Application of ozone in textile wastewater treatment

Textile wastewaters are known to be highly resistant to biodegradation under both natural and wastewater treatment plant conditions. However, ozonation can be used to increase the biodegradability of the biologically resistant compounds. The combined method of ozonation and subsequent biodegradation of both synthetic and real textile wastes was explored in laboratory-scale studies. Two kinds of industrial wastes were simulated for effluents from dyehouse and washing machines. Upon determining the ozonation conditions of synthetic wastes, the real industrial wastes were investigated. The real textile wastewater was taken from textile factories, located in Lodz, Poland, from subsequent stages of textile processing; dyeing, washing, rinsing and from an equalizer tank. Ozonation was carried out in a lab-scale bubble column sparged reactor, while the biological degradation proceeded in a trickle bed biofilter. The effluents before and after the treatment were analyzed according to requirements of the Polish Standards, which included: pH, color threshold, COD and BOD5, concentration of anionic and non-ionic surfactants, and soluble substances. The ozonation of wastes resulted in an essential increase of biodegradation effectiveness, so only the combination of both methods enables an almost complete degradation of toxic substances and may contribute to conserving and recycling of water in textile factories.