Sewerage
Treatment Systems for Single & Multiple Dwellings
1. Health & Safety
Right
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General
In accordance with the “Safety, Health & Welfare at Work
Act, 1989”, E.P.S. Pumping & Treatment
Systems wish to draw your attention to the following:
All sections of this manual should be read before working on the
equipment.
Installation should be carried out by suitably trained and competent
personnel.
Normal safety precautions should be taken at all times as well as
the appropriate procedures to avoid
the occurrence of accidents.
Health
The potential for contact with raw sewage is present when installing
or maintaining wastewater treatment
plants. Therefore, it is important that the correct protective clothing
is worn when either
installing or maintaining a wastewater treatment system.
Vaccinations are advisable for site personnel for the following:
Hepatitis A
Hepatitis B
Polio
Tetanus
Typhoid/Cholera
Safety
Sewage gases are potentially explosive and toxic, so it is important
to take precaution in this regard.
Do not enter any of the below ground compartments of the BisonTM
system once sewage has entered
it.
Should entry become necessary ensure the use of adequate gas detection
equipment and breathing
apparatus.
Before carrying out any maintenance work, the equipment must be
electrically isolated.
Do not leave covers open for any longer than necessary. Temporary
barriers and warning signs should
be erected around any open covers or manholes as appropriate.
It is essential that any excavation must be such that it allows
for the easy placement of the BisonTM
system and to allow pipe connections, levelling backfilling as per
the “Safety, Health & Welfare at
Work Act, 1989”.
_________________________________________
2. Plant Description
The E.P.S. Bison Sewage treatment system uses an extended aeration
process, which
incorporates longer retention times than the conventional activated
sludge process and
does not need to be preceded by primary settlement. This reduces
the need for periodic
desludging of any primary settlement tank.
Sewage flows from the home into the inlet section of the system
where is mixes with the
activated zone within the system. It is here that treatment takes
place and from where the
solid matter settles to the bottom for digestion and breakdown.
Power is required to
operate an air blower which aerates the contents of the tank. With
the addition of an air
supply and simple hydraulics, a continuous recirculation is achieved
within the system so
as to ensure continued treatment of the incoming sewage. At the
same time treated
effluent migrates upwards and exits the system at the outlet weir
for disposal to a
percolation area.
By its nature, an aerated system does not generate the conditions
that one normally
associates with a septic tank, ie. obnoxious smells or production
of hazardous gases, etc.
_________________________________________
3. Delivery
Off-Loading
The purchaser is responsible for off-loading at the nearest roadway
to the site, which is suitable for heavy
goods vehicles. If there are any electrical cables overhead ensure
that there is adequate clearance.
Payment
E.P.S. require payment in full for the system on the day of delivery,
unless other credit terms have been
agreed.
Scope of Supply
E.P.S. will deliver 1 No. complete BisonTM system to the site complete
with temporary cover.
Once the system is installed and has been connected to the sewers
and power is available to the unit, E.P.S.
should be contacted to commission the system.
We require one weeks notice for this.
At this stage the compressor will be installed, wired and commissioned
by E.P.S. personnel.
_________________________________________
4. Installation Instructions
Introduction
At all stages during installation the requirements
of the “Safety, Health & Welfare at Work Act, 1989”
should be adhered to.
Only competent responsible personnel should be involved in the installation.
All equipment used should be in good working order.
The BisonTM system should be installed in the ground as per the
procedures outlined.
Note:
Installing in an excavation that allows water to enter (ie not dry)
requires special advice. High water
table or flood conditions will cause problems during installation.
They may also affect the desluding
of the plant; again specialist advice must be taken in these conditions.
Backfill around tank with 20N
concrete to within 200mm of ground level.
The BisonTM is installed at the required level so as to connect
to the sewer discharge from the
dwelling. Where appropriate, the neck of the top section may be
trimmed to suit ground topography at
the commissioning stage.
Care should be taken to ensure that no large stones, etc are allowed
into the excavation during backfilling.
