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 polluting substances from wastewaters of textile industries. Both pilot plants used reproduced very closely a full-scale treatment in order to obtain indications about the feasibility of a transfer on industrial scale. By means of ozone treatment very high colour removal (95–99%) was achieved and treated waters were reused satisfactorily in dyeing even with light colours. This evidence despite the fact that the chemical oxygen demand of treated waters was still in a range (75–120 mg/l, a decrease up to 60%) that was usually considered 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 filtration are absolutely essential. The transfer on industrial scale of the treatment is currently under development under an already financed European project. Electrochemical treatment showed to be very efficient in removing colour (80–100%) and chemical oxygen demand (70–90%). Moreover, a sensible decrease of chloride and sulphate ions was detected. Removal of flocculated material (post-treatment) must be, however, perfected in order to establish a correct costs-to-benefits ratio and therefore, propose an implementation of the technique on an industrial scale.