Abstract
Lab-scale tests have been conducted on the reduction of residual COD in biologically purified effluents from mills with integrated waste paper treatment plants and/or TMP lines. For this purpose, waste water samples were subjected to ozonization or a combined ozone/UV treatment at varied temperatures and pHs. The influence of ozone on the biodegradability of biologically part-treated effluents was studied by means of the Zahn-Wellens test. For specific ozone consumption rates < 2.5 g 03/g eliminated COD, COD elimination rates of up to 82% and DOC elimination rates of up to 64% were obtained. Ozone consumption was considerably higher for a combined ozone/LJV treatment or treatment at pH > 9 or at elevated temperatures (40°C). For colour stripping of the waste waters and for destroying the surfactants contained in them, ozone additions of up to 80 mg 03 /1 waste water were required. The bioavailability of effluents that have been part-treated biologically in trickling filters or anaerobic stages to COD > 500 mg/l and BOD5/COD > 0.2 cannot be positively influenced by ozonization with up to 1.8 g 03/1 waste water. On the other hand, in fully biologically treated effluents (COD < 500 mg/1), ozonization brought about a rise in the BOD5/COD ratio from an initial < 0.05 to a maximum of 0.37 — an observation which clearly demonstrates an increase in biodegradability.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.