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Luiza C. Campos - One of the best experts on this subject based on the ideXlab platform.

  • Physico-chemical and biological aspects of a serially connected lab-scale constructed wetland-stabilization tank-GAC Slow Sand Filtration system during removal of selected PPCPs
    Chemical Engineering Journal, 2019
    Co-Authors: Xingguo Han, Bernd W. Brandt, Q Zhou, Lena Ciric, Luiza C. Campos
    Abstract:

    Abstract A serially connected lab-scale Greater duckweed constructed wetland (CW)-stabilization tank (ST)-GAC Sandwich Slow Sand Filtration system was tested to remove four widely detected pharmaceuticals and personal care products (PPCPs) from natural water with a spiked concentration of 25 μg/L. High removals were achieved rapidly (93.5–100%), being on average 95.9%, 99.1%, 98.1% and 97.4% for DEET, paracetamol, caffeine and triclosan (n = 3), respectively. Except for DEET, no significant difference was observed between overall removals with and without artificial aeration in CW tank (p > 0.05), showing good stability of the system. COD was considerably removed under aeration and final TOC removal was 64.7%. Nitrite, nitrate, ammonia and phosphate were not detected at the end of the test (day 26). The microbial community structure in three connected units of the tested system showed differences and good stability after the aerators were removed. Proteobacteria was the most dominant phylum among the 47 phyla found. Microbes attaching to the Greater duckweed contributed more to the microbial community structure in CW and ST tanks than original natural water. However, at the end of the run, the structural differences among three units decreased. After aeration stopped, phylum composition became more stable in ST tank while CW tank showed small structural variation throughout the test. Various correlations were found between detected phyla, among which Proteobacteria and Bacteroidetes showed a significant negative correlation (R = −0.73, p

  • Deterministic-Based Model of Slow Sand Filtration. I: Model Development
    Journal of Environmental Engineering, 2006
    Co-Authors: Luiza C. Campos, Stephen R. Smith, Nigel Graham
    Abstract:

    Slow Sand Filtration (SSF) is widely used throughout the world for the treatment of drinking water. However, relatively little attention has been given to the development of a comprehensive process model. Previous studies have considered separate aspects of the SSF process, such as developing an improved representation of the schmutzdecke layer, and a more detailed description of the microbial dynamics. The objective of this work was to develop a deterministic simulation model of the SSF process incorporating fundamental physicochemical and biological dynamics within a classical Filtration framework. The model was based on a temporal and spatial finite difference method and was calibrated and verified using operational data from pilot-scale SSF units. Results from the calibration showed that the model satisfactorily predicts headloss development in SSF units. There was no significant difference between many of the most sensitive model parameter values for two successive runs of the same filter. However, a few individual model parameters (e.g., in the fundamental headloss equations) were found to vary with Filtration run and it is speculated that this is due to seasonal factors.

  • Deterministic-Based Model of Slow Sand Filtration. II: Model Application
    Journal of Environmental Engineering, 2006
    Co-Authors: Luiza C. Campos, Stephen R. Smith, Nigel Graham
    Abstract:

    This paper describes the use of a deterministic Slow Sand filter process model to investigate and assess some of the fundamental aspects and mechanisms operating during Slow Sand Filtration (SSF). These include the role of the schmutzdecke, biomass development, and the initial condition of the filter, to the overall process performance. The SSF process model has been developed recently and is described in a companion paper by Campos et al., in 2006. It attempts to provide a simulation of the physicochemical and biological processes responsible for the Filtration mechanisms operating in SSF. The simulation of filter runs has been carried out with the help of extensive pilot plant data provided by Thames Water Utilities Ltd., involving both uncovered and covered filter beds. The results demonstrate that the presence and nature of a schmutzdecke layer profoundly influence the spatial and temporal development of interstitial biomass within the Sand and, consequently, the headloss profile. Microbial interactions in the filter bed play a fundamental role in the process and are involved in setting the pattern and magnitude of headloss development. The model also demonstrates the significance of residual deposits within the filter after surface cleaning, on the subsequent filter behavior.

