scholarly journals Designing the Next Generation of Fe0-Based Filters for Decentralized Safe Drinking Water Treatment: A Conceptual Framework

Processes ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 745 ◽  
Author(s):  
Huichen Yang ◽  
Rui Hu ◽  
Arnaud Igor Ndé-Tchoupé ◽  
Willis Gwenzi ◽  
Hans Ruppert ◽  
...  
Keyword(s):  
Drinking Water ◽  
Field Experiments ◽  
Preferential Flow ◽  
Drinking Water Treatment ◽  
Operating Conditions ◽  
Research Progress ◽  
Safe Drinking Water ◽  
Next Generation ◽  
Sand Filters ◽  
Small Communities

The ambitious United Nations Sustainable Development Goal for 2030 to “leave no one behind” concerning safe drinking water calls for the development of universally applicable and affordable decentralized treatment systems to provide safe drinking water. Published results suggest that well-designed biological sand filters (BSFs) amended with metallic iron (Fe0-BSFs) have the potential to achieve this goal. Fe0-BSFs quantitatively remove pathogens and a myriad of chemical pollutants. The available data were achieved under various operating conditions. A comparison of independent research results is almost impossible, especially because the used Fe0 materials are not characterized for their intrinsic reactivity. This communication summarizes the state-of-the-art knowledge on designing Fe0-BSFs for households and small communities. The results show that significant research progress has been made on Fe0-BSFs. However, well-designed laboratory and field experiments are required to improve the available knowledge in order to develop the next generation of adaptable and scalable designs of Fe0-BSFs in only two years. Tools to alleviate the permeability loss, the preferential flow, and the use of exhausted filters are presented.

scholarly journals Effects of dynamic operating conditions on nitrification in biological rapid sand filters for drinking water treatment

2014 ◽  
Vol 64 ◽  
pp. 226-236 ◽  
Author(s):  
Carson O. Lee ◽  
Rasmus Boe-Hansen ◽  
Sanin Musovic ◽  
Barth Smets ◽  
Hans-Jørgen Albrechtsen ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Drinking Water Treatment ◽  
Operating Conditions ◽  
Sand Filters ◽  
Dynamic Operating

scholarly journals The Role of Catalytic Ozonation Processes on the Elimination of DBPs and Their Precursors in Drinking Water Treatment

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 521
Author(s):  
Fernando J. Beltrán ◽  
Ana Rey ◽  
Olga Gimeno
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Humic Substances ◽  
Hypochlorous Acid ◽  
Drinking Water Treatment ◽  
Disinfection Byproducts ◽  
Catalytic Ozonation ◽  
Operating Conditions ◽  
Halogen Compounds ◽  
Radiation Sources

Formation of disinfection byproducts (DBPs) in drinking water treatment (DWT) as a result of pathogen removal has always been an issue of special attention in the preparation of safe water. DBPs are formed by the action of oxidant-disinfectant chemicals, mainly chlorine derivatives (chlorine, hypochlorous acid, chloramines, etc.), that react with natural organic matter (NOM), mainly humic substances. DBPs are usually refractory to oxidation, mainly due to the presence of halogen compounds so that advanced oxidation processes (AOPs) are a recommended option to deal with their removal. In this work, the application of catalytic ozonation processes (with and without the simultaneous presence of radiation), moderately recent AOPs, for the removal of humic substances (NOM), also called DBPs precursors, and DBPs themselves is reviewed. First, a short history about the use of disinfectants in DWT, DBPs formation discovery and alternative oxidants used is presented. Then, sections are dedicated to conventional AOPs applied to remove DBPs and their precursors to finalize with the description of principal research achievements found in the literature about application of catalytic ozonation processes. In this sense, aspects such as operating conditions, reactors used, radiation sources applied in their case, kinetics and mechanisms are reviewed.

scholarly journals Fe0/H2O Filtration Systems for Decentralized Safe Drinking Water: Where to from Here?

