|Title of Invention||
PROCESS AND APPARATUS FOR NITRIFYING WATER IN CLOSED SYSTEM HATCHERIES OF PENAEID AND NON PENAEID PRAWNS"
|Abstract||A process and apparatus for nitrifying water in closed system hatcheries of penaeid and non penaeid prawns which comprises in a first step of treating water with an ammonia oxidizing consortia to convert the ammonium present in water of the hatchery system to NO2 and in a second step of nitride oxidizing with a nitride oxidizing consortia for converting NO2 into NO3 .|
|Full Text||FIELD OF INVENTION
This invention relates to a processt and an apparatus nitrifying water in closed system hatcheries
of penaeid and non penaeid prawns.
BACKGROUND OF INVENTION
In prawn hatcheries unionized ammonia,>0.1 ppm at alkaline pH(>7.5)is toxic to
the larvae Inclosed larval rearing systems ,NH4 /NHi is. accumulated as the excretory product of nitrogen metabolism of prawn larvae and also as the product of ammonification of faeces and left over feed. It is generally recognized that the presence of such ammonia in prawn hatcheries contributes to the toxicity. The hatchery systems known in the art may be the penaeid hatchery systems having a salinity optima at around 30 ppt or a non penaeid hatchery system having a salinity optima at around 13 ppt.
OBJECTS OF THE INVENTION
An object of this invention is to propose a process for nitrifying water in closed system hatcheries of penaeid and non penaeid prawns.
Another object of this invention is to propose a process for nitrifying water in closed system hatcheries of penaeid and non penaeid prawns which is simple and at the same time efficient
Still another object of this invention is to propose a bioreactor for nitrifying water in closed system hatcheries of penaeid and non penaeid prawns.
A further object of this invention is to propose a bioreactor for nitrifying water in closed system hatcheries of penaeid and non penaeid prawns which may be employed in the larval tank itself.
A still further object of this invention is to propose a bioreactor for nitrifying water in closed system hatcheries of penaeid and non penaeid prawns which is employed external to the hatchery system. DESCRIPTION OF INVENTION
According to this invention there is provided a process for nitrifying water in closed system hatcheries of penaeid and non penaeid prawn which comprises in a first step of treating water with an ammonia oxidizing consortia to convert the ammonium present in water of the hatchery system to NO2 and in a second step of nitride oxidizing with a nitride oxidizing consortia for converting NO2 into NO3.
Basically two kinds of organisms such as 1. Ammonia oxidizing (NH4+→ NO2- and 2 Nitrite oxidising (NO2→NO3) bacteria are required for the process and bioreactors of this invention. Just like any other organisms nitrifiers also have salinity optima and therefore both ammonia and nitrite oxidizers having salinity optima at around 30ppt have been developed for the bioreactors meant for penaeid hatchery systems and nitrifying consortia having salinity optima at around 13 ppt have been developed for the bioreactor meant for non penaeid hatchery systems. Such oxidizers are :
1. AMOPCU-1 : Ammonia oxidising consortia meant for penaeid culture
2. N1OPCU-1 : Nitrite oxidising consortia meant for penaeid culture
3. AMONPCU-1 : Ammonia oxidising consortia meant for non-penaeid
4. NlONPCU-1 : Nitrite oxidising consortia meant for non-penaeid
OPTIMUM GROWTH REQUIREMENTS OF THE CONSORTIA
Optimum pH, temperature, substrate concentration and salinity of these oxidizers have been determined as they are essential for their mass production in fermentorand also for immobilisation in the reactor support material.
Optimum growth requirements
MASS PRODUCTION OF NITRIFYING CONSORTIA IN FERMENTOR
The nitrifying consortia can be amplified as per the requirements supplying the above optimum growth conditions. The amplification can be started from a 10%(v/v) starter culture. The substrate as (NH4)2S04 and NaNO2 are added as small aliquots as they
are being consumed so as to maintain a level not less than 10 ppm NH4 N or NO2-N. The fermentor vessel is covered with black cloth to prevent photoinactivation of nitrifiers. It takes 25 to 30 days for attaining stationary phase characterised by
cessation of substrate (NH4 +N or NO2--N) uptake and product (NO2--N and NO3-N) formation. Profound wall growth is seen in all cases and they are scraped off and the entire culture drained ofl'from the fermentor, pll adjusted, substrate added to optimum and maintained at 4°C either in glass or polythene bottles. Whenever the substrate is depleted and pH alteration occurred they have to be adjusted manually.
