Showing papers on "Enhanced biological phosphorus removal published in 2011"
TL;DR: It was found that the inhibition of nitrogen and phosphorus removal induced by higher concentrations of ZnO NPs was due to the release of zinc ions from Zn O NPs dissolution and increase of reactive oxygen species (ROS) production, which caused inhibitory effect on polyph phosphate-accumulating organisms and decreased nitrate reductase, exopolyphosphatase, and polyphosphate kinase activities.
Abstract: With the increasing utilization of nanomaterials, zinc oxide nanoparticles (ZnO NPs) have been reported to induce adverse effects on human health and aquatic organisms. However, the potential impacts of ZnO NPs on wastewater nitrogen and phosphorus removal with an activated sludge process are unknown. In this paper, short-term exposure experiments were conducted to determine whether ZnO NPs caused adverse impacts on biological nitrogen and phosphorus removal in the unacclimated anaerobic-low dissolved oxygen sequencing batch reactor. Compared with the absence of ZnO NPs, the presence of 10 and 50 mg/L of ZnO NPs decreased total nitrogen removal efficiencies from 81.5% to 75.6% and 70.8%, respectively. The corresponding effluent phosphorus concentrations increased from nondetectable to 10.3 and 16.5 mg/L, respectively, which were higher than the influent phosphorus (9.8 mg/L), suggesting that higher concentration of ZnO NPs induced the loss of normal phosphorus removal. It was found that the inhibition of nitrogen and phosphorus removal induced by higher concentrations of ZnO NPs was due to the release of zinc ions from ZnO NPs dissolution and increase of reactive oxygen species (ROS) production, which caused inhibitory effect on polyphosphate-accumulating organisms and decreased nitrate reductase, exopolyphosphatase, and polyphosphate kinase activities.
342 citations
TL;DR: Lab experiments demonstrate that each of the three materials studies can selectively remove phosphate from the background of competing anions and phosphorus can be recovered as a solid-phase fertilizer upon efficient regeneration of the exchanger and addition of a calcium or magnesium salt in equimolar (Ca/P or Mg/P) ratio.
224 citations
TL;DR: 50 mg/L TiO(2) NPs inhibited the activities of ammonia monooxygenase and nitrite oxidoreductase after long-term exposure, but had no significant impacts on the activitiesof exopolyphosphatase and polyphosphate kinase, and the transformations of intracellular polyhydroxyalkanoates and glycogen were consistent with the observed influences of TiO (2)NPs on biological nitrogen and phosphorus removal.
Abstract: The expanding use of titanium dioxide nanoparticles (TiO2 NPs) in a wide range of fields raises concerns about their potential environmental impacts. However, investigations of the potential effects of TiO2 NPs on biological nitrogen and phosphorus removal and bacterial community in activated sludge are sparse. This study evaluated the influences of TiO2 NPs on biological nutrient removal in the anaerobic-low dissolved oxygen (0.15–0.50 mg/L) sequencing batch reactor. It was found that 1 and 50 mg/L TiO2 NPs had no acute effects on wastewater nitrogen and phosphorus removal after short-term exposure (1 day). However, 50 mg/L TiO2 NPs (higher than its environmentally relevant concentration) was observed to significantly decrease total nitrogen (TN) removal efficiency from 80.3% to 24.4% after long-term exposure (70 days), whereas biological phosphorus removal was unaffected. Denaturing gradient gel electrophoresis profiles showed that 50 mg/L TiO2 NPs obviously reduced the diversity of microbial community ...
211 citations
TL;DR: Activated sludge from a standard activated sludge WWTP equipped with enhanced biological phosphorus removal found triclosan removal to occur mainly under aerobic conditions while under anoxic and anaerobic conditions rather low removal rates were determined.
162 citations
TL;DR: This study presents a novel strategy to reduce the time required for granulation while ensuring a high level of nutrient removal, which consists of seeding the reactor with a mixture of crushed aerobic granules and floccular sludge.
140 citations
TL;DR: In this paper, the effect of temperature and requirement for mixing on VFA generation from waste activated sludge (WAS) generated in full scale non-EBPR wastewater treatment plant was investigated.
139 citations
TL;DR: Simulation studies showed that anaerobic VFA availability is critical to maintain EBPR activity, and a model based on ASM2d but considering two step nitrification and denitrification was developed and experimentally validated.
138 citations
TL;DR: The results show that the simultaneous nitrification-denitrification (SND) is significantly higher than conventional SBR reactor and the higher total phosphorus removal in FBSBR correlates with oxygen gradient in biofilm layer.
138 citations
TL;DR: Experimental results demonstrate that polyphosphate-accumulating granules were successfully cultured during the anaerobic/aerobic cycle and the diversity of the granular microbial community increased as the granules grew.
95 citations
TL;DR: It is demonstrated that post-anoxic BNR can achieve near-complete (>99%) inorganic nitrogen and phosphorus removal, with soluble effluent concentrations less than 1.0 mgN L(-1) and 0.14 mgP L (-1).
