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Industries receive large amount of water for their process but only small fraction of it is incorporated in their products and most is evaporated. The rest find its way into the water courses as wastewater.
The industrial wastewater is quite varied, from the domestic wastewater they contain organic solvents, oil, suspended solids to dissolved, inorganic solvents, Chemical compounds. If this untreated Industrial wastewater is allowed to accumulate, it causes the decomposition of the organic materials thus leading to the production of large quantities of harmful gases. The performance of CAACO was taken into consideration for the reduction of COD. Chemoautotrops can easily reduces the complex structure of Inorganic compounds such as Hydrogen, Sulphur, Ammonia, Nitrates, Iron etc., to its more simpler forms so that the Heterotropic bacterias can further reduce it easily. CAACO technology helps in the reduction of COD in wastewater , Unlike the General Activated Carbon media (which is an insulator); the CAACO media which is also having Activated Carbon as base, is but a conductor of electrons. Thus the chemoautotroph's can use carbon from the media as the carbon source for its cell synthesis. This makes the media an ideal residence for the chemoautotroph's and facilitates reduction of COD.
Key words :
Activated carbon, CAACO, Chemoautotrophs, COD ( Chemical Oxygen Demand ), wastewater.
Water is a vital Natural resource for the industrial production and agricultural development. Rapid Industrialization and economic growth and an Increasing needs for adequate and safe water resources at short distances from the point of consumption. Interms of water equation, 83%, of our surface and ground water is used for irrigation agricultural and the balance 17% is for domestic and industrial use. There is a considerable increase water demand for during as well as for the industrialized to increase in population, urban development, agriculture and industrial growth.
Water is become a precious natural resource and also raw water for industrial development particularly some industries water used as specific role placed as a production source like thermal power plant, soft drink, distillery etc. The dramatic economic liberalization begun in 1991, is turning the country export oriented relatively free market system. India is highly promising market. There is tremendous need for low-cost technologies which would appreciate for various industries.
Wastewater can be classified by theirs origin . Domestic wastewater is wastewater, which is discharged from the residential and commercial establishments .Industrial wastewater is that which discharged from the manufacturing plant. Waste water contains both organic and inorganic matter as well as soluble and insoluble material. Various components of wastewater are potentially harmful to the environment and to the human health.
Every community produces both liquid and solid waste. The liquid portion wastewater is essentially the water supply of the community after it has been fouled by a variety of uses. From the stand point of sources of generation wastewater may be defined as a combination of the liquid or water carried waste removed from Institutions, Residences, and Commercial and Industrial establishments.
The ultimate disposal of wastewater can only be onto the land or into the water. But, whenever the water courses are used for the ultimate disposal, the wastewater is given a treatment to prevent any injury to the aquatic life in receiving water.
The pharmaceuticals manufacturing industry encompasses the manufacturing, extraction, processing, purification and packing of chemical materials to be used as medication. Most of the active ingredients marketed and sold as drugs are manufactured by chemical synthesis. Chemical synthesis is a process of manufacturing pharmaceuticals using organic and inorganic chemical reactions.
A variety of pollutants released during chemical synthesis include benzene, chloro
benzene, chloroform, chloromethane, o-dichlorobenzene, 1, 2-dichloroethane, methylene chloride, phenol, toluene and cyanide. The non-conventional pollutants associated with chemical synthesis are methanol, ethanol, isopropanol , acetone and ethyl acetate. Compounds such as xylem, pyridine and toluene are widely used as organic solvents; they are either used in manufacture of synthesized pharmaceuticals or produced as a result of unwanted side reactions.
Pharmaceuticals active ingredients are generally produced by batch processes in bulk form and may be converted to dosage form for consumer use. The common dosage forms are tablets, capsules, liquids and ointments.
Working Principle of CAACO reactor:
The patented media facilitates the growth of Chemoautotroph in the mesopores which actively breaks the organic compounds and finally converts to water and bicarbonates. These bicarbonates facilitate effective algae growth which enhances the plant life thus greening the environment in the true sense. In this process catalytic oxidation also occurs thus breaking complex organics also thus ensuring maximum degradation of organics.
Fig.: CAACO Reactor
The sludge consists of microorganisms and they degrade the pollution material of the waste (BOD and COD) and finally converts water and energy in the absence of oxygen. The chemoautotrophic activated carbon oxidation (CAACO) treatment process the microbes held in the pores break down the heavier organics into smaller molecules while the wastewater carrying the heavier organic moves down the reactor.CAACO technology mainly consists Anaerobic digester, CAACO reactor.
The waste water after passing through screen chamber and oil & grease trap will be collected in the Collection cum Equalization Tank (EQT). Air shall be provided in this tank to keep the suspended solids in suspension & to avoid any potential odor problem.
From Equalization, waste water to be pumped to Flash Mixer (F/M) Chamber to here Alkali/Acid to dosed & high speed agitation achieves the complete mixing of effluent with chemicals.
