Shinhi Kumokawa Ph.D
Center for International Cooperation of Johkasou System
Japan Education Center of Environmental Sanitation (JECES)

11. Legal framework for johkasou O&M
2. Practice of johkasou O&M, etc.
3. Training system for johkasou technicians2

Device/equipment in johkasou
Primary treatment(1st step)

Sedimentation tank, Anaerobic filter tank, Slit screen, Aerated screen, Gritchamber,
Bar screen, Flow equalization tank,

Secondary treatment
2nd step

Contact aeration tank, moving bed tank, aeration tank,

3rd step

Sedimentation tank

4th step

Disinfection tank5th step

Sludge thickening/storage tank, sludge storage tank,Mechanics

Electromagnetic blower, Control panel, mechanical blower, pump,3

o Technical standard for operation and maintenance(Article 2, Ordinance for Enforcement of Johkasou Act)
This standard stipulates maintenance items and adjustment/repair items thatmust be carried out during operation and maintenance for every johkasou andthe auxiliary device.
o Technical standard for desludging (Article 3, Ordinance for Enforcement ofJohkasou Act)
Desludging standards stipulate items to be carried out for each unit andauxiliary device during desludging (e.g. methods for drawing out sludge)
o Guidelines for johkasou operation and maintenance (Official notice)
These guidelines are issued by the Ministry of the Environment as specificpolicies for operations and maintenance technicians. They are designed toensure that operation and maintenance as well as desludging are carriedout optimally and in line with the specific characteristics of each treatment
process.
4Technical standard for johkasou O&M, (1983, Johkasou Act) Guideline for O&M of Tandoku-shori johkasou (2000)
 Guideline for O&M of small-scale johkasou (1993)
 Guideline for O&M of medium/large-scale johkasou (2000)
 Guideline for O&M of N/P removal type johkasou (2000)
 Guideline for O&M of Membrane johkasou (2000)

Technical standard for johkasou desludging (1983, Johkasou Act)

5
1950s

Tandoku-shori johkasou (treat black water only)

1980s

2010s

Johkasou (treat black + grey water)

(i)(Rule of Using)
Article 1 Rules of using johkasou under the provisions prescribed in Article 3
paragraph 3 of Johkasou Act (hereinafter referred to as "Act") shall be as follows.
(i) Water amount for flushing toilet shall be appropriate.
(ii) Materials like insecticide, detergent, deodorant, fatty, disposable diaper,sanitary goods etc. which interfering with the normal functioning of johkasou,shall not be flowed.
(iii) abbr.
(iv) Industrial wastewater, rain water and other special wastewater shall not be
flowed into johkasou.
(v) Johkasou with electric equipment shall not be turned the power supply off.
(vi) The top or around of johkasou shall has no structural object that may interferewith operation, maintenance and desludging of johkasou.
(vii) The top of johkasou shall not be loaded which may interfere with its normalfunctioning.
(viii) The opening part of aerator shall not be blocked.
(ix) When the failure or malfunction is found in the johkasou, it should be notified
to the johkasou manager immediately.

(ii)

(v)

(vi, vii)

6

(Article 6-2, Ordinance for Enforcement of Johkasou Act)
Treatment process

Type/size of johkasou

Frequency Separation-contact aeration process Anaerobic filter-contact aeration process Denitrification type anaerobic filtercontact aeration process

1. Johkasou with a size less than 20 PE

4 month

2 . Johkasou with a size more than 21 PE
and less than 50 PE

3 month Activated sludge process( > 100PE, M/L )1 week Rotating biological contactor process Contact aeration process
 Trickling filter process

