Abstract
Aeration, as a process in pulp and paper wastewater treatment, uses the greatest share of the energy. Therefore, if the energy efficiency of the treatment has to be improved, the focus must be on aeration. A key finding from the trials conducted for this paper, with effluent from a paper and pulp mill, was that the oxygen transfer coefficient could be doubled and the chemical oxygen demand could be decreased by 25%, if the effluent was pre-treated with 30 mg/l of aluminium coagulant (equivalent to 9.4 tonnes per day of AVR to 20000 cubic metres of effluent). Decrease in oxygen requirement implies decreases in aeration energy use. Pulp and paper mill effluents are not as biodegradable as municipal sewage, and the improvement in oxygen transfer properties of the effluent will have a positive influence over a longer period of time in the biological treatment. If the sludge is digested anaerobically, pre-treatment will also result in doubling the potential for methane generation. A holistic analysis of modifications to processes entails a study of the economic and environmental consequences as well. While the economic aspect is beyond the scope of this paper, only the net global warming as an environmental impact category has been studied, by taking recourse to specific emission coefficients. Of the four dosages of ferric aluminium sulphate considered in this analysis, the net greenhouse gas emissions are the least – 426 kg carbon dioxide equivalent per day when the daily consumption is 9.4 tonnes.
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.