Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5116508 | Journal of Environmental Management | 2017 | 8 Pages |
â¢The source of Fe3+ influence the efficiency of coagulation-flocculation.â¢The mineralization efficiency increases significantly using UV-C and H2O2.â¢BOD5 and oil & fats discharge limits were reached using H2O2/UV-C.â¢Less toxic degradation compounds were formed using UV-C and H2O2/UV-C.â¢UV-C treatment is a good alternative for pre-treatment before a biological process.
The feasibility of biodiesel effluent treatment combining coagulation-flocculation with a photolytic process was evaluated, being the photolytic process involving the irradiation of the effluent by UV-C, or by UV-C irradiation with simultaneous addition of H2O2 (H2O2/UV-C). The coagulation-flocculation was performed at the natural pH of the effluent (pH 2.9) using different Fe3+ salts (chloride, nitrate and sulfate) at different concentrations (0.25, 0.50 and 1.0 mmol Lâ1) of the counterions. The best results were achieved using 0.50 mmol Lâ1 Fe(NO3)3. Following, the degradation of the organic load and toxicity reduction of the pre-treated effluent by UV-C irradiation was evaluated. The H2O2/UV-C process showed to be advantageous, mainly when multiple additions of H2O2 were used during the course of the reaction. Additionally, the influence of the initial pH on the degradation was also evaluated. A high level of mineralization (94%) was achieved after 6 h of irradiation concomitantly with multiple additions of 2,000 mg Lâ1 H2O2, and with the effluent at the natural pH. Thus, using coagulation-flocculation followed by the H2O2/UV-C process, it was possible to achieve a favourable condition for reuse of the pre-treated effluent, since, in addition to the significant reduction of the organic load, the final DBO5 (<120 mg Lâ1) and oils & fats (<50 mg Lâ1) are below the limits established by the Brazilian legislation. Furthermore, a reduction of 78% of acute toxicity to V. fischeri (from 89% to 20%) was reached. The results suggest, therefore, that this process is a viable option for treatment of this kind of effluent.
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