Prof. R. Shanthini Dept of Chemical & Process Engineering University of Peradeniya September 05, 2010 Industrial Pollution Control
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
Sap: BOD = 15,000 mg/L COD = 40,000 mg/L Wastewater: BOD = 10,000 mg/L COD = 20,000 mg/L Desiccated Coconut Natural Rubber Processing BOD = 5000 mg/L COD = 9000 mg/L Textile Mills Colour removal COD = 1900 mg/L BOD = 30 – 250 mg/L COD = 250 – 400 mg/L Rice Mills COD = 8000 mg/L National Environmental Act, No. 47 of 1980 (1990 & 2008 amendments) 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) Beer Beer manufacture Malted Barley Aerobic treatment Water Wastewater Treated wastewater Brewery Wastewater Sludge (BWS) Spent grain (wet) (may be used as cattle feed) 2006 Compost Standard: BOD = 30 mg/L & COD = 250 mg/L (inland surface water) BOD = 1000-1500 mg/L; COD = 1000-4000 mg/L
Brewery effluents continued……. Beer Beer manufacture Malted Barley Water Wastewater Biogas Leachate Anaerobic treatment Spent grain (wet) Dry spend grain Leach the spent grain using wastewater COD increased from 3000 to 50,000 mg/L (Leachate) Standard: BOD = 30 mg/L & COD = 250 mg/L (inland surface water) BOD = 1000-1500 mg/L; COD = 1000-4000 mg/L
Brewery effluents continued……. Beer Beer manufacture Malted Barley Water Wastewater Slurry Spent grain (wet) Spent grain slurries using wastewater COD increased from 3000 to 14,000 mg/L (slurry) Standard: BOD = 30 mg/L & COD = 250 mg/L (inland surface water) BOD = 1000-1500 mg/L; COD = 1000-4000 mg/L
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) Standard: BOD = 30 mg/L & COD = 250 mg/L (inland surface water) BOD = 1000-1500 mg/L; COD = 1000-4000 mg/L
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) Standard: BOD = 50 – 60 mg/L & COD = 400 mg/L (inland surface water) BOD = 1000-5000 mg/L; COD = 2000-9000 mg/L
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 Standard: BOD = 50 – 60 mg/L & COD = 400 mg/L (inland surface water) BOD = 1000-5000 mg/L; COD = 2000-9000 mg/L
Natural Rubber Processing Industrial Effluents continued……. Taxing the polluter Still Polluting (in 2006) Rs. 26/= of tax per 100 gm of COD per year Standard: BOD = 50 – 60 mg/L & COD = 400 mg/L (inland surface water) BOD = 1000-5000 mg/L; COD = 2000-9000 mg/L
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 Standard: BOD = 60 mg/L & COD = 250 mg/L (inland surface water) COD = 400-1900 mg/L; colour removal
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 Standard: BOD = 60 mg/L & COD = 250 mg/L (inland surface water) COD = 400-1900 mg/L; colour removal
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 Standard: BOD = 30 mg/L & COD = 250 mg/L (inland surface water) Standard: BOD = 30 mg/L & COD = 250 mg/L (inland surface water) Wastewater: BOD = 6000 -10,000 mg/L; COD = 17,000 - 20,000 mg/L Wastewater: BOD = 6000 -10,000 mg/L; COD = 17,000 - 20,000 mg/L
Rice Mill Effluents Up-flow anaerobic floating filter (UAFF) of Athula Jayamanne Wetlands with common cattail (Typha latifolia) ongoing Paddy husk charcoal as adsorbent Standard: BOD = 30 mg/L & COD = 250 mg/L (inland surface water) Wastewater: COD = 3,000 - 8,000 mg/L
Electrochemistry in effluent treatment Electrodialysis treatment of black liquor from pulp mill Electrodialysis treatment of photographic effluent Electrocoagulation treatment of oily wastewaters Published in 2010 Microbial fuel cell treatment 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 GRIM But, the pointer is here We want the pointer to be 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