The overflow from F/M chamber overflows to Flocculation Chamber (F/T) here the chemically treated effluent is made to mix with Poly- electrolyte to achieve higher degree of settling. Then the waste water is made to pass through the Primary Settling Tank (PST) to separate out the flocs/chemical sludge. This sludge to be collected into a small sludge pit from where it shall be disposed off through Filter Press. The overflow from PST is feed into the Up- Flow Anaerobic Reactor (UAR). The overflow from UAR is collected in the intermediate water tank (IWT). Then the water from IWT is passed through a Sand Filter and then through the special distribution system in the CAACO reactor. When the wastewater flows down the CAACO reactor through the specially developed catalyst based media, the immobilized microorganisms perform biological degradation of the organics & the media performs catalytic oxidation at the same time. Air is provided with the help of an Air Blower that provides the required oxygen to the facultative Microorganisms.
After this Biological Oxidation Process treatment there is no need of tertiary treatment. This treated water can be directly used for horticulture purposes.
Intermediate Water Tank
Treated Water Tank
Fig: Flow Chart of CAACO Process
The anaerobic digestion process is a multi -step process involving two physiologically different groups of bacteria. One group of bacteria(acidogenic bacteria) that convert organic matter into soluble compounds and volatile fatty acid is fast growing , prefers a slightly acidic environment (low pH of 4.5 to 5.5).The other group of bacteria (methanogenic bacteria), which converts soluble matter into biogas, is slow growing, prefer neutral to slightly alkaline(pH>7)
The fermentative Anaerobic organisms mostly use the lactic acid fermentation path
C6H12O6 + 2ADP + 2phosphate ïƒ 2Lactic acid + 2 ATP
Alcohol (ethanol) fermentation in Anaerobic conditions.
C6H12O6+ 2ADP + phosphate ïƒ 2C2H5OH + 2CO2 +2ATP
Anaerobic digestion is an age-old technology, which does not consume the energy, rather energy can be recovered. The digestion of anaerobic digester is application /size specific. There are various designs of Anaerobic digester such as bulk, hybrid, USAB, Fluidized bed, CSIR, SMAT, Upflow Anaerobic Bed Reactor etc.
The anaerobic digestion (AD) is the process of the breakdown of organic material in mixtures of primary settled and biological sludge under anaerobic conditions is biologically converted to methane and carbon dioxide. Process is carried out in an airtight reactor.Sludges are introduced continuously or intermittently and retained in the reactor for the varying period of time. The stabilized sludge, which drawn continuously or intermittently from the process and its pathogenic content is greatly .The faction of the Anaerobic digestion is to supernatant the digested solids from the supernatant liquor, additional digestion and gas production may occur. Detention time2.8 days.
Fig.: Anaerobic Digestion Pathway
Very low sludge generation.
COD reduction from 60% to 90% is possible.
Allows proper separation and digestion of oil& grease.
Removes of colloidal turbity.
Smell free, as it i9s fully enclosed.
Energy can be recovered.
After the anaerobic digestion effluent directly enters the CAACO rector. The digested effluent enters the filter; the effluent enters the Multi Grade Sand Filters helps to remove colour, odour, and dissolved solids from the effluent. The filtered effluent is sent to the CAACO reactor.
The system has the basic feature such that bacteria are immobilized in the pores of the carbon matrix. When activated carbon is equilibrated with wastewater containing multisolutes, they instantaneously adsorb onto the active sites of the outer pore surface of activated carbon. In the newly developed method the size of pores of the activated carbon was controlled only in the mesoporous range and the outer surface area was provided with active sites of varying degrees of energies. The mesopores of the activated carbon are utilized for immobilization of organisms. The organism held in the pores cannot be dislodged as the growth of the organism limits its escape from the pores. Active sites distributed in the outer pore surface area are abundant in number and thus all the sites in the outer pore surface area are available for the migrating solutes from solution.
The micro-organisms held in pores are also prevented from exposure to shock load application. The organics contained in wastewater when flows down the reactor through the activated carbon matrix forms of a layer of concentration gradient at the particle surface, which further diffuses into the pores as governed by Flick's law of diffusion. Since the products are not contained in activated carbon, clogging of the voids in the reactor is absolutely eliminated and thus back washing treatment is eliminated. The hydroxyl ions formed from the electron and molecular oxygen combination helps in opening of complicated molecules such as phenol and naphthalene compounds.
The dissolved organics estimated as COD and BOD have been proved to be decreased to a credible level such that the treated wastewater can be discharged into open land. The treated wastewater has been used for irrigation and it has recorded the growth of vegetative plants, commercial crops and ornamental plants. The treated wastewater has been tested for carcinogenetic and test results suggest that human population can safely handle the treated wastewater.
Initially the Anaerobic digester is proposed to reduce the organic load and eliminate the colloidal turbidity in the sewage. In addition, there will be a reduction in Solids and Sludge. This is then, followed by a Sand Filter and CAACO reactor.
