Treatment of Wastewater
including human waste
in disasters~ Heavy rain disasterand countermeasure ~Severe heavy rain disaster

Global warming and increase in risk of heavy rain
Changes in number of annual occurrences of heavy rain in Japan(more than 200mm of daily precipitation)(Times / spot)

Gray bar : average number of occurrences at the end of the 20th century
Blue bar : assumed number of occurrences under high level discharge of CO2
Japan Meteorological Agency https://www.jma.go.jp/jma/kishou/books/hakusho/2020/index1.html

Damage to rivers caused by heavy rain on July 2018

Situation of landslide disaster caused by heavy rainon July 2018

Number oflandslide857

Damage to sewage treatment system caused by heavy rain
2018
on July 2018

◆Public health perspective
Example : Spreading of waterborne disease at the time of flood disaster in the pastOccurrence of infection in 1938 in Ibaraki Pref.
Disease name Before flood
After flood
Death
Typhoid
36
56
13
Paratyphoid1118
0
Dysentery40
268
80
Weil's disease
2183
Guidance of disinfection method at the time of flood disaster frompublic health center
Outside・Place flooded by sewage
・Flooded underfloor

Benzalkonium
chloride

Dilute beenzalkonium chloride
to 0.1%

Cresol and soapsolution

1L of water with 30 ml of cresoland soap solution

Ortho agent

1L of water with 20 ml of orthoagent

Damage caseDamage to Johkasou in Okayama Pref. in 2018
Research on damage to Johkasou
Case①Number of damaged johkasou②Complete collapse (washing)

5-10 PE ≥11 PE
4,181
348
141
Damage to body53
3Motor68③Partial damage
Blower
1,37476
Drive part
Effluent pump
10Flow monitor
01④Inflow and outflow pipe
462
25
⑤Shutdown by blackout
2,559
146
⑥Shutdown by water outage
2,941
129
⑦Number of nonusable (assumed)27
7⑧Number of recovery after disaster
4,154
341

Total
4,529
15
56
14
1,450
1
1487
2,705
2,955
34
4,495

Damper car

Vacuum car

Heavy rain in Niigata, Fukushima Pref. on Jul 2011

写真：福島県浄化槽協会

Fall of Disinfectant holder by adverse water current

写真：福島県浄化槽協会

Inflow of rubble by adverse
water current

Severe damage often occurred near washout point of river
Very close to the levee breach site

Downstream area of the levee breach site

Temporary toilet at evacuation shelter(Case of maintenance of simple vault toilet by desludging vendor)* public facility such as school is used as evacuation shelter when in disaster.

Measure to prevent flood disaster(disaster preparedness)
1. Prevention of mechanical and electronicequipment from flood
Raise the installation position of equipment

2. Countermeasures against backflow from thedischarging pipe
Introduce non-return valves etc.

3. Prevention of Johkasou from floating
Implementation of proper burial / floating
prevention measures

Regarding the manipulation of Johkasou etc. provided in disaster
under the Building Standards Act

Summary : installation of Johkasou to prepare for the
malfunction of sewerage in disasters

Usage of Johkasou in disasters (under considering)
Hand pumpPoolwastewater

Assembled water tank

Wastewater(in disaster)

Sewerage system is
not able to use
when disasterIn normal period, Johkasou will be used
as a rainwater storage tank, but whendisasters, Johkasou will be used to treat
the wastewater from the shelter.

Johkasou installed atevacuation center

rain water(normalperiod)

effluent water(in disaster)