introduction of compact compost toilet as a disaster

Introduction of Compact Compost Toilet as a Disaster Preparedness to Detached Housing in Japan

Yoshiki Higuchi

Department of Living Design, Nippon Institute of Technology

Mr.Yadoben

Evacuation Center Introduction

Even if the house is not collapsed, if the toilet becomes unusable due to water cut-off etc., you have to ・・・・

Housing

The most important thing is to stock disaster toilets at home and increase the proportion of ”Home Evacuation”.

The main problem leads to deterioration in public health.

Decision of home evacuation after the introduction of a compost toilet

Introduction

セカンドトイレがあれば、家でトイレができる！！

さらに、避難所のトイレ利用者数も軽減できる！！

Disaster occurred

The house collapsed.

To evacuation center

Water Supply cutoff at home.

An evacuation

order was issued

Stay at home during a

disaster

(home evacuation)

Yes

No

No

Yes

Yes

No

No

Yes

Stay at home during a

disaster

(home evacuation)

To evacuation center

There is a compost toilet at

home

Composting toilet as a second toilet of the housing

Flush toilet

Composting toilet

Introduction

Flush toilet

Flush toilet

Flush toilets are convenient for everyday life. Compost toilet are convenient in case of disasters.

+

↓ Home Evacuation！

Procedure of the research Introduction

STEP1. Questionnaire survey on disaster toilet stockpiling ratio Whether a disaster toilet was stocked at home for detached houses was

investigated.

STEP2. Continuous usable days of compost toilet How much compost tank capacity would be needed when stockpiling a compost

toilet as a disaster toilet in a detached house was examined.

STEP3 Proposal of compost toilet for home evacuation at the time of

disaster The compost toilet for home evacuation at the time of a disaster was developed.

2. Questionnaire survey on disaster toilet stockpiling ratio

2.1. Questionnaire outline

Satte City, Saitama Prefecture

Total number of detached houses:

14,930

5200 questionnaires were distributed

2822 questionnaires were collected

54.3%

18.9%

2. Questionnaire survey on disaster toilet stockpiling ratio

2.2 Questionnaire result

2257

1772

1576

1013

946

777

668

610

542

446

345

255

71

0 400 800 1200 1600 2000 2400

Water and gas supply outage

Toilet can not be used

Fire and spread of fire at home

Failure to contact with family / friends

Fall of furniture

Physical fitness and behavioral power at evacuation

Communication of information

Stockpile

Difficult evacuation from the inside of the house to the outside

A neighboring relationship

Unknown evacuation location and evacuation route

Dangerous goods blown up

Others

n=2,778

(Total respondents)

63.8%

Number of people

Water, Gas supply and Electricity outage

Toilet can’t be used

Fire at home

Failure to contact with family

Fall of furniture

Physical fitness and mental strength


Lack of stockpiling

Difficult evacuation outside the house

Neighboring relationship


Dangerous goods blowing up

Others

Multiple answers allowed

What will you be troubled with in the event of a disaster?


What do you think you need as disaster prevention measures?

2292

1432

815

700

623

406

355

340

286

0 400 800 1200 1600 2000 2400

Stockpiling of daily necessities

Stockpiling of emergency toilet

Information transmission system

Power supply

Maintenance of evacuation centers

Private power generation

Disaster prevention map

Rainwater storage facility

Others

n=2,718

(Total respondents)

52.7%

Number of people



What do you have prepared in the event of a disaster?

24591951

17821670

16051503

13261294

1224121312121212

107610491022979

885860846846

766706703

654648627

586574571

526478

432426410

339296

217

0 500 1000 1500 2000 2500

Flashlight

Portable radio

Food

Vinyl bag

Cigarette lighter,Matchstick

Candle

Towel

Scissors

Knife · Can opener

Wet tissue

Gum tape

Toothbrushing tool

Bandage

Sneakers

Antiseptic solution

Raincoat

Whistle

Simple toilet

Others

n=2,822

(Total respondents)

12%

Flashlight Drinking water

Portable radio Work gloves

Food Spare battery

Vinyl bag mask

Cigarette lighter,Matchbox Adhesive plaster

Candle Tissue paper

Towel Saran wrap

Scissors Leisure sheet

Knife · Can opener Writing utensils

Wet tissue Underwear

Duct tape Outer wear Dental tool

Balm Bandage

Paper/Plastic dishware Sneakers

Heating pads Antiseptic solution

Rope Raincoat Tweezers

Whistle Cotton

Simple toilet Helmet Others


Here

１２％

2257

1772

1576

1013

946

777

668

610

542

446

345

255

71

0 400 800 1200 1600 2000 2400

Water and gas supply outage

Toilet can not be used

Fire and spread of fire at home

Failure to contact with family / friends

Fall of furniture

Physical fitness and behavioral power at evacuation


Stockpile

Difficult evacuation from the inside of the house to the outside

A neighboring relationship


Dangerous goods blown up

Others

n=2,778

(Total respondents)