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 429 ◽  
Author(s):  
Charles Nanseu-Njiki ◽  
Willis Gwenzi ◽  
Martin Pengou ◽  
Mohammad Rahman ◽  
Chicgoua Noubactep
Keyword(s):  
Drinking Water ◽  
Low Income ◽  
Universal Access ◽  
Low Cost ◽  
Low Income Countries ◽  
Future Research ◽  
Systematic Research ◽  
Safe Drinking Water ◽  
Iron Corrosion ◽  
Small Communities

Inadequate access to safe drinking water is one of the most pervasive problems currently afflicting the developing world. Scientists and engineers are called to present affordable but efficient solutions, particularly applicable to small communities. Filtration systems based on metallic iron (Fe0) are discussed in the literature as one such viable solution, whether as a stand-alone system or as a complement to slow sand filters (SSFs). Fe0 filters can also be improved by incorporating biochar to form Fe0-biochar filtration systems with potentially higher contaminant removal efficiencies than those based on Fe0 or biochar alone. These three low-cost and chemical-free systems (Fe0, biochar, SSFs) have the potential to provide universal access to safe drinking water. However, a well-structured systematic research is needed to design robust and efficient water treatment systems based on these affordable filter materials. This communication highlights the technology being developed to use Fe0-based systems for decentralized safe drinking water provision. Future research directions for the design of the next generation Fe0-based systems are highlighted. It is shown that Fe0 enhances the efficiency of SSFs, while biochar has the potential to alleviate the loss of porosity and uncertainties arising from the non-linear kinetics of iron corrosion. Fe0-based systems are an affordable and applicable technology for small communities in low-income countries, which could contribute to attaining self-reliance in clean water supply and universal public health.

Development of a hybrid ozonation biofilm-membrane filatration process for the production of drinking water

2005 ◽  
Vol 51 (6-7) ◽  
pp. 241-248 ◽  
Author(s):  
T. Leiknes ◽  
M. Lazarova ◽  
H. Ødegaard
Keyword(s):  
Drinking Water ◽  
Organic Matter ◽  
High Speed ◽  
Membrane Surface ◽  
Drinking Water Treatment ◽  
Rotating Disk ◽  
Operating Conditions ◽  
Operating Modes ◽  
High Concentrations ◽  
Biomass Separation

Drinking water sources in Norway are characterized by high concentrations of natural organic matter (NOM), low alkalinity and low turbidity. The removal of NOM is therefore a general requirement in producing potable water. Drinking water treatment plants are commonly designed with coagulation direct filtration or NF spiral wound membrane processes. This study has investigated the feasibility and potential of a hybrid process combining ozonation and biofiltration with a rotating disk membrane for treating drinking water with high NOM concentrations. Ozonation will oxidize the NOM content removing colour and form biodegradable organic compounds, which can be removed in biological filters. A constructed water was used in this study which is representative of ozonated NOM-containing water. A rotating membrane disk bioreactor downstream the ozonation process was used to carry out both the biodegradation as well as biomass separation in the same reactor. Maintenance of biodegradation of the organic matter while controlling biofouling of the membrane and acceptable water production rates was the focus in the study. Three operating modes were investigated. Removal of the biodegradable organics was consistent throughout the study indicating that sufficient biomass was maintained in the reactor for all operating conditions tested. Biofouling control was not achieved through shear-induced cleaning by periodically rotating the membrane disks at high speed. By adding a small amount of sponges in the membrane chamber the biofouling could be controlled by mechanical cleaning of the membrane surface during disk rotation. The overall results indicate that the system can favorably be used in an ozonation/biofiltration process by carrying out both biodegradation as well as biomass separation in the same reactor.

scholarly journals Biodegradation Behavior of Ozonated Natural Organic Matter in Sand Filters

2005 ◽  
Vol 9 (1) ◽  
pp. 3-16 ◽  
Author(s):  
J. Z. Wang ◽  
R. S. Summers
Keyword(s):  
Drinking Water ◽  
Organic Matter ◽  
Organic Carbon ◽  
Natural Organic Matter ◽  
Glyoxylic Acid ◽  
Complex Mixture ◽  
Drinking Water Treatment ◽  
Sand Filters ◽  
Substrate Removal ◽  
Exchange Resins