The wastewater is aerated and mixed by an airlift system in a reactor vessel packed with special matrix amorphous carbon. Air or Oxygen is introduced from the bottom of the reactor through venture or diffusers providing fine bubbles for efficient oxygen transfer. The media has a low surface area. Unlike biological systems - there is no sludge formation. The microbes remain in a high growth phase - forming a fully developed food chain. The acclimated microbe population is resistant to shock loads.
Simple Oxidation process:
An oxidation reaction process involving chemoautotroph. The complex ammonia compound is Oxidized by the chemoautotrophic bacteria.
2NH4+ + 3O2 -Nitosomonas bacteria-ïƒ 2 NO2 + 2H2O +4 H+ +Energy
CH3CH2 COOH -Chemoautotrophïƒ 2CH2COOH + HCOOH + 2e-
2CH2COOH + HCOOH ïƒ CO2 + H2O
2e - + 1/2 O2 +H2O ïƒ 2[.OH] (Oxidation Process)
Features of this system:
The reactor consists ofÂ meso-porous activated carbon catalyst.Â
The pores of the catalyst are used for immobilization of organisms.Â
The outer pore surface area containsÂ active sites that had been imparted with high amount of potential energy.Â
The high energeticÂ active sites attract the pollutants in wastewaterÂ and are oxidized.Â
For oxidation of organics, air is sent from the bottom of the reactor.
The microbes held in the pores break down the heavier organics into smaller molecules while the wastewater carryingÂ the heavier organics moves down the reactor.
The proliferation of the growth of the organisms around the periphery of the particle is controlled by cell damage induced by internal pressure (by nitrogen component of air) built up at the voids of the carbon bed. Therefore the production of sludge is eliminated in CAACO.
After completion of CAACO treatment no tertiary treatment required, both chemical and biological treatment carried in the CAACO reactor in single hybrid system. Treated water can be used for agricultural purpose or recirculation.
Fig.: Simplified comparison aerobic Vs anaerobic
Highly absorbent carbon obtained by heating granulated charcoal to exhaust contained gases, resulting in a highly porous form with a very large surface area. It is used primarily for purifying gases by adsorption, solvent recovery, or deodorization and as an antidote to certain poisons. Also called activated carbon.
The char particle is then activated by exposure to an oxidizing gas at a high temperature. This gas develops a porous structure in the char and thus creates a large internal surface area. The surface properties that result are a function of both the initial material used and the exact preparation procedure, so that many variations are possible. The type of base material from which the activated carbon is derived may also affect the pore size distribution and the regeneration characteristics. After activation, the carbon can be separated into or prepared in different sizes with different adsorption capacities.
Analysis of the Adsorption Process:
The adsorption process takes place in three steps: Macro transport, Micro transport and Sorption. Macro transport involves the movement of the organic material through the water to the liquid-solid interface by advection and diffusion. Micro transport involves the diffusion of the organic material through the macrospore system of the Granular Activated Carbon (GAC) to the adsorption sites in the microspores and submicropores of GAC granule. Adsorption occurs on the surface of the granule and in the macropores and mesopores, but the surface area of these parts of the GAC granule are so small compared with the surface area of the micropores and submicropores that the amount of material adsorbed there is usually considered negligible. Sorption is the term used to describe the attachment of the organic material to the GAC. The term sorption is used because it is difficult to differentiate between chemical and physical adsorption. When the rate of sorption equals the rate of desorption, equilibrium has been achieved and the capacity of the carbon has been reached.
Activated carbon in conjunction with biological treatment has been widely used for treatment of wastes containing non-biodegradable and toxic organics. It provides an attachment surface for microorganisms and protects them from shock loadings of toxic and inhibitory materials. It also finds application in water treatment for the removal of trace organics in biological activated carbon (BAC) or granular activated carbon (GAC) systems. There are still subjects that need to be investigated in this area. Therefore a network is needed where many researchers can exchange their ideas about the use of activated carbon.Â Â
Pharmaceutical industries use considerable quantities of poorly biodegradable organics. The biodiversities employed in effluent treatment units are ineffective to remove organics in wastewater as the compounds themselves or their metabolites are toxic. The present study consists of anaerobic and aerobic bacteria in rice bran based activated carbon and air was supplied for the oxidation of organics in wastewater, thus the system was named Chemoautotrophic activated carbon oxidation (CAACO).The immobilized bacterial species and activated carbon were quite successful in removing the organics in wastewater at low detention period of 2h. The efficiency of treatment of pharmaceutical wastewater is good when compared to the conventional process. Tertiary treatment was not required, it is coast effective system. Both biological and chemical process takes place in single hybrid system. It occupied the low place. The operation cost is low; it is resistance the shock loads.
Thus the above resin the CAACO treatment of wastewater is using with pharmaceutical more efficiency when compared to the conventional system.
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