
which cannot be readily biodegraded by bacteria.
Cellulose
• Cellulose provides strength and flexibility to the plants.
• It is the most abundant organic compound of natural
origin.
• The molecular weight of cellulose ranges from 300,000
to 500,000 (1800 to 3000 glucose units).
• Since certain bacteria can hydrolyse cellulose, biological
treatment of cellulose containing wastes is possible.
• However, aerobic treatment of cellulose is slow.
Cellulose (continued)
• Most of the cellulose does not get aerobically
biodegraded and will settle to produce sludge during
aerobic digestion.
• The sludge produced during aerobic treatment is
separated by sedimentation, filtration or centrifugation,
and is either used as a landfill or incinerated.
This sludge could also be subjected to anaerobic
digestion (in the absence of oxygen) to produce biogas.
Lignin
• Lignin, a macromolecular organic compound, is a major
structural component of all plant cell walls along with
cellulose.
• While cellulose provides strength and flexibility, lignin
supports and protects the cellulose from biological and
chemical attack.
• Lignin is thus very stable against bacterial degradation
even though white-rot fungi can degrade it to some extent
in a very slow reaction.
• Aromatic hydrocarbons and aliphatic compounds like
ester are type of organic compounds that are resistant to
bacterial degradation of any kind.
Chemical Oxygen Demand (COD)
• Since the BOD measurement includes only the readily
biodegradable organics that are decomposed aerobically
by simple bacteria, we use the chemical oxygen demand
(COD) measurement to indicate the amount of oxidisable
material present in the effluent sample that can be
oxidised by a strong chemical oxidant.
COD (continued)
• If the COD and BOD measurements are nearly the same
then the effluent can be biologically degraded under aerobic,
facultative and anaerobic conditions.
• Any difference between the COD and BOD measurements
may indicate the presence of cellulosic matter that cannot be
readily biodegraded aerobically by bacteria alone.
• If there is a large difference between the COD and BOD
measurements with very high COD values then it can be taken
as an indication of the amount of biologically resistant organic
matter such as lignin present in the effluent.
Recommended limit for discharges
• Into inland surface waters
- 30 mg/litre of BOD5 at 20oC
- 250 mg/litre of COD
• On land for irrigation purposes
- 250 mg/litre of BOD5 at 20oC
- 400 mg/litre of COD
• Into marine coastal areas
- 100 mg/litre of BOD5 at 20oC
- 250 mg/litre of COD
Source: National Environmental (Protection and Quality) Regulations No. 1 of 2008
under the National Environmental Act, No 47 of 1980
Desiccated
Coconut
Sap:
BOD = 15,000 mg/L
COD = 40,000 mg/L
Natural
Rubber
Processing
BOD = 5000 mg/L
COD = 9000 mg/L
Textile Mills
BOD = 30 – 250 mg/L
COD = 250 – 400 mg/L
Wastewater:
BOD = 10,000 mg/L
COD = 20,000 mg/L
COD = 1900 mg/L
Rice Mills
COD = 8000 mg/L
National Environmental Act,
No. 47 of 1980
(1990 & 2008 amendments)
Colour
removal
Brewery
BOD = 1500 mg/L
COD = 4000 mg/L
Brewery effluents
3 to 10 litres of water used per litre of beer produced
(Lions Brewery produces 45 million liters of beer per year)
Malted Barley
Water
Beer
Beer
manufacture Wastewater
Spent grain (wet)
(may be used
as cattle feed)
Aerobic
treatment
Treated
wastewater
Brewery Wastewater
Sludge (BWS)
Compost
BOD = 1000-1500 mg/L; COD = 1000-4000 mg/L
Standard: BOD = 30 mg/L & COD = 250 mg/L (inland surface water)
2006
Brewery effluents
Malted Barley
Water
continued…….
Beer
Beer
manufacture
Wastewater
Leachate Anaerobic
Spent grain (wet)
treatment
Biogas
Dry spend grain
Leach the spent grain using wastewater
COD increased from 3000 to 50,000 mg/L (Leachate)
BOD = 1000-1500 mg/L; COD = 1000-4000 mg/L
Standard: BOD = 30 mg/L & COD = 250 mg/L (inland surface water)
Brewery effluents
Malted Barley
Water
continued…….
Beer
Beer
manufacture
Wastewater
Slurry
Spent grain (wet)
Spent grain slurries using wastewater
COD increased from 3000 to 14,000 mg/L (slurry)
BOD = 1000-1500 mg/L; COD = 1000-4000 mg/L
Standard: BOD = 30 mg/L & COD = 250 mg/L (inland surface water)
Brewery effluents
continued…….
developed by
Dr. K. Kanagachandran
Manager, Special Projects, Lions Brewery
has a Bachelors Degree in Microbiology and PhD in
Biotechnology from Herefordshire University, UK
reduction of 3150 litres per day furnace oil,
and thereby 30% in fuel bill
($80,000 saved per year)
BOD = 1000-1500 mg/L; COD = 1000-4000 mg/L
Standard: BOD = 30 mg/L & COD = 250 mg/L (inland surface water)
Natural Rubber Processing Industrial Effluents
40-50 litres of wastewater produced per kg of rubber produced
(Sri Lanka produces 115 million kg of rubber per year)
BOD = 1000-5000 mg/L; COD = 2000-9000 mg/L
Standard: BOD = 50 – 60 mg/L & COD = 400 mg/L (inland surface water)
Natural Rubber Processing Industrial Effluents
continued…….
