Effects of nutrient loading on Anabaena flos-aquae biofilm: biofilm growth and nutrient removals

2016 ◽  
Vol 74 (2) ◽  
pp. 385-392 ◽  
Author(s):  
Xiaowei Li ◽  
Qun Wei ◽  
Xiaojie Tu ◽  
Yuxuan Zhu ◽  
Yanfei Chen ◽  
...  
Keyword(s):  
Nutrient Loading ◽  
Synthetic Wastewater ◽  
High Biological Activity ◽  
Biofilm Growth ◽  
Biofilm Thickness ◽  
Nutrient Loadings ◽  
High Nutrient ◽  
Removal Efficiencies ◽  
Algal Biofilm ◽  
Structure And Functions

Effects of three different nutrient loadings (low nutrient loading, medium nutrient loading and high nutrient loading, denoted as LNS, MNS and HNS, respectively) on the structure and functions of algal biofilm using Anabaena flos-aquae were investigated using synthetic wastewater. Nutrients removal efficiencies, biofilm thickness, microalgae dehydrogenase activity (DHA) and exopolysaccharide (EPS) productions were examined. Results showed that the changes of nutrient concentration were insignificant after 4 days of experiment for the case of HNS condition; 9 days for the case of MNS condition, and 6 days for the case of LNS condition, respectively. The biofilm thickness, nutrient removal efficiencies, algae DHA and EPS productions increased with the increase of nutrient loadings in synthetic wastewater. For the case of HNS condition, the microalgal biofilm exhibited the best performance in terms of C, N and P removal efficiencies, reaching the removal rates of 68.45, 3.56 and 1.61 mg·L−1·d−1 for C, N, P, respectively. This was likely because, fact with the high nutrient loading, the high biological activity could be achieved, thus resulting in high nutrient removals. The thickness of the biofilm in HNS condition was 75 μm, which was closely related to EPS production. DHA and EPS concentrations were 7.24 and 1.8 × 10−2 mg·mm−2, respectively. It was also shown that apart from the nutrient loading, the structure and functions of microalgal biofilm were also influenced by other factors, such as illumination and temperature.

Alternative stable states in the aquatic vegetation of shallow urban lakes. II. Catastrophic loss of aquatic plants consequent to nutrient enrichment

2003 ◽  
Vol 54 (3) ◽  
pp. 201 ◽  
Author(s):  
Kay Morris ◽  
Paul C. Bailey ◽  
Paul I. Boon ◽  
Leesa Hughes
Keyword(s):  
Aquatic Plants ◽  
Nutrient Enrichment ◽  
Aquatic Vegetation ◽  
Nutrient Loading ◽  
Alternative Stable States ◽  
Nutrient Concentrations ◽  
Stable States ◽  
Nutrient Loadings ◽  
High Nutrient ◽  
Catastrophic Loss

The theory of alternative stable states predicts that high nutrient concentrations increase the probability of shallow lakes switching from a state dominated by vascular macrophytes to one dominated by phytoplankton and/or other algae. In the first paper of this series it was demonstrated that chronic, low-level nutrient loading did not affect a switch across vegetation states. To test the possibility that higher nutrient loadings result in vegetation changes, replicated mesocosms (~3000 L) were placed in an urban lake densely colonized by Vallisneria americana Michaux, a submerged angiosperm, and were subjected to higher levels of chronic nutrient enrichment. Moderate and high nutrient loadings significantly increased phytoplankton biomass and produced extensive, dense mats of floating algae. Many mesocosms became covered by the floating fern Azolla pinnata R.Br. This reduced light penetration and concentrations of dissolved oxygen in the water column profoundly and resulted in the complete loss of V. americana from almost all nutrient-enriched mesocosms within 4 months. A catastrophic loss of submerged aquatic plants so rapidly after nutrient enrichment is a relatively novel experimental finding, particularly in terms of the likely mechanism; that is, shading and subsequent anoxia caused by dense mats of floating plants other than algae.

scholarly journals Nutrient Loading, Temperature and Heat Wave Effects on Nutrients, Oxygen and Metabolism in Shallow Lake Mesocosms Pre-Adapted for 11 Years

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 127
Author(s):  
Erik Jeppesen ◽  
Joachim Audet ◽  
Thomas A. Davidson ◽  
Érika M. Neif ◽  
Yu Cao ◽  
...  
Keyword(s):  
Heat Wave ◽  
Shallow Lake ◽  
Nutrient Loading ◽  
Global Changes ◽  
Significant Positive Effect ◽  
Mixed Effect ◽  
Chl A ◽  
Nutrient Loadings ◽  
Positive Effect ◽  
Oxygen Concentrations