1. Johkasou with sand filter device,activated carbon adsorption device
or flocculation tank ( > 50PE, M/L)

1 week

2. Johkasou with screen and flow
equalization chamber or flow
equalization tank ( > 50PE, M/L)

2 week

3. Other Johkasou ( > 50PE, M/L)(without screen equipment, etc.)3 month789Qualifications /vendor

Registrant/
number ofvendor

Business content

Johkasou Operator

80,042

Operation and maintenanceJohkasou Installation Worker

86,595

Installation/construction

Johkasou Technical Supervisor

29,794

Management of johkasou over 500 PE

Johkasou Desludging Technician

16,021

Desludging

Registered Johkasou Inspector

1,280

Legal inspection

Specified Inspection Agency

65

Legal inspection

Johkasou manufacturer

18

Research, development and manufacture

Johkasou maintenance vendor

12,435

Operation and maintenanceJohkasou desludging vendor

5,291

Desludging

Johkasou Installation vendor

28,356

Installation/construction

Legal basis

Johkasou Act

Enforcement
regulations ofJohkasou Act

Johkasou Act

Source: Ministry of Environment, Japan, etc. (as of March 31, 2016)10

1. Legal framework for johkasou O&M
2. Practice of johkasou O&M, etc.
3. Training system for johkasou technicians11Operations concerning to inspecting, maintaining andrepairing johkasou (Johkasou Act, Article 2-3)

・ Prevent loss of unit function and device breakdown
・ Maintain normal treatment performance
・ Promote proper regular desludging

12• Surrounding conditions• Water flow condition• Treatment performance• Sludge accumulation• Electrical and mechanical devices

13

Surrounding conditions
・abnormal noise/sound・ strong odor/smell

14

Check up the way of inflow water15

Outlet

Inlet

Aerobic Bio-filtertankPre-sedimentation
tankAnaerobic
Bio-filter tank16

Check the aeration device andthe aeration condition, adjust theair flow when necessary

Check the distribution device,
the amount of return water andthe condition of disinfection device

17Check the water quality (DO, pH, ORP, NO2-)
18

pHDOpH meter

DO meter

NH4, NO2, NO3

NH4, NO2, NO3 portable testing unit

NH4, NO2, NO3 test paper

19

Check the water quality (Transparency )20

Transparency meter• A simple but very usefulSign Board

item

the width ofblack lines:0.5 mm

Tr, cmWhite plastic board

Effluent• Indicates SS and/or BOD
indirectly

PinchcockRubber tube
Effluent BOD,mg/L

21

Check the accumulated sludge

22Check theaccumulatedsludge

23Inspecting wastewater flow

Checking remaining disinfectant

Measuring transparency

Measuring
depositedsludgeAn Example of johkasou O&M
Explaining inspection results

Creating maintenanceinspection report

Blower inspection

Measuring circulating water volume24

Desludging involves extracting the generated sludge and scum fromjohkasou and conditioning sludge in the tank, as well as cleaning tanks
and auxiliary equipment.
(Johkasou Act, Article 2-4)

Recover/reset treatment performance of johkasou
by removing sludge regularly

25Outlet

Inlet

Aerobic Bio-filtertankPre-sedimentation
tankAnaerobic
Bio-filter tank26

Vacuum Truck for Desludging

27

28

Preparation work

Drawing sludge out of the 1st-room ofanaerobic filter tank

Drawing sludge out of the 2nd-room ofanaerobic filter tank

An examples of johkasou desludging
Reporting the results ofdesludging to the owner

Filling the tanks with water
Cleaning the tank29

o Article 7 inspection (inspection after installation)
This inspection focuses on installation status and looks to see whether thejohkasou has the intended treatment functions. It is carried out when most of
the functions are up and running, between three and five months from thetime usage begins.

o Article 11 inspection (periodic inspection)
This inspection focuses on maintenance inspection and desludging status
and looks to see whether the intended treatment functions are being
maintained through proper operations and maintenance. It is carried out oncea year.

o Agencies authorized to carry out legal inspection
There are 66 Specified Inspection Agency designated by prefectural governors
to carry out legal inspection. To be designated, an agency must assign experts
who have knowledge of johkasou inspection as Johkasou Inspector
with the requisite skills and have inspection experience at least
two years.
30Review basic information(installation/usage start date, vendors involved, structural
application, target population equivalents served, actual
population equivalents served, treatment method, target treatedwater quality, etc.)

Exterior
inspection

Water quality
inspection

Document
inspection

Make decisions on each check item in each inspection(Good / Pass / Fail)

List up decisions made for each check item

Take the overall importance of each check item into account fromthe perspective of worsening effluent water quality and publichealth/sanitation

Final decision(Appropriate / Basically Appropriate / Inappropriate)31

User interview

Checking inside the johkasou

Water quality measurements

An example of johkasou legal inspection
BOD measurement

Reporting the inspection results to the owner
Measuring residual
chlorine concentration32

 85.0% johkasou out of 1,273,945
units shows
effluent BOD<20mg/L
 Johkasou shows high treatment
performance comparable tosewage treatment plants
Source: Ministry of the Environment, Japan, 2016

