biogas production from waste
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biogas production from waste

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muttappa khavi

muttappa khavi
ph.d scholor
college of fisheries
mangalore

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biogas production from waste biogas production from waste Presentation Transcript

  • BIOGAS PRODUCTION FROM SEWAGE  
  • Overview •Biogas •Composition of  biogas •Advantages and disadvantages •Biochemical reaction and stages of anaerobic digestion •Modes of operation •Types of anaerobic digesters •Paper presentation
  • What is biogas? Biogas  is  a  methane  rich  flammable  gas  that  results  from  the  decomposition of organic waste material Biogas  is  produced  by  anaerobic digestion  or  fermentation  of  biodegradable  materials  such  as  biomass,  manure,  sewage,  municipal waste, green waste, plant material and energy crops. Biogas also called as ‘Marsh gas’ Biogas is a type of biofuel.  This  type  of  biogas  comprises  primarily  methane  and  carbon  dioxide
  • Composition of biogas • • Biogas is generated by the activity of anaerobic bacteria Composition  depends  on:  the  composition  of  raw  material,  organic  loading  to  digesters,  time  and  temperature  of  anaerobic digestion Composition of biogas   Substances Symbol Percentage Methane  CH4  50 - 70  Carbon Dioxide  CO2  30 - 40  Hydrogen  H2  5 - 10  Nitrogen  N2  1 - 2  Water vapour  H2O  0.3  Hydrogen Sulphide  H S  Traces 
  • Advantages of biogas • Production of large amount of methane gas (ambient  temperature storage) • Production of free flowing thick sludge • Odourless sludge • Sludge can be used as  fertilizer and soil conditioner • Sanitary way for human and animal waste disposal • Conservation of scarce resources like wood
  • Disadvantages • • • • • Explosion chances High capital lost Incorrect handling of liquid sludge causes pollution Requires control and maintenance Needs proper condition • Use as a fuel requires removal of CO2 and H2S 
  • Factors affecting yield and production of  biogas  Many factors affecting the fermentation process of  organic substances under anaerobic condition are,   The quantity and nature of organic matter   The temperature   Acidity and alkanity (PH value) of substrate   The flow and dilution of material 
  • GENERAL FEATURES OF BIOGAS 
  • Biochemical reactions Organic matter  CH4 + CO2 + H2 + NH3 + H2S Stages of anaerobic digestion: 1.Liquefaction by hydrolytic enzymes 2.Acid formation 3.Methane formation with methanogen production 
  • Liquefaction by hydrolytic enzymes • Complex organic matter is degraded to basic structure by hydraulic bacteria.  Protein - Polypeptide and Amino Acid  Fat -Glycerin and Fatty Acid  Amylose - Monosacride and Polysacride
  • Acid Production • Also called the acidogenesis • Simple organic matters are converted into acetic acid, H2 and CO2 • Acting bacteria in this process are called hydrogenproducing bacteria and acid-producing bacteria.
  • Methane Production • Methanogenesis • In this process, acetic acid, H2, CO2, are converted into CH4. • Methane-producing bacteria have strict PH requirement and low adaptability to temperature. • Methanococcus jannaschii, Methanobacterium thermoautotrophicum
  • Flow chart of anaerobic digestion
  • Modes of operation • Batch • Semi-continuous – regular feeding of digester and decrease of organic matter at intervals • Continuous – for liquid waste treatment
  • Continuous-fed System • Suited for large-scale manure substrate bioreactor. • Steady biogas production can be expected. • May require auxiliary equipments. • Requires high liquid content. • Temperature, loading rate, and solid content need to be carefully monitored.
  • Batch-fed System • • • • • • The simplest design. Low cost. The feedstock is loaded one batch at time. Irregular biogas production. Can operate on high solid content. Requires manual labor.
  • Types of digesters A typical biogas system consists of the following components: • • • • • (1) Manure collection (2) Anaerobic digester (3) Effluent storage (4) Gas handling (5) Gas use. TWO MAIN TYPES: 1. Digesters utilizing dispersed growth of bacteria 2. Digesters utilizing attached growth of bacteria
  • DISPERSED GROWTH DIGESTERS 1. 2. 3. 4. 5. 6. Fixed dome digester Floating gas holder digester (Indian) Plug flow digester (horizontal displacement) Bag digester (Taiwan and Korea) Separate gas holder digester Conventional digester