  • Modelling and simulation of the biological and physical processes of Slow Sand Filtration.
    2002
    Co-Authors: Luiza C. Campos
    Abstract:

    Slow Sand Filtration (SSF) is the earliest form of engineered potable water treatment and remains one of the most efficient processes for improving the physical, biological and chemical quality of water. However, whilst widely used throughout the world, knowledge of the Filtration mechanisms remains limited. This is important in understanding and managing the processes that are responsible for gradually blocking the filter reducing its operational life and Filtration efficiency. The objective of this thesis was to develop a mechanistic simulation model of the fundamental physico-chemical and biological processes responsible for the Filtration mechanisms operating in Slow Sand filters. The model solves a set of equations describing schmutzdecke development above the Sand and microbial biomass growth within the Sand. The model assumes that the schmutzdecke layer contributes to the water purification process and its growth is described as linear function in relation to time. The dynamic interactions between the principal groups of microorganisms including: algae, bacteria and protozoa, were modelled using Monod-type kinetic equations. The Filtration performance of the filter media was defined in the model by the removal of particulate material from water and was represented by a combination of headloss and Filtration coefficient functions. The model was calibrated and verified using data from full and pilot plant-scale SSF operated by Thames Water Utilities Ltd. Simulation results showed that interstitial biomass was the smallest part of the bulk specific deposit in both covered and uncovered filters. However, microbial dynamics played an important role in the Filtration performance. Schmutzdecke development had a major influence on the operation of uncovered filters and was responsible for the significant increase of headloss observed during operation. The model provides a representation of the fundamental nature of SSF processes and could form the basis of an operational management system to optimise SSF.

Matthias Kastner - One of the best experts on this subject based on the ideXlab platform.

  • Removal of pathogen indicators from secondary effluent using Slow Sand Filtration: Optimization approaches
    Ecological Engineering, 2016
    Co-Authors: Eva M. Seeger, Jochen A. Müller, Mareike Braeckevelt, Nils Reiche, Matthias Kastner
    Abstract:

    Abstract In many arid regions, the reuse of wastewater is an economic option for crop irrigation. To avoid health risks for consumers, pathogens must be eliminated prior to application. Slow Sand Filtration (SSF) represents an effective low-tech treatment technology for pathogen removal from water. To further improve the time-space yield of SSF, innovative filter configurations were investigated regarding the removal of the pathogen indicators Escherichia coli , enterococci, Clostridium perfringens spores, somatic and F-specific RNA coliphages as well as heterotrophic bacteria. A standard filter ( N ), a recirculating filter ( R ), a static cascade ( N + N ) and a rotating cascade ( C ) were tested at high and low hydraulic loading rates, two recirculation rates and two rotation frequencies. Results showed that only C and N + N concurrently complied with European standards for E. coli and enterococci, achieving mean log removal of 2.7-4.7 and 2.1-2.4, respectively. The best performance was reached by C with weekly rotation; N + N may be a promising, technically simpler alternative. The crucial role of biological removal mechanisms for E. coli and enterococci elimination was indicated by (i) the increased efficiency of the standard SSF N after 1½ years of operation and (ii) the positive impact of several Schmutzdecke layers. C. perfringens spore removal performance was good for all SSFs. Considerable sorption of spores was indicated by decreased efficiency in N and C at long operation times. Somatic coliphages were reduced to concentrations close to the detection limit, while F-specific RNA coliphage removal was ∼1.1 log. Removal of heterotrophic bacteria was generally limited.

  • selective elimination of bacterial faecal indicators in the schmutzdecke of Slow Sand Filtration columns
    Applied Microbiology and Biotechnology, 2015
    Co-Authors: Kristina R. Pfannes, Matthias Kastner, Kilian M. W. Langenbach, Giovanni Pilloni, Torben Stührmann, Kathrin Euringer, Tillmann Lueders, Thomas R. Neu, Jochen A. Müller, Rainer U. Meckenstock
    Abstract:

    Slow Sand Filtration (SSF) is an effective low-tech water treatment method for pathogen and particle removal. Yet despite its application for centuries, it has been uncertain to which extent pathogenic microbes are removed by mechanical Filtration or due to ecological interactions such as grazing and competition for nutrients. In this study, we quantified the removal of bacterial faecal indicators, Escherichia coli and Enterococcus faecalis, from secondary effluent of a wastewater treatment plant and analysed the microbial community composition in compartments of laboratory model SSF columns. The columns were packed with different Sand grain sizes and eliminated 1.6-2.3 log units of faecal indicators, which translated into effluents of bathing water quality according to the EU directive (<500 colony forming units of E. coli per 100 ml) for columns with small grain size. Most of that removal occurred in the upper filter area, the Schmutzdecke. Within that same zone, total bacterial numbers increased however, thus suggesting a specific elimination of the faecal indicators. The analysis of the microbial communities also revealed that some taxa were removed more from the wastewater than others. These results accentuate the contribution of biological mechanisms to water purification in SSF.

