Beit Qad Commercial Aquaponic system Technical Manual

19 Pages·2013·3.09 MB·English

Beit
 Qad
 Commercial
 Aquaponic
 system

Technical
 Manual

Philip
 Jones

April
 2013

  1

Beit
 Qad
 Commerical
 Aquaponic
 System

Technical
 Manual

By
 Philip
 Jones

©
 Byspokes
 and
 Ma’an
 Development
 Centre,
 2013

All
 text,
 illustrations
 and
 photos
 by
 Philip
 Jones.

www.byspokes.org

[email protected]
Table
 of
 contents

SYSTEM
 OVERVIEW
  1

SYSTEM
 COMPONENTS
  2

Fish
 tanks
  2

Solids
 filtration
  3

Biological
 filtration
  4

Mineralisation
  6

Hydroponic
 component
  7

Seedling
 production
  8

Pumping
 and
 aeration
  8

MANAGEMENT
  10

Cycling
  10

Aquaculture
 system
  10

Hydroponic
 system
  11

Water
 quality
  12

SYSTEM
 OPERATION
  13

Daily
 tasks
  13

Weekly
 tasks
  13

Monthly
 tasks
  13

TROUBLESHOOTING
  14

DIRECTORY
  15
System
 overview

The
 commercial
 aquaponic
 system
 designed
 for
 the
 Beit
 Qad
 demonstration
 site

consist
 of
 two
 interlinked
 components;
 a
 recirculating
 aquaculture
 system
 (RAS)

and
 a
 hydroponic
 system.
 The
 two
 systems
 are
 linked
 by
 a
 double
 sump
 tank

which
 has
 been
 designed
 to
 allow
 for
 the
 RAS
 and
 hydroponic
 components
 to
 be

operated
 independently
 (as
 aquaculture
 and
 hydroponic
 systems)
 or
 together

(as
 an
 aquaponic
 system).

 The
 RAS
 component
 has
 been
 designed
 to
 be
 a
 “low

head”
  system
  –
  i.e.
  with
  minimal
  vertical
  height
  difference
  between
  the

maximum
 and
 minimum
 water
 levels
 across
 the
 components.
 This
 is
 to
 reduce

the
 energy
 required
 for
 pumping
 water.

Figure
 1:
 Overview
 of
 the
 aquaponic
 system
 showing
 aquaculture
 component
 (left)
 and

hydroponic
 component
 (right).

When
 both
 components
 are
 operating
 together,
 then
 dissolved
 nutrients
 from

the
 aquaculture
 wastes
 are
 delivered
 to
 the
 hydroponic
 component
 to
 be
 taken

up
  by
  plants.
  During
  independent
  operation,
  nutrients
  from
  the
  aquaculture

system
  are
  not
  passed
  to
  the
  hydroponic
  system
  and
  so
  supplementary

hydroponic
 nutrients
 must
 be
 used.
 However,
 enabling
 the
 two
 systems
 to
 be

operated
 independently
 greatly
 enhances
 the
 system’s
 resilience;
 a
 problem
 in

one
 of
 the
 systems
 may
 be
 isolated
 without
 risking
 the
 other
 system.

  1
System
 components

Fish
 tanks

The
  aquaponic
  system
  consists
  of
  four
  separate
  round
  fish
  tanks
  each
  of

approximately
 2.1m3,
 thus
 the
 total
 fish
 tank
 water
 volume
 is
 around
 8.4m3.

 The

fish
 tanks
 are
 constructed
 from
 standard,
 2.5m3
 (1.46m
 diameter)
 water
 storage

tanks
 (white,
 to
 reduce
 heat
 gain
 in
 the
 summer),
 which
 have
 been
 opened
 by

cutting
 off
 the
 top,
 just
 below
 the
 shoulder
 (1cm
 above
 the
 uppermost
 moulding

line).

The
 fish
 tanks
 are
 positioned
 close
 to
 each
 other
 in
 order
 to
 be
 able
 to
 share

common
 drain
 and
 influent
 pipe
 main
 lines.
 The
 fish
 tanks
 are
 all
 levelled
 with

each
 other,
 and
 excavated
 slightly
 into
 the
 ground
 (floor
 height
 -­‐40cm)
 in
 order

to
 facilitate
 levelling
 of
 the
 other,
 shorter,
 components.