Natural organic matter (NOM) in drinking water is a complex mixture of organic compounds. Some of the compounds are not biodegradable, while others are quickly biodegradable and a third group is more resistant to biodegradation. To have a better understanding of the biofiltration process in drinking water treatment, it is important to identify the elements of the quickly and slowly biodegradable NOM and to characterize the biodegradation rate of each element. In this study, an ozonated NOM solution was used as the substrate. The NOM was isolated from a groundwater in Germany using ion-exchange resins. The ozone dose was 0.35 mg O3/mg DOC (dissolved organic carbon). Previously bioacclimated sand was used as filter media and biomass source and was homogeneously distributed in the filter prior to each run. The substrate removal was evaluated by DOC, biodegradable DOC (BDOC), assimilable organic carbon (AOC), aldehyde and ketoacid analyses. When expressed in terms of the empty bed contact time (EBCT), the results showed that filter velocity in the range of 1.5 to 15 m/hr had no impact on substrate removal. This implies that substrate utilization, not external mass transfer, is the rate limiting step for substrate removal in drinking water biofilters. In this study, compounds or NOM fractions are termed quickly biodegradable if they are removed in the first three minutes of EBCT. 15% of the DOC was removed by the biofilter within three minutes of EBCT and was termed the quickly biodegradable fraction. The BDOC fraction of the ozonated solution was determined to be 40 to 45% of the DOC. In terms of BDOC, about one third of the total BDOC was quickly biodegradable. The AOC results show that about 90% of the total AOC was utilized by Spirillum sp. NOX (AOC-NOX). Most of the AOC was quickly biodegradable and was removed within one minute of EBCT. For aldehydes, glyoxal and methyl glyoxal were removed to below the detection limit after two minutes of EBCT. However, only 60% of formaldehyde removal was achieved in the first two minutes of EBCT, and no additional removal was achieved with increasing EBCT. Additionally, no significant removal of acetaldehyde was observed. The results of ketoacids show that their utilization rates were very high. More than 90% of glyoxylic acid and pyruvic acid were removed within one minute of EBCT.

A novel acoustic imaging tool for monitoring the state of rapid sand filters

2013 ◽  
Vol 14 (1) ◽  
pp. 107-118
Author(s):  
Nihed Allouche ◽  
Dick G. Simons ◽  
Paul Keijzer ◽  
Luuk C. Rietveld ◽  
Joost Kappelhof
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Acoustic Waves ◽  
Vertical Direction ◽  
Drinking Water Treatment ◽  
The State ◽  
Acoustic Response ◽  
Sand Filters ◽  
Cleaning Procedure ◽  
Filter Bed

A new technology based on acoustic waves is developed to monitor the state of sand filters used in drinking water treatment. Changes in the sand filter, due to the removal of suspended particles from the water and their accumulation in the pores, result in an increase of the bulk density and acoustic speed of the granular material. Consequently, the reflected acoustic response changes as the filter is in use. To monitor these changes, an instrument composed of an omnidirectional transmitter and an array of hydrophones was built. With frequencies ranging between 10 and 110 kHz, high resolution is achieved in the vertical direction enabling the detectability of clogged layers with a minimum thickness of 1 cm. The novel instrument is tested by conducting a monitoring experiment in a filter used in practice. A 2D scan over a part of the filter was performed and repeated every 2 hours over a period of 10 days. An analysis of the data revealed a local increase of the reflected acoustic response with increasing filter run time. The changes in acoustic signal are mainly observed at the upper 5 cm of the sand bed. It is also clear that the filter bed is slowly compacting as a function of time. The total compaction after a period of 10 days reached 3.5 cm. The filter bed is expanded again during the cleaning procedure. Once the procedure is completed, the upper 30 cm of the filter becomes more transparent, showing small accumulations of material at greater depth. The observed changes in the filter bed demonstrate the potential of this acoustic-based tool to monitor the state of rapid sand filters and optimise their performance. The new tool can be used to evaluate the cleaning procedure and is valuable in detecting lateral variations in the filter bed. These variations may indicate local clogging that needs to be removed effectively to avoid deterioration of the overall performance in the long term. This type of information is difficult to obtain from the monitoring techniques currently used in drinking water treatment.