BOD>60mg/L
1.7%
BOD<60mg/L
5.8%
BOD<30mg/L
7.9%

BOD<20mg
8.2%

BOD<5mg/L
37.3%

BOD<15mg/L
12.9%
BOD<10mg/L
26.2%

Effluent BOD concentrations33

1. Legal framework for johkasou O&M
2. Practice of johkasou O&M
3. Training system for Johkasou technicians34

1. Position of the qualifications in the Act
Johkasou Installation Worker
Article 42(1)(ii), Johkasou Act
Johkasou Operator
Article 45(1)(ii), Johkasou Act
Johkasou Technical Supervisor
Article 10(2), Johkasou Act
Johkasou Desludging Technician
Article 11(iv), Ordinance of Johkasou Act
Johkasou Inspector
Article 5(1)(iv), Ordinance of Johkasou Act
Examination/training Agency
Article 43, 46, Johkasou Act
2. Business content of the qualifications
As shown in the right figure.

• These regulations make the qualifications to be indispensable for persons who want to join johkasou businesses,and give incentives to them.
• The qualifications could be obtained by receiving training courses or passing national examinations.
• This training and qualification system has played an essential role to enhance the technical level of johkasou
technicians, and contributed to the appropriate spread of johkasou.

35

o Public Cleansing Act era ( ～ 1970)• Training for operators already regularly involved in johkasou desludging to makethem specialist technicians in operations and maintenanceo Waste Disposal and Public Cleansing Act era (1970–1985)• Operations and maintenance separated into maintenance inspection and cleaning,training for different johkasou managing engineers for each• Training for technicians who carry out johkasou construction• Training for technicians who carry out johkasou legal inspectionso Johkasou Act era (1985～)•

National qualifications established for Certified Johkasou Installation Worker andCertified Johkasou Operator with testing and training sessions implemented for each•Training sessions implemented for Certified Johkasou Engineering Managers,
Certified Johkasou Cleaning Technicians, and Certified Johkasou Inspectors36Working-level contents of curricula for johkasou businesses• Johkasou technicians should be equipped with extensive knowledge on not only wastewater
treatment/johkasou, but also water environment conservation and public health.
• Curriculums for johkasou operator and johkasou installation worker are as shown below
Training course for Johkasou Operator







Fundamental of johkasou
Laws and regulations related johkasou
Structure and function of johkasou
Introduction to installation of johkasou
Operation and maintenance of johkasou
Water quality management of johkasouIntroduction to desludging of johkasou
Total

8H
4H
22 H
4H
30 H
10 H
2H
80 Hours

Training course for Johkasou Installation Worker

Fundamental of johkasou
Laws and regulations related johkasou
Structure and function of johkasou
Management of johkasou installation
Introduction to O&M and desludging of johkasou
Total

8H
3H
15 H
8H
3H

37 Hours

37Follow-up for johkasou technicians and continuing professional development (CPD) Support the johkasou technicians by providing updated technical information on johkasou, and give themappropriate information/advice on johkasou O&M, desludging and legal inspection.
Publication of monthly journal JOHKASO and books related johkasou technology/administration
Holding a national conference on johkasou technology, johkasou technicians and other stake-holders
coming together for exchanging information and discussing issues on johkasou businesses.
 Seminar courses for CPD of johkasou techniciansSpecial seminar for johkasou desludging workers
Special seminar on installation management of johkasou
Special seminar on O&M of compact type johkasou
Special seminar on desludging practice of compact type johkasou38 As johkasou are required to treat and discharge wastewater free fromhygienic risk and complying with the water quality stipulated by thetechnical standard, the O&M, desludging and legal inspection are very
important to ensure the johkasou function as designed.
 Technical standards for O&M and desludging as well as the guidelines areprepared for johkasou of different sizes and treatment processes. These
documents make it possible for technicians to conduct O&M and desludging
of johkasou appropriately.
 A training system for certification of johkasou technicians has beenestablished. More than two hundred thousand of various johkasou
technicians have been raised so far. With the support of the technicians,johkasou industry has developed significantly in Japan.
 The experiences of Japan shows that appropriate O&M, desludging andmonitoring as well as a training system are essential to implementation ofdecentralized domestic wastewater treatment, and a legal institution shouldbe necessary to integrative
39

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