Figure
 2:
 Fish
 tanks
 being
 put
 into
 place
 (left)
 and
 detail
 of
 common
 fish-­‐tank
 drain

(right).

Effluent
 water
 is
 drawn
 from
 the
 bottom
 centre
 of
 the
 fish
 tank
 using
 a
 “solids
 lift

overflow”
 which
 sets
 the
 maximum
 water
 depth
 in
 the
 fish
 tank
 to
 135cm.
 The

overflow
 pipes
 (50mm
 diameter)
 from
 all
 the
 fish
 tanks
 extend
 outside
 the
 tanks

towards
 a
 central
 point
 between
 the
 tanks
 where
 they
 are
 united
 by
 a
 110mm

collector
 trap.
 The
 common
 drainage
 is
 by
 110mm
 pipe
 from
 this
 point.

Influent
 water
 is
 delivered
 to
 each
 fish
 tank
 at
 a
 height
 just
 above
 the
 water

surface
 level,
 at
 a
 rate
 of
 around
 3m3/h
 (to
 fully
 exchange
 fish
 tank
 water
 volume

1.4
 times
 per
 hour).
 The
 water
 is
 delivered
 parallel
 to
 the
 fish
 tank
 wall
 in
 such
 a

way
 as
 to
 set
 up
 a
 clockwise
 rotational
 current
 within
 the
 tank.
 This
 circular
 flow

facilitates
 settling
 of
 the
 solid
 wastes
 in
 the
 bottom
 centre
 of
 the
 fish
 tanks.

  2
Solids
 filtration

Coarse
 solids
 are
 removed
 from
 the
 system
 via
 a
 “radial
 flow
 separator”.
 The

radial
 flow
 separator
 works
 by
 forcing
 the
 water
 flow
 to
 change
 direction
 and

velocity,
 which
 encourages
 solid
 particles
 to
 settle
 out.
 Radial
 flow
 separators

are
  very
  space
  efficient
  when
  compared
  to
  standard,
  gravity
  based
  settling

ponds,
 and
 typically
 operate
 with
 loading
 rates
 of
 10m3/m2/hour.
 Thus,
 to
 match

the
  fish
  tank
  effluent
  flow
  rate
  of
  this
  system
  (12m3/hour),
  a
  radial
  flow

separator
 of
 1.2m2
 surface
 area
 is
 needed.

The
  radial
  flow
  separator
  is
  also
  constructed
  from
  a
  white,
  standard
  water

storage
 tank
 (1.5m3;
 1.35m
 diameter
 -­‐
 thus
 1.4m2
 water
 surface
 area)
 with
 the

top
 removed.
 The
 top
 of
 the
 water
 tank
 is
 inserted
 upside-­‐down
 into
 the
 tank
 to

make
 a
 slightly
 conical,
 funnel
 like
 false
 floor
 to
 facilitate
 collection
 of
 all
 solid

wastes
 in
 the
 centre.
 The
 tank
 is
 positioned
 such
 that
 the
 upper
 rim
 level,
 and

water
 surface
 level
 are
 the
 same
 as
 those
 of
 the
 fish
 tanks.

Figure
 3:
 Design
 of
 the
 radial
 flow
 filter,
 showing
 major
 components
 and
 internal
 layout.

  3
The
 fish
 tank
 effluent
 water
 enters
 the
 radial
 flow
 separator
 via
 a
 110mm
 pipe

which
 extends
 into
 the
 centre
 of
 the
 separator,
 where
 there
 is
 an
 upward
 facing

elbow,
  directing
  water

flow
  vertically
  upwards.