  • Selective elimination of bacterial faecal indicators in the Schmutzdecke of Slow Sand Filtration columns
    Applied microbiology and biotechnology, 2015
    Co-Authors: Kristina R. Pfannes, Matthias Kastner, Kilian M. W. Langenbach, Giovanni Pilloni, Torben Stührmann, Kathrin Euringer, Tillmann Lueders, Thomas R. Neu, Jochen A. Müller, Rainer U. Meckenstock
    Abstract:

    Slow Sand Filtration (SSF) is an effective low-tech water treatment method for pathogen and particle removal. Yet despite its application for centuries, it has been uncertain to which extent pathogenic microbes are removed by mechanical Filtration or due to ecological interactions such as grazing and competition for nutrients. In this study, we quantified the removal of bacterial faecal indicators, Escherichia coli and Enterococcus faecalis, from secondary effluent of a wastewater treatment plant and analysed the microbial community composition in compartments of laboratory model SSF columns. The columns were packed with different Sand grain sizes and eliminated 1.6-2.3 log units of faecal indicators, which translated into effluents of bathing water quality according to the EU directive (

  • Slow Sand Filtration of secondary clarifier effluent for wastewater reuse
    Environmental Science & Technology, 2009
    Co-Authors: K Langenbach, Peter Kuschk, H Horn, Matthias Kastner
    Abstract:

    Appropriate technologies are needed for disinfection of wastewater to allow safe reuse. Slow Sand Filtration is a simple technology used for pathogen and particle removal in drinking water purification. We investigated removal of fecal indicator bacteria relevant for wastewater reuse, particle removal, and runtime in Slow Sand Filtration of secondary clarifier effluent. The key process parameters hydraulic loading rate, Sand grain size distribution, and filter bed depth were systematically varied. Slow Sand filters for tertiary treatment of wastewater seem promising for wastewater reuse, especially in arid developing countries. They eliminated 1.9−2.6 log10-units of E. coli and 1.9−3.0 log10-units of intestinal Enterococci reaching effluent concentrations of 11−142 CFU per 100 mL of E. coli and 2−24 CFU per 100 mL of intestinal Enterococci. Bacteria removal was shown to be a function of Sand surface area, dirt layer, and supernatant water. Sand surface area per filter surface area should not be chosen bel...

Rainer U. Meckenstock - One of the best experts on this subject based on the ideXlab platform.

  • Selective elimination of bacterial faecal indicators in the Schmutzdecke of Slow Sand Filtration columns
    Applied microbiology and biotechnology, 2015
    Co-Authors: Kristina R. Pfannes, Matthias Kastner, Kilian M. W. Langenbach, Giovanni Pilloni, Torben Stührmann, Kathrin Euringer, Tillmann Lueders, Thomas R. Neu, Jochen A. Müller, Rainer U. Meckenstock
    Abstract:

    Slow Sand Filtration (SSF) is an effective low-tech water treatment method for pathogen and particle removal. Yet despite its application for centuries, it has been uncertain to which extent pathogenic microbes are removed by mechanical Filtration or due to ecological interactions such as grazing and competition for nutrients. In this study, we quantified the removal of bacterial faecal indicators, Escherichia coli and Enterococcus faecalis, from secondary effluent of a wastewater treatment plant and analysed the microbial community composition in compartments of laboratory model SSF columns. The columns were packed with different Sand grain sizes and eliminated 1.6-2.3 log units of faecal indicators, which translated into effluents of bathing water quality according to the EU directive (

  • selective elimination of bacterial faecal indicators in the schmutzdecke of Slow Sand Filtration columns
    Applied Microbiology and Biotechnology, 2015
    Co-Authors: Kristina R. Pfannes, Matthias Kastner, Kilian M. W. Langenbach, Giovanni Pilloni, Torben Stührmann, Kathrin Euringer, Tillmann Lueders, Thomas R. Neu, Jochen A. Müller, Rainer U. Meckenstock
    Abstract:

    Slow Sand Filtration (SSF) is an effective low-tech water treatment method for pathogen and particle removal. Yet despite its application for centuries, it has been uncertain to which extent pathogenic microbes are removed by mechanical Filtration or due to ecological interactions such as grazing and competition for nutrients. In this study, we quantified the removal of bacterial faecal indicators, Escherichia coli and Enterococcus faecalis, from secondary effluent of a wastewater treatment plant and analysed the microbial community composition in compartments of laboratory model SSF columns. The columns were packed with different Sand grain sizes and eliminated 1.6-2.3 log units of faecal indicators, which translated into effluents of bathing water quality according to the EU directive (<500 colony forming units of E. coli per 100 ml) for columns with small grain size. Most of that removal occurred in the upper filter area, the Schmutzdecke. Within that same zone, total bacterial numbers increased however, thus suggesting a specific elimination of the faecal indicators. The analysis of the microbial communities also revealed that some taxa were removed more from the wastewater than others. These results accentuate the contribution of biological mechanisms to water purification in SSF.

Martin Jekel - One of the best experts on this subject based on the ideXlab platform.

  • Pilot-scale investigation on the removal of organic foulants in secondary effluent by Slow Sand Filtration prior to ultraFiltration.
    Water research, 2010
    Co-Authors: Xing Zheng, Mathias Ernst, Martin Jekel
    Abstract:

    Abstract Natural bioFiltration processes have been verified as effective pre-treatment choice improving the performance of low-pressure membranes (MF/UF) in wastewater reclamation. In the present work, pilot-scale Slow Sand Filtration (SSF) was used to simulate bank Filtration at high Filtration rates (from 0.25 m/h to 0.5 m/h) to filter secondary effluent prior to UF. The results showed that SSF improved the performance of UF to a large extent. Related to previous work biopolymers are considered as major dissolved organic foulants in treated wastewater. The removal of these organic foulants in Slow Sand filters and factors affecting the performance of SSF were investigated. It was observed that the removal of biopolymers took place mainly at the upper Sand layer and was related to biological degradation. Tests on the degradability of biopolymers verified that they are biodegradable. Sixteen months monitoring of biopolymer concentration in the secondary effluent indicated that it varied seasonally. In winter season the concentration was much higher than during the summer months. Higher temperature and lower biopolymer concentration led to more effective foulants removal and more sustainable operation of SSF. During the whole experimental period, the performance of SSF was always better at Filtration rate of 0.25 m/h than at 0.5 m/h. Under the present experimental conditions, SSF exhibited stable and effective biopolymer removal at temperatures higher than 15 °C, at biopolymer concentrations lower than 0.5 mg C/L and with sufficient oxygen available.

  • Effect of Slow Sand Filtration of treated wastewater as pre-treatment to UF
    Desalination, 2009
    Co-Authors: Xing Zheng, R. Mehrez, Martin Jekel, Mathias Ernst
    Abstract:

    UltraFiltration (UF) of treated municipal wastewater has been used to produce high-quality reuse water for different applications. However, without pre-treatment, secondary treated wastewater effluent shows high fouling potential and reduces the performance of UF membrane Filtration significantly. To remove foulants prior to UF, Slow Sand Filtration (SSF) was investigated in the present work. Two pilot-scale Slow Sand filters were operated in tandem with UF. The performance of the UF plant was improved to a large extent by delivering Slow Sand filtrate compared to direct secondary effluent Filtration. Removal of common organic fouling indicators (i.e., proteins, carbohydrates, and biopolymers) by SSF was significantly higher at 0.25 m/h versus 0.5 m/h filter loading rate. Results of a comparative analysis of SSF effluent characteristics and UF performance showed that the biopolymer content detected by size exclusion chromatography displayed a good correlation with the filterability of corresponding water sample by UF, while photo-metrically detected proteins and polysaccharides did not present any relationship with UF performance.

Jochen A. Müller - One of the best experts on this subject based on the ideXlab platform.

