|Title of Invention||
COIR RETTING BIOREACTOR
|Abstract||The Coir Retting Bioreactor (CRB) developed has: a) a retting reactor tank with a perforated platform positioned 10 cm above the base, holding a 2 cm bed of crushed oyster shells on which crushed coconut husk pieces are packed and filled with 5ppt seawater for stripping polyphenols. After draining the liberated polyphenols, the same tank is filled with 20 ppt seawater, supplemented with nutrients, and inoculated with microbial consortium. Airlift pump is operated and retting is completed within 30 to 45 days. The ret liquor at this stage is passed through the ret liquor treatment system which comprises an activated sludge system and a packed bed reactor. b) an activated sludge system comprising, an aeration basin with an electric motor fixed with baffles, and a clarifier fitted with sludge arrestors on the inner side. c) a packed bed reactor fitted with a perforated platform 5 cm above the base of the tank and filled with oyster shells. d) a collecting tank for treated effluent and for reuse.|
The present invention relates to Coir Retting Bioreactor (CRB) for retting coconut Husk within a short period of time to yield good quality fibres.
The object of the present invention is to have a Coir Retting Bioreactor to ret coconut husks to produce good quality fibre.
In the present coir industry retting is carried out in backwaters. This process takes more than a year for completion. Moreover it impairs the natural environment due to the organic and toxic compounds liberated during the process.
So the present invention particularly relates to the retting process in a closed system reactor to prevent release of pollutants to the environment and also to increase the quality of coir fibre.
After careful research and experiments, the Coir Retting Bioreactor has been developed as a zero pollution technology with which good quality coir fibre can be produced within a short period of 30 to 45 days and the results obtained are very
The pith generated on defibering the husk retted in this reactor is with low polyphenol content, easily biodegradable, and is very much fit for bio-composting.
The ret liquor generated is biologically treated in the bioreactor and recirculated causing no environmental impairment.
The coir retting bioreactor has three discrete components which are closely integrated to form a single unit. They are a retting reactor, an activated sludge system and a packed bed reactor. This bioreactor can ret 10 numbers of coconut husks (about 8 kg. wet weight) at a time and can be scaled up to suit the requirements of coir industry.
The invention is now described in detail with reference to the accompanying drawings where like reference numerals always indicate the same parts throughout the description of the drawings, in which:
Fig. 1 shows the Coir Retting Bioreactor with its components.
Fig. 2 shows the retting reactor tank of the Coir Retting Bioreactor of fig. 1.
Fig. 3 shows the activated sludge system of the Coir Retting Bioreactor of fig. 1.
Fig. 4 shows the packed bed reactor component of the Coir Retting Bioreactor of fig. 1.
Retting reactor tank (Fig. 2)
The retting reactor tank of the bioreactor consists of a container (2) having 40 cm2 base and 40 cm height. A perforated platform (3) is positioned 10 cm above the base to support the husk. From the bottom of the tank an outlet pipe of 2 cm diameter connects with a 0.25HP monoblock magnetic coupled electric pump (1) which facilitates drawing water forcefully from the bottom to discharge at the top, thereby a strong circulation of water at a turnover of 40 litres per minute is generated. Through another outlet pipe (6) fixed at the opposite side, ret liquor can be drained off for concentration of polyphenols. The tank (2) can hold freshly split coconut husk weighing around 8 to 10 kg. The tank is made of fibre glass; pipes with PVC and valves of polypropylene. At the base of the tank a 2 cm thick bed of crushed clam or oyster shell pieces is given.
The retting reactor receives water from an overhead tank (24) made of fibreglass having 32 cm2 base and 40 cm height and is positioned 10 cm up above the retting reactor. The Coir Retting Bioreactor has closed system configuration and the ret liquor is passed through a treatment system after completion of retting and gets collected in a collecting tank (22). From here it is pumped to the overhead tank (24) and is fed to the retting reactor. In the retting reactor a perforated platform (3) is positioned 10 cm up above the bottom and at its centre an 1 inch pipe fitted functions as the airlift pump (4).
Air is passed from the compressor (5) through an air sparger (4a) near to the bottom of the pipe.
i. Polyphenol stripping as pre-retring operation:
The pre-retting operation is the first preparative step in the bioreactor technology developed for coir retting. The principal objective of the process is to strip off sizeable proportion of the polyphenol from husk so that microbial process can set in and proceed at a rapid rate.
