Improving the biogas potential of pulp and paper mills while decreasing the electricity demand for wastewater treatment
2013 (English)Conference paper, Presentation (Refereed)
Sludge formed during the necessary wastewater treatment in forest industry is currently considered to be a waste stream; rich in organic substances and poor in macronutrients, especially phosphorus and nitrogen. Previous work has shown that excessive use of electricity for aeration in wastewater treatment counteracts the potential for energy recovery in the subsequent sludge handling system, as prolonged aeration is used to degrade organic matter. This work shows that chemical oxygen demand of wastewater was not reduced further when the solids retention time was increased in aerated wastewater treatment from 2 days to 10 and 20 days respectively. The results presented here strengthen the previous conclusion that energy should only be used for sufficient effluent treatment, not for sludge reduction. A decreased need for aeration can be achieved by shortening the sludge retention time both by a decreased oxygen requirement and increased aeration efficiency. Shortened sludge retention time was shown here to increase production of biosludge as well as to increase the specific methane potential of biosludge. The results show that sludge with shorter solids retention time in the aerated treatment step gives more production of methane gas compared to sludge with longer solids retention time.
Place, publisher, year, edition, pages
anaerobic digestion, biosludge, efficient aeration, pulp and paper mill
Research subject Environmental and Energy Systems
IdentifiersURN: urn:nbn:se:kau:diva-26117OAI: oai:DiVA.org:kau-26117DiVA: diva2:602439
IWA Conference on Holistic Sludge Management, Västerås, 6-8 May 2013