Detailed document No.5

5 Hydrogen sulfide in a cesspit
is reduced to zero

● Preventing hydrogen sulfide generation and cost

reduction can be achieved at the same time

Aquablaster diffusion pipe
2019.12from the brochure published■ Current state of cesspits excerpt
by the Tokyo Metropolitan Government

The number of buildings designed by considering global warming prevention
measures is increasing, and smoking is prohibited inside buildings - everyone
cooperates with each other to make our buildings and town environment better.It wasbelieved that nothing could be done to get rid of foul odors coming from a cesspit(underground holding tank), but such a problem can be solved with everyone'
cooperation.To make our town more attractive and prevent buildings fromdeteriorating as well, we would like to have your cooperation in eradicating unpleasantodors from a cesspit. Don't give up and avoid bad smells by pinching your nose!
Let's remove them from our town!

Have you ever heard of this?
According to a study conducted by theTokyo Metropolitan Government, manybuilding owners were unaware that
unpleasant odors were being generated andthat such odors were coming from theirbuildings.This is because even though anodor coming from a cesspit is a strong
offensive odor, it is generated only for ashort period of time, such as a few minutes,
and is hardly detected inside a building.

What will happen to the facility?
Hydrogen sulfide corrodes
wastewater tanks and manholes
and makes them crumble.

Let's move to a different
town that does not
smell bad!

W(in aste* M side watert
by anag he p facof the ed rem ility
isethe ows)
bu nerilding

Hydrogen sulfide is generated
When wastewater is accumulated,
the state of putrefaction advances,
generating hydrogen sulfide.

F o u lWhat causes a bad smell?
You may think that your building
has nothing to do with it.

A bad smell iscoming!

It doesn't smell bad
inside the building,but tenants are
moving out!?

We even melt reinforced
concrete!

Aquablaster diffusion pipeo d o rWhen wastewater containing hydrogensulfide is pumped up and flows into sewers,
foul odors come out from "street inlets" onsecondary roads!

Street inlets on roads

Many people feelPu(p blic
* Mublic seweby anag road rde the ed partpa se)
rtm ween rtAmong complaints made to theTokyo Metropolitan Government,
the number of complaints supposed
to derive from odors from cesspits
has become as many as several
hundred per year. Moreover, it isthought that a large number ofpeople feel bad even though they
have not yet made any complaints.

It is caused by a cesspit.
When accumulated wastewater in theunderground holding tank (cesspit) of abuilding becomes rotten, for example,hydrogen sulfide is generated. Whenwastewater containing hydrogen sulfide
is pumped up and discharged intosewers, unpleasant odors come out from"street inlets" on secondary roads!
the TokyoIf odor prevention measures are not taken in time, punishments may be applied.
- Offensive Odor Control Law Once a complaint is made, the relevant organization is required to take some measures. If appropriate measures
are not taken to prevent offensive odors at levels exceeding the control standard, the head of the relevant
municipality must issue an improvement recommendation or order, and furthermore, a punishment such as
imprisonment or a fine may be applied. Even for a settlement agreement in court, huge costs and time are
required.If measures are taken after a complaint is made as above, not only is the burden heavy in terms ofmoney and labor, but also the public image of the organization can be ruined. Do not think that things are OK aslong as no complaint is being made. To avoid the above situation, let's make daily efforts to prevent foul odors!
(Excerpt from a Ministry of the Environment brochure"Offensive Odor Control Law Guide Pamphlet (September 2006)")❶■ Cesspit putrefaction mechanism

Foul odor (hydrogen sulfide)
generation

Aquablaster diffusion pipe

Frame deterioration
Insect pest occurrence

Condensation

Condensation

H2S+O2→H2SO4 (Sulfuric acid)
H2S (Hydrogen sulfide)

SulfateHydrogen sulfide

Oil film and oil ball formation
In most cesspits, putrefaction
advances due to a lack of oxygen, andhydrogen sulfide is generated, which
eventually results in the deteriorationof concrete in frames and sewers aswell as the generation of bad odors.

