1. Introduction to Domestic Sewage

Domestic sewage refers to wastewater discharged from daily residential activities, primarily originating from residential and public buildings such as homes, institutions, schools, hospitals, shops, public places, and industrial enterprise restrooms.

2. Classification of Domestic Sewage

Based on the environmental function and protection objectives of surface water bodies into which urban sewage treatment plants discharge, as well as the treatment processes used, the conventional pollutant standards for basic control items are classified into Level 1, Level 2, and Level 3 standards.

Level 1 standards are further divided into Standard A and Standard B. Heavy metal pollution and selective control items are not graded.

a. Standard A of Level 1 is the basic requirement for treated water from urban sewage treatment plants to be reused as reclaimed water. When the treated water is introduced into rivers or lakes with limited dilution capacity for purposes such as urban landscape water use and general reclaimed water applications, Standard A of Level 1 applies.

b. When treated water from urban sewage treatment plants is discharged into GB3838 Class II functional surface water bodies (excluding designated drinking water source protection zones and swimming areas), GB3097 Class II seawater functional zones, and enclosed or semi-enclosed water bodies like lakes and reservoirs, Standard B of Level 1 applies.

c. When treated water is discharged into GB3838 Class IV or V functional surface water bodies or GB3097 Class III or IV seawater functional zones, Level 2 standards apply.

d. For sewage treatment plants in non-key control basins and non-source water protection areas in towns, where enhanced primary treatment processes are adopted based on local economic conditions and water pollution control requirements, Level 3 standards apply. However, facilities for secondary treatment must be reserved, and compliance with Level 2 standards must be achieved in phases.

3. Hazards of Domestic Sewage

(1) Pathogen pollution

(2) Oxygen-consuming organic pollution

(3) Eutrophication pollution

(4) Odor pollution

(5) Acid, alkali, and salt pollution

(6) Increased groundwater hardness

(7) Toxic substance pollution

4. Testing Process

(1) Communicate to understand the relevant situation of the enterprise or unit.

(2) Our company provides testing solutions and quotations.

(3) Schedule an appointment via phone, prepare in advance, and our inspectors will collect samples on-site.

(4) Laboratory testing is conducted, and test reports are issued.

(5) If required by the customer, professional interpretation of the report can be provided.

5. Relevant Standards

"Pollutant Discharge Standards for Urban Sewage Treatment Plants" GB18918-2002