63.8%

Number of people

Water, Gas supply and Electricity outage

Toilet can’t be used

Fire at home

Failure to contact with family

Fall of furniture

Physical fitness and mental strength


Lack of stockpiling

Difficult evacuation outside the house

Neighboring relationship

Unknown evacuation location and

evacuation route

Dangerous goods blowing up

Others

24591951

17821670

16051503

13261294

1224121312121212

107610491022979

885860846846

766706703

654648627

586574571

526478

432426410

339296

217

0 500 1000 1500 2000 2500

Flashlight

Portable radio

Food

Vinyl bag

Cigarette lighter,Matchstick

Candle

Towel

Scissors

Knife · Can opener

Wet tissue

Gum tape

Toothbrushing tool

Bandage

Sneakers

Antiseptic solution

Raincoat

Whistle

Simple toilet

Others

n=2,822

(Total respondents)

12%

Flashlight Drinking water

Portable radio Work gloves

Food Spare battery

Vinyl bag mask

Cigarette lighter,Matchbox Adhesive plaster

Candle Tissue paper

Towel Saran wrap

Scissors Leisure sheet

Knife · Can opener Writing utensils

Wet tissue Underwear

Duct tape Outer wear Dental tool

Balm Bandage

Paper/Plastic dishware Sneakers

Heating pads Antiseptic solution

Rope Raincoat Tweezers

Whistle Cotton

Simple toilet Helmet Others

What will you be troubled with in the event of a disaster?

What do you have prepared

in the event of a disaster?

There are many people who are concerned about toilet

in the event of a disaster too. However, the proportion

of preparing toilets at home was very low.

3. Continuous usable days of compost toilet

3.1 Outline of experiment


Large size compost toilets are ・・・・

→ expensive.

→ involve construction work for installation.

It is not realistic to install it. It is realistic for preparation of disasters.

How many days can be used the toilet ?

Assuming that a disaster actually occurred, the continuous usable days of the compact

compost toilet was verified by subject experiments.



Estimated number of days for water restoration :

About 1Month


A family of four people

⇒ ⇒

When does the capacity of the compost tank

reach the limit ?


Excrete feces 2 to 4 times a day

Period, site and type of toilet


Table1. Period, site and type of toilet

Period Summer 7/1 to 8/5 Winter 11/7 to 12/18 Site Compost toilet experiment building of Nippon Institute of Technology (Japan)

Compost Toilet

Compact non-electrified compost toilet (Capacity:35Liters) (Fig.1)

This toilet uses “Separate Bowl” to collect feces and urine separately(Fig.2).

Fig.1 Compost toilet[4] Fig.2 Separate bowl[4]

Measurement items


Room temperature of the toilet [℃] Measured at 10 minute intervals

External air temprature [℃] Measured at 10 minute intervals

Temperature inside the compost tank [℃] Measured at 10 minute intervals

Moisture content inside the compost tank [%] Measured once a week

Weight of the compost tank [kg] Measured once a week

Odor and Comfortability Filled out the questionnaire at the time of use

Questionnaire items


Table3. Questionnaire items

Fecal excretion

amount [g]

Weight difference before and after excretion

Note) Urine is done before the experiment

Hardness of feces Constipation (Bristol Stool Form Scale : 1 ,2) , Normal (Bristol Stool Form Scale : 3 to 5)

Diarrhea (Bristol Stool Form Scale : 6 to 7)