UNIT. NITRIFY.ING ACTIVITY (UNA) OF THE CONSORT!A.
One unit nitrifying activity (UNA) of a nitrifying consortium is defined as the
quantity of nitrifying biomass which can bring about the generation of lu mole
NO2--N min-1 L-1 in the case of ammonia oxidizers (UNA a) and the consumption of
lumole NO2-N min L in the case of nitrite oxidizers (UNAn) under optimum conditions. This is the most appropriate method of quantifying the potential of any
nitrifying consortium, to evaluate it and to assess how much quantity of the culture should be used to charge a reactor for obtaining the expected activity.
DETERMINATION OF QUANTITY OF CONSORTIA
The appropriate medium is prepared with optimum pH, and substrate concentration in triplicate in 500 mL screw capped bottles (7.5cm O.Dand 21cm ht) and mainitained at the optimum temperature in a serological water bath. Filter sterilized
(by passing air either from air compressor or air blower through a pipeline
membrane filter device) air at a rate of IL.min -1 is passed through an air sparger
immersed in the medium. The bottles are inoculated with ImL aliquots of the consortium Evaporation loss is compensated by adding sterile distilled water. Once in two hours substrate utilization and product formation are measured for a period of 24 hours. Based on the value, the total number of units available with 1 mL aliquots of the consortium can be determined. From this the requirement of the quantity of consortium for one reactor also can be worked out and it is this volume that is to be used for immobilizing in the reactor bed.
Suppose ImL aliquot of the given AMOPCU-1 contains 10 UNAa, Capability of the
consortium is :
IUNAa: Production of lu mole NO2-N, min -1 ,L-1 NH4 -1N
lumole: 14.0ug NO2--N, min-1 ,L-1
lOu mole: 14x10 ug.min-1 ,L-1
That means, one mL aliquot of the consortium can produce 140ug NO2-N,min-1 .
L-1 the medium which contains lOug NH4+-N.mL-1 (10,000 ug NH4-1-N .L-1 ). This is
the measure of capability of the consortium which can consume the entire quantity of
NH4 +N(10,OOOug.L-1 ) with in 71.43 minutes under optimum conditions.
SUPPORT MATERIAL FOR IMMOBILIZING NITRIFYING BACTERIA
Considering various factors such as inertness in aquatic system, light weight, hydrophobicigy, easiness to mould in to any shape and easy availability, plastic has been selected as the basic material for the support. Beads of, for example, 5.0 mm diameter with a hole of 2.00 mm diameter at the centre and with sparkings on the surface are moulded out of high density polyetylene (HDPE), low density polyethylene (LDPE), polyvinylchloride (PVC), polypropylene (PP), polystyrene(PS), polycarbonate (PC), nylon and ABS and screened against each consortium. Considering the effectiveness in immobilizing cells, cost and easiness to mould the following type of plastics were selected for each consortium.
NAME OF THE CONSORTIUM TYPE OF PLASTIC
NIOPCU-1 Low density polyethylene
NIONPCU Low density Polyethylene
DESCRIPTION OF INVENTION WITH REFERENCE TO ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings and wherein:
Fig. 1. Shows the outer shell of an in-situ stringed bed suspended reactor (SBSBR),
Fig.2. Shows the inner cartridge of a SBSBR,
Fig 3. Shows an ex-situ packed bed bioreactor (PBBR)
Fig.4. Shows two PBBR reactors in series.
In accordance with this invention, the drawings illustrate two types of reactor. A first type of reactor shown in Figs. 1 and 2 is an In-situ stringed bed suspended bioreactor (SBSBR) for use in the larval rearing tank itself during the process of larval rearing, and the second type namely as Ex-situ packed bed bioreactor (PBBR) is
meant for nitrifying, fresh seawater before using for larval rearing and spent water after completion of the larval cycle, so that, the water may be recirculated is shown in Figs. 3 & 4. The reactors may be employed for both penaeid (Penaeus indicus and Penaeus monodon) and non penaeid (Macrobrachium resenbergii) prawns.