The base of the excavation should be adequately filled with stone
and sand and adequately compacted
so as to ensure that no lagging or subsidence occurs once the unit
is in operation.
A concrete flagstone may also be used at the base where appropriate
(450mm x 450mm x 35mm).
Installation Procedure
Step 1 Excavate a 2,200mm2 hole, 1,690mm below the
invert of the sewer discharge from the
dwelling.
Step 2 The base of the excavated hole must be firm,
undisturbed soil. Place some sand and stone and
compact well to ensure a firm bedding for the system.
Step 3 Lift the system into the hole utilising the
lifting bolts provided.
Ensure that the tank is empty when lifting at all times.
Step 4 Check that the sewer connections are aligned
correctly and that the tank is sitting properly in
the hole.
Make the connections and level the tank utilising
the marked neck as provided.
Step 5 Once satisfied that the tank is level, etc,
backfill to a depth of 750mm with the appropriate
backfill. At this stage the tank should have stabilised. Recheck
that it is still level, if not relevel the tank.
Step 6 At this stage start filling the tank with water up to the
outlet weir provided. At the same time
continue to backfill the excavation up to ground level with the
appropriate backfill.
Step 7 Leave the tank full of water to the TWL, ie. at the outlet
weir.
Replace the top cover on the tank and leave 2m of cable spare at
the neck of the unit for
commissioning the system at a later stage.
Notes:
1. Ensure that adequate ventilation as per regulations
is provided.
2. For BisonTM 10, BisonTM 15, BisonTM 20, check Appendix 1 for
excavation dimensions.
Installation hints.
Installation of The BisonTM should be carried out as per The BisonTM
Installation manual.
_________________________________________
Use concrete encasement below anti-flotation ring
where applicable.
_________________________________________
Use granular self-compacting material as backfill.
Avoid sharp / large stones in backfill.
_________________________________________
Ensure base is adequately compacted with stone /
sand to avoid subsidence.
_________________________________________
Ensure the system is levelled accurately to enable
continued operation of the system.
_________________________________________
Carry out all excavation, pipe connection, levelling
and backfilling as per Safety, Health & Welfare at Work Act,
1989.
_________________________________________
5. Commissioning
E.P.S. personnel will install the compressor housing complete with
compressor and safety cover at the
commissioning stage.
E.P.S. require one weeks notice to commission a unit when ready.
It is important that the following is provided for, before commissioning
can take place.
1. Unit installed correctly, and as per E.P.S. procedures as outlined
2. Unit is full of water to the required level
3. Power supply available to the unit.
4. For pumped systems please provide 11/4” hydradare piping
from Treatment Unit to proposed
raised bed area.
_________________________________________
6. De – Sludging
Bacteria and other micro-organisms present in the wastewater utilise
the soluble organic material as a
food source, converting it into a non-soluable mass. This nonsoluable
mass or floc is compromised of
living micro-organisms, sewage particles, as well as inert (non-biodegradable)
material. As the process
matures, the numbers of micro-organisms increase until there is
an adequate biomass to metabolise or
digest all of the soluable organic material in the incoming sewage.
At this point, competition for food
results in the dying (due to the starvation) of organisms as new
organisms are formed. These dying
organisms in turn are metabolised, thereby reducing the overall
sludge volume.
The volume of solids will gradually increase due to the accumulation
of the inert remains of dead organisms
(ash), combined with the non-degradable material in the raw wastewater.
As the solids increase, the
mixed liquor (i.e. contents of the aeration chamber) becomes thicker,
developing an increasing dexter
brown colour. Periodically, the excess solids must be de-sludged
(wasted) from the system in order to
ensure continued plant efficiency.
De-Sludging Frequency
The rate at which the solids (biomass) accumulates in the system,
and the subsequent rate at which the
excess solids must be removed, is dependant upon the total volume
and strength (ie BOD) of the wastewater
entering the plant. The typical residential system will need to
be de — sludged every 2—3 years.
