Anthracite Filter Research Articles

Column studies on the removal of dissolved organic carbon, turbidity and heavy metals from stormwater using granular activated carbon

Stormwater pollutants have the capacity to damage aquatic environments if they are discharged untreated. Suspended solids (turbidity), dissolved organic carbon (DOC) and heavy metals removal from stormwater were investigated in batch and fixed-bed column experiments. Field studies revealed that turbidity and DOC in stormwater were effectively removed at filtration velocities of 5, 10 and 11.5 m/h using a 100 cm high granular activated carbon (GAC) filter column. At the higher filtration velocities of 10 and 11.5 m/h, adding a pre-treatment 100 cm high anthracite filter column further improved DOC and turbidity removal. Batch and column laboratory adsorption experiments at pH 6.5–7.2 using GAC showed that the order of removal efficiency for solutions containing single and mixed metals was Pb, Cu > Zn > Ni, Cd. This order was related to the solubility product and first hydrolysis constants of these metals’ hydroxides. This study confirmed that GAC filter is effective in removing turbidity, DOC and heavy metals from stormwater.

Assessment of biological activity in contact flocculation filtration used as a pretreatment in seawater desalination

Contact flocculation filtration (CFF) is a promising pretreatment method to improve feed water quality prior to seawater reverse osmosis (SWRO). CFF is the combination of deep bed filtration and in-line flocculation. To date, CFF has been used mainly as a barrier for particle removal in the filter bed itself with hydrophobic organic compounds removal by flocculation. In this study, the potential of CFF was investigated as a biofilter in addition to its major function of flocculation and particle/floc separation. Two different media (sand; S-CFF and anthracite; A-CFF) were tested on CFF. Bacterial activity in the filter bed was assessed in terms of cell number and adenosine tri-phosphate (ATP) measurement. The microbial community test in the filtration bed was carried out over 50d in case of sand filter (S-CFF) and 90d for anthracite filter (A-CFF) filtration periods. With the growth of an active microbial population on the filter bed medium, significant removal of organic compounds, especially low molecular weight (LMW) organics, from the seawater was achieved. The results indicated that CFF functions both as flocculation and separation unit and also as biofilter with moderate efficiency in reducing biofouling potential. The results also showed that A-CFF needed longer time to achieve bio-stabilization but it showed more effective biofiltration potential than S-CFF.

Application of bacteriophages to selectively remove Pseudomonas aeruginosa in water and wastewater filtration systems

Water and wastewater filtration systems often house pathogenic bacteria, which must be removed to ensure clean, safe water. Here, we determine the persistence of the model bacterium Pseudomonas aeruginosa in two types of filtration systems, and use P. aeruginosa bacteriophages to determine their ability to selectively remove P. aeruginosa. These systems used beds of either anthracite or granular activated carbon (GAC), which were operated at an empty bed contact time (EBCT) of 45 min. The clean bed filtration systems were loaded with an instantaneous dose of P. aeruginosa at a total cell number of 2.3 (±0.1 [standard deviation]) × 107 cells. An immediate dose of P. aeruginosa phages (1 mL of phage stock at the concentration of 2.7 × 107 PFU (Plaque Forming Units)/mL) resulted in a reduction of 50% (±9%) and >99.9% in the effluent P. aeruginosa concentrations in the clean anthracite and GAC filters, respectively. To further evaluate the effects of P. aeruginosa phages, synthetic stormwater was run through anthracite and GAC biofilters where mixed-culture biofilms were present. Eighty five days after an instantaneous dose of P. aeruginosa (2.3 × 107 cells per filter) on day 1, 7.5 (±2.8) × 107 and 1.1 (±0.5) × 107 P. aeruginosa cells/g filter media were detected in the top layer (close to the influent port) of the anthracite and GAC biofilters, respectively, demonstrating the growth and persistence of pathogenic bacteria in the biofilters. A subsequent 1-h dose of phages, at the concentration of 5.1 × 106 PFU/mL and flow rate of 1.6 mL/min, removed the P. aeruginosa inside the GAC biofilters and the anthracite biofilters by 70% (±5%) and 56% (±1%), respectively, with no P. aeruginosa detected in the effluent, while not affecting ammonia oxidation or the ammonia-oxidizing bacterial community inside the biofilters. These results suggest that phage treatment can selectively remove pathogenic bacteria with minimal impact on beneficial organisms from attached growth systems for effluent quality improvement.

