Anthracite Filter Research Articles

Meta-omics profiling of full-scale groundwater rapid sand filters explains stratification of iron, ammonium and manganese removals

Rapid sand filters (RSF) are an established and widely applied technology for groundwater treatment. Yet, the underlying interwoven biological and physical-chemical reactions controlling the sequential removal of iron, ammonia and manganese remain poorly understood. To resolve the contribution and interactions between the individual reactions, we studied two full-scale drinking water treatment plant configurations, namely (i) one dual-media (anthracite and quartz sand) filter and (ii) two single-media (quartz sand) filters in series. In situ and ex situ activity tests were combined with mineral coating characterization and metagenome-guided metaproteomics along the depth of each filter. Both plants exhibited comparable performances and process compartmentalization, with most of ammonium and manganese removal occurring only after complete iron depletion. The homogeneity of the media coating and genome-based microbial composition within each compartment highlighted the effect of backwashing, namely the complete vertical mixing of the filter media. In stark contrast to this homogeneity, the removal of the contaminants was strongly stratified within each compartment, and decreased along the filter height. This apparent and longstanding conflict was resolved by quantifying the expressed proteome at different filter heights, revealing a consistent stratification of proteins catalysing ammonia oxidation and protein-based relative abundances of nitrifying genera (up to 2 orders of magnitude difference between top and bottom samples). This implies that microorganisms adapt their protein pool to the available nutrient load at a faster rate than the backwash mixing frequency. Ultimately, these results show the unique and complementary potential of metaproteomics to understand metabolic adaptations and interactions in highly dynamic ecosystems.

Removal of Chromium Species from Low-Contaminated Raw Water by Different Drinking Water Treatment Processes

The occurrence of Cr (VI) in drinking water resources in low but toxicologically relevant concentrations requires the development of reliable and industrially applicable separation processes in drinking water treatment. There is little information in the literature on the removal of chromium species at concentrations below 10 µg/L. Therefore, in this study, the removal of chromium in the concentration range ≤10 µg/L was investigated using three separation processes, activated carbon filtration (ACF), reduction/coagulation/filtration (RCF) and low-pressure reverse osmosis (LPRO), in both laboratory- and pilot-scale tests. In ACF treatment, Cr (III) was removed by deep bed filtration over 1.5 m of anthracite at a pH of 7.5 (which was used as a prefilter prior to ACF), while Cr (VI) was removed up to 75% via ACF at a filter bed depth of 2.5 m. Fresh activated carbon (AC) exhibited the highest adsorption capacity for Cr (VI), while reactivated AC had a significantly lower capacity for Cr (VI), which was attributed to calcium and iron deposits. In technical filters, where multiple reactivated activated carbon is used, this led to a low removal rate for Cr (VI). Using the RCF process with Fe (II) dosing in a continuous flow reactor at a specific coagulant dosing ratio, high Cr (VI) removal, down to a concentration of 0.1 µg/L, was achieved within minutes. The subsequent anthracite filtration ensured the complete removal of Fe (III) and Cr (III) precipitates. The RCF process was limited by the oxygen side reaction with Fe (II), which dominated at Cr (VI) concentrations below 1 µg/L. In addition, a four-step LPRO process with concentrate recycling showed effective removal (>99%) of both Cr (III) and Cr (VI) species in raw water as well as a negligible effect of pH in the testing pH range of 5.6 to 8.3 on the Cr (VI) removal. Nevertheless, the water hardness and pH of the LPRO permeate must be increased to make it available as drinking water. The three separation processes were found to be able to meet the expected more stringent future regulations for Cr (VI) level in drinking water. The most suitable technology, however, can be selected with respect to the raw water quality/characteristics, site-specific conditions and the already existing equipment.