Referring to Figs. 1 and 2, the SBSBR reactor comprises on outer shell OS made of for example, fibreglass and has an inlet Wl for introduction of water. An inner cartridge IC is disposed within shell OS. The reactor is kept suspended 1 foot below the water level on a float. Fig. 2 illustrates the inner cartridge IC made of a plastic, such as perspex Inner cartridges IC has an air lift pump L P. When airlift pump LP is operated water enters the reactor through holes PI on top wall TP of the shell and passes through the cartridge IC and comes out through the central pipe or air lift pump LP. The frame work of the inner catridge IC is made in such a way that larvae, plankton and food particles when entering the reactor passes out through air lift pump LP without mutilation and damage. The reactor has holes P: through which the string bead SB with the oxidizer immobilized thereon passes and as shown.
Ex-situ packed bed bioreactor (PBBR).
The reactor of Fig 3 is made of fibre glass shell SH mounted on a base SB of for example 30 cm 2 and an overall height of 45cm. The base plate SB is perforated and has, for example, 9 PVC pipes LP .of 2cm diameter, 10cm equidistance which is placed on a PVC support PS positioned 5cm above the base. An outlet pipe OP emerges from the base of the reactor and bends upwardly. Each pipe LP mounted on the perforated plate SB functions as an air lift pump when air is passed through. Each zone surrounding the air lift pump can be designated as an aeration cell when packed with the plastic beads PB with the oxidizer immobilizer thereon selected for each consortium and positioned through holes P2 Nine such aeration cells can be operated as by way of example. The reactor is filled to the top of the airlift pump with beads suitable for the consortium used.
The ex situ PBBR may have a water storage facility and with a recirculatory system, as shown in Fig. 4. The reactor of Fig. 4 has overhead tank (A) which opens to a tank at ground level (C). From the bottom of the tank (C) an outlet pipe (D) connects to the first reactor Fl (with ammonia oxidizers). An outlet pipe from this reactor connects to the second reactor (F2) which is with nitrite oxidizers. This reactors empties into the collecting tank (K) from where it can be pumped back to the overhead tank or used for larval rearing. The reactor F1 and F2 are of standard size
and the total number of such reactors required for each hatchery depends on the volume of water used per season.
In Fig. 4 reactors F1 and F2 are placed in between the tank C and K kept at ground level. There is, therefore, gravitational flow of water from the overhead tank A to tank C and succeesively to the reactors and finally to the collecting tank K. Energy needed for the operation is only to pump water (either spent water or fresh sea water after disinfection and salinity adjustments) to the overhead tank. In case nitrification is not completed by just one circulation/passage through the system, it can be recirculated through the treatment system over and again. But this recirculation can be effectively avoided if the rate of flow of water in the system is regulated in such a way that a prolonged hydraulic retention period is provided.
Tanks A, C and K may, if required be of uniform size and made of for example fibreglass The tank C serves as aeration basin also where degradation of organics can take place provided the water is adequately aerate.
One of the important advantantages is that different types filters for the removal of participate matter and UV water disinfection gadgets may also be connected on line with the bioreactor as required without any modification of the system.
The Ex situ PBBR has for example 9 aeration cells, through each one of which air can be passed, providing immense flexibility in the overall capability of the system.
+ Thus, if the contents of NH4 -N and NCh -N in the water to be nitrified are more,
it would be just sufficient to increase the quantity of air passed through the air lift pumps. This will enhance the rate of circulation of water and increase the contact time with the nitrifiers immobilized on beads, besides, the hydraulic retention time also can be regulated by regulating the flow rate to allow more contact period.
Another advantage of the reactor is that when used for penaeid prawn can be converted very easily for non penaeids by just replacing the reactor with the immobilised AMOPCU-1 and N1OPCU-1 with the ones immobilised with AMONPCU-1 and NIONPCU-1 meant for non-penaeid syste.ns.
