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 Methane emission and methanotrophic activity in groundwater-fed drinking water treatment plants

2020 ◽  
Vol 20 (3) ◽  
pp. 819-827 ◽  
Author(s):  
Edmundas Maksimavičius ◽  
Peter Roslev
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Methane Emission ◽  
Drinking Water Treatment ◽  
Ammonia Removal ◽  
Limited Information ◽  
Gas Stripping ◽  
Sand Filters ◽  
Water Treatment Plants ◽  
Methane Oxidizing Bacteria

Abstract Groundwater for drinking water production may contain dissolved methane (CH4) at variable concentrations. Most of this important greenhouse gas is often vented to the atmosphere during primary aeration and gas stripping processes at drinking water treatment plants (DWTPs). However, limited information exists regarding emission and fate of methane at many groundwater-fed DWTPs. This study estimates emission of methane from 1,004 DWTPs in Denmark and includes data from 3,068 groundwater wells. The fate of methane and occurrence of methane oxidizing bacteria in DWTPs was examined, including the potential role in ammonia removal. Methane emission from Danish DWTPs was estimated to be 1.38–2.95 × 10−4 Tg CH4/y which corresponds to 0.05–0.11% of the national anthropogenic methane emission. Trace levels of methane remained in the drinking water after primary aeration and entered the sand filters as a potential microbial substrate. Methanotrophic bacteria and active methane oxidation was always detected in the sand filters at groundwater-fed DWTPs. Methanotrophic consortia isolated from DWTP sandfilters were inoculated into laboratory-scale sand filters and the activity confirmed that methanotrophic consortia can play a role in the removal of ammonia via assimilation and co-oxidation. This suggests a potential for facilitating the removal of inorganic constituents from drinking water using methane as a co-substrate.

Use of bauxite for enhanced removal of bacteria in slow sand filters

2016 ◽  
Vol 17 (4) ◽  
pp. 1007-1015 ◽  
Author(s):  
Daniel Urfer
Keyword(s):  
Drinking Water ◽  
Drinking Water Treatment ◽  
Particle Removal ◽  
Sand Filters ◽  
Filter Surface ◽  
Second Stage ◽  
Slow Sand Filter ◽  
Different Depths ◽  
Filter Bed ◽  
Pilot Tests

Slow sand filtration (SSF) is a well-known process for drinking water treatment and is widely used for the production of biologically stable drinking water and particle removal. The removal process of particles and microorganisms is highly dependent on the buildup of the schmutzdecke at the filter surface. During the ripening period and especially for cold waters, the buildup of the schmutzdecke may take several months until such filters are biologically mature and at steady-state regarding their removal performance for particles and microorganisms. In order to improve the performance of SSF in terms of the removal of bacteria, e.g. Escherichia coli and Enterococcus, pilot tests using natural bauxite as a filter media have been performed. The results showed a significant improvement in bacteria retention within the filter bed of a second-stage slow sand filter containing different depths of bauxite.

scholarly journals Organic micropollutant removal in full-scale rapid sand filters used for drinking water treatment in The Netherlands and Belgium

Chemosphere ◽  
2020 ◽  
Vol 260 ◽  
pp. 127630 ◽  
Author(s):  
Camilla Di Marcantonio ◽  
Cheryl Bertelkamp ◽  
Nikki van Bel ◽  
Tessa E. Pronk ◽  
Peer H.A. Timmers ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
The Netherlands ◽  
Drinking Water Treatment ◽  
Full Scale ◽  
Sand Filters ◽  
Micropollutant Removal

Modifications of unit processes for finished water quality improvement at the Kueui water treatment plant in Seoul

2002 ◽  
Vol 2 (5-6) ◽  
pp. 193-199
Author(s):  
M.J. Yu ◽  
H.M. Cho ◽  
J.Y. Koo ◽  
I.S. Han ◽  
E.M. Gwon ◽  
...  
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Water Treatment ◽  
Treatment Plant ◽  
Drinking Water Treatment ◽  
Water Treatment Plant ◽  
Pilot Scale ◽  
Sand Filters ◽  
Water Treatment Plants ◽  
Sedimentation Basins

