Mechanical/Primary
Treatment Phase
The mechanical/primary treatment phase includes:
The
wastewater lifting pump set consists of two pumps, one operational
and one standby. The capacity of each pump is adopted based
on peak flow (2.5).
The
automatic screen is installed at the inlet of the grit chamber
and after the feed pumps.The construction material used
is cast iron; sand blasted SA 2.5 and protected with zinc
epoxy thickness 45 microns and coal tar epoxy thickness
.079 in. (2mm) x 6 in. (150 mm).The size of the opening
between the bars is 1/2 in. (12 mm). Operation of the screen
is automatic and on a 24 hour timer. The operation time
may be changed via a PLC integrated in the main control
panel.
The
grit removal chamber is a vortex type made of HDPE, capable
of handling the peak flow of the system.
Removal
rate is as follows:
-
0.012 in (0.30 mm) [mesh 50] %+95
-
0.009
in (0.24 mm) [mesh 70] %+85
-
0.006
in (0.15 mm) [mesh 100] %+65
Figure
2. Primary Treatment; Screen and Grit removal chamber.
Biological/Secondary
Treatment Phase (Patented)
The
biological/secondary treatment phase is shown in Fig 3 below.
Figure
3. BioShaft Secondary (Biological) Treatment
Unlike
the BioShaft System, conventional suspended growth process
systems require large aeration and sedimentation volumes.
With the BioShaft System, these volumes can be reduced significantly
with the use of a BioShaft Unit (vertical reactor) and biomass
carriers which have a high specific surface area.
Figure
4. BioShaft Unit Technology: The BioShaft Unit enables
the balance tank to operate at high biomass content rates
significantly higher than conventional activated sludge systems.
The
application of a large number of biomass carriers instead
of sedimentation by surface aeration has an exceedingly positive
effect on the efficiency and size of the required equipment,
enabling the balance tank to be operated at high biomass content
.93-1.87 lb/ft3 (15-30Kg/m3) compared to the conventional
aeration process sludge content .16-.19 lb/ft3 (2.5-3 Kg/m3).
Aeration is provided using highly efficient membrane diffusers
resulting in much higher oxygen transfer per unit volume.
This allows a purification degree up to 97 percent.
The
balance tank receives the flow after the screen, half of the
balance tank is aerated to ensure that the biomass is properly
oxygenated and the other half acts as a buffer area. The balance
tank is constructed from glass fused steel sheets or any other
approved material and is equipped with the aeration system
which is comprised of two types of fine bubble diffusers membranes;
vertical and disc type. The membrane material is ethylene/propylene
rubber compound (EPDM). The proposed membranes are highly
resistant against wastewater, ozone, weathering, aging, heat
and most chemicals. The proposed IFU membranes feature the
following characteristics:
The
proposed IFU membranes feature the following characteristics:
-
Endure
a wide variety of wastewater compositions;
-
Resistant
against acids and alkalis;
-
Have
great elasticity, lasting for many years;
-
Withstand
temperature up to 300 degrees F (150 degrees C);
-
Fine
bubble diffuser 0.039-0.157 in. bubble size (1 –
4 mm bubble size)
The
buffered wastewater flows from the balancing tank towards
the BioShaft units. Please see Figure 5.
Figure
5. Flow of the BioShaft System
The
wastewater enters the BioShaft unit where it flows through
the biological aeration filter chamber containing the hollow
plastic media (biomass carriers). See Figure 6. The unique
design of the biomass carrier results in anoxic decomposition,
which takes place on the inner surface (hollow area), while
on the outside of the carrier’s corrugated surface, the
process is aerobic. This ensures a very high level of sewage
purification at great speed.
Figure 6. BioShaft Unit Cross Section
The
oxygen demand for the decomposition process is provided by
the central air lift aerator shown in Figure 7. The air is
supplied by a compressor and is dispersed by a special maintenance
free membrane diffuser providing an enormous number of micro
bubbles which saturate the sewage with oxygen and simultaneously
force the sewage up to the surface.
Figure
7. Top of BioShaft Unit This
oxygen-rich fluid then passes back down through the aeration
chamber in intimate contact with the carriers. Because the
biomass carriers (See Figure 8) have a relative density less
than unity they will always try to rise towards the surface,
but are constantly forced downward under the pressure of the
aerated sewage. These two forces ensure that there is constant
upward and downward motion of the carriers within the aeration
chamber.
 
Figure 8. Biomass Carrier – 1 in (2.54cm) diameter
Collision
between the carriers occurs, removing the excess microbial
biomass by means of the down current. This self-cleaning feature
will protects the biological filter against any possible clogging
and makes the unit virtually maintenance-free.
Treated
water flows to the final sedimentation compartment in the
BioShaft unit where suspended particles sink down to the bottom
of the tank. This active biomass is then transferred back
to the balance tank at periodic intervals by the airlift system
which eliminates the need for sludge pumps. Purified water
rises up the outer compartment of the BioShaft unit to the
outlet and flows to the settlement tank and polishing before
discharge. Any remaining biomass settles to the bottom of
the settlement tank and will be periodically airlifted back
to the balance tank.
The BioShaft treatment technology has a particular and vital
advantage over more traditional processes as the matter in
the BioShaft Unit is converted into a highly active biomass
which is rich in oxygen. As described above, the biomass in
both the BioShaft unit and the settlement tank has a noted
tendency to settle, unlike activated sludge which normally
floats on the surface. This active, oxygen rich, biomass containing
large numbers of highly active bacteria from both the BioShaft
unit and the settlement tank is air lifted back to the balance
tank where it will initiate the decomposition process. The
recycling of the biomass in the process leads to the digestion
of sludge in the waste water. Since sewage has only a 2 to
4% solid content, the quantities of accrued insoluble solids
(sludge) will be minimal; hence the balance tank will require
emptying much less frequently than a balance tank of a conventional
plant.
Odors
are eliminated due to the absorption of large quantities of
oxygen in the system which converts odorous gases into dissolved
chemicals.
The
BioShaft unit is designed and constructed based on
the following codes and
standards:
| Parameter |
Detail
|
Remarks |
| Design
Code |
BS
4994: 1987: Cat 1 |
|
| HDPE
|
DIN
8075 |
Shell material
|
| Pressure |
Atmospheric
|
Operating |
| Pressure |
Atmospheric
|
Design |
| Inspection
& Test |
BS
4994:1987 |
Manufacturer’s
QC
ISO 9001 Design &
Build Certificate No. FM 81587 |
| Nozzles |
PN
16 to BS 4504 |
6
in (150 mm) |
Tertiary
Treatment Phase
Final
treatment of the effluent is handled through polishing filters,
and finally disinfected via chlorination units or UV sanitizers
to complete the process.
Figure
8. Filtration
Figure 9. Chlorination
Sludge (inert biomass) Treatment:
The
patented BioShaft system's attached growth process results
in the virtual elimination of sludge and the associated sludge
components found in conventional active sludge waste water
treatment systems (i.e. sludge drying beds, collection and
disposal). However, for larger capacity designs greater than
2.64 MGD (10,000m3/day), a biomass collecting tank will be
furnished to collect the inert biomass that may be infrequently
collected at the bottom of the balance tank.
(760)
901-5404 • 5927 Balfour Court, Suite 201 Carlsbad, CA
92008
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