91 citations
TL;DR: Success of the proposed process is predicated on providing sufficient organic acids in the influent wastewater, such that residual nitrate carried over from the post-anoxic period is reduced and polyhydroxyalkanoate (PHA) synthesis occurs.
TL;DR: The alkaline phosphatase activities (APA) and phosphorus fractions in activated sludge during wastewater treatment were studied and showed that the phosphorus concentration and fractions inactivated sludge were highly correlated with the characteristics of influents.
TL;DR: Through supplying the carbon sources to enhance denitrification and anaerobic phosphorus release, nitrite and FNA concentrations in the aerobic zone were reduced, and phosphorus removal was improved.
TL;DR: Results of nitrogen and phosphorus removal by microalgae (tertiary treatment) in a prototype of tubular photobioreactor tested under controlled and uncontrolled conditions show satisfactory nutrients removal and biomass and lipid production.
TL;DR: Using a new ppk1 gene-based dual terminal-restriction fragment length polymorphism (T-RFLP) approach, it is revealed that Accumulibacter diversity was highest in the floccular sludge inoculum but that when granules were formed, propionate readily favored the dominance of AccumULibacter type IIA.
Abstract: Aerobic granules are dense microbial aggregates with the potential to replace floccular sludge for the treatment of wastewaters. In bubble-column sequencing batch reactors, distinct microbial populations dominated propionate- and acetate-cultivated aerobic granules after 50 days of reactor operation when only carbon removal was detected. Propionate granules were dominated by Zoogloea (40%), Acidovorax, and Thiothrix, whereas acetate granules were mainly dominated by Thiothrix (60%). Thereafter, an exponential increase in enhanced biological phosphorus removal (EBPR) activity was observed in the propionate granules, but a linear and erratic increase was detected in the acetate ones. Besides Accumulibacter and Competibacter, other bacterial populations found in both granules were associated with Chloroflexus and Acidovorax. The EBPR activity in the propionate granules was high and stable, whereas EBPR in the acetate granules was erratic throughout the study and suffered from a deterioration period that could be readily reversed by inducing hydrolysis of polyphosphate in presumably saturated Accumulibacter cells. Using a new ppk1 gene-based dual terminal-restriction fragment length polymorphism (T-RFLP) approach revealed that Accumulibacter diversity was highest in the floccular sludge inoculum but that when granules were formed, propionate readily favored the dominance of Accumulibacter type IIA. In contrast, acetate granules exhibited transient shifts between type I and type II before the granules were dominated by Accumulibacter type IIA. However, ppk1 gene sequences from acetate granules clustered separately from those of propionate granules. Our data indicate that the mere presence of Accumulibacter is not enough to have consistently high EBPR but that the type of Accumulibacter determines the robustness of the phosphate removal process.
TL;DR: The results show that IFAS-EBPR systems enable decoupling of solid residence time (SRT) control for nitrifiers and PAOs that require or prefer conflicting SRT values, and that the EBPR-IFAS system facilitates separate SRT controls and overall optimization for both N and P removal processes.
TL;DR: The precipitation model proposed was able to reproduce the dynamics of amorphous calcium phosphate formation and later crystallization to hydroxyapatite under different scenarios and successfully characterised the EBPR performance of the SBR, including the biological, physical and chemical processes.
TL;DR: Sludge reduction and enhanced nutrient removal could be achieved simultaneously in the proposed system and the total nitrogen and phosphorus removal efficiencies reached to 80.1% and 90.0%, respectively.
TL;DR: Overall mechanisms of removal were biodegradation and sorption unto sludge biomass and Phytoremediation was also significant in the removal processes.
Abstract: Endocrine disrupting chemicals are discharged into the environment mainly through wastewater treatment processes. There is a need for better understanding of the fate of these compounds in the unit processes of treatment plant to optimise their removal. The fate of oestrone, 17β-estradiol, 17α-ethinyestradiol and nonylphenol in the unit processes of full scale wastewater treatment plants in the UK, including activated sludge plant, oxidation ditch, biofilter and rotating biological contactor were investigated. The overall removal efficiencies of all the compounds ranged from 41 %to 100%. The removals were predominantly during the secondary biological treatment with the rates of removal related to the nitrification rates and the sludge age. The removal efficiency of the treatment processes were in the order activated sludge > oxidation ditch > biofilter > rotating biological contactors. Activated sludge plant configured for biological nutrient removal showed better removal of the endocrine disrupting chemicals compared to conventional activated sludge plant effluents. Tertiary treatment was also significant in the removal process through solids removal. Overall mechanisms of removal were biodegradation and sorption unto sludge biomass. Phytoremediation was also significant in the removal processes. The endocrine disrupting chemicals persisted in the anaerobic sludge digestion process with percentage removals ranging fro 10–48 %. Sorption of the endocrine disrupting chemicals onto the sludge increased with increasing values for the partitioning coefficients and the organic carbon contents of the sludge.
TL;DR: The findings of this work show that while high levels of biomass concentration and luxury uptake can occur in the field it may be possible to redesign WSP to optimise these parameters.