Treatment of low-turbidity source water by permanganate pre-oxidation: In situ formed hydrous manganese dioxide as filter aid

This pilot study investigated the effects of in situ formed manganese dioxide (in situ δMnO2), produced from KMnO4 reduction, on the removal efficiency for turbidity and particles and the run length of filters through this pilot-scale study. The sedimentation effluent showed an insignificant difference in turbidity but a remarkable decrease in particle concentration after dosing KMnO4. The residual particle concentration decreased from 1504units/mL to 359, 302, 164units/mL in the anthracite filter effluent and from 994units/mL to 219, 134, 99units/mL in the granular activated carbon (GAC) effluent at KMnO4 dosages of 0.2, 0.3, and 0.4mg/L respectively. However, this effect was achieved at the expense of a rapid increase of water head loss (WHL), and the average run length decreased from 70h to 54, 52, and 48h accordingly. After dosing KMnO4 at 0.2, 0.3, and 0.4mg/L, the contributive ratios of the uppermost 200mm layers on WHL increased from 68.5% to 81.9%, 76.0%, and 82.2%, respectively.

Utilisation of wastewater nutrients for microalgae growth for anaerobic co-digestion

The feasibility of growing microalgae in natural light using wastewater high in nutrients (N & P) for the production of more bioenergy was examined. The main retrofitting unit would be a photobioreactor for wastewater treatment plants (wwtp) having anaerobic digesters in close proximity. Theoretical microalgae production rates from different wastewater sources (municipal wwtp, source separation of human and animal wastewaters) were estimated using mass balance. Mass and energy balances for a conventional wwtp using chemically enhanced primary treatment was investigated for microalgae growth for a situation limited by availability of carbon dioxide (CO2) generated onsite and where additional CO2 was imported from outside source. Reject water from dewatering of anaerobically digested sludge from four wwtp around Oslo region were pretreated for improved light penetration and examined for microalgae growth. Several pre-treatment methods were investigated. Pretreatment using flocculation + settling + anthracite filtration yielded high light transmittance. A maximum microalgae growth rate of 13 g TSS/m2-d was achieved using this pretreated reject water. The challenges of integrating photobioreactors with existing units have been highlighted.

A full-scale biological aerated filtration system application in the treatment of paints industry wastewater

This study was carried out to evaluate an existing treatment technology for wastewater treatment unit from a paint production factory. Biological aerated filter is a good technique for reducing land used in the purpose of wastewater treatment. Influent discharged from this factory ranged between 50–120 m 3 /day with an average of 70 m 3 /day. This unit composed of primary and secondary sedimentation tanks, gravel filter and finally sand anthracite (3:1 by volume) filter. Aeration units and two submersible pumps were equipped for aerobic treatment and sediments removal. The unit influent was characterized by average values of chemical oxygen demand (COD), biochemical oxygen demand (BOD 5 ) and total suspended solids (TSS) were 1711±795, 748±180 and 3821±1621 mg/l, respectively. Primary sedimentation of the wastewater for six hours reduced the COD, BOD, and TSS by 43, 26, and 76%, respectively. The treated wastewater characteristics are in compliance with the Egyptian law which regulates the discharge of industrial wastewater to the sewerage system. The results from each treatment process proved to be efficient for the treatment of such wastewater. Keywords: Paints wastewater treatment, Biological aerated filter and water quality

Composition and stability of bacterial communities associated with granular activated carbon and anthracite filters in a pilot scale municipal drinking water treatment facility

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.