Around
  this
  elbow
  is
  a

radial
  flow
  column
  made

from
  a
  200L
  blue
  barrel,

which
  extends
  slightly

above
  the
  water
  surface

level.
  This
  forces
  the

incoming
 water
 to
 change

direction
  from
  up-­‐flowing

to
 down-­‐flowing.
 Once
 the

water
  flows
  beyond
  the

lower
  end
  of
  this
  radial

flow
  column,
  it
  changes
  Figure
 4:
 Constructed
 radial
 flow
 filter

direction
 once
 again
 and
 flows
 upwards.
 With
 each
 change
 of
 direction,
 the

velocity
 of
 the
 water
 also
 decreases,
 which
 gives
 solid
 wastes
 the
 chance
 to
 settle

to
 the
 bottom
 of
 the
 separator
 by
 gravity.

Water
 exits
 the
 radial
 flow
 separator
 via
 a
 110mm
 pipe
 positioned
 just
 below
 the

water
 surface
 level.
 Solids
 can
 be
 periodically
 drawn
 out
 from
 the
 bottom
 of
 the

separator
 via
 a
 sludge
 drain,
 made
 from
 50mm
 pipe
 drawing
 from
 just
 above
 the

bottom
 centre
 of
 the
 separator.
 Sludge
 is
 discharged
 to
 a
 mineralisation
 tank

where
 it
 can
 be
 converted
 back
 to
 liquid
 plant
 nutrients.

In
 addition
 to
 this
 coarse
 solids
 separator,
 all
 water
 passes
 through
 a
 60μm
 in-­‐
line
 filter
 before
 reaching
 the
 hydroponic
 component.

Biological
 filtration

Biological
 filtration
 (the
 conversion
 of
 toxic

ammonia
  in
  fish
  wastes
  into
  nitrite
  and

then
 nitrate)
 is
 achieved
 by
 a
 “Moving
 Bed

Biofilm
 Reactor”
 MBBR.
 MBBRs
 are
 relative

newcomers
  to
  the
  aquaculture
  industry.

MBBR
  technology
  uses
  thousands
  of

polyethylene
  biofilm
  carriers
  (Error!

Reference
 source
 not
 found.)
 operating
 in

mixed
  motion
  within
  an
  aerated

wastewater
  treatment
  basin.
  Biocarriers

provide
  a
  very
  large,
  protected
  surface,

which
 supports
 the
 growth
 of
 heterotrophic

and
 autotrophic
 bacterial
 communities.
 The

specific
  surface
  area
  (SSA)
  of
  biocarrier

media
  is
  typically
  around
  500m2/m3.

Figure
 5:
 Kaldness
 type
 biomedia

  4
However,
 MBBRs
 function
 best
 at
 fill
 rates
 below
 70%
 (usually
 40-­‐60%)
 as
 this

ensures
 adequate
 movement
 of
 filter
 media
 within
 the
 MBBR.
 Effective
 surface

area
 within
 the
 MBBR
 vessel
 is
 therefore
 200-­‐300m2/m3.
 TAN
 (total
 ammonia

nitrogen)
 removal
 rates
 fluctuate
 depending
 on
 a
 range
 of
 environmental
 factors

(pH,
 alkalinity,
 temperature,
 DO,
 BOD
 of
 influent
 water)
 but
 for
 the
 purposes
 of

this
 project
 can
 be
 assumed
 to
 be
 in
 the
 region
 of
 1g/m2/day.
 Another
 advantage

of
 the
 MBBR
 is
 that
 it
 allows
 for
 supplemental
 oxygenation
 and
 CO
 stripping
 of

2
the
 wastewater
 –
 further
 enhancing
 the
 quality
 of
 effluent.

Daily
 TAN
 production
 is
 directly
 related
 to
 the
 amount
 of
 food
 given,
 and
 the

protein
 content
 of
 the
 food,
 and
 can
 be
 calculated
 using
 the
 following
 equation:

TAN
 =
 Feed
 weight
 x
 Protein
 content
 x
 0.092

 Time

It
  is
  proposed
  to
  use
  32%
  protein
  feed,
  delivered
  at
  2%
  body
  mass
  (for
  a

standing
 crop
 of
 around
 200kg)
 in
 this
 system.
 The
 daily
 total
 feed
 is
 therefore

around
 4kg.
 This
 gives
 a
 daily
 TAN
 production
 of
 118g.
 118m2
 of
 surface
 area
 is

required
 for
 bacterial
 nitrification
 of
 this
 ammonia.
 Given
 the
 biocarrier
 SSA
 of

500m3/m2,
 then
 236l
 of
 biocarrier
 media
 will
 be
 required,
 in
 a
 vessel
 of
 787l

 (at

30%
 fill).

