The document discusses various types of water filtration systems used in aquaculture. It describes biological, physical, and chemical filtration. Biological filtration uses beneficial bacteria to break down organic waste via the nitrogen cycle. Physical filtration removes suspended solids mechanically through screens and sedimentation. Chemical filtration removes dissolved materials and fine particulates using methods like activated carbon absorption. The document provides details on common filtration equipment and processes used in recirculating aquaculture systems.

1. Submitted by:-
Sarman Vagh,
4th sem,
COF, Veraval

2.  Aquaculture is water based farming system.
 So the adequate quality & quantity of water is required.
water can get polluted by the excrete of the culture
organisms, decaying of leaves of aquatic plants and
other organic materials.
 So the filtration process is commonly required into the
pond.

3.  Filtration is the biological ,chemical and mechanical
process to separate solid particles ,fecal matters and
impurities from the water.
 There are mainly three types of filters are present .
Which are,
1. Biological filters
2. Physical filters
3. Chemical filters.

4.  Biological filtration is the use of beneficial bacteria to
eliminate organic waste compounds from a body of
water.
 It is distinguished from mechanical filtration, which is a
process whereby water is strained and suspended
material is physically removed from the water.
 The bacteria that do the work in a biological filter are
part of the "nitrogen cycle," a series of events that also
occurs in nature.
 In to the biological filtration the main aim is to remove
ammonia and convert it to nitrite and than to nitrate .

5.  Ammonia is toxic to fish in the range of 1 ppm ,
 Toxic level of this three nitrogen compounds depend on
temp ,PH , fish health ,ion concentration in to the water
and other factor.
 Ammonia is produced in pond by directly execration of fish
and by breakdown of organic compounds by the bacteria.

6.  The nitrogen cycle consists of three basic steps; 1) ammonia to nitrite, 2)
nitrite to nitrate, 3) nitrate to free nitrogen.
 Ammonia is created from two sources- fish and other animal waste, and
decaying organic debris (leaf litter, pollen, etc.) that gets into the pond.
 To complicate matters, ammonia is present in two forms - free (NH3) which
is very toxic to fish, and ionized(NH4-) which is still toxic but less so.
 The higher the pH, the greater the ratio of the more toxic free form to the
ionized form. Nitrosamines bacteria oxidize ammonia into nitrite by the
addition of oxygen, and nitrobacter bacteria oxidize nitrite into nitrate.
 These two types of bacteria are referredto as "nitrifying bacteria," and live
on surfaces in the pond, such as plant stems, rocks and even on the fish
themselves. They require oxygen in order to live and to perform their
function.

8.  Nitrate is eliminated by "denitrifying bacteria" that live in
the bottom mud. These mud dwellers are anaerobic
bacteria that die in the presence of oxygen, and, as they
do their work converting nitrate to free nitrogen, also
release hydrogen sulfide and methane gases - the
swamp smell.

9.  It can be simply categorized as down flow or upper flow
, simple down flow submerged filter was the earliest
filter type used for aquaculture purpose and is still use
to some degree today.
 Basically the filter consist of a vessel filled with a media
upon which nitrifying bacteria grow.
 Rock is the most common type of a media used in
submerged filter . Lime stone rock is popular since it
provides buffering against rapid PH change

10.  .

11.  Trickling filter basically function the same as submerged
filter except that media is not submerged , the culture
water trickles down ward through the media and keeps
the bacteria moist but never completely submerged.
 The media is expensive in terms of volume , sand is not
recommended for use in the trickling filter .

12.  .

13.  In fluidized bed reactor the media is content in a vertical
vessel with a cylindrical or square shape.
 A layer of cores gravel is normally used to support the
sand. A perforated plate is used to support the gravel
and evenly distribute the in coming water to limit short
circulating.
 Fluidized bed reactor are recommended for ammonia
removal only since they do not have the capability to
trap solids. The reactor have much higher capacity for
ammonia and nitrate removal then most other filter
types

15.  Solid can be removed from aquaculture waste water
using physical filter ,
1. Screen :- screening is the simplest and oldest water
treatment process . It is often used as a pretreatment
process before primary treatment.
 screens are placed across path of the waste stream
and trap a broad range of micro and macro solids ,
screens are constructed from a variety of materials
include carbon , steel , brass , stainless steel . Screen
either static or rotary.

16.  Sedimentation :- waste water in recirculating systems
first treated by simple sedimentation , it is the process
by which suspended and settable matter are separated
waste water by gravity setting.
 Four zones are there in sedimentation system ,
1) Inlet zone
2) Setting zone
3) Sludge zone
4) Outlet zone

17.  Setting of externally find suspended and dissolved
solids can often be enhanced with the addition of
polymer or other chemicals .
 The mostly chemicals used are aluminum sulphate ,
ferric and ferrous chloride , ferric and ferrous sulphate ,
activated silica .

18.  Centrifuges increase the gravitational force practical
with a spinning motion , causing increased setting rates.
 Centrifuges are available in batch and continues flow
units but only the continues flow models significantly
application in aquaculture .
 Hydroclones are separates are conical shaped structure
in which particle to move outward to wall of unit and
downward .

20.  Cartidge filter are usually placed the directly in line and
should be located downstream from pump since
considerable back pressure is developed .
 They function must like oil filtration in automobiles .

21.  chemical filters are used primarily for removal of
dissolved materials or very fine particulates .
 Activated carbon :- it is used to remove volatile organics
, colours , odor, turbidity, from waster water , however
they also remove certain essential trace elements .
 To most common sizes are powdered activated carbon
(PAC), granular activated carbon (GAC)

22.  It is a process that removes dissolved organic carbon
(DOC) and particulates organic carbon ((POC) from fish
culture water by absorbing then in to the surface of air
bubbles by raising in a closed content column .
 The bubble create a foam at the top of the liquid column
and accumulated organic waste are thus discarded
along with the foam produced .

24.  RAS can be define as an aquaculture system that in
corporates the treatment and reuse of water with less
then 10% of total water volume replaced per day.
 solid removal mechanisms is available for operation in
RAS in relation to partial size ,
1. Settable solids control
2. Suspended solids control
3. floatable and dissolved solids control