Updated on January 12, 2024


Created on August 9, 2019


Upcoming Update

Johkasou tanks are wastewater treatment tanks that can be set up in areas without sewage infrastructure.

Developed By
  1. Kubota
Content Partners


Product Description

Johkasou tanks are commercialized wastewater treatment tanks that can be set up in areas without sewage infrastructure, combining both anaerobic and aerobic microorganisms. Steps include a solid-liquid separation tank, an anaerobic filter bed tank, a moving bed tank or membrane bioreactor, a carrier filter tank or sedimentation tank, followed by the disinfection tank. The product is designed and manufactured by Kubota in Japan, and distributed primarily in Asia.

Six different models exist: KZ II, HCZ, KM-SG-NP, K-HC-T, K-HC-R, KTZ


Target SDGs

SDG 6: Clean Water and Sanitation

Target Users (Target Impact Group)

Household, Small and Medium-sized Enterprises, Public Sector Agencies

Distributors / Implementing Organizations


Manufacturing/Building Method

Manufactured in Japan for small, medium, and large application settings.

Intellectural Property Type


User Provision Model

Users can contact local sales information centers

Distributions to Date Status

1,000,000 units have been distributed in Japan, and an additional 1,000 distributed overseas

Flow rate (L/min)

Flow rate for different available models:

KZ II: 0.7-1.4 L/min

HCZ: 2.9-6.9 L/min

KM-SG-NP: 13.9-138.9 L/min

K-HC-T: 6.9-20.8 L/min

K-HC-R: 13.9-69.4 L/min

KTZ: 6.9 L/min

Power Supply Type


Technology type

Solid-liquid separation tank, anaerobic filter bed tank, moving bed tank, membrane bioreactor, carrier filter tank, sedimentation tank

BOD Removal Efficiency

BOD, mg/L, for available different models:

KZ II: ?20

HCZ: ?20

KM-SG-NP: ?5

K-HC-T: ?20

K-HC-R: ?20

KTZ: ?20

COD removal efficiency

COD, mg/L, for available different models:

KM-SG-NP: ?10

KTZ: ?30

NH4-N Removal Efficiency

Total N, mg/L, for available different models:

KZ II: ?20

HCZ: ?20

KM-SG-NP: ?10

TSS removal efficiency

SS, mg/L, for available different models:

KZ II: ?15

HCZ: ?15

KTZ: ?15

Total Phosphorus Removal Efficiency

Total P, mg/L, for available different models:

KM-SG-NP: ?1

Fecal Coliform Removal Efficiency


Design Specifications

Johkasou design specifications vary according to model. Six products exist: KZ II, HCZ, KM-SG-NP, K-HC-T, K-HC-R, KTZ    

Product Schematics

Technical Support

Provided by Kubota

Replacement Components

Submerged membrane unit



Manufacturer Specified Performance Parameters

Manufacturer states product has 90% or higher BOD removal rate and delivers treated water quality with BOD of 20 mg/L or less (in case influent BOD is 200 mg/L).

Vetted Performance Status



Blower must remain on for microorganisms (stopping will result in untreated wastewater and bad odor). Do not throw foreign objects (such as rubber, absorbent cotton, food wastewater, or cooking oil) in toilet to avoid clogging. Do not add chemicals (hydrochloric acid, insecticide, deodorant, chlorine agent, etc.) into the tank. Always close the manhole cover (and lock it if it has a locking mechanism). Prevent children from playing near the wastewater treatment plant. When closing a cover with bolt nuts, tighten cap nuts evenly using a special opening/closing handle. Be careful not to lose parts such as washers and gasket. Remove small stones and other foreign objects from the frame. Do not put any objects on the manhole, blower or power cable, or in the nearby area. Be sure to keep combustible or hazardous things away.

Complementary Technical Systems

Power source for blower

Academic Research and References

Ewiss, M.Z., Ahmed, Z.A., et al.,  2017, Application Of The Japanese Johkasou Decentralized Sewage Wastewater System In Egypt, Sylwan 161(9): 180-193.

Gaulke, L.S., 2006, On-site wastewater treatment and reuses in Japan, Proceedings of the Institution of Civil Engineers-Water Management 159: 103-109.

Lam, L. Kurisu, K. Hanaki, K., 2015, Comparative environmental impacts of source-separation systems for domestic wastewater management in rural China, Journal of Cleaner Production 104(1): 185-198.

Nguyen, L.H. Mohan, G. et al., 2016, Low-Carbon Watershed Management: Potential of Greenhouse Gas Reductions from Wastewater Treatment in Rural Vietnam, The Scientific World Journal.

Goal 6. Available: https://sdgs.un.org/goals/goal6

Compliance with regulations


Evaluation methods


Other Information

Specifications of each product:  KZ II, HCZ, KM-SG-NP, K-HC-T and K-HC-R.

Leave a Reply

Explore similar solutions


January 11, 2024

Sequential Batch Reactor

Read Solution


January 12, 2024

Membrane Biofilm Reactor

Read Solution


January 12, 2024

NG-SEPCLEAN (Next Generation Septic Tank)

Read Solution

Implemented by

Emergy Enviro Pvt. Ltd


January 15, 2024

Anaerobic Baffled Reactor

Read Solution


January 11, 2024

Decentralized Wastewater Treatment Systems (DEWATS)

Read Solution

Implemented by



January 18, 2024

The WaterHub

Read Solution

Implemented by

NextEra Distributed Water


January 11, 2024

AquaDisk Cloth Media Filter

Read Solution

Implemented by

Aqua-Aerobic Systems, Inc.


January 16, 2024


Read Solution

Implemented by

Wetlands Work


January 16, 2024

Integrated Wetland Technology

Read Solution

Implemented by

Emergy Enviro Pvt. Ltd


January 12, 2024

The Living Machine

Read Solution

Implemented by

Living Machine Systems, L3C

All Solutions

Contribute to E4C's Library of Breakthrough Sustainable Development Technology Solutions

Suggest A Solution

Get more information about Solutions Library and its features.

Learn More

Have thoughts on how we can improve?

Give Us Feedback

Join a global community of changemakers.

Become A Member