Global changes (e.g., warming and population growth) affect nutrient loadings and temperatures, but global warming also results in more frequent extreme events, such as heat waves. Using data from the world’s longest-running shallow lake experimental mesocosm facility, we studied the effects of different levels of nutrient loadings combined with varying temperatures, which also included a simulated 1-month summer heat wave (HW), on nutrient and oxygen concentrations, gross ecosystem primary production (GPP), ecosystem respiration (ER), net ecosystem production (NEP) and bacterioplankton production (BACPR). The mesocosms had two nutrient levels (high (HN) and low (LN)) combined with three different temperatures according to the IPCC 2007 warming scenarios (unheated, A2 and A2 + 50%) that were applied for 11 years prior to the present experiment. The simulated HW consisted of 5 °C extra temperature increases only in the A2 and A2 + 50% treatments applied from 1 July to 1 August 2014. Linear mixed effect modeling revealed a strong effect of nutrient treatment on the concentration of chlorophyll a (Chl-a), on various forms of phosphorus and nitrogen as well as on oxygen concentration and oxygen percentage (24 h means). Applying the full dataset, we also found a significant positive effect of nutrient loading on GPP, ER, NEP and BACPR, and of temperature on ER and BACPR. The HW had a significant positive effect on GPP and ER. When dividing the data into LN and HN, temperature also had a significant positive effect on Chl-a in LN and on orthophosphate in HN. Linear mixed models revealed differential effects of nutrients, Chl-a and macrophyte abundance (PVI) on the metabolism variables, with PVI being particularly important in the LN mesocosms. All metabolism variables also responded strongly to a cooling-low irradiance event in the middle of the HW, resulting in a severe drop in oxygen concentrations, not least in the HN heated mesocosms. Our results demonstrate strong effects of nutrients as well as an overall rapid response in oxygen metabolism and BACPR to changes in temperature, including HWs, making them sensitive ecosystem indicators of climate warming.

Predicting bed dynamics in three-phase, fluidized-bed biofilm reactors

1994 ◽  
Vol 29 (10-11) ◽  
pp. 231-241 ◽  
Author(s):  
H. T. Chang ◽  
B. E. Rittmann
Keyword(s):  
Fluidized Bed ◽  
Flow Rate ◽  
Liquid Flow ◽  
Gas Flow ◽  
Liquid Flow Rate ◽  
Gas Flow Rate ◽  
Biofilm Growth ◽  
Biofilm Thickness ◽  
Three Phase ◽  
Proper Design

This paper presents a unified model that inter-relates gas flow rate, liquid flow rate, and hold-ups of each of the liquid, gas, and solid phases in three-phase, fluidized-bed biofilm (TPFBB) process. It describes how carrier properties, biofilm properties, and gas and liquid flow velocities control the system dynamics, which ultimately will affect the density, thickness, and distribution of the biofilm. The paper describes the development of the mathematical model to correlate the effects of gas flow rate, liquid flow rate, solid concentration, and biofilm thickness and density. This knowledge is critically needed in light of the use of TPFBB processes in treating industrial wastewater, which often has high substrate concentration. For example, the proper design of the TPFBB process requires mathematical description of the cause-effect relationship between biofilm growth and fluidization.

Evaluation of a hybrid vertical membrane bioreactor (HVMBR) for wastewater treatment

2012 ◽  
Vol 65 (6) ◽  
pp. 1109-1115 ◽  
Author(s):  
L. Rodríguez-Hernández ◽  
A. L. Esteban-García ◽  
A. Lobo ◽  
J. Temprano ◽  
C. Álvaro ◽  
...  
Keyword(s):  
Membrane Bioreactor ◽  
Municipal Wastewater ◽  
Fixed Bed ◽  
Bulk Liquid ◽  
Membrane Unit ◽  
Membrane Cleaning ◽  
Biofilm Thickness ◽  
Support Medium ◽  
Removal Efficiencies ◽  
Solids Removal

A new hybrid membrane bioreactor (HMBR) has been developed to obtain a compact module, with a small footprint and low requirement for aeration. The aim of this research was to assess its performance. The system consists of a single vertical reactor with a filtration membrane unit and, above this, a sponge fixed bed as support medium. The aeration system is located under the membrane unit, allowing for membrane cleaning, oxygenation, biofilm thickness control and bulk liquid mixing. Operated under continuous aeration, a bench-scale reactor (70 L) was fed with pre-treated, raw (unsettled) municipal wastewater. BOD5 and suspended solids removal efficiencies (96 and 99% respectively) were comparable to those obtained with other membrane bioreactors (MBRs). Total nitrogen removal efficiencies of 80% were achieved, which is better than those obtained in other HMBRs and similar to the values reached using more complex MBRs with extra anoxic tanks, intermittent aeration or internal deflectors.

