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Abstract: From the environmental point of view, the textile industry dealing with operations such as fibre and fabric preparation, dyeing, finishing, printing etc. can be identified among the very chemical intensive sectors. Therefore the characterisation and management of textile auxiliaries within aqueous dyehouse effluents are becoming a challenging responsibility for the textile manufacturer. Although there is much speculation about the types and quantities of these chemicals released to the environment during textile manufacturing, there are only few data about the behaviour of these chemicals both in receiving water bodies and in wastewater treatment systems. Besides current understanding of industrial pollution control emphasizes the relevance of segregated stream management. This issue gains a further importance when segregated effluent streams containing auxiliaries with xenobiotic nature are considered. In this context the objective of the present study is to investigate the effect of ozonation on the toxicity and biodegradability of a naphthalene sulphonic acid derivative commonly applied in textile mills. The naphthalene sulphonic acid derivative prepared to simulate the actual situation in a dyebath discharge from a textile finishing industry has a COD of 1150mg/l and a BOD of 10mg/l, and pH of 5.5. Due to the highly soluble characteristic of the sulphonic groups the sample is completely soluble in nature. Ozonation experiments [conducted under the following conditions: 1200mgO3/h and 2400mgO3/h both at pH 5 and pH 11; 5325mgO3/h at both pH 12 and at the original pH (pH=5.5)] show that the application of 5325mgO3/h ozone for 30min at original pH can be considered as the optimum condition which is further evaluated in terms of inert COD fractions and acute toxicity. According to the experimental findings, raw naphtalene sulphonic acid derivative has an inert COD content of 1027mg/l. With ozone application of 30min 5325mgO3/h at original pH the inert COD concentration can be reduced down to 295mg/l. The molecular weight cut-off experiments indicate that 58% of the COD originates from the 10kDa–30kDa fraction for the raw naphtalene sulphonic acid derivative. Due to chemical degradation under ozone, the fraction with the highest COD shifted to the <1kDa range for the ozonated naphtalene sulphonic acid derivative. Since the results related to the acute toxicity (in 50% v/v EC values) towards the marine algae Phaeodactylum tricornutum indicate that the toxicity of the formulation under investigation is increased considerably, it is recommended to run a further investigation by the use of another chemical oxidant instead of ozone. [Copyright &y& Elsevier]

The aim of this study was to investigate the effects of dyes, salts and auxiliary chemicals in reactive dye baths on the separation performance of nanofiltration membranes. A reactive dye bath was simulated for this purpose with auxiliary chemicals. A DS5-type nanofiltration membrane was used in the experimental runs. Performance of the nanofiltration membrane was evaluated by measuring permeate flux, salt and color rejections in five steps. Reactive black 5, reactive orange 16, NaCl, NaOH, Na2SO4, acidic acid, mollan and slipper were used to prepare synthetic dye baths. Pressures in the range of 8 to 24 bars were applied, and flow velocity was kept constant at 0.74 m/s. NaCl rejection of 20% and color rejection of more than 95% were achieved throughout the experiments. Permeate quality was satisfactory enough to recycle these effluents in reactive dyeing. Acidification ofthe original synthetic dye bath solution with HCl and H2S04 decreased the membrane fouling and also increased the NaCl recovery and color rejection. Besides, using HCI instead of H2SO4 increased these positive effects. The effects of auxiliary chemicals were determined by using salt rejection model parameters of α and kD in the presence of an organic ion. There was a correlation among the results of experiments and the model. The model parameters (α and kD were also calculated for all steps. [Copyright &y& Elsevier]