The tank (2) which forms retting reactor is used for stripping polyphenol. At the base of the tank a 2 cm thick bed of crushed clam or oyster shell pieces is given and over which freshly split coconut husk, crushed either manually or mechanically are arranged inverted with the split-side upward, and, the tank is filled with 5ppt seawater. After 6 hours soaking, the pump (1) is operated for another 18 hours with intermittent stops. This forms the first stage of stripping. The experiment indicated that maximum liberation of polyphenols is achieved within 24 hours and for the recovery of the compound this is the right time to drain off the fluid. Further maintenance of the liquor in the reactor leads to degradation of the polyphenols. Therefore, the liquor has to be immediately drained off through the outlet pipe (6) and subjected for concentration by reverse osmosis. This concentrated ret liquor can find several commercial applications.
ii. Retting Operation:
As soon as the polyphenol stripping is over, the ret liquor is drained off for concentration and the tank (2) is filled with seawater of salinity 20 ppt from the overhead tank (24). Commercial grade ammonium phosphate to the final concentration of 1% is added and the airlift pump (4) operated for 1 hour for oxygenating the system. pH is checked after 1 hour and normally it remains within 6.5 to 7 since a bed of crushed clam or oyster shells is provided. Subsequently the reactor is inoculated with 1 litre consortium from the stock. Polyphenol content, pH, NK/" - N and PCV - P are regularly monitored.
When NH4 -N and PO*" -P are consumed by 50 % they are supplemented by adding aqueous commercial grade ammonium phosphate.
During the process, pH remains almost steady between 6.5 to 7. There will be an increase in the polyphenol content in the initial phase, which get stabilized soon and subsequently become undetectable. The usual red colour of the ret liquor also disappears. After about 20 days, the husks start to become progressively softer and attain satisfactory softening for fibre extraction within 45 days. At this stage, the pericarp could be peeled off and the fibre could be freed from husk by beating them 10 to 15 times manually with a wooden rod.
iii. Retting Microbial Consortium:
The microbial consortium used for the bioreactor is maintained in seawater based medium (20ppt salinity) supplemented with 0.5% NH4C1, 0.1% NH4N03 and 0.1% KH2PO4. The medium is supplemented with 10%(w/v) crushed pieces of clam or oyster shells. Incubation of husk pieces along with consortium over a magnetic stirrer set at 100 rpm at room temperature (28 + 2°C) result faster disintegration of the husk. Husk pieces used should be the ones stripped off polyphenols previously. Once the husk pieces disintegrates fully it can be subcultured as described above.
iv. Effluent quality:
Quality of the effluent generated during retting is assessed in terms of the polyphenol content. It is seen that the polyphenol builds up in the initial phase of retting, which later stabilizes and comes down dramatically and registers zero towards termination of the process. The ret liquor remains very clear without any odour and can be reused in the reactor, the pH remains neutral which eliminates the need of adjusting it during the process and also before reuse of the effluent.
For reuse, the retted husk is completely removed and the water is allowed to flow down from the overhead tank (24) to the reactor (2). This will facilitate the movement of effluent from the retting reactor to ret liquor treatment system.
v. Quality of pith:
For converting pith to manure, it should have very low polyphenol content (less than 0.1%). The pith generated from husk retted in the bioreactor contained very less polyphenols (less than 0.1%) comparable to that of the naturally retted husk.
Ret liquor treatment system
The ret liquor treatment system has got the following components, an activated sludge system and a packed bed reactor.
Activated Sludge System (Fig. 3)
The activated sludge system, integrated in to the retting reactor, has an aeration basin and a clarifier. The aeration basin (8) made of perspex has 50cm height and 32cm2 base. An inlet pipe having 1.5 cm inner diameter is connected to the tank at a point 36cm from the bottom. The inlet is connected to the retting reactor through a flexible hose (7). At the opposite side an outlet pipe of the same diameter is fixed at the same height. An electric motor fixed with baffles (9) is used for agitating the effluent. The clarifier (12), fixed after the aeration basin, is also made of perspex having 40cm height, 36cm2 base and is fitted with sludge arrestors (13) having baffles on the inner side. To receive the treated effluent from the aeration basin there is an inlet pipe (11) of 1.5cm inner diameter fixed at 36cm height which bends and reaches the bottom of the tank. From the point at which the settled sludge from the clarifier is drained off, a portion of the sludge is taken to the aeration basin as return sludge through a hose of 1.5cm diameter operated by a pump (14). Rest of the sludge is drained out through waste sludge outlet (15). From the
clarifier the clear fluid flows through an outlet tube of 1,5-cm inner diameter to a packed bed reactor (16) for final polishing of the effluent.
