A recent study in Scientific Reports by Vishal Kumar U. Shah, Pratima Gajbhiye, Anand Mohan Yadav, Jay B. Trivedi, Aparna Singh, Aditee Pandya, Xu Yong, Choon Kit Chan, Saurav Dixit, Anand Patel, and Md irfanul Haque Siddiqui demonstrates that an integrated treatment process utilizing chemically modified Canna indica plant biochar combined with an ozone gas treatment eliminates 96.90 percent of chemical oxygen demand and 99.10 percent of color from highly contaminated real-world textile factory wastewater.

The global economy benefits immensely from operations tied to textile, dye, and pigment production, yet these manufacturing plants generate vast quantities of dark wastewater that lacks natural biodegradability. When dumped directly into waterways without processing, even minuscule concentrations of dye block vital sunlight penetration and stop photosynthesis in aquatic plants, while adding unpleasant odors and tastes to the ecosystem. Historically, researchers evaluated a wide array of separate chemical, biological, and physical filtration setups to handle industrial runoffs, but single treatment methods struggle to eliminate both the high chemical oxygen demand and the complex artificial coloring found in actual industrial factory mixtures. This research overcomes past performance limitations by successfully joining agricultural waste reuse with advanced oxidation to treat genuine wastewater gathered from an active printing and dyeing plant located in Surat, India.

The research focuses heavily on the direct treatment outcomes of raw plant charcoalCharcoal is a black, brittle, and porous material produced by heating wood or other organic substances in a low-oxygen environment. It is primarily used as a fuel source for cooking and heating.   More that was modified using either potassium hydroxide or sodium hydroxide to boost final extraction performance. When tested under optimized conditions, the potassium hydroxide treated charcoal reduced the initial chemical oxygen demand of the real effluent by an impressive 96.90 percent at a dosage of 2.5 grams per liter under a neutral to slightly alkaline environment. Simultaneously, the sodium hydroxide treated charcoal showed specialized efficiency for decolorization, achieving a near perfect color removal rate under highly comparable operating environments. This represents a significant breakthrough for practical industrial setups because the raw textile effluent naturally possesses an alkaline nature, meaning factory operators can implement this combined purification system directly without purchasing expensive chemical additives to constantly adjust the acidity of the fluid.

A deep evaluation of how the pollutants interact with the charcoal reveals that chemical sorption acts as the dominant mechanism during the main cleaning cycle, creating permanent chemical bonds between the organic dye molecules and the active functional groups on the filtering material. The absolute order of importance for controlling the purification process was determined to be the background acidity or alkalinity, followed by the specific charcoal dosage, the total contact duration, and finally the ozone flow rate. The maximum theoretical adsorption capacities reached high levels, with the potassium modified version achieving a higher performance than the sodium version due to a superior internal pore layout that grants structural accessibility to large, stubborn pollutant molecules. When ozone gas is bubbled into the fluid after the primary charcoal filtering step, it generates highly reactive oxygen radicals that rapidly snap the remaining double bonds of the dissolved dyes, pushing the total purification efficiency beyond the limits of standalone filtration.

Source: Shah, V. K. U., Gajbhiye, P., Yadav, A. M., Trivedi, J. B., Singh, A., Pandya, A., Yong, X., Chan, C. K., Dixit, S., Patel, A., & Siddiqui, M. I. H. (2026). Integrated adsorption-ozonation process using activated canna indica biochar for enhanced COD and color removal from real textile effluent. Scientific Reports.