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BOD, evaluation method of environmental standard of COD

Last update date October 9, 2019

In this page, annual result of a measurement of BOD (river) or COD (sea area) speaks the Environmental Agency notification about evaluation method (75% value evaluation) to judge how about adapting to environmental standard.

Evaluation methods of environmental standard that annual result of a measurement of BOD or COD adapts to environmental standard are as follows.

(extract)

July 1, 1977
Ring water pipe No. 52

About evaluation method of water quality measurement result when we appoint topology of water regions of 1 environmental standard
We evaluate water quality measurement result to apply topology of water regions of environmental standard with ratio of number of the data meeting the standard value of type that we are going to apply among all data of the days mean through the year, but judge to adapt to the standard when there is the ratio more than 75%.
In addition, we shall use "the 75% quality of the water value" that we found by the following methods when we judge degree of the quality of the water in comparison with environmental standard.
The 75% quality of the water level
Line up from small thing of the value sequentially and do all data of the annual days mean with the 75% quality of the water level with data level of 0.75 X n joint (in n the number of the data of the days mean). (when 0.75 X n is not integer, we assume value of integer joint which rounded off fraction.)
About judgment method about compatibility for environmental standard of water quality measurement result in 2 environment thresholds
When we determine whether you met environmental standard through the year in the environmental threshold, among data meeting the standard value of type that we are going to apply among all data of the mean like 1 on day through the year, 75% or more of data judge threshold satisfying the standard value to adapt to standard.
About judgment method about compatibility for environmental standard of water quality measurement result in area of the sea having environmental threshold of plural 3
When we apply the environmental standard type concerned and meet environmental standard in all environmental thresholds in area of the sea about this, we judge that the area of the sea concerned achieves environmental standard.

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