Determining De-Sludging Frequency
In order to ensure optimum treatment efficiency and
effluent quality, it is necessary to maintain the level
of aeration solids (MLSS) within a suitable range (refer to Operational
Control Chart). A low level of
solids in the aeration chamber (i.e. during plant start-up) reduces
the treatment plant's ability to provide
adequate treatment during peak operating periods. Excessive solids,
on the other hand, may result in
poor settling during periods of hydraulic surges; or, in the development
of septic conditions in the plant.
In order to determine when the system should be de-sludged it is
necessary to perform a solid settlement
test (30 minute) during each semi-annual service check.
Procedure
1. Mark a large transparent jar into l0 equal portions.
2. While the compressor is running fill the jar with the liquid
(MLSS) from the aeration chamber.
This sample should be collected at mid depth in the tank Do not
collect sample from within the draft
tube.
3. Allow the sample to sit for 30 minutes. If the sample settles,
slowly allow it to sit for 24 hours in
order to ensure complete settling.
4. Measure the volume of the settled sludge as a percentage of the
total volume of the sample.
Occasionally, after the sample sits, a portion of the settled sludge
may float to the top of the sample.
If this occurs, add together the volume of settled sludge and the
volume of floating sludge.
5. Compare the percent of settled sludge (i.e. sludge volume) to
the figures given in the
"Operational Control Chart". The optimum level of solid
settlement is normally between 5-50%.
Whenever the sludge volume exceeds 50%, the plant should be de-sludged.
Procedure for De-Sludging
1. Remove 30" access cover.
2. Remove the compressor box and place to one side. Open the threaded
union on the air delivery
line at the same time remove the air delivery line and diffuser.
3. Carefully lower the tanker hose into the inner (aeration) chamber
Slide the hose down the wall
of the inner tank until it rests on the bottom of the outer tank
(clarifier).
Do not insert the hose down the draft tube since this will damage
the diffuser and airline.
4. Pump solids from the bottom of the outer tank. This will lower
the liquid level in both the inner
tank and outer tank simultaneously.
5. As the liquid level drops, the scum layer between the inner tank
and scum baffle will normally
break loose and drop to the bottom of the tank where it can be sucked
out. With a garden hose,
flush any remaining scum or residue to the bottom of the tank.
6. Unless the plant is septic or there is an excessive scum build-up,
it is not necessary to pump the
system totally dry. Leaving a small amount of sludge in the bottom
(5-10 gallons) will reduce the
normal start — up period.
7. In areas with a high water table. immediately re-fill the tank
with clear water to prevent shifting
or flotation.
Sludge Characteristics
It is important to observe the MLSS (mixed liquor suspended solids)
sample which is collected from the
aeration chamber. As the sample settles you should note the following:
1. What is the colour of the sludge?
2. Do the sludge particles clump together in a dense floc, that
settles rapidly?
3. Is the liquid above the settled sludge (supernatant) clear?
4. Does the sample have a noticeable odour?
A good healthy sludge should have a chocolate brown colour. It should
form a dense floc that settles
rapidly leaving a clear, odourless supernatant. A sludge sample
that has a grey I black colour, settles
slowly, has a cloudy supernatant containing very fine, suspended
particles, usually indicates poor treatment
plant operation. Therefore, it is important to compare your observations
of the plant as well as the
sample of mixed liquor suspended solids to the conditions described
on the "Operational Control Chart"
to determine if the plant is operating properly or if any corrective
action needs to be taken.
_________________________________________
7. Maintenance
The operation of the treatment plant is the responsibility of the
owner and also for ensuring the continued
quality of effluent does not breach the discharge standards required.
The maintenance of any percolation areas, soakways, drains and the
desludging of the system remain the
responsibility of the owner.
To ensure that the system operates efficiently, it should be operated
as per E.P.S. instructions and should
be maintained as per E.P.S. Guidelines.
E.P.S. offer a maintenance contract on a yearly basis which will
ensure continued efficient operation of
the system.
