Preventing trihalomethane formation: the ability of granular activated carbon and brimac media to remove colour and total organic carbons, from drinking water in the north west of Scotland

2010 ◽  
Vol 10 (4) ◽  
pp. 526-533
Author(s):  
K. M. Courtnadge ◽  
A. Muir ◽  
S. Sandilands ◽  
J. Martin

Background: Granular activated carbon (GAC) and Brimac media has been used for many years in water treatment works to reduce and remove colour and total organic carbon (TOCs). This reduces the formation of trihalomethanes (THMs) formed by disinfection with chlorine. The TOCs arise from humic and fulvic acids found in source waters for many, small, scattered remote communities in Scotland. A number of different configurations and empty bed contact times (EBCTs) of GAC and Brimac media were studied at Scottish Waters Acharacle water treatment works using a purpose built pilot plant of flexible design. This was used to establish the absolute design threshold for colour and TOC to meet Scottish Water's water specifications for their removal. Results: The 50:50 combination of Brimac and GAC in series reduced raw colour of up to 39°Hazen to below 10°Hazen and raw TOCs from up to 5.7 mg/l to <2.0 mg/l producing the lowest levels of THMs after chlorine addition of <10 μg/l. An EBCT of 5.4 hours produced an average colour removal of 79.2% and average TOC removal of 79.1%. Conclusions: 50:50 Brimac then GAC in series with an EBCT of 5.4 hours was the best configuration for the removal of colour and TOCs and gave rise to the lowest formation of THMs. The trials have successfully proved how the THM precursors can be removed by the GAC once the colour has been removed by the Brimac. This has not only provided a design solution for Acharacle WTW but the “way forward” for Scottish Water with regard to media change out on their numerous existing GAC plants which are faced with similar problems.


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):  
O.J.I. Kramer ◽  
C. van Schaik ◽  
P.D.R. Dacomba-Torres ◽  
P.J. de Moel ◽  
E.S. Boek ◽  
...  


2019 ◽  
Vol 5 (3) ◽  
pp. 609-617 ◽  
Author(s):  
Yifeng Huang ◽  
Zhijie Nie ◽  
Jie Yuan ◽  
Audrey Murray ◽  
Yi Li ◽  
...  

A test was developed to measure the present-day adsorptive capacity of granular activated to help drinking water treatment professionals to determine when the GAC needs replacement.



2012 ◽  
Vol 10 (2) ◽  
pp. 244-255 ◽  
Author(s):  
T. B. Shirey ◽  
R. W. Thacker ◽  
J. B. Olson

Granular activated carbon (GAC) is an alternative filter substrate for municipal water treatment as it provides a high surface area suitable for microbial colonization. The resulting microbial growth promotes biodegradation of organic materials and other contaminants from influent waters. Here, the community structure of the bacteria associated with three GAC and two anthracite filters was examined over 12 months to monitor changes in community composition. Nearly complete 16S rRNA genes were polymerase chain reaction amplified for terminal restriction fragment length polymorphism (T-RFLP) analyses. The identity of commonly occurring peaks was determined through the construction of five representative 16S rRNA clone libraries. Based on sequence analysis, the bacterial communities associated with both anthracite and GAC filters appear to be composed of environmentally derived bacteria, with no known human pathogens. Analysis of similarity tests revealed that significant differences in bacterial community structure occurred over time, with filter substrate playing an important role in determining community composition. GAC filters exhibited the greatest degree of bacterial community variability over the sampling period, while anthracite filters showed a lower degree of variability and less change in community composition. Thus, GAC may be a suitable biologically active filter substrate for the treatment of municipal drinking water.





2004 ◽  
Vol 55 (8) ◽  
pp. 879 ◽  
Author(s):  
G. M. Lodge

Studies of Phalaris aquatica L. were used to collect data for basal bud (all below ground shoot material) weights, their water-soluble carbohydrate (WSC) content, and green vegetative tillers. A glasshouse study of cvv. Australian and Sirosa was conducted on regrowth after 26 days of plants previously exposed to either non-limiting or limiting (simulated Mediterranean environment, and 3- or 6-week drought) watering treatments. The other studies were of Sirosa phalaris pastures that had previously been subjected to continuous or lenient (resting in both spring and autumn each year) grazing by Merino wethers. In the glasshouse study, weight of basal buds (g/plant) was highest (13.88 g/plant) for Australian plants in the non-limiting water treatment, but not significantly different among watering treatments for Sirosa plants. Basal bud WSC values ranged from 2126 mg/plant (Australian phalaris, non-limiting water) to <200 mg/plant in 6-week drought and Mediterranean watering treatments of both cultivars. Tiller regrowth was higher in Australian non-limiting water treatment compared with all other treatments. Post-drought field studies (6 weeks tiller regrowth in May–June 1995) showed that plants in continuously grazed treatments had basal bud weights <11 g/plant, basal bud WSC contents <600 mg/plant, and green vegetative tiller weights <2.5 g/plant, compared with values of >11 g/plant, >1300 mg/plant, and >3.6 g/plant, respectively, for treatments rested for 12 weeks in both autumn and spring. At the end of spring 1995, when plants were post stem elongation and anthesis, basal bud WSC (mg/plant) was significantly higher in autumn–spring rest treatments compared with plants that were continuously grazed (mean values for 2 sites of 2889 and 1458 mg/plant, respectively). From these data, threshold values of basal bud WSC contents of <600 mg/plant after 6 weeks of regrowth in autumn–early winter, or <2000 mg/plant in flowering plants in late spring in continuously grazed pastures >3 years old, were proposed as useful indicators that management intervention may be required to maintain Sirosa phalaris persistence on the North-West Slopes of New South Wales.



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.



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