Microbial communities and processes in biofilters for post-treatment of ozonated wastewater treatment plant effluent

Ozonation is an established solution for organic micropollutant (OMP) abatement in tertiary wastewater treatment. Biofiltration is the most common process for the biological post-treatment step, which is generally required to remove undesired oxidation products from the reaction of ozone with water matrix compounds. This study comparatively investigates the effect of filter media on the removal of organic contaminants and on biofilm properties for biologically activated carbon (BAC) and anthracite biofilters. Biofilms were analysed in two pilot-scale filters that have been operated for >50,000 bed volumes as post-treatment for ozonated wastewater treatment plant effluent. In parallel, the removal performance of bulk organics and OMP, including differentiation of adsorption and biotransformation through sodium azide inhibition, were carried out in bench-scale filter columns filled with material from the pilot filters. The use of BAC instead of anthracite resulted in an improved removal of organic bulk parameters, dissolved oxygen, and OMP. The OMP removal observed in the BAC filter but not in the anthracite filter was based on adsorption for most of the investigated compounds. For valsartan, however, biotransformation was found to be the dominant pathway, indicating that conditions for biotransformation of certain OMP are better on BAC than on anthracite. Adenosine triphosphate analyses in the media-attached biofilms of the pilot filters showed that biomass concentrations in the BAC filter were significantly higher than in the anthracite filter. The microbial communities (16S rRNA gene sequencing) appeared to be similar with respect to the types of organisms occurring on both filter materials. Alpha diversity also exhibited little variation between filter media. Beta diversity analysis, however, revealed that filter media and bed depth substantially influenced the biofilm composition. In practice, the impact of filter media on biofilm properties and biotransformation processes should be considered for the design of biofilters.

Cryptosporidium surrogate removal in pilot-scale rapid sand filters comprising anthracite, pumice or engineered ceramic granular media, and its correlation with turbidity

Removal of Cryptosporidium protozoa by granular media filtration is a critical step in conventional multi-barrier drinking-water treatment, and turbidity is commonly used to monitor system performance. We assessed the efficiencies of 3 different filter media at removing a Cryptosporidium parvum surrogate comprising glycoprotein-coated 4.5 μm polystyrene microspheres, and evaluated the responses of turbidity levels to surrogate concentrations. Field trials were performed using pilot-scale rapid sand filters comprising anthracite, pumice or engineered ceramic sand, while simulating a typical water treatment plant's operational conditions. Data from 44 trials indicated that the surrogate's log10 reduction values (LRVs) based on the peak concentrations were >3 in 100%, 70% and 41% of the trials with the ceramic sand, pumice sand and anthracite filters, respectively. The LRVs achieved in the ceramic sand filter trials (4.44 ± 0.38) were significantly greater than those in the pumice sand (3.21 ± 0.30) and anthracite (3.01 ± 0.70) filter trials (P < 0.00001).Correlations (P < 0.05) between turbidity levels and surrogate concentrations were observed in 17%, 44% and 29% of 51 trials involving the ceramic sand, pumice sand and anthracite filters, respectively. At peak surrogate breakthrough, the filtered water contained hundreds to thousands of surrogate particles/L, but the turbidity levels were <0.1 NTU in 63% and 71% of the trials with pumice and anthracite filters, respectively. In contrast, despite the ceramic sand filter achieving LRVs >3 consistently, the peak turbidity levels exceeded 0.30 NTU in 17% of the trials. Our findings highlight the need to introduce supplementary tools alongside turbidity to monitor filter performance more sensitively.

Biological and physico-chemical mechanisms accelerating the acclimation of Mn-removing biofilters

