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Sugar beet industries produces sugar beet pulp as a by product. EU only produces the 108 ton per year (Spagnuolo et at. 1997). Sugar beet pulp should be important renewable resources, its bioconvertion resources appeares to be of great biotechnological importance. Almost 250 kg of exhausted pressed pulp producing when 1 tone sugar beet pulp use, with the water content aproximetely 75-80% (Spagnuolo et al. 1997). The lignocellulosic fractional of dried pulp composed of 3 to 4 % lignin, 24 -32% of hemicellulose , 22-30% cellulose and 24-32% pectins substances (Spagnuolo et al. 1997). Hydrolysis of beet pulp yield following monosaccharides L-arabinose , D-glucose and D-galaturonic acid release as a component of main chains of hemicellulose, cellulose and pectin respectively. L- rhamnose, D- xylose, D-galactose, D-manose produce in lower amounts (Spagnuolo et al. 1997). Sugar beet pulp mainly contains pactins (15-30%). It contains soaring amounts of arbinose and galacturonic acid. Beet pactins enclose the general structure descricption of pactins and charactrized by a (1 2) linked rhamnose back bone of Î± - (1 4)- linked galacturonic acid residues and forming long " smooth" regions which many be interrupted by "hairy" regions consisting of galacturonic acid (Micard et al. 1996). Various rhamnose residues take side chains consisting mostly of (1 5) - linked Î±-arbinans with branches attached to position 3. Other structural character might consist of (1 4) - linked Î²-galactans of small polymerization degree, grately branched (1 3, 6) - linked galactans (Micard et al. 1996). However beet pectins are altered from the fruits. A number of variations have been noted between citrus pectins and apple and beet pectin. Between them is the presence of acetyl group linked to Î± D - galacturonic acid, the content of rhamose and presence of furic acid.
Galacturonic acid, arbinose, rhamnose and ferulic acid may have a different commercial uses. Galacturonic acid is able to transform by esterfication with a range of fatty acids in to tensioactive agents. L- Arbinose may be used for diagnostic purpose in bacteriology. It also has been found for anti Parkinson properties. Rhamnose may be used as an aroma precursor eg. "furaneol" through chemical transformation. Ferulic acid to facilitate chemically resembles vanillin, may be biotransfered with lignolytic microorganisms into an aroma. Sugar beet pulp is also used for the production of biogas through anaerobic digestant.
21.1Composition of Sugar beet Pulp (Dry matter basis) (Micard et al. 1996).
Process and system for treatment of biochemical waste:
Anaerobic stabilization process is used for the treatment of biochemical waste such as activate sludge. Anaerobic stabilization processes involve two major reactions.
Acid fermentation: In which the molecular weight of the organic substances are reduced by anaerobic acid fermentation bacteria and substances are converted into volatile acids such as butyric acids, acetic acids and propionic acids.
Methane fermentation: In which methane gas is obtained from the organic acid by methane fermentation bacteria.
Anaerobic stabilization process in conventional practice, both phases of Acid fermentation and methane fermentation co-exit within the similar chemical and physical background along with control requirement and method efficiency determined by kinetic characteristic and the sensitivity of the rate limiting phase. As a result, such extensive periods as 30 to 50 days are normally required for achievement of the anaerobic stabilization process. On the other hand, the energy reduction and pollution preventing characteristics of the anaerobic stabilization processes are freshly review and several research efforts are being made to get better the fatal failing of these processes.
Procedure for anaerobic sugar beet pulp digestant sample:
Biochemical waste water including waste such as a sugar beet pulp, sludge, garbage and waste water from alcohol distillation method or concentrated waste water released from food industrialized processes is bring in to an acid reactor for acid fermentation, in which fermentation occurred by the waste contact with acid fermentation bacteria and anaerobically preserved at a prescribed temperature used for numerous days. While the acid fermentation effected in the acid reactor, macromolecules substances are transfer to law molecule substances and further decomposed in the direction of volatile organic acids.
The waste within the acid reactor is preferred to keep at 300C to 500C temperature and a pH of 3 to 7. The pH in the acid reactor can be maintained by adding suitable level of various neutralizing agents such as NaOH, KOH, CaCO3 or Ca(OH)2, Na2CO3.