Treatment of synthetic wastewater and hog waste with reduced sludge generation by the multi-environment BioCAST technology

2013 ◽  
Vol 67 (3) ◽  
pp. 587-593 ◽  
Author(s):  
L. Yerushalmi ◽  
M. Alimahmoodi ◽  
C. N. Mulligan
Keyword(s):  
Removal Efficiency ◽  
Removal Rate ◽  
Oxygen Demand ◽  
Synthetic Wastewater ◽  
Nitrogen And Phosphorus ◽  
Treatment Technology ◽  
Minimal Impact ◽  
Biological Sludge ◽  
Removal Efficiencies ◽  
Cod Removal Rate

Simultaneous removal of carbon, nitrogen and phosphorus was examined along with reduced generation of biological sludge during the treatment of synthetic wastewater and hog waste by the BioCAST technology. This new multi-environment wastewater treatment technology contains both suspended and immobilized microorganisms, and benefits from the presence of aerobic, microaerophilic, anoxic and anaerobic conditions for the biological treatment of wastewater. The influent concentrations during the treatment of synthetic wastewater were 1,300–4,000 mg chemical oxygen demand (COD)/L, 42–115 mg total nitrogen (TN)/L, and 19–40 mg total phosphorus (TP)/L. The removal efficiencies reached 98.9, 98.3 and 94.1%, respectively, for carbon, TN and TP during 225 days of operation. The removal efficiencies of carbon and nitrogen showed a minimal dependence on the nitrogen-to-phosphorus (N/P) ratio, while the phosphorus removal efficiency showed a remarkable dependence on this parameter, increasing from 45 to 94.1% upon the increase of N/P ratio from 3 to 4.5. The increase of TN loading rate had a minimal impact on COD removal rate which remained around 1.7 kg/m3 d, while it contributed to increased TP removal efficiency. The treatment of hog waste with influent COD, TN and TP concentrations of 960–2,400, 143–235 and 25–57 mg/L, respectively, produced removal efficiencies up to 89.2, 69.2 and 47.6% for the three contaminants, despite the inhibitory effects of this waste towards biological activity. The treatment system produced low biomass yields with average values of 3.7 and 8.2% during the treatment of synthetic wastewater and hog waste, respectively.

scholarly journals Enhanced removal of emerging micropollutants by applying microaeration to an anaerobic reactor

2019 ◽  
Vol 24 (4) ◽  
pp. 667-673 ◽  
Author(s):  
Patrícia Marques Carneiro Buarque ◽  
Ricardo Bruno Pinheiro de Lima ◽  
Carla Bastos Vidal ◽  
Hugo Leonardo de Brito Buarque ◽  
Paulo Igor Milen Firmino ◽  
...  
Keyword(s):  
Functional Organization ◽  
Synthetic Wastewater ◽  
Anaerobic Conditions ◽  
Anaerobic Reactor ◽  
Operational Conditions ◽  
Anaerobic Reactors ◽  
Bacterial And Archaeal Communities ◽  
Removal Efficiencies ◽  
The Impact ◽  
Archaeal Communities

ABSTRACT The present paper aimed to evaluate the impact of microaeration on both the removal performance of some emerging micropollutants (pharmaceuticals, hormones, and bisphenol A) and the microbial community structure of an anaerobic reactor treating synthetic wastewater. Under anaerobic conditions, the removal efficiencies of the micropollutants were very low (< 10%). However, the microaeration (1.0 mL air·min-1 at 27 °C and 1 atm, equivalent to a QAIR/QINF ratio of 0.1) expressively improved the removal efficiencies of all compounds (> 50%). Therefore, supplementing anaerobic reactors with low amounts of oxygen seems to be an interesting strategy to enhance the removal of the micropollutants tested. However, further studies should be carried out with other compounds in order to evaluate the wide applicability of microaeration to different classes of micropollutants in lab- and full-scale treatment systems. Concerning the microbiota structure, both bacterial and archaeal communities were not compromised by the different operational conditions and preserved their functional organization with high richness during the whole experiment.

