Cost-effective water treatment of polluted surface water by using direct filtration and granular activated carbon filtration

2002 ◽  
Vol 2 (1) ◽  
pp. 233-240 ◽  
Author(s):  
J. Cromphout ◽  
W. Rougge

In Harelbeke a Water Treatment Plant with a capacity of 15,000 m3/day, using Schelde river water has been in operation since April 1995. The treatment process comprises nitrification, dephosphatation by direct filtration, storage into a reservoir, direct filtration, granular activated carbon filtration and disinfection. The design of the three-layer direct filters was based on pilot experiments. The performance of the plant during the five years of operation is discussed. It was found that the removal of atrazin by activated carbon depends on the water temperature.

Author(s):  
Nguyet Thi-Minh Dao ◽  
The-Anh Nguyen ◽  
Viet-Anh Nguyen ◽  
Mitsuharu Terashima ◽  
Hidenari Yasui

The occurrence of pesticides even at low concentrations in drinking water sources might induce potential risks to public health. This study aimed to investigate the removal mechanisms of eight pesticides by the nitrifying expanded-bed filter using biological activated carbon media at the pretreatment of a drinking water plant. The field analysis demonstrated that four pesticides Flutolanil, Buprofezin, Chlorpyrifos, and Fenobucard, were removed at 82%, 55%, 54%, and 52% respectively, while others were not significantly removed. Under controlled laboratory conditions with continuous and batch experiments, the adsorption onto the biological activated carbon media was demonstrated to be the main removal pathway of the pesticides. The contribution of microorganisms to the pesticide removals was rather limited. The pesticide removals observed in the field reactor was speculated to be the adsorption on the suspended solids presented in the influent water. The obtained results highlighted the need to apply a more efficient and cost-effective technology to remove the pesticide in the drinking water treatment process. Keywords: biological activated carbon; drinking water treatment; nitrifying expanded-bed filter; pesticide removal.


2021 ◽  
Author(s):  
Nick Dimas

Drinking Water Treatment Plants employ biofiltration systems to increase water quality through nutrient reduction. Microbial biofilms housed in biofilter media, are responsible for nutrient uptake and biodegradation. The purpose of this study was to re-evaluate the function and efficiency of biofilter media and investigate seasonal changes in the microbial populations. TOC and DO were more reduced in Granular Activated Carbon (GAC) media than in anthracite. Heterotrophic plate counts (HPC) were conducted to establish seasonal trends on microbial population. PCR-amplified 16S rRNA fragments were sequenced to compare microbial communities. Summer samples have higher HPC than winter samples. Summer samples yielded a reduction in microbial diversity and no detectable overlap with winter samples. Confocal microscopy conducted to qualitatively visualize the structure of biofilms was complemented by quantitative COMSTAT analysis showing GAC with double the biomass due to a greater level of attachment sites. GAC outcompetes anthracite in chemical adsorption and biological activity.


2021 ◽  
Author(s):  
Nick Dimas

Drinking Water Treatment Plants employ biofiltration systems to increase water quality through nutrient reduction. Microbial biofilms housed in biofilter media, are responsible for nutrient uptake and biodegradation. The purpose of this study was to re-evaluate the function and efficiency of biofilter media and investigate seasonal changes in the microbial populations. TOC and DO were more reduced in Granular Activated Carbon (GAC) media than in anthracite. Heterotrophic plate counts (HPC) were conducted to establish seasonal trends on microbial population. PCR-amplified 16S rRNA fragments were sequenced to compare microbial communities. Summer samples have higher HPC than winter samples. Summer samples yielded a reduction in microbial diversity and no detectable overlap with winter samples. Confocal microscopy conducted to qualitatively visualize the structure of biofilms was complemented by quantitative COMSTAT analysis showing GAC with double the biomass due to a greater level of attachment sites. GAC outcompetes anthracite in chemical adsorption and biological activity.