This study investigated treatment strategies which accelerated the acclimation of new Mn-removing biofilters to help utilities respond to changing Mn regulations, such as the recent introduction of a health-based maximum acceptable concentration and a reduction in the aesthetic objective for Mn in drinking water by Health Canada. Bench-scale filters of either GAC or anthracite media were fed with applied water containing Mn (17–61 μg/L) from a full-scale plant over 294 days. Treatment strategies included the addition of H2O2 (1 mg/L) and/or an increase in pH from 6.8 to 7.5 through the addition of NaOH. The potential physico-chemical and biological mechanisms responsible for accelerated biofilter acclimation under the various redox conditions were investigated through thermodynamic modelling, to predict homogeneous Mn oxide formation, and 16S rRNA gene amplicon sequencing, to characterize the microbial community within the filters. GAC filters treated with NaOH, and both H2O2 and NaOH, were the first to acclimate (< 20 μg/L Mn in filter effluent) after 59 and 63 days respectively, while the ambient GAC filter took almost 3 times as long to acclimate (168 days), and the anthracite filters which received the same chemically adjusted water took almost 4 times as long (226 and 251 days, respectively). The accelerated acclimation in the treated GAC filters was likely due to physico-chemical oxidation via three potential mechanisms: (1) homogeneous oxidation of dissolved Mn(II) to Mn(III)/Mn(IV) oxides and the subsequent removal of oxides from solution through adherence to the GAC surface, (2) adsorption of dissolved Mn(II) to GAC and subsequent homogeneous or biological oxidation, or (3) formation of colloidal Mn(III)/Mn(IV) oxides and subsequent adsorption of dissolved Mn(II) to the Mn colloids. In the untreated GAC filter and all anthracite filters, which did not benefit from improved redox conditions or an active surface, physico-chemical mechanisms alone were insufficient for consistent Mn removal to less than 20 μg/L. Acclimation in these filters was delayed until a microbiome enriched with bacteria capable of biological nitrification and Mn oxidation evolved within the filters. The acclimated microbiome was consistent between GAC and anthracite filters and was significantly different from the non-acclimated microbiome (p < 0.001) initially formed during the early operation of the filters. Interestingly, treatment with NaOH, and NaOH and H2O2, which accelerated physico-chemical oxidation in GAC filters, was observed to delay the development of biological oxidation in anthracite filters, and thus deferred acclimation. Although some filters took longer to acclimate than others, once acclimation was reached all filters had a similar microbiome and were able to consistently remove Mn to below 20 µg/L.

Start-up of bench-scale biofilters for manganese removal under tropical conditions: a comparative study using virgin pumice, silica sand, and anthracite filter media

The suitability of biofiltration for Mn removal was confirmed under tropical conditions. The similarity in the performance of pumice with the other media confirmed its suitability for biological Mn removal.

Development of a complete and straightforward hybrid model for gray water treatment

One of the most essential methods for preserving water resources is water reuse. The present study has been aimed at adjusting a gray water treatment system with high purification efficiency, low cost, easy maintenance, and high availability in every environment. To this goal, a new simple hybrid model for gray water treatment was made. In this model after conducting the settlement and aeration processes, seven different combinations of polypropylene activated carbon and anthracite filters beside resins were utilized for removing the contaminants in single and combined forms with three repetitions, and the results of each step were compared with the available standards. The different flow rates of 5, 2, 1, 0.5, 0.25, and 0.1 l/min were passed through the selected system to assess their effects on the reduction efficiencies of the pollutants in the system. The instantaneous ozonation method was used at the ozone concentrations of 1, 2.5, and 5 g/h. The results suggested the weakness of each filter alone for reducing the pollutants. After investigating the seven combinations, the combined filter of “polypropylene + resin + activated carbon” was recognized as the best filter for nondrinking purposes. The pH accounted for the lowest change of 10%, and chlorine and BOD5 accounted for the highest omissions of 90% and 80%, respectively. The system displayed the best performance at the flow intensity of 0.25 l/min or 15 l/h. The minimum rate of ozone production 1 g/h was able to remove all the coliform within any periods. This treated gray water is suitable for nondrinking uses such as irrigation and washing places.

Efficiency of the Single and Dual Media Filters for the Removal of Heavy Metal Ions from Water in Ekbatan and Shahid Beheshti Water Treatment Plants in city of Hamedan