❷■ Actual worksite conditions

Aquablaster diffusion pipe

Hotel cesspit photo ①

Hotel cesspit photo ②

An underwater stirrer was installed. Thewhite blurred parts in the photo are
numerous sand flies. A huge number ofmaggots grow in oil floating on thewater surface, and the hydrogen sulfide
concentration is over 50ppm.

Although aeration is performed, it justforms oil balls because the amount of
air is not enough. The hydrogen sulfide
concentration has exceeded 700ppm
before, and the problem is yet to besolved.
❸■ Sewer pipe life shortened due to hydrogen sulfide

Aquablaster diffusion pipeNow, sewer pipes are corroding steadily due to hydrogen sulfide
produced from cesspits. It is of great concern to municipalities.

To those who install a cesspit
Design a building without odor.
○ Cesspit (wastewater tank) structure
The structure is specified as follows by building code related regulations(Notification no. 1597 of the Ministry of Construction, 1975).

Inlet pits must be provided
at the bottom of thewastewater tank.

1/10 to 1/15 must be secured
for the gradient of thebottom surface.

However, using the above
only, it is possiblethat
anoffensive odor isstill generated.
To prevent offensive odors,
the Tokyo Metropolitan
Government established"Cesspit Measures Guidelines".
the Tokyo

Tokyo Metropolitan Government Guideline Brochure
http://www.gesui.metro.tokyo.jp/ Measures against odors from cesspits

Differences in sewer pipe life due to differences inhydrogen sulfide concentration
Life (year)
Pipe

Hydrogen sulfide
concentration
Average: 4.1ppm

Hydrogen sulfide
concentration
Average: 11.6ppm

Shortened life400mm

39.1 years

13.8 years25.3 years

450mm

44.0 years

15.6 years

28.4 years

500mm

50.9 years

18.0 years

32.9 years

600mm

65.5 years

23.1 years

42.4 years

700mm

81.1 years

28.7 years

52.4 years

According to the Tokyo Metropolitan Gov., Bureau of Sewerage survey
data, a trial calculation shows that due to the influence of hydrogensulfide produced from cesspits, if no measures are taken, the sewer
pipe life will be shortened by a maximum of 50 years or more.
❹■ Danger of hydrogen sulfide
Persons/occurrences
20181614

Aquablaster diffusion pipe

Hydrogen sulfide poisoning occurrence situation (1987 to 2006)
No.of incidents
No.ofpeople affected
No.of deaths

The chart on the left shows statistics on
industrial accidents caused by hydrogen sulfide,
as published bythe Ministry of Health, Labourand Welfare. Every year,

1210864201987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 Year

Danger of hydrogen sulfide
Hydrogen sulfide (ppm)

Effect0.03

Smell detection lower limit

5Unpleasant smell

50 to 100

respiratory tract irritation, conjunctivitis

100 to 200Loss of sense of smell

200 to 300

Subacute poisonings in one hour

600

Fatal poisonings in one hour

1,000 to 2,000

Instantaneous death* When the concentration becomes high, contrarily it becomes more difficult to detect an odor and the sense of smell is lost. Special care must be taken.
❺■ Previous putrefaction prevention devices

Aquablaster diffusion pipe

Conclusion

MethodDescription

Feature and effect

Jet ejector intake
stirring method

Using the force of the water
blast produced by a pump, air
is taken in from the ejector toproduce gas-liquid mixedcurrents.

The device can be easily installed at low cost. However, withkitchen wastewater load, it is difficult to secure a dissolved
oxygen concentration of 2.0mg/L or more.
Price: 400,000 to 1,000,000 yen/set. Installation cost required
separately.

A ventilator is available from Aience.
However, many such products must be
installed to secure a dissolved oxygen
concentration of 2.0mg/L; this method istherefore not so effective.