Necessity for replacing the filter media in the water treatment plant based on effective size and uniformity coefficient

Aims: This study aims to compare the parameters in filtration unit of the plant with international guidelines. The results of this study would determine the necessity for replacing or renewing the anthracite and sand filter beds in phase I of IWTP. Materials and Methods: In this field study, a total of 11 samples with a mass of 5 kg sand and anthracite media were analyzed. The media samples were evaluated in view of uniformity coefficient and effective size according to international soil classification. Data obtained were statistically analyzed using t-test at significance level (P < 0.05). Results: Results of this study showed that the uniformity coefficients of anthracite and sand media were 3.6 ± 0.4 and 1.93 ± 0.11 mm, respectively. Also, the effective sizes of anthracite and sand media were 0.68 ± 0.08 and 0.63 ± 0.05 mm, respectively. These values exceeded the international guidelines and had a significance difference with them (P-value < 0.05). Conclusion: The results were shown that the uniformity coefficient and effective size of sand and anthracite media in the filters used in phase I of IWTP exceeded the guidelines and they need to be replaced with new media. Finally, based on the current study, filter beds were renewed.

Comparison of two online flocculation monitoring techniques for predicting turbidity removal by granular media filtration

Particulate matter removal in drinking water treatment via direct granular filtration requires specific flocculation conditions (a process typically termed ‘high energy flocculation’). Predicting filtered water turbidity based on flocculated water characteristics remains difficult. This study has sought to establish a relationship between filtered water turbidity and the flocculated water characteristics. Flocculation of low‐turbidity raw water was evaluated online using a Photometric Dispersion Analyser (PDA) and a Dynamic Particle Analyser in a modified jar test followed by a bench‐scale anthracite filter. Coagulants used were alum, PASS100 and ferric sulphate, in addition to a polydiallyldimethylammonium chloride (polyDADMAC) cationic polymer. They were dosed in warm and cold waters, and flocculated with intensities (G) from 0 to 100 s−1. Of the two instruments selected to analyse flocculation performance, the Dynamic Particle Analyser was shown to be the most sensitive, detecting small changes in floc growth kinetics and even floc growth under low flocculation conditions which remained undetected by the PDA. Floc size was shown to be insufficient in predicting particulate matter removal by direct granular filtration as measured by turbidity, although a threshold dv value (50 µm) could be identified for the test conditions evaluated in this project, above which turbidity was systematically lower than 0.2 NTU.

Biofiltration as pre-treatment to water harvesting and recycling

This paper presents the results of the long term biofilter experiments conducted with raw stormwater collected from a canal at Carlton, in Sydney. Anthracite and granular activated carbon (GAC) were used as a single filter media in biofilter columns. Media heights of 75 and 40 cm were used. The filter columns were operated at filtration velocities of 0.12 and 0.25 m/h. The removal efficiency for turbidity and DOC for the GAC filter media were found to be 75% and almost 100% respectively. The removal efficiency for the anthracite filter was much lower. Molecular weight distribution analysis showed an almost similar trend to the DOC removal. Compared with anthracite filter media, the GAC biofilter removed a much larger range of organic compounds present in the stormwater. The GAC biofilter removes organic matter earlier as compared to anthracite. Based on a limited sample of stormwater, the removal efficiency for phosphorus was upto 74% and that of nitrogen was up to 30%. In general GAC filter shows higher heavy metal removal efficiency than anthracite. The removal of zinc, iron, lead and nickel were good. However the concentration of heavy metal in the raw surface water sample was low.

