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The radiological density of sewage sludge

Last update date January 8, 2021

Reason why radioactive material came to be included in in sewage sludge destruction by fire ash

Diffuse radioactive material reaches the Yokohama-shi sky by atmospheric flow with Tokyo Electric Power The Fukushima Daiichi nuclear disaster and flows into sewage pipe by rain and reaches water reproduction center. We handle in water reproduction center and sludge exploitation of resources center, and sewage finally becomes sewage sludge destruction by fire ash. As radioactive material flowed into sewage pipe like the said article, radioactive material came to be included in sewage sludge destruction by fire ash. As for such phenomenon, the local government of neighborhood is in a similar situation, too.

Figure of flow of radioactive material included in sewage

About landfill disposal of sewage sludge destruction by fire ash

Land of Minamihonmoku landfill carries out landfill to part targeting at destruction by fire ash after April, 2014.
About inning disposal of sewage destruction by fire ash (PDF: 353KB)

Past process of sewage sludge destruction by fire ash

  1. We announce landfill to Minamihonmoku landfill on September 9, 2011
  • Confirmation safe about landfill of sewage sludge destruction by fire ash → We announce landfill after September 15
  1. We freeze landfill to Minamihonmoku landfill on September 14, 2011
  • Till as explanation was inadequate for people concerned, give enough explanations, landfill "freeze"
  1. The explanation situation to citizen, the person concerned
  • Using information which explained contents of "safe evaluation examination book about landfill of sewage sludge destruction by fire ash to management type disposal ground" clearly, we explained to citizen, the person concerned.
  1. We suggested and explained future correspondence plan of sewage sludge destruction by fire ash in various places of citizen, the person concerned in September, 2013.

Oh, as the first stage, we utilize when we make occurring destruction by fire ash land of disposal ground every day and examine landfill

About destruction by fire ash which has already kept i in the sewer facility, we examine the future handling

We promote utilization as resources in cormorant lower water sludge sequentially

(we follow clearance level (100 becquerels/kg or less) surely, and exploitation of resources as use of improved soil plans exploitation of resources sequentially.)

  1. We start exploitation of resources as construction material in addition to exploitation of resources as past improved Hijiwara charges in July, 2014.
  2. We carry out examination landfill in Minamihonmoku refuse landfill of mixed ash which mixed garbage main ash and sewage sludge destruction by fire ash of Resources and Waste Recycling Bureau for from February to March in 2015.
  3. We start landfill by method like examination landfill in July, 2015.
  4. We finish landfill in Minamihonmoku refuse landfill in September, 2017.

Change of the storage situation and the radiological density of destruction by fire ash

The storage situation of the present and past sewage sludge destruction by fire ash is as follows.
The storage situation (PDF: 847KB) of sewage sludge destruction by fire ash

The storage situation of sewage sludge destruction by fire ash approached to about 38,000 tons in the south, northern part sludge exploitation of resources center at peak hour, but disposal advances and gradually decreases. However, it is in a situation that we cannot but put in the hall and influences facility administration.
On the other hand, the radiological density of sewage sludge destruction by fire ash decreases to about 1 per 50 in comparison with the beginning of storage start.

The radiological density of sewage sludge

It is result of a measurement of radioactive material levels of inflow sewage, discharge water, dewatering sludge, sludge destruction by fire ash, improvement soil in Motoichi sewer facility and inning disposal mixture ash in Minamihonmoku refuse landfill.

  1. Inflow sewage, discharge water
  1. Dewatering sludge, sludge destruction by fire ash, improved soil
Unit (becquerel /kg)
NameNorthern sludge exploitation of resources centerSouthern sludge exploitation of resources center

Dewatering sludge

Sludge destruction by fire ash

Improved soil

Dewatering sludge

Sludge destruction by fire ash

Sampling day2020
December 21
2020
December 28

2020
December 28

2020
December 7

2020
December 28

Cesium 134The non-detectionThe non-detectionThe non-detectionThe non-detectionThe non-detection
Cesium-137

The non-detection

36.06.0The non-detection

40.0

※We show that it is less than fixed-quantity lower limit level with the non-detection.

※About iodine 131, we began the measurement for index to confirm influence of nuclear plant accident, but, based on half-value period of iodine 131 having already passed more than three years for 8th, we remove from measurement item from September 1, 2014 and itemize 2 of cesium 134 and cesium-137.

In addition, sludge destruction by fire ash keeps in the northern part and site of southern sludge exploitation of resources center.

  1. Inning disposal mixture ash

We carried out examination landfill in Minamihonmoku refuse landfill of mixed ash which mixed garbage main ash and sludge destruction by fire ash of Resources and Waste Recycling Bureau for from February, 2015 to March. We confirmed safety by examination landfill and carried out landfill from July, 2015 to September, 2017 as air dose and radioactive material concentration were able to confirm security afterwards without abnormality being recognized.

Unit (becquerel /kg)
DateSeptember 15, 2017
Mixed ash cesium concentration83.5
  • Past radioactive material concentration data PDF (PDF: 63KB) excel (Excel: 50KB) 
  • As we fill up in September, 2017 and finished disposal, about inning disposal mixture ash, there will not be update in future.

Space emission dose rate of site border

Unit (in microsievert/) 
NameThe east sideThe westThe south sideThe north sideThe measurement day
Northern sludge exploitation of resources center (Suehirocho, Tsurumi-ku)0.050.050.050.06

2020
December 21

Southern sludge exploitation of resources center (Sachiura, Kanazawa-ku)

0.05

0.050.050.05

2020
December 21

※We measure at point of 1 meter in height from ground

Radioactive material concentration in effluent gas

It was the non-detection about effluent gas.

Materials

※As for "the radioactive exposure around the figure 3-4 body" of these 20 pages of explanation materials, data of origin of quotation are updated. Please refer to the following URLs for the details.
http://jccu.coop/food-safety/qa/pdf/qa03_03_02.pdf (the outside site)


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Environmental Planning Bureau sewer Facilities Department sewer facility management section

Telephone: 045-671-3965, 3966

Telephone: 045-671-3965, 3966

Fax: 045-641-4870

E-Mail address [email protected]

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