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Integration of continuous biological and chemical (ozone) treatment of domestic wastewater: 1. Biodegradation and post‐ozonation
Author(s) -
Beltrán Fernando J,
GarcíaAraya Juan F,
Álvarez Pedro M
Publication year - 1999
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/(sici)1097-4660(199909)74:9<877::aid-jctb117>3.0.co;2-2
Subject(s) - chemical oxygen demand , biodegradation , chemistry , activated sludge , wastewater , ozone , biochemical oxygen demand , hydraulic retention time , nitrification , pulp and paper industry , sewage treatment , environmental chemistry , mixed liquor suspended solids , nitrogen , environmental engineering , environmental science , organic chemistry , engineering
The continuous treatment of domestic wastewater by an activated sludge process and by an integrated biological–chemical (ozone) oxidation process were studied in this work. Chemical oxygen demand (COD), biochemical oxygen demand (BOD), absorbance at 254 nm (UV 254 ) and nitrogenous compound content were the parameters followed in order to evaluate the performance of the two processes. Experimental data showed that both UV 254 and COD reductions are improved in the combined biological–chemical oxidation procedure. Thus, reductions of 59.1% and 37.2% corresponding to COD and UV 254 , respectively were observed after the biological process (hydraulic retention time = 5 h; mixed liquor volatile suspended solids concentration = 3142 g m −3 ) compared with 71.0% and 78.4% obtained when a post‐ozonation step ( D O3 = 41.7 g m −3 ) was included. During conventional activated sludge treatment, appropriate nitrification levels are only achieved with high hydraulic retention time and/or biomass concentration. Ozonation after the secondary treatment, however, allows improved nitrogen content reduction with total nitrite elimination. Post‐ozonation also leads to a higher biodegradability of the treated wastewater. Thus, the ultimate BOD/COD ratio goes from 0.16 after biological oxidation to 0.34 after post‐ozonation with 41.7 g O 3 m −3 . © 1999 Society of Chemical Industry