Effect of Hydrous Manganese Dioxide on the Treatment of Low-Turbidity Source Water: Plant-Scale Experience

The effect of potassium permanganate (KMnO(4)) preoxidation on the treatment of low-turbidity reservoir water was investigated through two years of operational data in a large-scale drinking water treatment plant (DWTP). KMnO4 facilitated the removal of pollutants [e.g., turbidity and chemical oxygen demand (COD(Mn))] by different units such as clarification, sand filtration, and granular activated carbon (GAC) adsorption. Although the addition of KMnO(4) increased the color and total Mn concentrations, the results of removal by clarification and filtration are promising. The average run length of anthracite filters decreased from 48 to 40.8 hours after the introduction of KMnO(4) and exhibited a negative correlation with KMnO(4) dosages (r(2) = 0.6912). The hydrous manganese dioxide in situ formed (delta MnO(2)) dominated in aiding coagulation and improving filtration to enhance pollutant removal in the KMnO(4) preoxidation process, and these effects were achieved at the expense of more frequent backwashing of anthracite filters. DOI: 10.1061/(ASCE) EE. 1943-7870.0000349. (C) 2011 American Society of Civil Engineers.

Hybrid filtration method for pre-treatment of stormwater

In this study the hybrid filtration process (combining fibre filter with deep bed dual media filtration) was investigated as pre-treatment to stormwater. This process was investigated in-terms of reduction in turbidity, dissolved organic carbon (DOC), colour, headloss development across the filters, suspended solids removal, organic matter removal, nutrients and heavy matter (such as iron, copper, lead, zinc) removal efficiency. A comparison was made between the hybrid filter with single media (sand) deep bed filter and fibre filter. It was found that the hybrid filtration system successfully removed turbidity (98%), colour (99%), suspended solids (99%), and DOC (55%). The removal efficiency of heavy metal was relatively low as the concentration of heavy metals present in stormwater was low. The removal efficiency of nitrate, nitrite and phosphorous (as orthophosphate) was 27, 35 and 72% respectively. Hybrid filtration processes showed a better reduction of Modified Fouling Index (MFI) value (from 15.500 s/l(2) to 9 s/l(2)) compared with single media sand, anthracite and fibre filter which were 35 s/l(2), 13 s/l(2)and 14 s/l(2) respectively when operated at FeCl(3) dose of 15 mg/l.

Rich microbial communities inhabit water treatment biofilters and are differentially affected by filter type and sampling depth

Factors affecting microbial diversity (richness) and community structure in biofilter columns were investigated. At a pilot filtration plant, granular activated carbon (GAC), anthracite and sand-based filters were used to treat stormwater from an urban catchment. After 12 weeks operation, sand media filters clogged (hydraulic conductivity declining by 90%) and all filters were destructively sampled. All biofilters had similar levels of polysaccharide in the surface layer, however only the sand columns clogged. This clogging may have been due to a combination of polysaccharide and small particle size, the development of a sand-specific microbial community, or other biogeochemical interactions. DNA fingerprinting was used to show that bacterial, archaeal and eukaryotic communities were present in all filter types and at all sampling depths (to 45 cm). The bacterial community was far richer (Margalefs index, d, 1.5–2) than the other groups. This was consistent across filter types and sampling depths. The structure of the bacteria and archaea communities in sand filters differed to those in GAC and anthracite filters (P&amp;lt;0.05). In contrast, eukaryotic communities were similar in surface biofilm layers, irrespective of filter type. As such, physicochemical properties of filters differentially influence the microbial community. Furthermore, we have established that archaea are distributed throughout biofilters; the role of these microorganisms in water treatment and filter function, particularly clogging, requires attention.