 The
 MBBR
 in
 this
 system
 has
 been
 purposefully
 oversized
 to
 allow
 for

future
 expansion
 of
 the
 aquaculture
 component.
 The
 MBBR
 is
 constructed
 from

two
 1m3
 IBC
 tanks,
 each
 with
 a
 maximum
 fill
 volume
 of
 800l.
 Thus,
 at
 maximum

operating
 capacity,
 and
 a
 biocarrier
 fill
 rate
 increased
 to
 60%,
 the
 MBBR
 could

denitrify
 480g
 TAN/day
 –
 equivalent
 to
 16kg
 feed.

Figure
 6:
 Completed
 MBBR
 chamber
 (left
 image)
 showing
 influent
 pipe
 (lower
 left
 of

image),
 effluent
 pipe
 (top
 of
 image)
 and
 aeration
 grid
 (at
 the
 base
 of
 the
 chamber).

Images
 on
 the
 right
 detail
 assembly
 of
 the
 aeration
 grid.

  5
Water
 enters
 and
 leaves
 the
 MBBR
 via
 110mm
 pipe.
 Aeration
 is
 provided
 via
 5

parallel
 20mm
 PVC
 pipes,
 with
 2mm
 holes
 drilled
 each
 20mm
 along
 opposing

sides,
 located
 at
 the
 bottom
 of
 each
 MBBR
 chamber.

 Water
 exits
 the
 MBBR
 via

110mm
 pipe
 to
 the
 aquaculture
 sump
 tank.

Mineralisation

Mineralisation
 is
 an
 aerobic,
 bacterial
 process
 by
 which
 the
 complex
 organic

molecules
 found
 in
 solid
 wastes
 are
 broken
 down
 into
 simple
 mineral
 ions.
 Full

mineralisation
 requires
 approximately
 28
 days
 of
 aerobic
 bacterial
 activity,
 thus

a
  mineralisation
  tank
  must
  be
  large
  enough
  to
  allow
  a
  minimum
  28-­‐day

residence
 time
 of
 discharged
 sludge.

Sludge
 from
 the
 radial
 flow
 separator
 is
 discharged
 into
 a
 mineralisation
 tank
 –

constructed
 in
 the
 same
 was
 as
 one
 of
 the
 MBBR
 chambers,
 from
 an
 IBC
 tank
 and

aeration
 grid.
 Biocarrier
 media
 is
 added
 to
 the
 mineralisation
 tank
 to
 provide

additional
 surface
 area
 for
 bacterial
 activity,
 and
 also
 to
 facilitate
 mechanical

breakdown
 of
 larger
 particles
 through
 collision
 and
 agitation.
 The
 daily
 sludge

discharge
 volume
 is
 around
 20l
 (around
 5l
 sludge
 is
 produced
 per
 1kg
 feed),
 thus

a
 minimum
 volume
 of
 560l
 is
 required
 to
 provide
 the
 requisite
 28-­‐day
 residence

time.
 The
 functional
 volume
 of
 the
 mineralisation
 tank
 is
 actually
 800l,
 and
 so

this
 requirement
 is
 exceeded
 in
 the
 current
 system
 design.

Figure
 7:
 Mineralisation
 tank
 showing
 vigorous
 aeration
 (left)
 and
 screened
 pump

chamber
 (right).

As
  fresh
  slurry
  is
  discharged
  into
  the
  mineralisation
  tank,
  the
  water
  level

increases
 slightly
 and
 the
 supernatant
 overflows
 into
 a
 mineralised
 nutrient

sump.
  The
  overflow
  is
  screened
  to
  prevent
  the
  exit
  of
  larger
  particles,
  and

effluent
 passes
 through
 a
 60μm
 filter
 before
 reaching
 the
 sump.
 The
 sump
 is

fitted
 with
 a
 float-­‐switch
 activated
 pump
 to
 deliver
 this
 nutrient
 laden
 water

directly
 to
 the
 hydroponic
 system.

  6