For the development of activated sludge, 15 bacterial cultures belonging to Bacillus, Pseudomonas, Aeromonas, Coryneform group, Enterobacteriaceae, Micrococcus, Acinitobacter and Alteromonas have been isolated from retting grounds and maintained as pure cultures. All of them have varying capability to utilize polyphenols as sole source of carbon and energy. To generate activated sludge in the aeration basin (8) the above bacterial cultures grown in nutrient agar (containing 2% NaCI) were harvested in to 20ppt seawater and inoculated the ret liquor in the aeration basin. pH of the ret liquor is adjusted to 7.5 and nutrients such as NH/ - N and PO4" - P are added in the form of commercial grade ammonium phosphate to a final concentration of 1%. The preparation is agitated using the agitator (9) and aerated continuously by an aerator (10). Once in 24 hours, pH is adjusted and nutrient level and the concentration of polyphenols monitored. Gradually floes develop and get settled and the capability of the sludge to consume polyphenols rise to the rate of 5mg.L" polyphenols per hour and the mixed liquor suspended solids (MLSS) around 11,250 mg.L"1. At this stage, the overhead tank (24) can be opened and water allowed to flow to the retting reactor (2), thereby ret liquor enters in to the aeration basin (8). The hydraulic retention time can be adjusted by adjusting the valve in the overhead tank so that effluent flowing out of the clarifier (12) shall be having polyphenol less than O.lppm. This effluent is directed to the packed bed reactor (16).
Packed bed reactor (Fig. 4)
The packed bed reactor (16) is also made of perspex having the same dimensions of the clarifier (12) (40cm height and 36cm2 base), A perforated platform (19) is positioned 5cm above the base of the tank and has 31cm tall pipe with 1.5cm inner diameter fixed at the center. An outlet pipe (18) fitted at the base of the tank takes an 'IT turn and rises up to 36cms height and discharges the effluent to a collecting tank (22). The column is packed with oyster shells and the bacterial cultures used for developing the
activated sludge were used for charging the packed bed reactor. To get the organisms adsorbed on to the shell pieces the reactor is filled with ret liquor, supplemented with commercial grade ammonium phosphate. The airlift pump (20) is operated by the air from the compressor (21) through an air sparger near the bottom of the pipe. This facilitates activation of the reactor, which can be detected by measuring the rate of consumption of polyphenols in the reactor. When the reactor is conditioned, it can be connected to the activated sludge system.
The treated effluent gets collected in a collecting tank (22) made of fiberglass having a volume of 40cm3. The effluent, which gets collected, will be having a neutral pH as it passes through a bed of crushed oyster shells (17) and do have polyphenol less than O.lppm as it has been subjected for dual treatment. This water is fit for reuse in the retting reactor. It can be pumped to the overhead tank (24) using a magnetic coupled pump (23).
We claim: -
1. A Coir Retting Bioreactor (CRB), to ret coconut husk within a short period of time to yield good quality fibres, consisting of retting reactor, activated sludge system, packed bed reactor comprises:
i) a retting reactor tank having 40 cm2 base and 40 cm height (2) with a perforated platform (3) positioned 10 cm above the base along with an outlet pipe of 2 cm diameter from the bottom of the tank connected to a 0.25HP monoblock magnetic coupled electric pump (1) facilitating drawing water forcefully from the bottom to discharge at the top tank (24) and another outlet pipe (6) fixed at the opposite side to drain off ret liquor:
ii) an aeration basin (8) made of perspex 50cm height and 32cm2 base with an inlet pipe and outlet pipe of the same diameter having an electric motor fixed with baffles (9):
iii) a clarifier (12) fixed after the aeration basin made of perspex having 40cm height, 36cm2 base fitted with sludge arrestors (13) having baffles on the inner side and an inlet pipe (11) of 1.5cm inner diameter fixed at 36cm height which bends and reaches the bottom of the tank:
iv) a packed bed reactor (16) made of Perspex, filled with oyster shells, having 40cm height and 36cm2 base with a perforated platform (19) positioned 5cm above the base of the tank and having 31cm tall pipe with 1.5cm inner diameter fixed at the center and an outlet pipe (18) fitted at the base of the tank taking an 'IT turn and rising up to 36cms height discharging the effluent to a collecting tank (22).
|Indian Patent Application Number||130/MAS/2002|
|PG Journal Number||23/2006|
|Date of Filing||18-Feb-2002|
|Name of Patentee||DR. T.R. SATYAKEERTHY|
|Applicant Address||THONDUPARAMBIL HOUSE, NEERATTUPURAM P.O., ALLEPPEY 689571|
|PCT International Classification Number||D01C1/00|
|PCT International Application Number||N/A|
|PCT International Filing date|