Phosphorus Release in Aerobic Sludge Digestion

Ju, Lu‐Kwang; Shah, Hemant K.; Porteous, J.D.

doi:10.2175/106143005x67476

Cited by 19 publications

(7 citation statements)

References 15 publications

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“…Other studies have also reported phosphorus release, glycogen consumption and MLVSS decrease during aerobic starvation (Brdjanovic et al, 1998, Ju et al, 2005. Different from those studies, we observed delay of 1.5 days in aerobic phosphorus release.…”

Section: Discussioncontrasting

confidence: 99%

Calibration of Aerobic Endogenous Processes in Activated Sludge Models for Enhanced Biological Phosphorus Removal

Lopez¹,

Morgenroth²

2007

proc water environ fed

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Activated sludge systems operated for enhanced biological phosphorus removal (EBPR) are particularly sensitive to dynamic loading conditions. Increases in effluent phosphorus are often reported immediately after low loading conditions, such as weekends or rain events. Mathematical models for EBPR can be used to predict a system's response to low loading conditions. However, it is not clear to what extent do existing EBPR models represent the endogenous processes that dominate during low loading and/or starvation conditions. The purpose of this study is to evaluate the endogenous processes during aerobic starvation and determine whether current EBPR models are able to predict the response of an EBPR system to aerobic starvation. Activated sludge from a laboratory EBPR system was used to perform batch experiments. Phosphorus release and storage product utilization were monitored during aerobic starvation. Based on the observed results, we hypothesized that PAO preferentially use polyhydroxyalkanoates, then glycogen, and then polyphosphate during starvation. The Activated Sludge Model No. 2 and EAWAG models over predicted phosphorus release during aerobic starvation. Modifications to the EAWAG model were proposed to accurately describe the observed transformations of polyphosphate and glycogen. The modified model was in close agreement with the phosphorus release and glycogen oxidation observed during starvation. It is expected that the modified model can better predict the performance of systems exposed to low loading conditions, but further research is needed to further validate the proposed model modifications.

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Section: Discussioncontrasting

confidence: 99%

Calibration of Aerobic Endogenous Processes in Activated Sludge Models for Enhanced Biological Phosphorus Removal

Lopez¹,

Morgenroth²

2007

proc water environ fed

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“…Previous studies have revealed an increase of P levels in USS‐amended soils correlated to application rates (Hamdi et al., 2019; Torri, Correa, & Rinella, 2017; Zoghlami et al., 2016a). This is also attributed to the high concentrations of total P in USS (Ju, Shah, & Porteus, 2005). As such, the highest P concentration was observed in Soil S for USS‐120 at W1 (154 mg kg −1 ) (Table 2).…”

Section: Resultsmentioning

confidence: 99%

Carbon mineralization, biological indicators, and phytotoxicity to assess the impact of urban sewage sludge on two light‐textured soils in a microcosm

et al. 2020

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The agricultural reuse of urban sewage sludge (USS) modifies soil properties depending on sludge quality, management, and pedo‐environmental conditions. The aim of this microcosm study was to assess C mineralization and subsequent changes in soil properties after USS addition to two typical Mediterranean soils: sandy (Soil S) and sandy loam (Soil A) at equivalent field rates of 40 t ha−1 (USS‐40) and 120 t ha−1 (USS‐120). Outcomes proved the biodegradability of USS through immediate CO2 release inside incubation bottles in a dose‐dependent manner. Accordingly, the highest rates of daily C emission were recorded with USS‐120 (3.7 and 3.9 mg kg−1 d−1 for Soils S and A, respectively) after 84 d of incubation at 25 °C. The addition of USS also improved soil fertility by enhancing soil macronutrients, microbial proliferation, and protease activity. Protease showed significant correlation with N, total organic C, and heterotrophic bacteria, reflecting the biostimulation and bioaugmentation effects of sludge. Soil indices like C/N/P stoichiometry and metabolic quotient (qCO2) varied mostly with mineralization rates of C and P in both soils. Despite a significant increase of soil salinity and total heavy metal content (lead, nickel, zinc, and copper) with USS dose, wheat germination was not affected by these changes. Both experimental soils showed intrinsic (Soil A) and incubation‐induced (Soil S) phytotoxicities that were alleviated by USS addition. This was likely due to the enhancement of biodegradation and/or retention of phytotoxicants originating from previous land uses. Urban sewage sludge amendments could have applications in soil remediation by reducing the negative effects of allelopathic and/or anthropogenic phytoinhibitors.