Background: Anthracite is capable of adsorption and removal of contaminants especially heavy metals from potable water. This study was carried out to assess the efficiency of single (sand) and dual media (sand+ anthracite) filters for the removal of Fe, Zn and Mn from potable water in Shahid Beheshti and Ekbatan water treatment plants in City of Hamedan in 2016. Methods: In this cross-sectional descriptive study, due to the fact that the water supply in both water treatment plant is similar, totally 24 water samples were collected from both water treatment plants output. After preparation and processing of the samples in the laboratory, element (Fe, Zn and Mn) contents in samples were determined using inductively coupled plasma-optical emission spectrometer with three replications. All statistical analyses were performed using SPSS based on the Shapiro-Wilk test, Independent T-Test, Pearson Correlation Coefficient and One Sample T-Test. Results: The maximum average concentrations of elements (µg/l) were 1200±1070 for Fe, 110±50 for Zn and 170±140 for Mn respectively and for all metals related to Ekbatan water treatment plant. Also, comparing the mean concentrations of the evaluated metals with maximum permissible limits established by WHO showed a significant difference. Thus, the mean concentrations of Zn and Mn were significantly lower than the MPL in both water treatment plants. It was also noted that there were no statistically significant differences found in the mean content of analyzed elements between the water samples collected from the Shahid Beheshti and Ekbatan water treatment plants. Conclusion: Considering that the filters with anthracite layer in Ekbatan water treatment plant have lost the capability for removal of heavy metals ions due to their long-term function and possibly poor quality properties, restoration or replace the anthracite layer of filter media of this water treatment plant is recommended.

Application of double filtration with granular activated carbon for Atrazine reduction on water treatment processes

La Atrazina es uno de los herbicidas de mayor aplicación en el mundo, ingresa a los cuerpos de agua superficial por escorrentía, aplicación directa o dispersión aérea. Los métodos de tratamiento convencional de agua no remueven eficientemente este tipo de contaminantes, mientras que la adsorción con Carbón Activado Granular (CAG), es una técnica apropiada para la remoción de compuestos orgánicos del agua. En este trabajo, se evaluó la reducción de Atrazina de un agua dopada con dos concentraciones Atrazina, durante el proceso de tratamiento convencional (coagulación, floculación, sedimentación y filtración con arena y antracita) seguido de una doble filtración con dos medios adsorbentes granulares (CAG de origen Vegetal y Mineral), la cual permitió obtener una eficiente reducción de UV254 (86%) y Atrazina (99%).

The impact of filter bed depth and solids loading using a multimedia filter

ABSTRACTDesign and operation of tertiary wastewater filters are not always well understood because of the inherent complexities of the wastewater matrix. Here, comparison of single, dual, triple and quadruple media (anthracite, flint, alumina and magnetite) filters were made to understand how the depth, media type and solids concentration influenced performance. The filter was improved by making the media deeper; however, the top 0.1 m of the filter retained the most solids. Additional layers of filter materials from single, dual, triple to quadruple improved the filter performance for the same depth of filter bed.

Performance comparison of anthracite filter media of different origin in the removal of organic traces from copper electrolyte

Eight anthracite granule species used as filter media were tested for organic phase separation from copper electrolyte in a filter bed. The effects of filter bed depth and fluid velocity were studied. The macro porosity, density, surface area, bed expansion, pressure loss during backwash, mechanical strength, surface micro porosity and morphology of the anthracite species were analyzed. The organic droplet average diameter and zeta potential of the electrolyte suspension were also measured. In addition, SEM analysis was used to investigate aging and separation performance of filter media. For the different anthracite species, the aging and a similar separation performance were found. However, some variation in performance was detected during backwash experiments. Pilot scale runs with inversed flow indicated that testing of the anthracite species before selection is advantageous.

Applicability of anthracite filtration‒micro electrolysis‒sand filtration for the treatment of surface waters containing high turbidity

The effect of combined filtration efficiency on the performance of anthracite filtration‒micro electrolysis‒sand filtration (AMS) was investigated. Impact of different operating parameters, such as iron‒carbon ratio of micro electrolytic units, filtration velocity of AMS, were studied. It was found that when iron‒carbon ratio was 6: 4, the AMS’s average turbidity removal rate was 96.75% at the filtration velocity of 3 m h‒1. The results showed that when the filtration rate was 3‒9 m h‒1 and iron‒carbon ratio was 6: 4, the turbidity removal efficiency was over 94%, and the turbidity of the effluent was less than 1 NTU in effective filtration cycle. The effective filtration cycle can last for more than 5 h or longer. Meanwhile, the removal rate of UV254 was above 33%, and the concentration of iron ions in the effluent is less than 0.15 mg L‒1. Turbidity and iron indicators have reached the national drinking water standards. It was also found the mechanism of iron‒carbon micro electrolytic enhanced filtration by infrared spectroscopy and scanning electron microscopy. And It was also speculated the reasons for the reaction passivation.