Using the force of a water
blast produced by a pump,
air is taken in from the ejector
to produce gas-liquid mixedcurrents.

This method does not reach the point of stirring water in the pit
efficiently, and compared to the Aquablaster diffusion pipe, it is
not expected to be effective, and maintenance is also difficult.
Price: 2 million yen/set of 4 units.
Pump control panel included. Installation cost separately required.

A similar product, the Sludge Eater
diffusion pipe, is available among Aience
products. However, many such products
must be installed to secure a dissolved
oxygen concentration of 2.0mg/L; thismethod is therefore not so effective.

In this method, water is stirredwith pumps and air is fed withblowers at the same time.

Stirring water with pumps and feeding air with blowers appear tobe effective at first, but it is not true because the oxygen
dissolution efficiency is rather low considering power
consumption.
Price: 500,000 to 800,000 yen/set

In some hotels using this type of device,a problem with odor occurred. TheAquablaster diffusion pipe improved thesituation related to not only odor but also
water quality.

In this method, pumps are
installed in the pit so thatwastewater is discharged
before it accumulates.

This method simply prevents water from accumulating in the pit.
However, since wastewater is discharged with untreated oilcontent and while pH is low, it leads to sewer deterioration.

This method is symptomatic treatment,
and does not give consideration tosewer pipe deterioration, so it does notseem to be a fundamental solution.

Shaft-aeration typeunderwater stirring
aeration method

Underwater stirring
aeration aerator
methodImmediate wastewater
pump-up method

ProductHowever, none of the above was conclusive. But then…

Aeration method byusing the Aquablaster
diffusion pipe

A method of securing adissolved oxygen
concentration of 2.0mg/L or
more with a diffusion pipewith high oxygen dissolution
efficiency

When Aquablaster units are laid out properly according to thetank, since the oxygen dissolution efficiency is very high, to say
nothing of putrefaction prevention, water purification can beexpected.
Price: 100,000 to 150,000 yen/㎥ (Actual capacity of water tank)
Air blower, installation cost included

When an Aquablaster diffusion pipe unit
is properly designed and laid out, thedissolved oxygen concentration reaches
2.0mg/L or more. This solves theproblem.

❻■ Diffusion pipe Aquablaster mechanism

Aquablaster diffusion pipe

❶ Air from the blower is emitted through the nozzle asa high speed air blast.

❷ Water and sludge at the bottom are swept up
by an air lift effect.

❸ With special shaped fins newly developed by using❸

fluid ynamics (patent pending),air and water are
vigorously mixed together to generatenano air bubbles and swirling flows.

❹❹ When swirling flows are generated, nano air❶

bubbles are also supplied to the corner sections at
the bottom of the water tank, where the dissolved
oxygen concentration does not increase easily.

Conventional aeration system

Circulating aeration system

Sludge accumulates at the bottom andbecomes anaerobic.

Oxygen spreads over the entire tank andsludge does not settle at the bottom.

❷❼

■ Performance comparison table

MethodOxygenCapability to stophydrogen sulfide dissolution

Stirring

Aquablaster diffusion pipe

Initial costs Running costs

Problem solving
capability

Full aeration method by using theAquablaster diffusion pipe

101096810

Jet ejector intake stirring method

566885

Shaft-aeration type underwater
stirring aeration method

577665Underwater stirring
aeration577433

Immediate wastewater pump
pump-upmethodaerator method

322885❽

■ Advantages of introducing the Aquablaster diffusion pipe

Aquablaster diffusion pipe

① The Aquablaster diffusion pipe can provide a fundamental solution to water putrefaction.
② The Aquablaster diffusion pipe prevents frame and device deterioration caused by hydrogensulfide and maintains property values.
③ The amount of generated sludge is radically reduced, so that the equipment cost can bedepreciated in a few years.
④ Insect pests attracted by putrid odors are fended off, making the facility sanitary.

