In February ChemLinked reported that some wastes produced during the manufacture of the water based coatings were going to be removed from the Inventory of Hazardous Wastes by amendment. The Ministry of Environmental Protection (MEP) officially released the final version of the Inventory and water based coating waste is not included in the inventory.
The new version of the Inventory of Hazardous Wastes makes several major changes to the former one. Four hazardous waste codes concerning the water based coating industry are modified under the category HW12 (wastes from dyes and coatings) as follows:
Category | Source | Waste Code | Hazardous Waste | Hazardous Property |
HW12 Wastes from dyes and coatings | Manufacture of coatings, printing inks, pigments and similar products | 264-011-12 | Waste mother solution, residues and waste intermediates during the manufacture of printing inks, dyes, pigments and paints (excluding water based coatings) | T |
264-012-12 | Sludge and adsorbents for waste water treatment during the manufacture of printing inks, dyes, pigments and paints (excluding water based coatings) | T | ||
No specific industry | 900-251-12 | Wastes produced during the block layer application of paints (excluding water based coatings) and organic solvents | T, I | |
900-252-12 | Wastes produced during the spray of paints (excluding water based coatings) and organic solvents | T, I |
Despite some preferential policies carried out by the government (such as VOCs emission charges), the water based coating industry has been struggling in China’s market. Take the furniture industry for example, the market penetration of water based coatings is just 10%, 20 years after they entered the market. So undoubtedly this amendment is welcomed by the water based coating industry, whose production cost will be remarkably reduced due to lack of hazardous wastes treatment equipment and processing. However, the change has raised some controversy and debate on whether the authorities should completely ignore water based coatings.
The fundamental advantage of water based coatings over the traditional solvent based coatings is that they use water based solvents instead of organic ones. This new technique hugely reduces the VOCs emission during the manufacture and application and thus poses less risk to the environment and human beings. However, there are still many other chemicals involved in the production of water based coatings, such as resins, pigments, auxiliaries etc. Some of these chemicals will remain in the production wastes and thus wastes shouldn’t be regarded as totally safe without further tests and supervision.
Water based coatings have better hazardous waste gas profiles compared with solvent based coatings however solid and water wastes might be a problem. One of the major treatments for solid wastes is incineration. The combustion of many hazardous solid wastes will produce dioxins (highly toxic environmental persistent organic pollutants) at a temperature of 200~300℃. So the incinerator for hazardous solid wastes are specially designed to shorten the incineration stage at 200~300℃ to reduce the production of dioxins. After incineration, the ashes should be kept in special concrete containers and buried at designated landfills. Now that the water based coating wastes are removed from the inventory of hazardous wastes, the treatment of these wastes will be simplified and might pose a serious risk to the environment.
Water waste is another issue. The water based coating industry has been suffering from a lack of technical capacity in treating waste water. The flocculation, COD (chemical oxygen demand) exceeding the limit, bio-degradation are all technical obstacles in the waste water treatment of water based coatings that haven’t been solved completely. Once the authorities loosen the supervision and restrictions on waste treatment, the industry will lose the incentive to further improve the treatment techniques and therefore harm the environment.
The newly published Inventory of Hazardous Wastes is extremely beneficial for the water based coating industry. However it would be foolish to reduce VOCs and other waste gases at the expense of increasing hazardous solid and water wastes. The authorities should still keep an eye on the waste treatment development of the water based coating industry.
