Scheda di dettaglio – i prodotti della ricerca
| Dato | Valore |
|---|---|
| Title | Ozonation of tannery secondary effluents: effects on biodegradability and toxicity and kinetics characterization |
| Abstract | The paper reports the results of an experimental investigation aimed to investigate the effects of ozonation of tannery secondary effluents on biodegradability and acute toxicity of such streams and to study the kinetics of the process. Real biologically treated effluent (COD=330 mgO2/L; TOC= 94 mgC/L; pH=8; conducibility=17,000 ?S/cm; BOD5=0 mgO2/L) from a centralised tannery wastewater treatment plant located in Northern Italy (Santa Croce) has been ozonated (4.5 mg O3/min), in the pH range 8?12.6, in a semi-batch continuous reactor (2 L). The results have indicated that ozonation enhances the biodegradability of the treated wastewater. BOD5, in fact, regularly increases with ozonation time in the pH range 9?11.5, even though such increase is negligible after 1 h. pH affects the extent of this increase. In fact, after 60 min, BOD5 goes from zero up to 26, 37 and 45 (mg O2/L) at pH 11.5, 10 and 9 respectively. At pH 8 and 12.6 no biodegradability enhancement takes place. The influence of pH on biodegradability enhancement has been confirmed even by OUR measurements. Recorded OUR profiles point out the presence in the treated wastewater of distinct substrates characterised by different biodegradability whose OUR values range between 13 and 63 mgO2/(gVSS?h). Referring to acute toxicity, measured as EC20, it has been demonstrated that ozonation reduces toxicity at every pH. The higher the pH value the greater the toxicity reduction. At the highest pH value (12.6), the treated wastewater resulted even "non-toxic". After modelling the experimental data, it has been demonstrated that the kinetics of ozonation reaction is first order in COD and zero order in ozone. The kinetic constant of the reaction increases in the pH range 8?9 and remains constant in the pH range 9?12.6. |
| Source | International Conference: Wastewater Treatment Technologies for the 21st Century, Leeds-UK, 4-6 April 2000 |
| Year | 2000 |
| Type | Contributo in atti di convegno |
| Authors | Di Iaconi C.(1), Lopez A.(2), Ramadori R.(3), Ricco G.(4), Tomei C.(5) |
| Text | 237441 2000 Ozonation of tannery secondary effluents effects on biodegradability and toxicity and kinetics characterization Di Iaconi C. 1 , Lopez A. 2 , Ramadori R. 3 , Ricco G. 4 , Tomei C. 5 CNR Istituto di Ricerca sulle Acque The paper reports the results of an experimental investigation aimed to investigate the effects of ozonation of tannery secondary effluents on biodegradability and acute toxicity of such streams and to study the kinetics of the process. Real biologically treated effluent COD=330 mgO2/L; TOC= 94 mgC/L; pH=8; conducibility=17,000 S/cm; BOD5=0 mgO2/L from a centralised tannery wastewater treatment plant located in Northern Italy Santa Croce has been ozonated 4.5 mg O3/min , in the pH range 8 12.6, in a semi batch continuous reactor 2 L . The results have indicated that ozonation enhances the biodegradability of the treated wastewater. BOD5, in fact, regularly increases with ozonation time in the pH range 9 11.5, even though such increase is negligible after 1 h. pH affects the extent of this increase. In fact, after 60 min, BOD5 goes from zero up to 26, 37 and 45 mg O2/L at pH 11.5, 10 and 9 respectively. At pH 8 and 12.6 no biodegradability enhancement takes place. The influence of pH on biodegradability enhancement has been confirmed even by OUR measurements. Recorded OUR profiles point out the presence in the treated wastewater of distinct substrates characterised by different biodegradability whose OUR values range between 13 and 63 mgO2/ gVSS h . Referring to acute toxicity, measured as EC20, it has been demonstrated that ozonation reduces toxicity at every pH. The higher the pH value the greater the toxicity reduction. At the highest pH value 12.6 , the treated wastewater resulted even non toxic . After modelling the experimental data, it has been demonstrated that the kinetics of ozonation reaction is first order in COD and zero order in ozone. The kinetic constant of the reaction increases in the pH range 8 9 and remains constant in the pH range 9 12.6. Proceedings of the International Conference Wastewater Treatment Technologies for the 21st Century, Leeds UK, 4 6 April 2000, Vol. 2, 625 638. Ruolo ricoperto primo autore International Conference Wastewater Treatment Technologies for the 21st Century Leeds UK 4 6 April 2000 Internazionale Contributo Contributo in atti di convegno claudio.diiaconi DI IACONI CLAUDIO antonio.lopez LOPEZ ANTONIO roberto.ramadori RAMADORI ROBERTO |