TL;DR: The potential of a new wet chemical process for phosphorus and aluminium recovery from sewage sludge ash by sequential elution with acidic and alkaline solutions has been investigated: SESAL-Phos (sequential elution of sewagesludge ash for aluminium and phosphorus recovery).
TL;DR: Intermittent chemical dosing proves recommendable for simultaneous chemical phosphorus removal and shows persistent inhibition from the accumulation of chemical doses in sludge mass.
TL;DR: Enhanced nitrogen and phosphorus removal and optimized organics utilization were obtained simultaneously in the modified UCT type with both internal and sludge recycle ratios of 75% as well as anaerobic/anoxic/oxic volume ratio of 1:3:6.
TL;DR: Several genes involved in EBPR are tightly regulated at the transcriptional level, suggesting that more acetyl-CoA was metabolized through the TCA cycle.
Abstract: Enhanced biological phosphorus removal (EBPR) activated sludge communities enriched in 'Candidatus Accumulibacter' relatives are widely used in wastewater treatment, but much remains to be learned about molecular-level controls on the EBPR process. The expression of genes found in the carbon and polyphosphate metabolic pathways in Accumulibacter was investigated using reverse transcription quantitative PCR. During a normal anaerobic/aerobic EBPR cycle, gene expression exhibited a dynamic change in response to external acetate, oxygen, phosphate concentrations and probably internal chemical pools. Anaerobic acetate addition induced expression of genes associated with the methylmalonyl-CoA pathway enabling the split mode of the tricarboxylic acid (TCA) cycle. Components of the full TCA cycle were induced after the switch to aerobic conditions. The induction of a key gene in the glyoxylate shunt pathway was observed under both anaerobic and aerobic conditions, with a higher induction by aeration. Polyphosphate kinase 1 from Accumulibacter was expressed, but did not appear to be regulated by phosphate limitation. To understand how Accumulibacter responds to disturbed electron donor and acceptor conditions, we perturbed the process by adding acetate aerobically. When high concentrations of oxygen were present simultaneously with acetate, phosphate-release was almost completely inhibited, and polyphosphate kinase 1 transcript abundance decreased. Genes associated with the methylmalonyl-CoA pathway were repressed and genes associated with the aerobic TCA cycle exhibited higher expression under this perturbation, suggesting that more acetyl-CoA was metabolized through the TCA cycle. These findings suggest that several genes involved in EBPR are tightly regulated at the transcriptional level.
TL;DR: The anaerobic P-release rate was found to be an effective indicator of EBPR and four classifications of the principal components were identified to improve the EBPR effluent quality and sludge activity.
TL;DR: Results showed that the presence of aquatic worms decreased the total phosphorus removal efficiency while it had no impacts on chemical oxygen demand and nitrogen removal.
TL;DR: In this article, the phosphorus balance of an upflow anaerobic sludge blanket reactor treating concentrated black water (toilet water) showed a phosphorus conservation of 61% in the effluent.
TL;DR: The phosphorus uptake to nitrogen consumed ratio (P/N ratio) was shown to be affected by pH in the range of 7-8.2, achieving higher values for lower pH values (7.0-7.5) and the effect of pH on P removal seems to follow a similar trend for both nitrate and nitrite.
TL;DR: In this article, the effects of carbon source shocks on N2O production during denitrifying phosphorus removal were investigated using biomass that was initially acclimated with acetate in three laboratory-scale anaerobic/anoxic (An/A) reactors using acetate, acetate/propionate or propionate as the carbon sources.
TL;DR: The potential for the antiviral contamination of receiving waters is highlighted and the risk of destabilizing WWTP microbial consortia as a result of high concentrations of bioactive pharmaceuticals during an influenza pandemic is indicated.
Abstract: The 2009–2010 influenza pandemic saw many people treated with antivirals and antibiotics. High proportions of both classes of drugs are excreted and enter wastewater treatment plants (WWTPs) in biologically active forms. To date, there has been no study into the potential for influenza pandemic-scale pharmaceutical use to disrupt WWTP function. Furthermore, there is currently little indication as to whether WWTP microbial consortia can degrade antiviral neuraminidase inhibitors when exposed to pandemic-scale doses. In this study, we exposed an aerobic granular sludge sequencing batch reactor, operated for enhanced biological phosphorus removal (EBPR), to a simulated influenza-pandemic dosing of antibiotics and antivirals for 8 weeks. We monitored the removal of the active form of Tamiflu®, oseltamivir carboxylate (OC), bacterial community structure, granule structure and changes in EBPR and nitrification performance. There was little removal of OC by sludge and no evidence that the activated sludge community adapted to degrade OC. There was evidence of changes to the bacterial community structure and disruption to EBPR and nitrification during and after high-OC dosing. This work highlights the potential for the antiviral contamination of receiving waters and indicates the risk of destabilizing WWTP microbial consortia as a result of high concentrations of bioactive pharmaceuticals during an influenza pandemic.