Possible Co-fermentation of Water and Sewage Sludge

The article describes problems related to intensification of energy production at a wastewater treatment plant. The authors analyzed anaerobic co-digestion of sludge from both water treatment plant and sewage treatment plant. Water sludge is produced during coagulation, ozonation and backwashing of rapid anthracite filters. Its characteristic and properties depend on a raw water quality, treatment methods as well as types of chemicals used and their doses. According to the Polish Act of 4 December 2012 (Journal of Laws from 2013, item 21) the water sludge should be treated as hazardous waste. An alternative way to dispose water sludge and reduce its volume may be sludge reuse. The authors suggested a research methodology and analyzed the preliminary results, which showed that co-digestion of sewage and water sludge enhanced biogas production. The authors assume that the results of the study will provide a basis for development of methodology for sludge control and disposal.

Treatment of hospital laundry wastewater by UV/H2O2 process.

Hospitals consume a large volume of water to carry out their activities and, hence, generate a large volume of effluent that is commonly discharged into the local sewage system without any treatment. Among the various sectors of healthcare facilities, the laundry is responsible for the majority of water consumption and generates a highly complex effluent. Although several advanced oxidation processes (AOPs) are currently under investigation on the degradation of a variety of contaminants, few of them are based on real wastewater samples. In this paper, the UV/H2O2 AOP was evaluated on the treatment of a hospital laundry wastewater, after the application of a physicochemical pretreatment composed of coagulation-flocculation and anthracite filtration. For the UV/H2O2 process, a photoreactor equipped with a low-pressure UV-C lamp was used and the effects of initial pH and [H2O2]/chemical oxygen demand (COD) ratio on COD removal were investigated through a randomized factorial block design that considered the batches of effluent as blocks. The results indicated that the initial pH had no significant effect on the COD removal, and the process was favored by the increase in [H2O2]/COD ratio. Color and turbidity were satisfactorily reduced after the application of the physicochemical pretreatment, and COD was completely removed by the UV/H2O2 process under suitable conditions. The results of this study show that the UV/H2O2 AOP is a promising candidate for hospital laundry wastewater treatment and should be explored to enable wastewater reuse in the washing process.

Performance comparison of granular media filter beds

Particle capture, head loss development, and efficiency of in-line coagulation in contact filtration were studied using two types of laboratory filters with varying coagulants. One filter consisted of sand and anthracite, whereas the other filter contained crushed glass and anthracite. Effects of in-line coagulation on filter performance were evaluated using a charge measuring device. Performance of filters was monitored in terms of effluent quality as a function of time and development of head loss by anthracite layer and by the entire filter bed. Filterability index was used to provide a measure of effectiveness of filter media and/or operational variables such as coagulant type and dosage. This study found that the crushed glass–anthracite filter was as effective at removal of particles and metals (Fe and Al) as sand–anthracite filters.

Physical-chemical treatment of rainwater runoff in recovery and recycling companies: Pilot-scale optimization

Pilot-scale optimisation of different possible physical-chemical water treatment techniques was performed on the wastewater originating from three different recovery and recycling companies in order to select a (combination of) technique(s) for further full-scale implementation. This implementation is necessary to reduce the concentration of both common pollutants (such as COD, nutrients and suspended solids) and potentially toxic metals, polyaromatic hydrocarbons and poly-chlorinated biphenyls frequently below the discharge limits. The pilot-scale tests (at 250 L h−1 scale) demonstrate that sand anthracite filtration or coagulation/flocculation are interesting as first treatment techniques with removal efficiencies of about 19% to 66% (sand anthracite filtration), respectively 18% to 60% (coagulation/flocculation) for the above mentioned pollutants (metals, polyaromatic hydrocarbons and poly chlorinated biphenyls). If a second treatment step is required, the implementation of an activated carbon filter is recommended (about 46% to 86% additional removal is obtained).