This should be availed of, however, this maintenance contract does
not transfer the responsibility of
general maintenance from the owner to E.P.S. General maintenance
is to be carried out by the owner of
the system.
Maintenance Schedule
Weekly
1. Check that the air pump is operational, where an alarm system
is fitted, any malfunctions will be
detected immediately.
6 Monthly
1. Ensure that there is no build-up of debris at the entrance or
exit to the system.
2. Check the quality of the final effluent for a visual assessment
at the outlet manhole.
Yearly
1. Contact E.P.S. to carry out a full service on the system. This
will ensure the continued long term
operation of the system.
2. Desludge the system when required either after 2 to 3 years operation
dependent on loadings to plant.
_________________________________________
8. Appendix I
Model |
Dimensions |
Approximate
Backfill |
|
A |
B |
C |
D |
BisonTM 5 |
1.85m |
1.69m |
1.59m |
2.26m |
1.5m3 |
BisonTM 10 |
2.31m |
2.02m |
1.92m |
3.38m |
2.0m3 |
BisonTM 15 |
2.31m |
2.02m |
1.92m |
3.38m |
2.0m3 |
BisonTM 20 |
2.31m |
2.02m |
1.92m |
3.38m |
2.0m3 |
A. Outside Diameter
B. Inlet Invert from Base of Tank
C. Outlet Invert form Base of Tank
D. Final Grade from Bottom of Excavation
_________________________________________
Operation Control Chart
| Problem/Condition Observed |
Possible Cause |
Corrective Action |
1. Aeration Chamber (Inner Tank)
a. Compressor is running but little or no turbulence is observed
in aeration chamber.
Aeration contents have greyish (dishwater) appearance.
Noticeable odour. Poor effluent quality.
|
1. Insufficient air supply due to compressor
failure. Check with air gauge.
2. Blocked diffuser
3. Loose connection on air line. Leakage of air at these location
is reducing air to plant.
4. Damaged air line. |
1. Verify operation
of air pump.
2. Disconnect union on airline and remove lower airline with
diffuser. Clean or replace diffuser.
3. Check and tighten all airline connections, including union
and connections at the compressor and tank.
4. Expose airline and replace damaged or crushed sections. |
b. Aeration chamber contents has a greyish
brown to black appearance. Slight to strong
septic odour observed. Compressor is running
and good turbulence is noted. Poor quality
effluent has a grey colour.
|
1. Heavy hydraulic surge flows due to excessive water discharges
from laundry or kitchen activities. Generally this problem
observed only on commercial applications. Residential systems
will usually be characterised by light or sporadic usage comprised
mostly of laundry.
|
1. For commercial applications,
provide (surge) tank to eliminate surge flows. Residential
systems may improve operation by reducing frequency of laundry
to 1-2 loads per day. |
c. Aeration chamber has a clear appearance
with very few solids (MLSS<5%). Effluent is clear, no odour.
White suds observed in aeration chamber. |
1. Light loading to BISON resulting in complete oxidation
(digestion) of solids in plant.
|
1. No action required if effluent is clear. Typical of intermittent
use.
|
d. Aeration chamber has the same appearance
as in c (above). <5% solids with very fine suspended particles
in supernatant. |
1. Excessive aeration due to light loading of plant. Turbidity
in effluent due to “ash”. |
1. Reduce air by providing timer on compressor. Better setting
should result on clear effluent.
1. Seed plant with 100gal. of fresh
activated sludge to help initiate startup.