2004 ◽  
Vol 4 (4) ◽  
pp. 71-78 ◽  
Author(s):  
D.H. Metz ◽  
J. DeMarco ◽  
R. Pohlman ◽  
F.S. Cannon ◽  
B.C. Moore

The objective of this study was to compare the adsorption capabilities of the virgin carbon to the twelve and five times reactivated granular activated carbon (GAC). From a water treatment plant operator's perspective, there were very few practical differences in adsorption among the carbons tested for total organic carbon (TOC) and disinfection byproduct (DBP) precursors. However, some overall trends were observed. The GAC that was regenerated 5 times (R5) generally showed greater DBP precursor adsorption than the other GACs especially at the beginning of the runs. In some cases the carbon that was reactivated 12/13 times (R12 and R13) adsorbed slightly less DBP precursors than the other GACs especially in the latter part of the runs. The virgin (V) carbon performed better than the other GACs relative to DBP precursor removal in the latter part of the runs.


2010 ◽  
Vol 61 (10) ◽  
pp. 2603-2610 ◽  
Author(s):  
F. Schoonenberg Kegel ◽  
B. M. Rietman ◽  
A. R. D. Verliefde

Drinking water utilities in Europe are faced with a growing presence of organic micropollutants in their water sources. The aim of this research was to assess the robustness of a drinking water treatment plant equipped with reverse osmosis and subsequent activated carbon filtration for the removal of these pollutants. The total removal efficiency of 47 organic micropollutants was investigated. Results indicated that removal of most organic micropollutants was high for all membranes tested. Some selected micropollutants were less efficiently removed (e.g. the small and polar NDMA and glyphosate, and the more hydrophobic ethylbenzene and napthalene). Very high removal efficiencies for almost all organic micropollutants by the subsequent activated carbon, fed with the permeate stream of the RO element were observed except for the very small and polar NDMA and 1,4-dioxane. RO and subsequent activated carbon filtration are complementary and their combined application results in the removal of a large part of these emerging organic micropollutants. Based on these experiments it can be concluded that the robustness of a proposed treatment scheme for the drinking water treatment plant Engelse Werk is sufficiently guaranteed.


1992 ◽  
Vol 26 (5-6) ◽  
pp. 1255-1264
Author(s):  
K. L. Martins

During treatment of groundwater, radon is often coincidentally removed by processes typically used to remove volatile organic compounds (VOCs)-for example, processes such as liquid-phase granular activated carbon (LGAC) adsorption and air stripping with vapor-phase carbon (VGAC). The removal of radon from drinking water is a positive benefit for the water user; however, the accumulation of radon on activated carbon may cause radiologic hazards for the water treatment plant operators and the spent carbon may be considered a low-level radioactive waste. To date, most literature on radon removal by water treatment processes was based on bench- or residential-scale systems. This paper addresses the impact of radon on municipal and industrial-scale applications. Available data have been used todevelop graphical methods of estimating the radioactivity exposure rates to facility operators and determine the fate of spent carbon. This paper will allow the reader to determine the potential for impact of radon on the system design and operation as follows.Estimate the percent removal of radon from water by LGAC adsorbers and packed tower air strippers. Also, a method to estimate the percent removal of radon by VGAC used for air stripper off-gas will be provided.Estimate if your local radon levels are such that the safety guidelines, suggested by USEPA (United States Environmental Protection Agency), of 25 mR/yr (0.1 mR/day) for radioactivity exposure may or may not be exceeded.Estimate the disposal requirements of the waste carbon for LGAC systems and VGAC for air stripper “Off-Gas” systems. Options for dealing with high radon levels are presented.


1986 ◽  
Vol 18 (1) ◽  
pp. 31-42 ◽  
Author(s):  
E. A. Shpirt ◽  
K. T. Alben

The particle size distribution at different bed depths of a fixed bed of granular activated carbon (GAC) has been monitored during 50 weeks of a pilot column run at the Waterford, New York potable water treatment plant. Initial backwashing resulted in significant stratification of GAC in the column: larger particles (average diameter 1.18 mm) settled in the bottom of the column (105 cm), and smaller particles (average diameter 0.97 mm) were concentrated near the top (24 cm), compared to samples of unstratified virgin Calgon F400 (average diameter 1.09 mm). During column loading and initial backwashing, more fines were created than were present in the virgin GAC (average 6.5% of GAC fines in the > 40 mesh fraction, compared to only 0.3% in the > 40 mesh fraction for virgin Calgon F400). After 50 weeks of service there was an overall trend toward a smaller average particle size (0.9 mm) with development of a more regular pattern of bed stratification (1.08 mm at the bottom and 0.75 mm at the top). These changes are attributed to breaking of large particles (12-20 mesh) and creation of intermediate size particles (20-30 and 30-40 mesh).


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