Thinley Namgay

The Johkasou sewage treatment tank, a Japanese technology, is viewed by many as the potential alternative to address the growing sewage-related issues in the capital.

The thromde’s existing treatment plants are unable to cater to all locations considering the topography and the population.

Johkasou is a decentralised wastewater treatment system that treats human waste from flush toilets and domestic wastewater from kitchens, baths, and others.

As of now, the two pilot Johkasou sewage tanks installed by the Bhutan Toilet Organisation (BTO) and Thimphu Thromde in July last year at Motithang have benefited the residents.

The tanks were sponsored by JOYLET Japan, and both tanks have a carrying capacity of 1,000 litres of wastewater. Two more tanks are under construction at Mithrup Lhakhang and Ludrong park in Thimphu.

How does a Johkasou tank function?

The whole system is run by electricity.

When the wastewater comes from the home, the first compartment collects it and also blows oxygen and makes fecal matter into small pieces. 

As it flows, it will get to the next compartment where microbes will eat the fecal matter and settle down, but the liquid part will move to the third compartment where chlorine will detoxify and kill bacteria.

Then the wastewater is released into the environment. 

The Johkasou tank has different sizes. The existing tanks at BTO weigh around 100kg. 

How did the pilot project benefit, and what are the issues?

These two tanks are connected to the two households out of around 20 households at Motithang camp.

It has reduced the burden on their single common septic tank, which the residents have been facing  due to the overflow of sewage. Residents have been calling the thromde to clear it or dispose of it directly into the nearby stream.    

Tshering Dema, a beneficiary, noted the significance of this technology, stating that it would reduce the burden for the Thromde in the future. “It is also user-friendly in general.”

She said the tank brought bad odour. “It could be due to either chlorine or fecal matter. Other residents passing nearby are complaining.”

She demands a longer drain-out pipe so that water could easily reach the stream.

However, the two owners also didn’t care about the tank. During the site visit by Kuensel, there were even sanitary pads in the tanks.

None of the residents in that community have got training on Johkasou as of now. However, many residents said that BTO and the thromde should place more Johkasou in the capital.

Why Johkasou and the challenges?

BTO’s Project Manager, Tshedrup Dorji, said more than 50 percent of the residents of Thimphu today use non-sewer treatment plants.

According to Tshedrup, Johkasou tanks provide an alternative to the non-sewer users.

He said the existing septic tanks were not up to standard or were not properly built. He said the homeowners had to empty it every month, a burden for the thromde.

He said that the sewage issue was more in the towns owing to less space and more population. “Even the two-house owner can share the cost and place one larger Johkasou. It will instill a sense of responsibility.”

“In some areas, the sewer plant is located above the community and not able to facilitate because of the elevation,” he said, adding that the Johkasou tank could cost between Nu 200,000 and Nu 300,000. 

BTO’s Executive Director, Chablop Passang Tshering, said the capital’s outskirts did not have access to the  sewer plants of the thromde.

“In a space where you build a septic tank, it can accommodate two or three Johkasou tanks,” he said.

He stressed on the subsidy from the government to carry forward the Johkasou project. “For that, the government should provide Johkasou at a subsidised rate to encourage private individuals.”

Johkasou is new technology in the country

He said that the initial cost will be a bit high to purchase Johkasou, but it will be more sustainable as it requires less maintenance and clean-up. “Electricity consumption is low.”

The challenges of the Johkasou project include the lack of proper understanding of the technology by people, refusal to change for better sanitation, and a lack of a sense of responsibility.   

Popularity of Johkasou

Johkasou is popular in Japan. It has gained momentum since the 1970s. Some countries are also adopting this technology.

In the SAARC region, this technology is not popular at present. Countries in the SAARC region still struggle to have proper toilets where most of the countries venture for safely managing sanitation.

Chablop Passang Tshering said that during the FANSA network regional meeting earlier this year, SAARC countries are showing interest in Johkasou.

Sewage challenges in the capital

Chablop Passang Tshering said that different kinds of things are found in septic tanks such as hair, clothes, household items, and sanitary pads. “These things will also destroy the treatment plant.”

He said if there is fecal matter and water only, septic tank blocks won’t happen. He said some put rainwater into the septic tanks which overflow easily.

Today, even with slight rain, septic tank leakage occurs in some areas of the capital. Moreover, the waste filter net is not in most of the houses.  

He said Thimphu has no adequate area to build a good septic tank as it is getting crowded.

Some residents directly pump their wastewater to Wangchhu, which is regarded as contaminated water. There is a presence of  echola bacteria.  

Framers in the downstream of Wangchhu use it for irrigation, and health risks are there.

How thromde is addressing the sewage issue?

There are seven sewer treatment plants developed by Thromde at Dechencholing, Taba, Jungzhina, Hejo, Lungtenzampa, and Babesa. Six plants are functional.

Dechencholing plant is not working due to under capacity and worn out electro-mechanical parts.

The Thromde’s sewage section is facilitating household sewerage connection to the sewer network system.  

Thromde’s media focal, Dawa Gyeltshen, said: “The gutter water (rain and storm) is discharged to drainage, whereas the wastewater – black water (toilet) and grey water (kitchen) are being connected to the sewer network system.”

Thromde keeps advocating for the public to refrain from connecting the gutter and storm water to the sewer network system.

Thromde also notified the residents not to connect wastewater from building plinth drains to the sewer network and to properly seal the manhole and inspection chamber cover so that surface runoff during rainfall does not enter the sewer network.

Way forward

In the 13th Plan, the Thimphu Thromde plans to upgrade the existing plant and develop a new plant at Dechencholing.

Dawa Gyeltshen said that thromde would also install Johkasou soon and study its efficiency. “Thromde may not invest in Johkasou but can encourage house owners to use the technology where the reach of Thromde sewer network system is not possible.”

As per the review of Thimphu Structural Plan 2047, there are recommendations for the setup of bigger capacity sewer treatment plants. 

Officials from the health ministry said that sewage issues require a comprehensive approach, and the ministry would invest in infrastructure development, behaviour change campaigns, community engagement, policy support, and adequate funding.

There will be a replacement for the existing sewer trunk line with bigger diametre pipes as per Thromde’s media focal person.