2. Spread out laundry and limit to
2-3 loads/day. Once the plant
achieves normaloperation, the
laundry usage may be increased
somewhat. Extreme condition (or
commercial application) may require
flow equalisation.
|
e. Aeration chamber has greyish appearance with a slightly
septic odour. System has been in use for less than 6 months. |
1. Slow start-up due to low loadings.
2. Excessive surge flows (grey water) due to heavy laundry
activities. |
1. Eliminate discharge of food scrap,
grease, oil etc.. into garbage disposal. |
f. Aeration chamber has a grey, dishwater appearance. Effluent
has a grey septic odour. Accumulation of grease balls are
observed.
|
1. Organic overload due to excessive use of garbage disposal.
2. Excessive laundry usage.
3. Insufficient air being supplied
|
2. Check air pressure at compressor.
If appropriate for specific model,
check dissolved oxygen (DO) in aeration
tank. Shut off compressor 10-
15 minutes before test. If DO is less
than 1.0 ppm during peak usage period,
contact EPS Ltd for assistance.
|
2. Clarifier (Settling Chamber)
a. (Start-up) Effluent is slightly turbid or cloudy. Slight
odour detected. Plant is in the first 3 months of operation.
Excessive
amount of white suds in aeration chamber. |
1. Normal start-up period 6-8 weeks is required to attain
sufficient numbers of bacteria. During this period treatment
efficiency may not be at its highest, especially during periods
of hydraulic surge loading, (i.e. laundry periods).
2. Septic tank is installed prior to the
BISON. The problem is usually apparent when the daily flow
is light or when excessive laundry usage occurs. |
1. No major action is required.
Reducing the frequency of laundry
will help. Re-check plant in 4-6
months unless other problems
develop sooner.
2. Reduce frequency of laundry until
plant achieves normal operation (6-8
weeks). Seeding the BISON with
100gal. of fresh activated sludge will
reduce start-up period. Extreme cases
may require the removal of septic
tank if it proceeds the BISON unit. |
b. Effluent has very fine suspended particles which settle
slowly leaving a
clear supernatant.
c. Effluent contains brown suspended solids. Condition is more
noticeable during periods of heavy water usage.
System has not been de-sludged in 2-3 years. Settable solids
test indicates sludge
volume >50%.
d. Excessive (>5inches) of scum has accumulated in 6-12 months
of use.
Grease balls may be observed in aeration chamber. System requires
De-sludging on a frequent basis.
e. Excessive solids carry over with effluent. Aeration chamber
has normal colour but sludge (MLSS) settles slowly, forming
a light floc. |
1. Over aeration.
1. Heavy build-up of MLSS (mixed
liquor suspended solids) due to normal, long term usage.
1. Over use (or abuse) of garbage
disposal.
2. Excessive use of powdered laundry
detergent.
1. Overabundance of “Fillementous”
micro-organisms that prevent compaction
and settling of sludge. The
presence of these organisms should be
eliminated. |
1. Refer to 1 d
1. De-sludge BISON Unit. Refer to
“Maintenance Procedures:
De-sludging
(wasting) sludge”.
1. Discontinue dumping grease, food
scraps, etc.. into the disposal. This
material should be put in dustbin.
2. Use liquid detergent or the concentrated powders.
1. Contact EPS Ltd for specific recommendations. |
CLICK
HERE TO VIEW DIADRAM ALL WORK OTHER THAN COMISSIONING TREATMENT
UNIT DONE BY OTHERS
1. Model Specifications
2. Dimensions
3. Safety Instructions
4. Installation (Septic Tank Application)
5. Maintenance (Refer to Sketches
below)
4. Recommended Maintenance Parts
Selecting BISON
WHAT'S INVOLVED?
The Bison sewage treatment system for single dwellings is a simple
system to install, operate and
maintain while also being versatile, robust and durable.
The system is manufactured in Ireland by E.P.S. Pumping & Treatment
Systems. The company has over
30 years experience in providing and maintaining pumping and treatment
systems in Ireland, the U.K.
and other parts of the World. It is with this experience and continued
involvement in the Industry that
we are providing an advanced, environmentally friendly, cost effective
product for our customers.
HOW DOES IT WORK?
The E.P.S. Bison sewage treatment system uses an extended aeration
process, which incorporates
longer retention times than the conventional activated sludge process
and does not need to be
preceded by primary settlement. This reduces the need for periodic
desludging of any primary
settlement tank.
