The generation of high-coloured wastewater is one of the main environmental problems of the textile industry. Reactive dyes are widely used in the dyeing of cellulosic fibres. However, they have low exhaustion degree (70–90%). The degradation of residual dyes by aerobic biological treatment is very poor, being necessary the application of specific treatments. In this work, three different methods for the removal of reactive dyes were compared: electrochemical treatment, coagulation with Moringa oleifera waste and enzymatic treatment with laccase. Two azo bifunctional dyes with different reactive groups were selected: C.I. Reactive Black 5 (vinyl sulphone) and C.I. Reactive Red 231 (chlorotriazine). The influence of pH (5 and 9) and dye hydrolysis on the decolourisation yield was studied. The electrochemical treatment was the most efficient, with 95–100% colour removal yield. The coagulation with M. oleifera waste also achieved high colour removal efficiency (91–94%). Both methods showed an independent behaviour with respect to pH or dye hydrolysis. The enzymatic treatment should be performed at pH 5. This method was suitable to remove the chlorotriazine dye (92–93% efficiency), whereas the vinyl sulphone one showed a marked dependence on dye hydrolysis: moderately efficient for the hydrolysed dye and highly efficient without hydrolysis. The activity of laccase was not modified by the usual salinity of the reactive dyeing effluent (20 g/L NaCl). Nevertheless, the effluent salinity enhanced the electrochemical and M. oleifera treatment yield.
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机译：高色废水的产生是纺织工业的主要环境问题之一。活性染料被广泛用于纤维素纤维的染色。但是，它们的疲劳度较低（70-90％）。通过好氧生物处理对残留染料的降解非常差，这是应用特殊处理的必要条件。在这项工作中，比较了三种不同的去除活性染料的方法：电化学处理，用辣木废料混凝和用漆酶进行酶处理。选择了两种具有不同反应性基团的偶氮双功能染料：C.I.。活性黑5（乙烯基砜）和C.I.活性红231（氯三嗪）。研究了pH（5和9）和染料水解对脱色率的影响。电化学处理是最有效的，具有95-100％的脱色率。油橄榄分枝杆菌废物的凝结也达到了较高的脱色效率（91-94％）。两种方法均显示出有关pH或染料水解的独立行为。酶处理应在pH 5下进行。此方法适用于去除氯三嗪染料（效率为92–93％），而乙烯基砜显示出对染料水解的显着依赖性：对水解的染料适度有效，而对不水解的则为高效水解。漆酶的活性未因反应性染色废水的通常盐度（20 g / L NaCl）而改变。然而，废水的盐度提高了电化学和油分枝杆菌处理的产率。
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