  • Fixed dome digester  Drumless digester.  Underground brick masonry compartment (fermentation chamber) with a dome on the top for gas storage.  The fermentation chamber and gas holder are combined as one unit.  Eliminates the use of costlier mild steel gas holder which is susceptible to corrosion.  20 to 50 years.
  • Floating gas holder digester  Jashu Bhai J Patel developed a design of floating drum biogas plant  Popularly known as Gobar Gas plant.  In this design, the digester chamber is made of brick masonry in cement mortar.  A mild steel drum is placed on top of the digester to collect the biogas produced from the digester. Thus, there are two separate structures for gas production and collection.
  • Bag Biodigester • It consists of a long cylinder made of PVC or red mud plastic. • The bag digester was developed to solve the problems experienced with brick and metal digesters.
  • Attached growth digesters 1. Anaerobic filter 2. Up-flow anaerobic sludge blanket (UABSR)
  • Anaerobic filter  It consists of a column filled with a packing medium.  A great variety of nonbiodegradable materials have been used as packing media for anaerobic filter reactors such as stones, plastic, coral, mussel shells, reeds, and bamboo rings.  The methane forming bacteria form a film on the large surface of the packing medium and are not carried out of the digester with the effluent.  For this reason, these reactors are also known as "fixed film" or "retained film" digesters.
  • UASBR  The UASB reactors contain no packing medium, instead, the methane forming bacteria are concentrated in the dense granules of sludge blanket which covers the lower part of the reactor.  The feed liquid enters from the bottom of the reactor and biogas is produced while liquid flows up through the sludge blanket.
  • Gas Production potential of various types of dung Types of Dung Gas Production Per Kg Dung (m3) Cattle (cows and buffaloes) 0.023 - 0.040 Pig 0.040 - 0.059 Poultry (Chickens) 0.065 - 0.116 Human 0.020 - 0.028 Source: www.fao.org.in
  • Material and methods • The Sewage Treatment Plant has capacity to treat 18 mld sewage from main pumping station. • After primary and secondary treatment, sludge is remain left that is being collected in thickener. • Around 96X105 liters sludge is being drained from thickener to digester tank at each 12 hrs. • • The sludge was taken from thickener and digester tank and Temperature, pH, Total solids %, Volatile solids %, and Alkalinity parameters were analyzed
  • Results  The present study was done in the months of winter and summer and the sampling were done seasonally from the sewage treatment plant.  Raw sewage consists of organic and inorganic solids in dissolved and suspended form with 90-99.9% of water
  • Materials and methods • In this study, experiments were conducted to investigate the production of biogas from municipal solid waste (MSW) and domestic sewage by using anaerobic digestion process. • The MSW is collected from the Perungudi yard at the Chennai metropolitan city. The yard has an area of approximately 10 km2. • Domestic sewage is collected from a college campus before disposal to the treatment plant. It is used in all digestion experiments for diluting the feedstock to achieve the required total concentration of TS. • The domestic sewage is added to MSW, which is in the form of dry and shredded waste. Here both the wastes are mixed so that it forms slurry.
  • Experimental set up
  • Results
  • • The digester was operated at different organic feeding rates of 0.5, 1.0, 2.3, 2.9, 3.5 and 4.3 kg of volatile solids (VS)/m3 of digester slurry per day. • Biogas generation was enhanced by the addition of domestic sewage to MSW. • The maximum biogas production of 0.36m3/kg of VS added per day occurred at the optimum organic feeding rate of 2.9 kg of VS/m3/day.
  • References Henry, C., 2006." What is an Anaerobic biodigester?” http://manure.unl.edu/adobe/v7n10_01.pdf http://www.fao.org.in (Biogas technology: a training manual for extension" (FAO/CMS, 1996) http://www.habmigern2003.info/biogas/Barondigester/Baron-digester-Dateien/image006.jpg http://www. en.wikipedia.org/wiki/Biogas http://www.renewableoil.com/pages/applications.html http://www.omafra.gov.on.ca/english/engineer/facts/04097.html Polprasert, C., 1989. Biogas production. In: Organic waste recycling. John Wiley Sons. Ltd., Great Britain. 105-144