Development of pre-treatment for the injection water into the aquifer storage and recovery(ASR) in Korea: The two-step rapid filter to reduce physical clogging and secure the volume of the injected water

Two step rapid filter system as a pre-treatment for the injected water into aquifer storage and recovery (ASR) in Korea was developed to reduce physical blockage and secure the volume of the injected water. First, single rapid sand filters with three different media sizes (0.4~0.7, 0.7~1.0 and 1.0~1.4 mm) were tested. Only two sizes (0.4~0.7 and 0.7~1.0 mm) satisfied target turbidity, below 1.0 NTU. However, they showed the fast head loss. To prevent the fast head loss and secure the volume of the injected water, a rapid anthracite filter with roughing media size (2.0~3.4 mm) were installed before a single rapid sand filter. As results, both the target turbidity and reduction of head loss were achieved. It was determined that the media size for a rapid sand filter in two step rapid filter system (i.e. a rapid anthracite filter before a rapid sand filter) was 0.7~1.0 mm. In addition, the effects of coagulant doses on the removal of natural organic matter (NOM), which might cause a biological clogging, were preliminarily evaluated, and the values of , dissolved organic carbon (DOC) and SUVA were interpreted.

Effective production of rapid filters with polystyrene granules as a media filter

In conventional water treatment stations, the filter cleaning is performed with the use of filtered water. To save water and obtain higher production, the use of polystyrene (PS) beads has been proposed as a granular filter element because it is a granular element with a low specific mass. By being lightweight, this material requires a lower water velocity during backwash. The PS beads were applied in a descending rapid filter and compared to a conventional sand and anthracite filter, and its hydraulic performance was evaluated during the backwash with air and water interspersed. Although it presents a high fluidity, with lower rates (compared to conventional filters) of backwash, this fact does not necessarily represent an economy of backwash water, because it requires more time for cleaning. It was also observed that there is an optimal value for the removal of particles collected during the filtration without loss of material.

Domestic wastewater treatment in a novel sequencing batch biofilm filter.

Biological treatment of domestic sewage low C/N ratio was accomplished in a pilot-scale sequencing batch biofilm filter (SBBF). The novel hybrid bioreactor consisted of bio-band in the upper and anthracite filter media in the bottom, which combined a sequencing batch biofilm reactor (SBBR) with a biological filter. The average removal efficiency values of chemical oxygen demand (COD), ammonium nitrogen (NH4 (+)-N), total nitrogen (TN), and total phosphorus (TP) were 89.4, 83.3, 62.9, and 48.7%, respectively. A 454-pyrosequencing technology was employed to investigate the microbial communities of the influent (J1) and the biofilm (J2) on the bio-band on day 40. Pyrosequencing analysis of the 16S rRNA gene revealed the community of the biofilm consisted of Gammaproteobacteria (48.6%), Planctomycetacia (18.0%), Alphaproteobacteria (13.7%), Clostridia (9.6%), Desulfonatronum (18.5%), Actinobacteria (1.9%), and Bacilli (1.7%), accounting for 93.6% of total operational taxonomic units at genera level. Acinetobacter tjernbergiae and Acinetobacter lwoffii were the most abundant species, suggesting that denitrifying phosphorus removal was achieved in the SBBF.

Water quality produced by polystyrene granules as a media filter on rapid filters

Many devices are used to improve the performance of rapid filters, increasing the filter run and reducing the velocity of the wash water filter with the use of multiple layers and the adoption of different filter materials. This study constructed a descending rapid filter utilizing polystyrene granules as a new filter element; this was compared to a sand and anthracite descending rapid filter. The filter performance was compared in terms of water quality, turbidity, apparent and true color, conductivity, total dissolved solids, temperature, pH, residual aluminum, and removal of cyanobacterium (Cylindrospermopsis raciborski) under the same operating conditions of filtration. The sand and anthracite filter reached the greatest filtration run, but the water quality of the polystyrene filter had a similar quality to the sand and anthracite filter. Furthermore, the filter containing polystyrene granules as a media filter can represent savings with decreased wash water and the construction of reservoirs with a lower hydraulic load.