About partial revision such as the Yokohama-shi sewer regulations in 2009

Last Updated July 19, 2024

At the 1st regular meeting of the Yokohama City Council in 2009, a part of the Yokohama City Sewerage Ordinance (hereinafter referred to as the "Ordinance") was revised and promulgated on March 5. As a result of this revision, nitrogen and phosphorus regulations have been added to business wastewater discharged to public sewers. In addition, along with this, some of the Yokohama City Sewerage Ordinance Enforcement Regulations (hereinafter referred to as "rules") were revised, promulgated on May 15, and the number of water quality measurements was added, so these contents were announced I will let you know.

1 Revision of Ordinance

(1)　Water quality standards (Related to Article 6 and Article 8-2 of the Ordinance)

Table 1 Water Quality Standards
Regulation items	Target business sites for each inflow area and amount of wastewater
	The treated water at the Water Reclamation Center Areas that flow into Tokyo Bay		The treated water at the Water Reclamation Center Area that flows into Sagami Bay
	50 m3/day Above	50 m3/day Less than	50 m3/day Above	50 m3/day Less than
Nitrogen content	120 mg/L Less than	―	―	―
Phosphorus content	16 mg/L Less than	―	―	―
Ammonia Nitrogen, etc. content	Less than 380 mg/L

(Note) Ammonia nitrogen, etc. content: Ammonia nitrogen, nitrite nitrogen, nitrite nitrogen and nitrate nitrogen content

Water Reclamation Center where treated water flows into Tokyo Bay: Northern 1st, Northern 2nd, Kanagawa, Chubu, Southern, Kanazawa, Kohoku, Tsuzuki
Water Reclamation Center where treated water flows into Sagami Bay: West, Sakae Daiichi, Sakae Daini

Regarding nitrogen content and phosphorus content, the wastewater standards stipulated in the Ordinance of the Ministry of the Environment apply to wastewater from business sites where the daily amount of effluent to Tokyo Bay is 50 m3 or more. Business sites where the treated water flows into Tokyo Bay and the average amount of discharged water per day is 50 m3 or more.
Regarding the content of ammonia nitrogen, etc., all business establishments that discharge to public sewers are eligible.
The Ministry of the Environment Ordinance sets gentle standards for industries where it is difficult to comply with drainage standards, so even in the ordinance, the standards of the Ministry of the Environment Ordinance shall be applied to applicable industries.

(2)　Effective Date (Supplemental Ordinance)

October 1, 2009

(3)　Transitional measures (supplementary regulations)

A. Provisional Standards

Table 2 Provisional Standards
Regulation items	Target business sites for each inflow area and amount of wastewater				Provisional standards Applicable period
	At the Water Reclamation Center The treated water goes to Tokyo Bay Area to flow in		At the Water Reclamation Center The treated water goes to Sagami Bay Area to flow in
	50 m3/day Above	50 m3/day Less than	50 m3/day Above	50 m3/day Less than
Nitrogen content	240 mg/L Less than	―	―	―	For the time being
Phosphorus content	32 mg/L Less than	―	―	―	For the time being
Ammonia Nitrogen, etc. content	(As shown in Table 1)	760 mg/L Less than	(As shown in Table 1)	760 mg/L Less than	From the date of enforcement September 30, 2014 Up to

B. grace period

The water quality standards for nitrogen and phosphorus for wastewater from existing business sites do not apply until March 31, 2010.

2. Revision of Rules

(1)　Measurement of water quality (Article 16 of the Regulations)

Table 3 Measurement of Water Quality
Water quality items	Number of measurements
Ammonia nitrogen, nitrite nitrogen, nitrite nitrogen and nitrate nitrogen content Nitrogen content Phosphorus content	If the average amount of effluent per day is less than 20 m3, at least once every drainage period that does not exceed 3 months.
	If the average amount of effluent per day is between 20 m3 and less than 50 m3, at least once every drainage period that does not exceed 2 months.
	If the average amount of effluent per day is 50 m3 or more, at least once per drainage period that does not exceed one month.

(Note) Regarding nitrogen content and phosphorus content, the wastewater standards stipulated in the Ordinance of the Ministry of the Environment apply to wastewater from business sites where the daily amount of effluent to Tokyo Bay is 50 m3 or more. Business sites where the treated water from the center flows into Tokyo Bay and the average amount of discharged water per day is 50 m3 or more.

(2)　Effective Date (Supplemental Provisions)

October 1, 2009

(3)　Transitional Measures (Supplemental Provisions)

A. grace period

Measurement of nitrogen and phosphorus water quality from wastewater from existing business sites will not be applied until March 31, 2010.

３　Yokohama-shi sewer regulations old and new comparison table (summary version) (PDF: 112KB)

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