scholarly journals Modeling of symbiotic bacterial biofilm growth with an example of the Streptococcus-Veillonella sp. system

2020 ◽  
Author(s):  
Dianlei Feng ◽  
Insa Neuweiler ◽  
Regina Nogueira ◽  
Udo Nackenhorst
Keyword(s):  
Numerical Solutions ◽  
Bacterial Biofilm ◽  
Thickness Direction ◽  
Biomass Distribution ◽  
Biofilm Growth ◽  
Numerical Examples ◽  
Biofilm Thickness ◽  
Coupled Partial Differential Equations ◽  
Numerical Investigations ◽  
Numerical Strategy

AbstractWe present a multi-dimensional continuum mathematical model for modeling the growth of a symbiotic biofilm system. We take a dual-species namely, the Streptococcus - Veillonella sp. biofilm system as an example for numerical investigations. The presented model describes both the cooperation and competition between these species of bacteria. The coupled partial differential equations are solved by using an integrative finite element numerical strategy. Numerical examples are carried out for studying the evolution and distribution of the bio-components. The results demonstrate that the presented model is capable of describing the symbiotic behavior of the biofilm system. However, homogenized numerical solutions are observed locally. To study the homogenization behavior of the model, numerical investigations regarding on how random initial biomass distribution influences the homogenization process are carried out. We found that a smaller correlation length of the initial biomass distribution leads to faster homogenization of the solution globally, however, shows more fluctuated biomass profiles along the biofilm thickness direction. More realistic scenarios with bacteria in patches are also investigated numerically in this study.

scholarly journals Coke oven wastewater treatment by two activated sludge systems

2013 ◽  
Vol 8 (1) ◽  
pp. 16-22
Keyword(s):  
Organic Matter ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Nutrient Removal ◽  
Municipal Wastewater ◽  
Treatment Plant ◽  
Coke Oven ◽  
Synthetic Wastewater ◽  
Removal Efficiencies ◽  
Activated Sludge Systems

In this study two bench scale activated sludge systems were used, a CSTR and an SBR for the treatment of coke – oven wastewater. Both reactors were inoculated with activated sludge from a municipal wastewater treatment plant. At the first stages of operation, reactors were feed by a mixture of municipal wastewater and synthetic wastewater. Full acclimatization of the microorganisms to synthetic wastewater was achieved in 60 days. The operation of the reactors was divided into three distinct periods. The first period was characterized by the treatment of high organic but non-toxic synthetic wastewater. During this period COD and BOD5 removal efficiencies reached 95 and 98% respectively, in both reactors. Nutrient removal was better in the SBR reactor rather than in the CSTR. In the second period phenol was added in concentrations up to 300 mg l-1. Degradation of phenol started about the 20th day after its introduction to the reactors. In this period no effects of phenol to nutrient removal were observed, whereas the removal efficiency of organic matter in both reactors was slightly decreased. During the third period phenol concentrations of the influent were gradually increased to 1000 mg l-1, while cyanide and thiocyanite were added to the influent composition to concentrations reaching concentrations of 20 and 250 mg l-1 respectively. The composition of the influent of this period was a full assimilation of coke oven wastewater. Introduction of increased phenol concentrations along with cyanide compounds initiated irreversible effects on the activated sludge microfauna of the CSTR causing inherent problems to the treatment process, while SBR showed greater capacity to withstand and degrade toxic compounds. The beginning of this period was characterized by decreased settleability of the suspended solids as well as decrease of organic matter and nutrient removal efficiencies. Monitoring of the effluent characteristics during this period reported over 90% for organic load, 85% of nutrient removal and over 90% of phenol and cyanide removal in SBR, while the removal efficiencies for the CSTR were 75, 65 and 80% respectively.

