Radiation Processing of Wastewater and Possibilities for Reuse

In the framework of the CRP IPEN has worked on the irradiation and toxicity assessment for the improvement of dyes standard solutions and real complex effluents (textile) in order to achieve recommended quality for reuse of treated effluents during the process as well as for a suitable environmental discharge. Three different types of effluents were submitted to irradiation including standard solution of two reactive dyes (Remazol Black B - RPB and Remazol Orange 3R – R3AR). It was also identified that different chemical formulas of these reactive dyes can contribute to a higher toxic charge during effluents discharges. In general the toxicity control was carried out on crustaceans and luminescent bacteria but a lot of experiments were performed with the aquatic snail Biomphalaria glabrata, this last biological assay was developed at "Instituto Butantan (USP, SP)". Irradiations and measurements with UV spectrophotometer resulted always on less colored effluents and most often on less toxic liquid residues, after irradiation. Percentage of reductions for toxicity and color depended on the effluent source and the radiation doses applied varied from 1 to 10 kGy. The decoloration of remazol black B and orange 3R solutions was effective for 1kGy and 2.5 kGy which is a relatively low dose and may contribute to a suitable cost for irradiation technology. Since the possibility of different formula of dyes be present at environment exist, the toxicity was measured for all of them and it was noted that vinylsulphone form was the worst in terms of effects for V.fischeri ( Black B 133%) and D.similis (Orange 3R). Regarding biological effects of these remazol dyes after irradiation, this same dye solution resulted at 60% removal only for V.fischeri (not for daphnids) and when treated with 5 kGy and 10 kGy. Irradiation of real textile BVT effluents resulted in good colour removal but the acute toxicity reduction varied widely 97% (0.5kGy), 54% (2.5kGy) and 19% (1.0kGy), BTV1 – BTV3. The chemical effluent required higher radiation doses to reduce toxicity (20kGy up to 40kGy). (author)