ACTIVATION OF T HE REACTORS
a. In situ stringed bed suspended bioreactor
The bioreactor are placed in the activation mode in an activation system. This consists of a serological water bath set at the optimum temperature of the consortium used The top lid of the reactors are removed and covered with with transparent aerosol arresters made in perspex. The reactors are filled with actoclaved sea water with the required salinity and supplemented with lOppm
NH4+ -N and NO2- -N respectively. Reactors are charged with the required units of nitrifying consortium to obtain the desired activity (the quantity of inoculum is determined based on UNA of the consortium and the minimum nitrifying potential required per reactor). The air lift pump is operated by passing air from a compressor at the rate of 1L per minute. Once in 24 hours the consumption of
NH4+ -N and NO2-N build up of NO2--N and NO2- N in both ammonia and nitrite
Oxidizing reactors respectively are determined along with adjustment of pH. In accordance with the removal, the substrates are added and the activation continued for 72 hours. By this period the nitrifying consortia will have adsorbed on to the support material.
Now the reactors are ready enough to be moved on to the filed. The reactors on reaching the site are allowed to hang on the float. The air tubing is connected to the main air supply of the hatchery and the air flow rate is regulated at the rate of 1 L per minute.
b Ex-situ packed bed reactor
The reactors (Fi and F 2) are filled with seawater in the appropriate salinity
supplemented with lOppm NH4+ -N and NO2--N. The air lift pumps are operated
and an a liquot of 20 L consortia (ammonia oxidising and nitrite oxidising respectively in the reactors Fi and F 2) are inoculated and the operation continued till the nitrification is established. Subsequently circulation of water is established by opening the valve of the overhead tank and the flow rate regulated to give sufficient hydraulic retention for attaining complete nitrification.
A processs for nitrifying water in closed system
hatcheries of penaeid and non penaeid prawn which
comprises in afirst step of treating water with an
ammonia oxidizing consortia as herein described to
convert the ammonium present in water of the hatchery
system to N02 and in a second step of nitride oxidizing
with a nitride oxidizing consortia as herein described
for converting NO2 into N03.
A process as claimed in claim 1 wherein the ammonia
oxidizing consortia for penaeid culture system is
different to that of a non-penaeid culture system as
A process as claimed in claim 1 wherein the nitride
oxidizing consortia for a penaeid culture system is
different to that of a non-penaeid culture system as
A process as claimed in claim 1 wherein the consortia is
immobilized on a support.
A process as claimed in claim 4 wherein said support
comprises plastic beads.
An apparatus for carrying the process as claimed in claim
1, nitrifying water in closed system hatcheries of penaid
and non penaeid prawns comprising a reactor having an
outer shell (OS), a base (CS) with a plurality of pipe
extending upwardly therefrom and one pipe being an air
lift pump (LP) , said inner cartridge (1C) having an
ammonia or nitrite oxidizing consortia for penaeid and
non-penaeid culture systems.
An apparatus as claimed in claim 6 wherein said reactor
comprising a plurality of strands or strings of beads the
consortia immobilized on said beads.
9. An apparatus as claimed in claim 6 wherein said inner
cartridge has plurality of spaced slits for allowing
water to flow therthrough, and a plurality of spaced
holes for said strands or strings of beads to pass
10. An apparatus as claimed 6 wherein said pipes being air
pipes, an ammonia or nitrite oxidizing consortia disposed
within said reactor, an outlet connected to said base for
discharge of the treated water.
11. An apparatus as claimed in claim 10 wherein said ammonia
or nitrite oxidizing consortia is embedded in beads,
strands or strings of said beads extending within said
12. An apparatus as claimed inclaims 10 or 11 comprising an
overhead tank (A) connected to a lower tank (C) , the
outlet (D) of said lower tank connected to a first
reactor (Fl) having an ammonia oxidizer therein, said
first reactor connected to a second reactor(F2) having a
nitrite oxidizer therein, the outlet from said second
reactor connected to a collecting tank(K) and from where
is pumped to said overhead tank.
|Indian Patent Application Number||828/DEL/2000|
|PG Journal Number||30/2010|
|Date of Filing||13-Sep-2000|
|Name of Patentee||THE SECRETARY, DEPARTMENT OF BIOTECHNOLOGY|
|Applicant Address||BLOCK-2, 7-8 FLOOR, C.G.O. COMPLEX, LODI ROAD, NEW DELHI-110003, INDIA.|
|PCT International Classification Number||CO2F 1/00|
|PCT International Application Number||N/A|
|PCT International Filing date|