Browsing by Author "Kampas, Pantelis"

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Comparison between disintegrated and fermented sewage sludge for production of a carbon source suitable for biological nutrient removal
    (Elsevier Science B.V., Amsterdam., 2010-03-15T00:00:00Z) Soares, Ana; Kampas, Pantelis; Maillard, Sarah; Wood, Elizabeth; Brigg, Jon; Tillotson, Martin; Parsons, Simon A.; Cartmell, Elise
    There is a need to investigate processes that enable sludge re-use while enhancing sewage treatment efficiency. Mechanically disintegrated thickened surplus activated sludge (SAS) and fermented primary sludge were compared for their capacity to produce a carbon source suitable for BNR by completing nutrient removal predictive tests. Mechanically disintegration of SAS using a deflaker enhanced volatile fatty acids (VFAs) content from 92 to 374 mg l−1 (4.1-fold increase). In comparison, primary sludge fermentation increased the VFAs content from 3.5 g l−1 to a final concentration of 8.7 g l−1 (2.5-fold increase). The carbon source obtained from disintegration and fermentation treatments improved phosphate (PO4-P) release and denitrification by up to 0.04 mg NO3-N g−1 VSS min−1 and 0.031 mg PO4-P g−1 VSS min−1, respectively, in comparison to acetate (0.023 mg NO3-N g−1 VSS min−1and 0.010 mg PO4-P g−1 VSS min−1). Overall, both types of sludge were suitable for BNR but disintegrated SAS displayed lower carbon to nutrient ratios of 8 for SCOD:PO4-P and 9 for SCOD:NO3-N. On the other hand, SAS increased the concentration of PO4-P in the settled sewage by a further 0.97 g PO4-P kg−1 SCOD indicating its potential negative impact towards nutrient recyc
  • Thumbnail Image
    ItemOpen Access
    Mechanical sludge disintegration for the production of carbon source for biological nutrient removal.
    (Elsevier, 2007-04) Kampas, Pantelis; Parsons, Simon A.; Pearce, Peter; Ledoux, Sandrine; Vale, Peter C. J.; Churchley, J.; Cartmell, Elise
    The primary driver for a successful biological nutrient removal is the availability of suitable carbon source, mainly in the form of volatile fatty acids (VFA). Several methods have been examined to increase the amount of VFAs in wastewater. This study investigates the mechanism of mechanical disintegration of thickened surplus activated sludge by a deflaker technology for the production of organic matter. This equipment was able to increase the soluble carbon in terms of VFA and soluble chemical oxygen demand (SCOD) with the maximum concentration to be around 850 and 6530 mg l−1, for VFA and SCOD, respectively. The particle size was reduced from 65.5 to 9.3 μm after 15 min of disintegration with the simultaneous release of proteins (1550 mg l−1) and carbohydrates (307 mg l−1) indicating floc disruption and breakage. High performance size exclusion chromatography investigated the disintegrated sludge and confirmed that the deflaker was able to destroy the flocs releasing polymeric substances that are typically found outside of cells. When long disintegration times were applied (10 min or 9000 kJ kg−1 TS of specific energy) smaller molecular size materials were released to the liquid phase, which are considered to be found inside the cells indicating cell lysis.
  • Thumbnail Image
    ItemOpen Access
    Sidestream treatment for improved BNR process performance
    (Cranfield University, 2007-02) Kampas, Pantelis; Parsons, Simon; Cartmell, Elise
    The removal of nutrients from the wastewaters through biological processes is a cost effective and environmentally sound alternative to chemical treatment. The primary driver for the success of the biological nutrient removal (BNR) processes is the availability of suitable carbon sources in the influent wastewater. Unfortunately, in the UK the wastewaters considered being weak for the BNR carbon limited processes and hence many methods have been examined in the past for the enhancement of BNR. In this project an internal carbon source was proposed and examined. The carbon was produced from the disintegration of activated sludge by a mechanical process, which was explored and its impact on the BNR carbon limited processes was evaluated. The equipment used in this study for mechanical sludge disintegration was a deflaker, which was able to cause significant increase in chemical oxygen demand and volatile fatty acids (VFA) in the soluble phase of sludge. Laboratory scale tests revealed that this carbon source can improve the phosphorus release and denitrification process and hence the phosphorus and nitrogen removal. These results led us to investigate the carbon source produced from disintegration in pilot scale and two BNR reactors were used for this purpose. The mechanical disintegration of 5.8% of return activated sludge was able to increase the concentration of VFA in the influent wastewater by 2.5-7 mg l-1 and successfully replace the equivalent amount of acetic acid, which is normally considered to be the best carbon source for biological phosphorus removal. The performance of the test reactor in terms of nitrogen, suspended solids and chemical oxygen demand was also unaffected. In addition, the sludge disintegration affected the bacteria growth yield, which combined with the longer sludge age by 6 days compared to the control reactor caused a 20-26% reduction in sludge production. In order to examine whether this process could be used by the water utilities a cost analysis took place, which revealed that the operational cost of the specific disintegration process and under the conditions examined in this study outweighs the savings from the produced carbon source and reduced amount of sludge.