Treatment of Domestic Strength Wastewater with Anaerobic Hybrid Reactors

1987 ◽  
Vol 22 (3) ◽  
pp. 474-490 ◽  
Author(s):  
R.L. Droste ◽  
S.R. Guiot ◽  
S.S. Gorur ◽  
K.J. Kennedy
Keyword(s):  
Retention Time ◽  
Suspended Solids ◽  
Hydraulic Retention Time ◽  
Oxygen Demand ◽  
Anaerobic Treatment ◽  
Synthetic Wastewater ◽  
Solids Retention Time ◽  
Solids Retention ◽  
Removal Efficiencies ◽  
Hybrid Reactors

Abstract Anaerobic treatment of dilute synthetic wastewater (300-1,000 mg chemical oxygen demand/L using laboratory upflow sludge blanket filter reactors with and without effluent recycle is described. Treatment of dilute synthetic wastewater at hydraulic retention times less than 1 and 2 h in reactors without and with recycle, respectively, resulted in biomass washout as the solids retention time decreased to less than 12 d. Reseeding would be required to operate at these critical hydraulic retention times for extended periods. Treatment of dilute synthetic wastewater at hydraulic retention times between 3-12 h resulted in soluble COD removal efficiencies between 84-95% treating 300 mg COD/L. At a 3 h hydraulic retention time, solids retention time of 80 d and stable reactor biomass concentrations of 25 g volatile suspended solids/L were maintained.

Investigating the in-situ bacterial production of aquatic fluorescent organic matter using a freshwater laboratory model

2020 ◽  
Author(s):  
Eva Perrin ◽  
John Attridge ◽  
Robin Thorn ◽  
Stephanie Sargeant ◽  
Darren Reynolds
Keyword(s):  
Organic Matter ◽  
Nutrient Availability ◽  
Bacterial Production ◽  
Nutrient Loading ◽  
Laboratory Model ◽  
Freshwater Systems ◽  
Laboratory Conditions ◽  
Fluorescence Characteristics ◽  
High Nutrient

&lt;p&gt;This research explores the &lt;em&gt;in-situ&lt;/em&gt; bacterial production of aquatic fluorescent organic matter (AFOM) under controlled laboratory conditions. Whilst fluorescence techniques have long been used to monitor AFOM distribution, origin and dynamics within aquatic systems, the extent to which AFOM characteristics are defined by microbial processing in surface freshwaters has largely been overlooked. Current convention champions the assumption that humic-like (Peak C) and protein-like (Peak T) fluorescence signatures are exclusively derived from terrestrial (allochthonous) or microbial (autochthonous) origins respectively, with Peak T having been directly correlated with microbial enumeration. Under intensifying anthropogenic perturbations and changing catchment characteristics, the complexities associated with bacterial-organic matter (OM) interactions in freshwater systems are increasing, challenging our understanding as to the origin and fate of aquatic OM. To what extent the observed AFOM in freshwater systems is defined by bacterial processing and how such processing may be influenced by nutrient availability are key knowledge gaps that need to be addressed. Previous research has observed the &lt;em&gt;in-situ&lt;/em&gt; bacterial production of humic-like compounds in a laboratory model system with a high-nutrient and high-carbon content synthetic growth medium. This work describes a non-fluorescing, simulated freshwater matrix which is low in both nutrient and organic carbon concentrations. Using this model, growth curve incubation experiments have been undertaken over a 48-hour period with a monoculture laboratory strain of &lt;em&gt;Pseudomonas aeruginosa&lt;/em&gt;. Microbiological and fluorescence analyses undertaken at regular time intervals demonstrate the bacterial production of humic-like OM (Peak C) under oligotrophic (after 8hrs) and simulated high-nutrient conditions (after 6hrs). These findings, albeit under laboratory conditions, are important as they show that this fluorescence region, currently viewed as allochthonous in origin, can also represent labile OM generated &lt;em&gt;in-situ&lt;/em&gt; by bacteria and, furthermore, that this bacterial production increases as a function of nutrient loading. In addition, the data quantitatively demonstrates that fluorescence intensities increase independently of cell density. These results challenge the assumption that humic-like AFOM is exclusively terrestrial in origin and suggest that bacteria may &amp;#8220;engineer&amp;#8221; OM&lt;em&gt; in-situ&lt;/em&gt; that gives rise to these fluorescence characteristics as a function of metabolism. Importantly, nutrient availability is a key driver of metabolic activity, outlining the potential for the use of fluorescence as a marker for stream metabolism as opposed to a measure of bacterial numbers. Further development of the laboratory model via the utilisation of environmentally-sourced bacterial communities is required. Ultimately, this laboratory model will inform field studies that look to improve our understanding of how microbial communities respond to catchment stressors, and how these responses influence AFOM fluorescence signatures and ultimately the origin and fate of OM in freshwater systems.&lt;/p&gt;

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