Sewage flows from the home into the inlet section of the system
where it mixes with the activated
zone within the system. It is here that treatment takes place and
from where the solid matter
settles to the bottom for digestion and breakdown. Power is required
to operate an air blower
which aerates the contents of the tank. With the addition of an
air supply and simple hydraulics,
a continuous recirculation is achieved within the system so as to
ensure continued treatment of the
incoming sewage. At the same time treated effluent migrates upwards
and exits the system at the
outlet weir for disposal to a percolation area.
By its nature, an aerated system does not generate the conditions
that one normally associates
with a septic tank, i.e. obnoxious smells or production of hazardous
gases, etc.
Population Equivalent: 6
Treatment Principle: Extended Aeration
| Final Effluent Standard: |
20mg / L BOD
30mg / L SS
(Prior to Percolation) |
| Outside Diameter |
1.85mtrs |
| Capacity Holding |
2,271L |
| Height from Base to Inlet |
1.69mtrs |
| Capacity Treated |
1,893L |
| Height from Base to Outlet |
1.59mtrs |
| Maximum Organic Load |
360g BOD/day |
| Weight Empty |
120kg |
| Maximum Daily Flow |
1,200L |
| Power Consumption |
86Watt |
* Peak flow must not exceed three times average flow
rate for a period of more than half an hour
in every two hour period.
Installation hints.
Installation of The BisonTM should be carried out as per The BisonTM
Installation manual.
_________________________________________
Use concrete encasement below anti-flotation ring
where applicable.
_________________________________________
Use granular self-compacting material as backfill.
Avoid sharp / large stones in backfill.
_________________________________________
Ensure base is adequately compacted with stone /
sand to avoid subsidence.
_________________________________________
Ensure the system is levelled accurately to enable
continued operation of the system.
_________________________________________
Carry out all excavation, pipe connection, levelling
and backfilling as per Safety, Health & Welfare at Work Act,
1989.
PERCOLATION AREA
Following treatment final effluent is passed through a percolation
area to further treat and polish
the effluent prior to discharge to groundwaters.
This polishing system can be sized by E.P.S. provided the relevant
site/ground type data is supplied.
The system does however need to be installed as per EPA Guidelines.
| Feature |
Recommended
Separation Distance (m)
Bison System Percolation
Area |
| Dwelling
served |
7(1) |
5-10 |
| Adjacent
dwelling |
7(1) |
5-10 |
| Walls |
3(1) |
3 |
| Roads |
3(1) |
3 |
| Site
Boundaries |
3(1) |
3 |
| Drinking
Water Sources |
10 |
10-100(2) |
| Water
Course |
10 |
10 |
(1) The depth of the excavation to accommodate the
treatment system must be taken into
consideration when determining this distance as it will be governed
by the invert depth of the
soil pipe where it reaches the treatment system. The separation
distance should be such that
the excavation does not undermine adjacent buildings, roads or walls.
This distance should not
be less than 1.5 times the depth of the excavation.
(2) This separation distance should not be less than 10m except
in the case of very free draining
soils or gravels, where a minimum distance of 40m should be maintained.
The disposal area
should be “down gradient” of any nearby well. Where
it is not possible to locate the disposal
area “down gradient” of any well, including those on
neighbouring properties, an appropriate
separation distance must be maintained ie 100 metres.
MAINTENANCE AND CONTINUAL OPERATION
The Bison system has been designed to minimise the
amount of maintenance required. There are no
internal moving parts to give trouble at any stage after installation.
All of our units come with a 24 month warranty on parts, following the date of commissioning.
For increased efficiency E.P.S. recommend the use of phosphate free
detergents in the household
and grease or fat should not be allowed to enter the plant.
MAINTENANCE CONTRACT
E.P.S. offer full maintenance contracts for all our units which
comprise the following:
- One visit annually to inspect and service the system.
- Repair or replace any equipment as per E.P.S. Bison system warranty
conditions.
- Provision of full service record to customer.
Right
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