Compliance Requirements for Environmental Emissions of Injection Molding Production in China
2026-06-30 11:57:35
Chinese Injection Molding
In China, injection molding plants generate four major pollutants including waste gas, wastewater, solid waste and noise. All emission control must comply with mandatory national standards, supplemented by stricter local limits. Enterprises need to meet standards for pollutant concentration, pollution control equipment operation and on-site management simultaneously to achieve full compliance. This article sorts out the standardized emission requirements under China’s environmental regulatory system, with a total word count of about 890.
1. Waste Gas Emission Compliance Standards for Domestic Injection Molding WorkshopsWaste gas is produced during melting, mold opening, crushing and material drying, with key controlled pollutants including non-methane total hydrocarbons, styrene, toluene, particulate matter and odor. Three-layer supervision covering organized exhaust, in-plant fugitive emission and factory boundary shall be implemented according to GB 31572-2015 and GB 37822-2019.
For organized exhaust stacks, general limits set non-methane total hydrocarbons ≤100mg/m³ and particulate matter ≤30mg/m³, while key regions implement special strict limits of 60mg/m³ and 20mg/m³ respectively. Most Yangtze River Delta and Pearl River Delta regions further tighten the limit to 50mg/m³ or lower. Exhaust stacks must be at least 15 meters high with standard sampling ports, without bypass pipelines for direct discharge.
2. Wastewater Treatment and Discharge Standards in Chinese Injection Molding FactoriesThree types of wastewater exist: circulating cooling water, domestic sewage and cleaning wastewater. Enterprises must implement separate rainwater and sewage pipelines as the basic hardware requirement.Cooling water for molds and equipment shall operate in fully closed circulation without random discharge. Domestic sewage after septic tank and oil separator pretreatment shall meet Grade 3 limits of GB 8978-1996 before entering municipal pipe networks, with COD ≤500mg/L, SS ≤400mg/L and ammonia nitrogen ≤45mg/L. Wastewater from waste gas spray cleaning and mold oil washing cannot be directly discharged; it shall be collected separately as hazardous waste and transferred to qualified disposal units.All ground cleaning water and material leakage liquid must flow into sewage collection tanks, with interception gates set at rainwater outlets to prevent rainwater from carrying oil and plastic residues out of the factory. The pH value of treated effluent shall stably remain between 6 and 9.
3. Classified Disposal Standards for Solid Waste Stipulated by China’s Hazardous Waste RegulationsSolid waste is divided into general industrial solid waste, hazardous waste and domestic garbage under GB 18597-2023. Clean plastic leftover materials, defective products and head materials belong to general solid waste, which can be crushed and reused internally or sold to qualified recyclers, stored in windproof and rainproof yards with complete production ledgers.
Hazardous waste includes waste activated carbon, waste filter cotton, waste lubricating oil, oil-stained rags and waste oil drums. Independent closed hazardous waste temporary storage rooms with anti-seepage floors, diversion ditches and emergency barrels are mandatory. Each category shall be labeled clearly and stored in separate partitions. All transfers adopt five-part waybills, with ledgers preserved for more than 5 years, and private burial or resale to unlicensed parties is strictly prohibited. Domestic waste is collected separately and transported by municipal sanitation departments without mixing with industrial waste.
4. Factory Boundary Noise Compliance Limits and Supporting MeasuresNoise sources include injection molding machines, crushers, air compressors and cooling towers, complying with GB 12348-2008. Factories in industrial Category 3 areas shall control noise within 65dB(A) in daytime and 55dB(A) at night; those adjacent to residential areas under Category 2 standards shall keep noise below 60dB(A) by day and 50dB(A) at night. Supporting facilities such as equipment shock-absorbing pads, fan sound insulation covers and independent sound insulation compartments for crushers are required. High-noise crushing procedures should be avoided during night hours to prevent continuous loud noise exceeding limits at factory boundaries.
5. Full-Process Administrative Compliance Mandatory for Domestic Injection Molding EnterprisesConcentration compliance alone cannot pass environmental inspections; enterprises must complete environmental impact assessment and acceptance procedures, apply for pollutant discharge permits and operate strictly within licensed indexes. Key polluting units shall install online monitoring equipment for non-methane total hydrocarbons and COD, uploading real-time data to ecological environment platforms without tampering or shielding.Enterprises shall establish complete ledgers covering activated carbon replacement, hazardous waste inbound and outbound records, equipment operation and self-monitoring reports. Priority shall be given to low-VOC raw materials, low-volatility release agents and cleaning agents to reduce pollutant generation from the source, meeting basic clean production indicators required by local authorities.