The temperature and agitation controls are achieved by conventional method used for anaerobic stabilization processes for example a direct vapour blowing process, a gas agitation process, a process using heat exchanger and a mechanical agitation process.
As acid fermentation bacteria, acid former bacteria belong to the genera of Staphylococcus, Clostridium, Bacillus and Escherichia. In ordinary two or more types of bacteria employed at the similar time. On the other hand a solo species of bacteria may be employed as acid former.
Later than the acid fermentation has been finished, the waste is bring in a separator where the waste is separated into the waste solid and supernatant liquid by solid liquid separation process such as a low speed centrifugation separation method. As well as the undigested filtrate partly and cells of acid fermentation bacteria are recycled to the acid reactor.
The supernatant fluid is introduced in to the methane reactor for methane fermentation, in which methane and carbon dioxide gas achieved from the volatile acid. In order to carry out this methane fermentation is favoured to heat the supernatant fluid at 300C to 500C temperature under the anaerobic environment though satisfactorily adjusting and agitating the pH 7 to 8. Agitating and Heating might be accomplished by process explained above with the respect to the acid fermentation.
Alteration of pH can be done by using an organic acid or mineral acid. Since the methane former, any known methane fermentation bacteria such as bacteria belonging to genera of Metanococcus, Metanobacterium and Metanosarcina can be used. The gas formed while methane fermentation contains 10 to 40% of carbon dioxide, 60 to 90 % of methane as main component and small amounts of H2, N2 and H2S. The gas formed by methane fermentation mixed with the gas formed though acid fermentation and used as a heat supply for the temperature control of the power source and treatment system for agitation.
After the completion of the methane fermentation in the methane reactor, remain waste is separated into waste solid and supernatant liquid. The supernatant liquid released as waste matter. This dehydrated and dried waste solid which is withdrawn as a waste sludge used for organic fertilizer. In additional to enhance the treatment efficiency of stabilization process, a part of waste solid may be recycled in the acid reactor. Prior to acid fermentation the waste is treated at a pH of 1.0 to 3.0 with heating.
Activated sludge including regular biochemical waste may be a kind of hydrophilic colloid which having a state that be similar to a state of hydrated gel, it has a solid concentration nearly about 5% pasty or slurry structure. So a huge agitation power is requiring for the digestion. Still in the case of biochemical waste, by performing macromolecule components, heat treatment under acid condition should be customized to reduce the viscosity of the waste. Subsequently digestion process may be facilitated and both the gas yield and the digestion efficacy highly improved, good effects are obtained when the pH is lower than 3.5 in the pre-treatment tank. Since the economical view point, it is favoured that initial treatment can be conducted at a pH of 1.0 to 3.0. Organic acid such as citric acid and acetic acid are also used effectively along with mineral acids such as HCL and H2SO4 for this acidification. Mostly HCL and H2SO4 are preferable because of economical point of view. An amount and concentration of the acid used depending on kind of solid content of raw material. Generally, in order to obtain the above preferred pH condition for example, in amount of 0.1 to 1.0 % w/w waste requires 30 % of HCL.
Viscosity cannot be reduced by preliminary treatment under the high temperature, even above 1500C. When the heat is using in the alkaline condition, the viscosity is quite increased so it is crucial that the heating can be conducted at a temperature of 600C for a minute. On the other hand, if the treatment is carrying out at extremely higher temperature for long times for example at 1700C for 20 minutes, corrosion products inhibiting the digestion are formed. Consequently, the preliminary treatment favourably conducted not higher than 1600C temperature for 10 minutes in the acid condition. But, the preliminary treatment may be omitted for simplifying the method. In addition, while the waste has large solid it can prefer to crush the waste to slurry before to the acid fermentation.
Repeat the procedure with the reaming waste as per the step no. II to IV. Then add the calcium carbonate, Calcium nitrate, calcium hydroxide, calcium nitrate to improve the agglomeration and sedimentation rate. Then repeat the procedure step V and VI.