Odor Comfortability

5. Intense odor

4. Strong odor

3. Easily perceptible odor

2. slight odor

1. Very slightly perceptible odor

0. Odorless

-4. Extremely uncomfortable

-3. Very uncomfortable

-2. Uncomfortable

-1. A bit uncomfortable

0. It is neither comfortable nor uncomfortable

1. A bit comfortable

2. Comfortable

3. Very comfortable

4. Extremely comfortable

Both Filled out at the time of entering the toilet and opening the toilet lid

0

200

400

600

800

1000

1200

1400

7.1

7.2

7.3

7.4

7.5

7.6

7.7

7.8

7.9

7.1

07

.11

7.1

27

.13

7.1

47

.15

7.1

67

.17

7.1

87

.19

7.2

07

.21

7.2

27

.23

7.2

47

.25

7.2

67

.27

7.2

87

.29

7.3

07

.31

8.1

8.2

8.3

8.4

8.5

Summer period

0

200

400

600

800

1000

1200

1400

11.7

11.8

11.9

11.1

01

1.1

11

1.1

21

1.1

31

1.1

41

1.1

51

1.1

61

1.1

71

1.1

81

1.1

91

1.2

01

1.2

11

1.2

21

1.2

31

1.2

41

1.2

51

1.2

61

1.2

71

1.2

81

1.2

91

1.3

01

2.1

12.2

12.3

12.4

12.5

12.6

12.7

12.8

12.9

12.1

01

2.1

11

2.1

21

2.1

31

2.1

41

2.1

51

2.1

61

2.1

71

2.1

8

g ※ Color coding indicates the number of people used per day.

Daily average fecal excretion amount:

426g/day

Daily average fecal excretion amount:

351g/day

※ Color coding indicates the number of people used per day.

Winter period

g

3.2 Experimental result

Fecal excretion amount to compost tank

155.5g/use

Winter

Before

After

⇓

Summer

⇓

Before

After


Situation in the compost tank before and after the experiment

The amount of feces in the

compost tank did not increase

much.

The feces in the compost tank

increased and the capacity limit of the

tank was approaching.

0

2

4

6

8

10

12

14

16

18

Summer WinterTotal fecal excretionRemaining amount of feces

[kg]

Degradation

and

evaporation

of moisture

82.7%

60.7

%

Amount of decomposition or evaporation in summer and winter


Decomposition

0

10

20

30

40

50

60

-20 0 20 40 60

External air temperature oC

Summer

Winter

R2=0.5221

Inte

rnal

Tem

per

atu

re o

f th

e ta

nk

oC

Internal temperature of the tank and external air temperature 51.2℃(MAX)

※ Effect of rice bran

5.7℃（≒External air temperature)

23.4℃（≒ External air temperature）

53.3℃( MAX)


Declaration of odor 3.2 Experimental result

3% 3%

12% 7%

20%13%

31%

28%

31%

41%

2%17%

0%

20%

40%

60%

80%

100%

Summer Winter

0:Odorless

1:Very slightly perceptible

odor2:slight odor

3:Easily perceptible odor

4:Strong odor

5:Intense odor

N=87 N=109

0

10

20

30

40

50

Sta

rt

1w

eek

late

r

2w

eek

s

late

r

3w

eek

s

late

r

4w

eek

s

late

r

5w

eek

s

late

r

6w

eek

s

late

r

7w

eek

s

late

r

8w

eek

s

late

r

9w

eek

s

late

r

10w

eek

s

late

r

11w

eek

s

late

r

12w

eek

s

late

r

13w

eek

s

late

r

14w

eek

s

late

r

15w

eek

s

late

r

Summer Winter

[Litter]

Estimated number of days

for water restoration

Capacity limit line


Progress of feces capacity in the composting tank

About 6 weeks

About 11 weeks

[Liter]

Simple estimation formula of the number of days that the compost toilet can be used continuously

y = z・x・k


y: Fecal volume in the compost tank [g]

z: The amount of feces per excretion [g/use] (155.5) x: Number of fecal excretions [use]

k:Season coefficient [-] (0.17 in summer and 0.39 in

winter) Applicable condition: (1) Fecal excretion of the day is limited to 4 times. (2) The range of external air temperature in Japan.

4. Proposal of compost toilet for home evacuation at the time of a disaster

4.1 Production outline of homemade compost toilet

Making with easily available materials

Low Cost

Able to make it on your own

Composting performance equivalent to or higher than that of

commercial products

45-liter garbage can, Only one piece of plywood,

PVC pipe and etc.

Use worn-out duvet feathers or blankets as

insulation

Double skin structure

4.1 Production outline of homemade compost toilet

Comparison of costs

Commercial compost

toilet Simple Toilet (50 times)

Homemade compost toilet

(Prototype)

About 210,000 yen[4] 4,980 yen/set →29,800 yen/month About 28,374 yen

1/7

≒

5. Conclusion

Continuous usable days 11 weeks (in summer)

6 weeks (in winter)

Estimated number of days for water restoration

About 1Month

y = z・x・k

Made with easily available materials Low Cost Able to make it on your own Composting performance equivalent to or higher than commercial compost toilet

I hope that the stockpiling rate of disaster toilets will

increase in Japan and households that can evacuate at

home will increase.

Thank you for your attention Mr.Yadoben

The End

introduction of compact compost toilet as a disaster

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