❾■ Aquablaster diffusion pipe installation example

Diffusion pipe Aquablaster Type AL-1500

500

1000

1000
4000

1000

500

Air injection angle : 30 degrees(* The design is prepared so that injection
trajectories intersect themselves on thewater surface. Therefore, the lower the water
depth, the more injection trajectories it takes.)

3500

750

Recommended water depth:
Used at a level of 600 to 2000mm(This is not applicable when using in an
adjustment tank. Usable also at amaximum water level of 4500mm)

550
Used at a level of2000 or more

475

Diffusion pipe Aquablaster
Type AS-200/250

Used at a level of2000 or less

300

30°

2000

3500

850

850

850

475

750

Diffusion pipe Aquablaster Type AS-200/250

Aquablaster diffusion pipe

30°

750

1250

1250

750

Diffusion pipe Aquablaster
Type AL-1500
Recommended water depth:
Used at a level of 2000 to 6000mm(This is not applicable to high-load
circulating water like a paint booth ordeep water aeration.)
Air injection angle: 30 degrees(* The design is prepared so that
injection trajectories intersect
themselves on the water surface.
Therefore, the lower the water depth,
the more injection trajectories it takes.)

4000

❿

■ Supply examples

Aquablaster diffusion pipe

Food plant

Food plant

Fixed route bus
storage yard

Wastewater
treatment pit

Wastewater
treatment pit

Car wash wastewater
treatment pit

Water purification andputrefaction prevention

Water purification andputrefaction prevention

Water purification andputrefaction prevention

January 2009

February 2009

December 2008

Food plant

Vehicle factory

Vehicle factory

Wastewater
treatment pit

Circulating water pit

Circulating water pit

Water purification andputrefaction prevention

Putrefaction prevention andwater purification

Putrefaction prevention andwater purification

January 2009

February 2009

April 2001

SHIMADZU CORPORATIONHead office

Fixed route bus
storage yard

Industrial wastewater
treatment

Kitchen wastewater
treatment pit

Car wash wastewater
treatment pit

Water purification anddeodorization

Putrefaction prevention
and water purification

September 2007

July 2008

Aience is a water
treatment professional
not only in putrefaction
prevention but also inwastewater treatment.

First class hotel

Truck manufacturing
plant

Plastic drum test unit

Kitchen wastewater
treatment pit

Circulating water pit

Water purification anddeodorization

Putrefaction anddeterioration prevention

February 1999

October 2008

We guarantee thathydrogen sulfide is not
generated underwater,
but you can use ourtest unit for checking,if necessary.

⓫■ System's device configuration and scope of work
Power control panel
Degrading bacteria
supply device (Optional)

Roots blower

Aquablaster diffusion pipe

Aquablaster diffusion pipe
Ring blower

Product nameApplied air volume (per unit)

Applied water depth

AS-2000.15‑0.20㎥/min

0.6‑2.0m

AS-2500.20‑0.30㎥/min

0.6‑2.0m

AL-1500

0.75‑1.50㎥/min

1.5‑6.0m

Aeration blower
Aquablaster[ Basic scope of work ]Design and manufacture from the Acquablaster diffusion pipe toheader piping, 50L tank 30cc/min to ...roots blower selection andsupply, degrading bacteria supply device(optional) selection andsupply, power control panel design and supply[ Scope separate from basic scope ]On-site unit piping installation work, connecting piping work
(material supply and work), electrical work for both primary andsecondarysides, cost of transportation, cost of implementation
management, cost of water quality analysis, cleaning of existing
facility, removal of existing items, foundation and civil work

ModelTotal air volume

Applied water depth

Ring blower

1.0‑6.0 ㎥/min

0.6‑1.2m

Roots blower

1.0‑20.0 ㎥/min

1.2‑6.0m

Degrading bacteria supply device (Optional)
Model

Drip amount

50L tank

30cc/min to ...

100L tank

30cc/min to ...

200L tank

30cc/min to ...
⓬https://www.aience.co.jp/en/