Enterprises in the textile industry are the most environmentally polluting enterprises. The main emission source results from fabric design, where decorative design or text is applied using various screen printing methods. This process leads to recalcitrant molecules and Volatile Organic Content (VOC) gas in the production of wastewater. Applying environmental constraints requires efficient functioning of air or water flows to ensure a healthy working environment and to avoid contaminated water receivers. In many plants, jeans or other garments are often bleached to create a “washed” look. Ozone applications in the textile industry is a great benefit for cutting costs and achieving great results.
In the textile industry, the effective method of reducing operational costs and reducing environmental emissions compared to traditional techniques is ozonation.
Ozonization for screen printing emissions:
Ozone technology is an effective method to treat organic molecules in both wastewater and VOC by oxidation. Wastewater typically contains a high level of COD with a COD: BOD ratio of 4: 1 to 5: 1.
Ozone not only oxidizes organic pollutants, but it can also convert the biodegradable COD into easily biodegradable BOD, then reduce the ratio of COD: BOD for biological treatment. Depending on the COD and BOD concentration, ozone can oxidize most of the compounds that reduce wastewater load to acceptable legal levels.
The ozone system for textile wastewater saves significant operating costs and reduces operational footprint.
Burning VOC fugitive gases by burning is an effective but very costly method. Ozone can be applied in place of the burning process with high energy consumption and can decrease operating costs by 1000 times.
Ozone reacts effectively with these pollutants in the gas phase compared to typical processes by combustion of volatile compounds. This eliminates the main energy demands following the combustion process. Ozone for VOC gases typically has been found that ozone treatment with secondary polishing reduces VOC gases by 90% to completely reduce fugitive gases.
In modern design garment production, fabrics such as jeans are bleached by chemicals using oxidation to achieve a washed look.
The high oxidative properties of ozone provide a sustainable bleaching method without excessive chemical treatment or cost. In addition, as a result of bleaching by ozonation, no by-products are formed.
Textile wastewater is treated in the field, mostly using biological wastewater treatment processes. This can result in an approximately 90% reduction in incoming COD and BOD. The remaining COD and BOD can still generate significant environmental loads. Typically, it is not possible to remove the discolouration of the wastewater caused by the textile production described above.
Ozone is a very effective colour removal technology as part of the tertiary treatment step. Depending on the ozone capacity, full-colour removal can be achieved with 5-15 minutes of ozone exposure.