Anaerobic treatment
Covered Activated Ditch (CAD)
Biogas
- concrete reinforced cement block ditches
- lined with UV stabilized polythene sheet for waterproofing
- covered with odour filters to control odour emissions
- equipped with stationary bio-brush media to retain biomass
coir-fibre arranged in bottle-brush configuration
bounded by a novel plastic binding technique
developed for the industry since 1991 by
M. Thurul Warnakula
BOD = 1000-5000 mg/L; COD = 2000-9000 mg/L
Standard: BOD = 50 – 60 mg/L & COD = 400 mg/L (inland surface water)
Natural Rubber Processing Industrial Effluents
continued…….
Taxing the polluter
Still Polluting (in 2006)
Rs. 26/= of tax per 100 gm of COD per year
BOD = 1000-5000 mg/L; COD = 2000-9000 mg/L
Standard: BOD = 50 – 60 mg/L & COD = 400 mg/L (inland surface water)
Textile Mill Effluents
Adsorption by burnt-brick and other selected materials
good treatment in all sense
Up-flow anaerobic attached-growth bioreactors
filled with pre-treated coir fibres
Fe and Mn removal in SO42- reducing conditions
COD = 400-1900 mg/L; colour removal
Standard: BOD = 60 mg/L & COD = 250 mg/L (inland surface water)
Textile Mill Effluents
continued…….
Use of water hyacinth at the Veyangoda Mills
good; effluent requires further polishing
Water hyacinth with rubber factory effluent
Water hyacinth for N and P removal from synthetic effluents
COD = 400-1900 mg/L; colour removal
Standard: BOD = 60 mg/L & COD = 250 mg/L (inland surface water)
Desiccated Coconut Industrial Effluents
40,000 – 60,000 litres of sap + wastewater per day in a
50,000 nuts per day capacity industry
Sap:
BOD = 13,000 - 15,000 mg/L; COD = 40,000 mg/L
Wastewater:
BOD = 6000 -10,000 mg/L; COD = 17,000 - 20,000 mg/L
Standard: BOD = 30 mg/L & COD = 250 mg/L (inland surface water)
Desiccated Coconut Industrial Effluents
continued…….
Up-flow anaerobic floating filter (UAFF) system
- three anaerobic filter reactors in series
- coir fibre as the bacteria growth media
- a sedimentation tank and a biogas filter
good; effluent requires further polishing
developed by M.D.A. Athula Jayamanne
used with DC mills, distilleries, breweries, textile mills,
garment factories, rice mills, hotels, bakeries, piggeries,
farms and slaughterhouses
Sap: BOD = 13,000 - 15,000 mg/L; COD = 40,000 mg/L
Wastewater: BOD = 6000 -10,000 mg/L; COD = 17,000 - 20,000 mg/L
Standard: BOD = 30 mg/L & COD = 250 mg/L (inland surface water)
Rice Mill Effluents
Up-flow anaerobic floating filter (UAFF) of Athula Jayamanne
Wetlands with common cattail (Typha latifolia)
ongoing
Paddy husk charcoal as adsorbent
Wastewater: COD = 3,000 - 8,000 mg/L
Standard: BOD = 30 mg/L & COD = 250 mg/L (inland surface water)
Electrochemistry in effluent treatment
Electrodialysis treatment of black liquor from pulp mill
Electrodialysis treatment of photographic effluent
Electrocoagulation treatment of oily wastewaters
Microbial fuel cell treatment
Published in 2010
96.5% COD removal
84% lignin removal
81% phenol removal was 81%
2.3 W/m3 power produced
Microbial Fuel Cells
wastewater
anode
cathode
Source: http://parts.mit.edu/igem07/images/2/2d/Fuelcell.JPG
To the Water
BOD
COD
oil and grease
Suspended particles
Colour
Chemicals
Toxic materials
Heated water
State of freshwater in 2000
GOOD
We want
the pointer
to be here
GRIM
But,
the pointer
is here
State of freshwater in 2000
Water consumption
has increased
35 times in the
last 300 years
Population rose
only sevenfold
in the
last 300 years
Concluding Remarks
no-electricity, no-maintenance anaerobic treatment
methodologies which generate biogas are available –
innovated by Sri Lankans
Yet, industrial pollution persists
Pollution tax is suggested
Modelling is not done (most of them are laboratory studies;
some are with synthetic effluents)
Sustainable process technology are not researched
Life cycle analysis are not done