  • Removal of pathogen indicators from secondary effluent using Slow Sand Filtration: Optimization approaches
    Ecological Engineering, 2016
    Co-Authors: Eva M. Seeger, Jochen A. Müller, Mareike Braeckevelt, Nils Reiche, Matthias Kastner
    Abstract:

    Abstract In many arid regions, the reuse of wastewater is an economic option for crop irrigation. To avoid health risks for consumers, pathogens must be eliminated prior to application. Slow Sand Filtration (SSF) represents an effective low-tech treatment technology for pathogen removal from water. To further improve the time-space yield of SSF, innovative filter configurations were investigated regarding the removal of the pathogen indicators Escherichia coli , enterococci, Clostridium perfringens spores, somatic and F-specific RNA coliphages as well as heterotrophic bacteria. A standard filter ( N ), a recirculating filter ( R ), a static cascade ( N + N ) and a rotating cascade ( C ) were tested at high and low hydraulic loading rates, two recirculation rates and two rotation frequencies. Results showed that only C and N + N concurrently complied with European standards for E. coli and enterococci, achieving mean log removal of 2.7-4.7 and 2.1-2.4, respectively. The best performance was reached by C with weekly rotation; N + N may be a promising, technically simpler alternative. The crucial role of biological removal mechanisms for E. coli and enterococci elimination was indicated by (i) the increased efficiency of the standard SSF N after 1½ years of operation and (ii) the positive impact of several Schmutzdecke layers. C. perfringens spore removal performance was good for all SSFs. Considerable sorption of spores was indicated by decreased efficiency in N and C at long operation times. Somatic coliphages were reduced to concentrations close to the detection limit, while F-specific RNA coliphage removal was ∼1.1 log. Removal of heterotrophic bacteria was generally limited.

  • Selective elimination of bacterial faecal indicators in the Schmutzdecke of Slow Sand Filtration columns
    Applied microbiology and biotechnology, 2015
    Co-Authors: Kristina R. Pfannes, Matthias Kastner, Kilian M. W. Langenbach, Giovanni Pilloni, Torben Stührmann, Kathrin Euringer, Tillmann Lueders, Thomas R. Neu, Jochen A. Müller, Rainer U. Meckenstock
    Abstract:

    Slow Sand Filtration (SSF) is an effective low-tech water treatment method for pathogen and particle removal. Yet despite its application for centuries, it has been uncertain to which extent pathogenic microbes are removed by mechanical Filtration or due to ecological interactions such as grazing and competition for nutrients. In this study, we quantified the removal of bacterial faecal indicators, Escherichia coli and Enterococcus faecalis, from secondary effluent of a wastewater treatment plant and analysed the microbial community composition in compartments of laboratory model SSF columns. The columns were packed with different Sand grain sizes and eliminated 1.6-2.3 log units of faecal indicators, which translated into effluents of bathing water quality according to the EU directive (

  • selective elimination of bacterial faecal indicators in the schmutzdecke of Slow Sand Filtration columns
    Applied Microbiology and Biotechnology, 2015
    Co-Authors: Kristina R. Pfannes, Matthias Kastner, Kilian M. W. Langenbach, Giovanni Pilloni, Torben Stührmann, Kathrin Euringer, Tillmann Lueders, Thomas R. Neu, Jochen A. Müller, Rainer U. Meckenstock
    Abstract:

    Slow Sand Filtration (SSF) is an effective low-tech water treatment method for pathogen and particle removal. Yet despite its application for centuries, it has been uncertain to which extent pathogenic microbes are removed by mechanical Filtration or due to ecological interactions such as grazing and competition for nutrients. In this study, we quantified the removal of bacterial faecal indicators, Escherichia coli and Enterococcus faecalis, from secondary effluent of a wastewater treatment plant and analysed the microbial community composition in compartments of laboratory model SSF columns. The columns were packed with different Sand grain sizes and eliminated 1.6-2.3 log units of faecal indicators, which translated into effluents of bathing water quality according to the EU directive (<500 colony forming units of E. coli per 100 ml) for columns with small grain size. Most of that removal occurred in the upper filter area, the Schmutzdecke. Within that same zone, total bacterial numbers increased however, thus suggesting a specific elimination of the faecal indicators. The analysis of the microbial communities also revealed that some taxa were removed more from the wastewater than others. These results accentuate the contribution of biological mechanisms to water purification in SSF.