HDPE MBBR Filler Full QC Inspection Standard

1. Incoming Raw Material Inspection (IQC)

Purpose: To ensure that only genuine virgin HDPE is used; the addition of recycled material is strictly prohibited.

Test Items	Standard Requirements	Test Methods
Grades and Certifications	In accordance with the procurement requirements, a Certificate of Analysis (COA) must be provided.	Verify Documents
Density	0.940～0.970 g/cm³	Impregnation method according to GB/T 1033
Melt Flow Rate (MFR)	Within the tolerance limits specified for the designated grade	In accordance with GB/T 3682
Appearance	The granules are uniform in size, free of impurities and black spots.	Visual Inspection

2. In-Process Quality Control (IPQC)

Purpose: Timely detect defects during injection/extrusion molding to avoid mass non-conforming products.

2.1 First Article Inspection

Appearance: Uniform color (normally white/natural color), free of bubbles, cracks and obvious sink marks.
Dimension: Measure outer diameter, height and wall thickness with calipers, compare with drawings; deviation shall be within ±5%.
Weight: Weigh 10 pcs to control weight fluctuation range.

2.2 Patrol Inspection (once every 1–2 hours)

Check mold flash, burrs, product scratching & deformation.
Verify cooling shaping effect to prevent product adhesion.
Spot check process parameters: temperature, pressure, cycle time.

3. Finished Product Performance Inspection

Sampling Plan: In accordance with GB/T 2828.1, adopt single sampling plan for normal inspection. The AQL for general appearance is 1.5, and the AQL for functional items is 0.65. A minimum of 3 samples shall be taken for performance testing per batch.

3.1 Physical & Mechanical Properties

Test Items	Technical Index (CJ/T 461)	Test Methods
Filler Density	0.940～0.970 g/cm³	GB/T 1033
Tensile Strength	≥20 MPa	GB/T 1040, prepare test strips from finished filler
Elongation at Break	≥350%	GB/T 1040
Charpy Impact Strength (unnotched)	≥6 kJ/m²	GB/T 1043

3.2 Hydraulic & Structural Characteristics

Core functional indicators of MBBR filler, directly affecting biofilm attachment efficiency and fluidization energy consumption.

Test Items	Technical Index	Brief Test Method
Effective Specific Surface Area	≥500 m²/m³ (common specifications reach over 800)	Liquid discharge method + calculation per Appendix A of CJ/T 461
Porosity	≥90%	Water drainage method: calculate (Bulk Volume - Skeleton Volume) / Bulk Volume
Density after Biofilm Attachment (optional test)	Density close to water (slightly higher than 1.0 g/cm³)	Test apparent density after rapid biofilm cultivation

3.3 Environmental Resistance Performance (Type Inspection / Annual Inspection)

Item	Test Condition	Requirement
Heat Resistance	Soak in 80℃ hot water for 72h continuously	No cracks or obvious deformation; tensile strength retention rate ≥80%
Freezing Resistance	Store at -25℃ for 24h	No obvious drop in impact strength

4. Outgoing Quality Control (OQC)

Packaging: Confirm breathable woven bags / bulk jumbo bags with inner protective lining.
Marking: Clear labeling of product name, specification, batch number, production date, net weight and executive standard.
Quantity Verification: Recheck weight to confirm weight tolerance per bag.
Final Appearance Sampling: Re-inspect before/after bagging to eliminate crushed & deformed products caused by transportation.

5. Loading Inspection

Loading workers conduct final outer package inspection for every bag. Foam boards are placed inside containers to guarantee complete and intact delivery to customers.

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