scholarly journals The Dutch secret: safe drinking water without chlorine in the Netherlands

2008 ◽  
Vol 1 (2) ◽  
pp. 173-212 ◽  
Author(s):  
P. W. M. H. Smeets ◽  
G. J. Medema ◽  
J. C. van Dijk
Keyword(s):  
Drinking Water ◽  
Surface Water ◽  
The Netherlands ◽  
Distribution System ◽  
Drinking Water Treatment ◽  
Quantitative Microbial Risk Assessment ◽  
Safe Drinking Water ◽  
Microbial Risk Assessment ◽  
Production And Distribution ◽  
Water Companies

Abstract. The Netherlands is one of the few countries where chlorine is not used at all, neither for primary disinfection nor to maintain a residual disinfectant in the distribution network. The Dutch approach that allows production and distribution of drinking water without the use of chlorine while not compromising microbial safety at the tap, can be summarized as follows: Use the best source available, in order of preference: – microbiologically safe groundwater, – surface water with soil passage such as artificial recharge or bank filtration, – direct treatment of surface water in a multiple barrier treatment; Use a preferred physical process treatment such as sedimentation, filtration and UV-disinfection. If absolutely necessary, also oxidation by means of ozone or peroxide can be used, but chlorine is avoided; Prevent ingress of contamination during distribution; Prevent microbial growth in the distribution system by production and distribution of biologically stable (biostable) water and the use of biostable materials; Monitor for timely detection of any failure of the system to prevent significant health consequences. New developments in safe drinking water in the Netherlands include the adaptation of the Dutch drinking water decree, implementation of quantitative microbial risk assessment (QMRA) by water companies and research into source water quality, drinking water treatment efficacy, safe distribution and biostability of drinking water during distribution and \\textit{Legionella}. This paper summarizes how the Dutch water companies warrant the safety of the drinking water without chlorine.

scholarly journals Evaluation of Indicators for Cyanobacterial Risk in 108 Temperate Lakes Using 23 Years of Environmental Monitoring Data

2020 ◽  
Author(s):  
JING LI ◽  
Kenenth M Person ◽  
Heidi Pekar ◽  
Daniel Jansson
Keyword(s):  
Drinking Water ◽  
Water Supply ◽  
Anthropogenic Activities ◽  
Drinking Water Treatment ◽  
Drinking Water Supply ◽  
Cyanobacterial Blooms ◽  
Safe Drinking Water ◽  
Water Treatment Plants ◽  
Monitoring Strategies ◽  
Level 1

Abstract Background: Cyanobacterial blooms are of increasing concern for drinking water supply. Cyanobacterial risk in 108 temperate freshwater lakes were examined for drinking water supply. Results: In Sweden, a survey among drinking water producers showed that the sense of urgency was little. At 60 % of the Swedish drinking water treatment plants, operators lacked monitoring strategies. The study shows that blooms can produce a variety of toxins such as anatoxins, cylindrospermopsins, microcystins and saxitoxins. We confirmed the anthropogenic activities’ impact on cyanobacterial risk and evaluated that total phosphorus (TP) concentration can be used to indicate cyanobacterial risk by applying non-linear quantile regression for 108 Swedish monitoring lakes.Conclusion: We suggest that TP concentration should be investigated thoroughly to provide important knowledge which can be used to set nutrient targets to sustain safe drinking water supply and recreational services.TP should be targeted lower than 15 μg L-1, allowing 10 % exceedance of WHO Drinking Water Alert Level 1.

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