Deep bed filter as pre-treatment to stormwater

This paper presents the results of experiments on the application of dual media and single media deep bed filters as pre-treatments to stormwater. In-line flocculation-filtration experiments were conducted with dual and single media filter. The single filter media (80 cm) consisted of either anthracite or sand, and the dual media filter consisted of sand (40 cm at the bottom) and anthracite (40 cm on top). Filtration velocities of 5 m/h, 10 m/h and 15 m/h were examined. The removal efficiency for turbidity, suspended solids and TOC was found to be 95%, 99% and 30–45% respectively at a flocculant dose of FeCl3 of 15 mg/L. The anthracite filter media showed a lower headloss development (26 cm, operated at 5 m/h filtration velocity with FeCl3 dose of 5 mg/L). The removal efficiency for nitrogen was lower than phosphorus which was relatively good (up to 50%). The removal efficiency for heavy metals such as Cd, Pb, Cr and Ni was found to be very low for all tested filtration systems because concentrations of these metals in the influent were also low. This filter can be used as a pretreatment to a membrane filter as the modified fouling index was reduced from 750 s/L2 (for stormwater) to 15 s/L2 (for filtered effluent). Detailed submerged membrane filter experiments conducted with pre-treated water showed that the membrane filter can be successfully be used as post-treatment to in-line flocculant-filter at a sustainable flux of 10 L/m2.h to remove the remaining solids and pathogens. An increase of air scouring in the membrane unit decreased the pressure development although it did not have any effect on increasing the critical flux beyond 10 L/m2.h.

Removal of Mn2+ from water by “aged” biofilter media: The role of catalytic oxides layers

The present work was aimed at evaluating the surface coatings characteristics and autocatalytic manganese oxidation potentials of two groups of "aged" biofilter media. This refers to the anthracite filter media of a biological water treatment plant on which metal oxides and a biofilm have deposited on the surface of the filter media over long time of filtration. Duplicate samples of anthracite filter media were collected from each of the six filter wells in the plant and classified into two groups, based on their duration of operation, as 3-years filter media and 15-years filter media. Batch experiments showed that the 15-years filter media exhibited very high manganese sorption capacity and were less dependent on the microbial activity than the 3-years filter media. Results of the surface coatings analyses indicated that the biofilter materials is predominantly composed of variable layers of manganese and iron oxides, with microbial biomass contributing only about 3.5 and 1.4% of the dry weight of the surface coatings on the 3- and 15-years filter media respectively. Investigations onto the Mn2+ sorption by the lyophilized biofilter media showed that, the sorption kinetics on the catalytic oxides layers followed the pseudo-second-order kinetics model, thus suggesting chemisorption as the dominant mechanism of Mn2+ removal. This implied that manganese removal by these biofilters is mainly by adsorption of Mn2+ onto the iron and manganese (catalytic) oxides layers and autocatalytic oxidation. The present study has clearly linked Mn2+ oxidation to the catalytic oxides layers on the aged biofilter media.

Investigating the fate of saxitoxins in biologically active water treatment plant filters

The saxitoxins are potent neurotoxins, which can be produced by freshwater cyanobacteria. This study assessed the fate of five saxitoxins variants through biologically active laboratory filters containing media sourced from the filters beds of two water treatment plants (WTPs). Decreases in the concentration of the less toxic variants coincided with increases in the concentrations of the more toxic variants through the filters containing anthracite sourced from two different WTPs. No changes in toxin concentrations were evident through parallel filters containing sand. The results strongly suggest that organisms within the biofilm of the anthracite filters possessed the ability to biotransform the saxitoxins variants, which has important implications for drinking water treatment, particularly since this has the potential to increase the toxicity of the filtered water.

Biofiltration for removal of BOM and residual ammonia following control of bromate formation

Nitrification was developed within a biological filter to simultaneously remove biodegradable organic matter (BOM) and residual ammonia added to control bromate formation during the ozonation of drinking water. Testing was performed at pilot-scale using three filters containing sand and anthracite filter media. BOM formed during ozonation (e.g., assimilable organic carbon (396–572 μg/L), formaldehyde (11–20 μg/L), and oxalate (83–145 μg/L)) was up to 70% removed through biofiltration. Dechlorinated backwash water was required to develop the nitrifying bacteria needed to convert the residual ammonia (0.1–0.5 mg/L NH 3-N) to nitrite and then to nitrate. Chlorinated backwash water resulted in biofiltration without nitrification. Deep-bed filtration (empty-bed contact time (EBCT)=8.3 min) did not enhance the development of nitrification when compared with shallow-bed filtration (EBCT=3.2 min). Variable filtration rates between 4.8 and 14.6 m/h (2 and 6 gpm/sf) had minimal impact on BOM removal. However, conversion of ammonia to nitrite was reduced by 60% when increasing the filtration rate from 4.8 to 14.6 m/h. The results provide drinking water utilities practicing ozonation with a cost-effective alternative to remove the residual ammonia added for bromate control.