Recently, Seoul city has tried to modify and upgrade the existing facilities and utilities and to improve the established water treatment plants, instead of application of a new treatment process. These efforts have finally lowered the turbidity of finished water below 0.1NTU. Small lab-scale and pilot-scale experiments have been conducted and they have provided optimum parameters for the design and operation of drinking water treatment plants. In addition, quantitative and/or trace analysis technologies developed for monitoring water quality of effluent from unit processes and automization of facilities, have contributed to the improvement of turbidity in drinking water. The Kueui water treatment plant, one of the drinking water treatment plants in Seoul, produces finished water with 0.08 NTU. It results from the operators' continuous endeavor to lower the turbidity in a scale of 0.01 NTU. The data for 12 months indicated that turbidity of settled water was less than 1.16 NTU and that of filtered water was less than 0.12 NTU for 95% of the period. Sedimentation basins and sand filters satisfy the recommended turbidity criteria, 2 NTU and 0.3 NTU, respectively. Also Kueui water treatment plant has focused on the control of organic matters to decrease in DBPs and on the removal of microorganisms.

scholarly journals Bioaugmented sand filter columns provide stable removal of pesticide residue from membrane retentate

2020 ◽  
Author(s):  
Lea Ellegaard-Jensen ◽  
Morten Dencker Schostag ◽  
Mahdi Nikbakht Fini ◽  
Nora Badawi ◽  
Alex Gobbi ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Pesticide Residues ◽  
Drinking Water Treatment ◽  
Residual Water ◽  
Sand Filters ◽  
Water Stream ◽  
Sand Filter ◽  
Degrading Bacteria ◽  
Membrane Treatment

ABSTRACTDrinking water resources, such as groundwater, are threatened by pollution. The pesticide metabolite 2,6-dichlorobenzamide (BAM) is one of the compounds frequently found in groundwater. Studies have attempted to add specific BAM-degrading bacteria to sand-filters at drinking water treatment facilities. This biotechnology has shown great potential in removing BAM from contaminated water. However, the degradation potential was formerly lost after approximately 2-3 weeks due to a decrease of the degrader population over time.The aim of the present study was to overcome the constraints leading to loss of degraders from inoculated filters. Our approach was threefold: 1) Development of a novel inoculation strategy, 2) lowering the flowrate to reduce washout of cells, and 3) increasing the concentration of nutrients hereunder the pollutant in a smaller inlet water stream. The two latter were achieved via modifications of the inlet water by applying membrane treatment which, besides producing an ultra-pure water fraction, produced a residual water stream with nutrients including BAM concentrated in an approximately 10-fold reduced volume. This was done to alleviate starvation of degrader bacteria in the otherwise oligotrophic sand-filters and to enable a decreased flowrate.By this approach, we achieved 100% BAM removal over a period of 40 days in sand-filter columns inoculated with the BAM-degrader Aminobacter sp. MSH1. Molecular targeting of the degrader strain showed that the population of degrader bacteria persisted at high numbers throughout the sand-filter columns and over the entire timespan of the experiment. 16S rRNA gene amplicon sequencing confirmed that MSH1 dominated the bacterial communities.IMPORTANCEMany countries rely partly or solely on groundwater as the source of drinking water. Here groundwater contamination by pesticide residues poses a serious threat to the production of high quality drinking water. Since scarcity of clean groundwater may occur in progressively larger areas both locally and globally, the need for efficient purification technologies is growing. This study shows that a novel system combining membrane treatment and bioaugmented sand-filters can efficiently remove pesticide residues in laboratory columns when applying specific inoculation and flow conditions. Once upscaled, this system can be used directly for pump-and-treat of contaminated groundwater wells or at drinking water treatment plants.

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
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