The treatment and reuse of wastewater in the textile industry by means of ozonation and electroflocculation

Two different oxidation treatments, ozonation and electroflocculation, were experimented on a pilot scale to test their efficiency in removing polluti ng substances from wastewaters of textile industries. Both pilot plants use d reproduced Very closely a full-scale treatment in order to obtain indicat ions about the feasibility of a transfer on industrial scale. By means of o zone treatment very high colour removal (95-99%) was achieved and treated w aters were reused satisfactorily in dyeing even with light colours. This ev idence despite the fact that the chemical oxygen demand of treated waters w as still in a range (75-120 mg/l, a decrease up to 60%) that was usually co nsidered to be too high for recycling purposes, especially for dyeing light colours. Treating plants working at the above-mentioned conditions should guarantee low operating costs. A biological pre-treatment and a sand filtra tion are absolutely essential. The transfer on industrial scale of the trea tment is currently under development under an already financed European pro ject. Electrochemical treatment showed to be very efficient in removing col our (80-100%) and chemical oxygen demand (70-90%). Moreover, a sensible dec rease of chloride and sulphate ions was detected. Removal of flocculated ma terial (post-treatment) must be, however, perfected in order to establish a correct costs-to-benefits ratio and therefore, propose an implementation o f the technique on an industrial scale. (C) 2000 Elsevier Science Ltd. All rights reserved.