Iron Behavior in the Ozonation and Filtration of Groundwater

In Finnish groundwater, the main substances that require treatment are iron and manganese. In addition to this, groundwaters are soft and acidic. Iron removal is usually relatively effective by oxidizing dissolved iron into an insoluble form, either by aeration or chemical oxidization and removing the formed precipitate by sand filtration. Sometimes, if the untreated water contains high amounts of organic matter, problems may arise for iron removal. In Finland, it is quite common that groundwater contains high levels of both iron and natural organic matter, mainly as humic substances. The groundwater of the Kukkala intake plant in Liminka has been found to be problematic, due to its high level of natural organic matter. This research studied the removal of iron from this water by means of oxidation with ozone and filtration. While the oxidation of iron by ozone was rapid, the precipitate particles formed were small, and thus could not be removed by sand and anthracite filtration, and the iron residue in the treated water was more than 2 mgL−1. And while the filtration was able to remove iron well without the feed of ozone, the iron residue in the treated water was only 0.30 mgL−1. In this case, iron was led to the filter in a bivalent dissolved form. So, the result of iron removal was the best when the sand/anthracite filter functioned largely as an adsorption filter.

Factors affecting the removal of geosmin and MIB in drinking water biofilters

Bench‐scale experiments were conducted using four parallel dual‐media filter columns containing biologically active anthracite or granular activated carbon media and sand. The factors under investigation were low‐ (8°C) and high‐ (20°C) temperature operations, geosmin and 2‐methylisoborneol (MIB) concentration, media type, and biodegradable organic matter (BOM) level. Source water consisted of dechlorinated tap water to which geosmin and MIB were added, as well as a cocktail of easily biodegradable organic matter (i.e., typical ozonation by‐products). Phase 1 experiments used a high BOM level (280 μg/L carbon [C]) to simulate water that had been subjected to ozonation before filtration. Phase 2 experiments used a low BOM level (28 μg/L C) to simulate nonozonated water. Factorial design experiments showed that all four main factors (temperature, concentration, media, and BOM level) were important to both geosmin and MIB removal. Temperature and media interaction and concentration and BOM level interaction were significant for geosmin removal only. Temperature and BOM level interaction as well as media and BOM level interaction were significant for the removal of both geosmin and MIB. Overall, removals of geosmin and MIB were lower in phase 2 (low BOM level), in particular in the anthracite media filters. Biomass levels in the filters appeared to have a significant effect upon the removal efficiencies of both odor compounds.

A case study for process optimization of direct filtration in Korea

In the case of S water treatment plant, it was designed to be mostly operated by direct filtration mode all the year round. To evaluate the conditions of such operation mode, in this study, we operated pilot plant by direct filtration process by making flocculation treatment water flow into anthracite filter and active carbon (Calgon, Norit) filter which is an assembly of deep bed filter paper, and studied to find out the principle in which turbidity is removed in filter paper by measuring turbidity and head loss by the depth of filter, and an appropriate operation method. Also we conducted comparison evaluation according to kinds of coagulant and evaluation according to the injection of a polymer coagulant, a filter aid, before letting filter flow into flocculation treatment water. On the basis of the optimum operation of direct filtration process using deep bed filtration, it is necessary to decide and inject the optimum injection volume of filter aids taking account for the quality of raw water and to operate anthracite filter, which will also contribute to lowering the operation expenses of a filtration plant and improving the quality of treatment water.