Comparison between disintegrated and fermented sewage sludge for production of a carbon source suitable for biological nutrient removal

Abstract

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 (PO(4)-P) release and denitrification by up to 0.04 mg NO(3)-Ng(-1)VSS min(-1) and 0.031 mg PO(4)-Pg(-1)VSS min(-1), respectively, in comparison to acetate (0.023 mg NO(3)-Ng(-1)VSS min(-1)and 0.010 mg PO(4)-Pg(-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:PO(4)-P and 9 for SCOD:NO(3)-N. On the other hand, SAS increased the concentration of PO(4)-P in the settled sewage by a further 0.97 g PO(4)-P kg(-1)SCOD indicating its potential negative impact towards nutrient recycling in the BNR process.

Enhancing denitrification using a carbon supplement generated from the wet oxidation of waste activated sludge

“…With WO material little difference was observed when changing from a low to high background of primary wastewater, which would support the notion that WO liquor has a greater mixture of carbon compounds (and/or nutrients or trace elements) and the increase in background carbon made little difference with this supplement. Other studies had indicated that complex substrates and mixture of VFAs from solubilised sludge stimulated higher denitrification rates than just acetate (Kampas et al, 2009;Soares et al, 2010). Kristensen and Jørgensen (1990) had also observed similar denitrification rates when supplementing with acetate or biologically hydrolysed sludge.…”

“…In this manner the WO material could be ranked in terms of known carbon sources. The batch assay allowed for higher throughput and required smaller volumes than a full SBR study and was modelled upon work by Kampas et al (2009);Kampas (2007) and Soares et al (2010). Biomass from each of the five parent reactors was centrifuged at 2000 rpm for 1 min in a swing head centrifuge (International Equipment Company, Biolab Scientific Ltd.), washed with fresh media (10% wastewater diluted with water containing phosphate buffer at 20 mM at pH 7.5, 30 mg/l CaCO 3 , 75 mg/l CaCl 2 Á 2H 2 O, 100 mg/l MgCl 2 Á 6H 2 O) and then resuspended in the media.…”

Influence of Microwave Pre-Treatment on the Digestion and Higienisation of Waste Activated Sludge/Wpływ Dezintegracji Mikrofalowej Na Proces Fermentacji Oraz Higienizacji Nadmiernych Osadów Ściekowych

“…An increased concentration of organic and inorganic substances in post-digestion waters undergoing pre-treatment influenced also the sludge susceptibility to dewatering in a negative way (Table 5). Such liquors exhibited a negative impact on the wastewater treatment processes, especially the denitrification [34,35]. Nowadays, the post-digestion liquors are more and more frequently treated separately with the application of biological as well as physical and chemical methods.…”

Post-Digestion Liquor Treatment in the Method Combining Chemical Precipitation with Reverse Osmosis

“…15-0.20), which has a negative impact on the wastewater treatment process, especially on the denitrifi cation. Their treatment in such way requires the addition of external carbon source [19,35].…”