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“…Are the concentrations and fluxes of inorganic nitrogen in the sidestream high enough to interfere with EBPR in the mainstream treatment process? Bishop and Farmer (), Matsuda, Ide, and Fujii (), Tonkovic (), Anderson and Mavinic (), Kim et al (), and Ju et al () have partially addressed these questions in bench‐ or pilot‐scale systems, but to the best of our knowledge, there has not yet been an investigation of nutrient mass fluxes at a full‐scale facility employing aerobic digestion.…”

Section: Introductionmentioning

confidence: 99%

“…However, if sludge is digested (either aerobically or anaerobically), significant fractions of the nitrogen and phosphorus contained in the sludge are likely to be re-released back into the liquid phase (e.g., Holloway, Childress, Dennett, & Cath, 2007;Ju, Shah, & Porteous, 2005;Martí, Pastor, Bouzas, Ferrer, & Seco, 2010;Münch & Barr, 2001;Phillips, Kobylinski, Barnard, & Wallis-Lage, 2006). This can be problematic because the liquid portion of the digester effluent (sometimes called the "sidestream" or the "centrate") is typically returned to the headworks of the mainstream treatment facility, thereby recycling the nitrogen and phosphorus back into the system.…”

Section: Introductionmentioning

confidence: 99%

Mass fluxes of nitrogen and phosphorus through water reclamation facilities: Case study of biological nutrient removal, aerobic sludge digestion, and sidestream recycle

Kassouf

Parra

Mulford

et al. 2019

Water Environment Research

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At water reclamation facilities, recycling of nutrients (nitrogen and phosphorus) from solids‐handling processes to the mainstream treatment process can have detrimental effects on biological nutrient removal systems. In this study, mass fluxes of nitrogen and phosphorus were quantified through the treatment trains at the Northwest Regional Water Reclamation Facility (NWRWRF) and the adjoining Biosolids Management Facility (BMF), which receives sludge from several water reclamation facilities in Hillsborough County, Florida. The driving objectives were to determine (a) whether the return stream from BMF to NWRWRF (i.e., the “sidestream”) represents a significant source of nitrogen and phosphorus to NWRWRF, and (b) whether the sidestream return from BMF is interfering with biological nutrient removal processes at NWRWRF. We determined that nearly half of the overall phosphorus flux into NWRWRF is recycled from the BMF sidestream. This leads to an increased cost of treatment, for example, for alum used in phosphorus removal at NWRWRF. In contrast to phosphorus, the flux of nitrogen from BMF to NWRWRF is small (~3%) compared with the flux of nitrogen entering NWRWRF in raw wastewater. However, nitrogen in the sidestream is mostly in the form of nitrate, which prevents anaerobic conditions from developing in the fermentation basin at NWRWRF, and thereby interferes with the enhanced biological phosphorus removal (EBPR) process. Some measurements suggest that fermentation and release of phosphorus may occur in the return activated sludge line (despite the relatively short residence time in that line), which supports EBPR and may partially compensate for anoxic (denitrifying) conditions in the fermentation basin. Therefore, overall, NWRWRF is able to meet its permit limits for phosphorus through a combination of EBPR and alum addition. Although the fluxes measured here are particular to the treatment systems under consideration, the general trends observed are likely to apply to many similar facilities that employ biological nutrient removal, aerobic digestion, and sidestream recycle, particularly those with regional biosolids management facilities. We recommend that such facilities consider (a) removal or recovery of phosphorus from their sidestreams and (b) returning sidestreams downstream of fermentation basins to avoid inhibition of EBPR processes. Practitioner points Sidestreams from aerobic digestion can represent significant sources of phosphorus to mainstream wastewater treatment. Recycle of nitrate in aerobic digestion sidestreams can interfere with enhanced biological phosphorus removal (EBPR) during mainstream treatment. Fermentation of return activated sludge (RAS) can support EBPR, even under short average hydraulic residence times (minutes).

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Phosphorus Release in Aerobic Sludge Digestion

Cited by 19 publications

References 15 publications

Calibration of Aerobic Endogenous Processes in Activated Sludge Models for Enhanced Biological Phosphorus Removal

Calibration of Aerobic Endogenous Processes in Activated Sludge Models for Enhanced Biological Phosphorus Removal

Carbon mineralization, biological indicators, and phytotoxicity to assess the impact of urban sewage sludge on two light‐textured soils in a microcosm

Mass fluxes of nitrogen and phosphorus through water reclamation facilities: Case study of biological nutrient removal, aerobic sludge digestion, and sidestream recycle

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