Nitrate Leaching from Sand and Pumice Geomedia Amended with Pyrogenic Carbon Materials - MDPI
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environments Article Nitrate Leaching from Sand and Pumice Geomedia Amended with Pyrogenic Carbon Materials Jihoon Kang 1, * ID , Marissa Davila 2 , Sergio Mireles 1 and Jungseok Ho 3 1 School of Earth, Environmental and Marine Sciences, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA; email@example.com 2 Harlingen Waterworks System, Harlingen, TX 78550, USA; firstname.lastname@example.org 3 Civil Engineering, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA; email@example.com * Correspondence: firstname.lastname@example.org; Tel.: +1-956-665-3526 Received: 1 September 2017; Accepted: 30 September 2017; Published: 3 October 2017 Abstract: There is increasing interest in using pyrogenic carbon as an adsorbent for aqueous contaminants in stormwater. The objective of this study was to investigate pyrogenic carbon materials as an amendment to geomedia to reduce nitrate leaching. Batch adsorption and column experiments were conducted to evaluate the performance of a commercial activated carbon and two biochars incorporated (5% by weight) into sand and pumice columns. The batch adsorption with 50 mg L−1 of nitrate solution showed that only activated carbon resulted in a substantial adsorption for nitrate up to 41%. Tested biochars were not effective in removing aqueous nitrate and even released nitrate (
Environments 2017, 4, 70 2 of 7 Environments 2017, 4, 70 2 of 7 nutrients (nutrient (nutrient retention)retention) or even providing or even providing nutrients tonutrients plants withto plants with increase in increase microbialinactivity microbial are activity claimed are claimed to be to be the the benefits benefits of commercially of commercially available available biochars soldbiochars in USA.sold in USA. There Therehave havebeen beenincreasing increasing adoptions adoptionsof raingardens, of raingardens, bioswales, and infiltration bioswales, basinsbasins and infiltration in urban in landscapes, which which urban landscapes, are designed to slow are designed and and to slow filterfilter stormwater stormwaterrunoff runoffas as a part a partofoflow low impact impact development development(LID)(LID)practices practices. .For Forexample, example,the theLower LowerRio RioGrande GrandeValley Valley(LRGV) (LRGV)in inSouth SouthTexas Texas has has increasingly increasingly adopted adopted bioswale bioswale systems systemsandand more more are are expected expected to to be be built built in in parking parking lots lots and and driveways drivewaysas as aa green green infrastructure infrastructure projects projects . . The The objective objectiveofof this this study study was was to to investigate investigate thethe performance of pyrogenic carbon materials (AC and biochars) as an additive performance of pyrogenic carbon materials (AC and biochars) as an additive to selected geomedia to selected geomedia (sand (sand and and pumice) pumice) forfor reducing reducing nitrate nitrate leaching. leaching. Specific Specific objectives objectives were were to to (1) (1) determine determine nitrate nitrate adsorption adsorption capacity capacity ofof the the carbon carbon materials, materials, and and (2) (2) evaluate evaluate nitrate nitrate retention retention inin sand sand andand pumice pumice columns columns amended amended with with thethe carbon carbon materials materials (5% (5% byby weight). weight). 2. Materials 2. Materialsand andMethods Methods 2.1. Filter 2.1. FilterMedia Mediaand andPyrogenic PyrogenicCarbon Carbon Materials Materials Commerciallyavailable Commercially availableplay play sand sand (Quikrete (Quikrete International InternationalInc., Inc., Atlanta, Atlanta, GA, GA, USA) USA) and and pumice pumice (Nature’sFootprint, (Nature’s Footprint,Inc., Inc.,Bellingham, Bellingham, WA,WA, USA) USA) were were used used in this in this studystudy as geomedia as geomedia (Figure (Figure 1). 1). The The play sand was determined to be fine sand having 97.5% sand, 1.8% silt, and play sand was determined to be fine sand having 97.5% sand, 1.8% silt, and 0.7% clay according to 0.7% clay according to the the particle particle sizesize analysis analysis byby hydrometer hydrometer method method .The . Thepumice pumicewas wasaafelsic felsicvolcanic volcanicrock rock with with highly vesicular highly vesicular rough rough texture texture andand itit isisoften oftenfound foundtotofloat floaton onthe thebeaches beachesofofthetheTexas coast Texas coastdue to to due its low density (0.2 to 0.6 g cm −3 ) . No textural analysis was performed with pumice as it contained its low density (0.2 to 0.6 g cm ) . No textural analysis was performed with pumice as it contained −3 grain sizes grain sizes coarser coarser than than 22 mm mm in in diameter. diameter. Both Both materials materials were were air-dried air-dried before before use. use. Figure Figure1.1.Geomedia Geomediatested testedin inthis thisstudy. study. Three pyrogeniccarbon Three pyrogenic carbonmaterials—a materials—a commercial commercial AC ACand and two biochar two biochar products, products, Hoffman Hoffman biochar biochar (HB) and Wakefield biochar (WB)—were used as amendments (HB) and Wakefield biochar (WB)—were used as amendments to the sand or pumice geomedia to the sand or pumicein geomedia in this study (Figure 2). The AC (CR610A, Carbon Resources LLC, Oceanside, this study (Figure 2). The AC (CR610A, Carbon Resources LLC, Oceanside, CA, USA) was a granular CA, USA) was a granular product sold forproduct sold for water water purification in purification aquaculturein aquaculture and and it was it was produced fromproduced fromby selected coal selected a high coal by a high temperature steam activation process according to the manufacturer. temperature steam activation process according to the manufacturer. The HB (A.H. Hoffman The HB (A.H. Inc., Hoffman Inc., Lancaster, NY, USA) was a pelletized charcoal product sold as a soil conditioner Lancaster, NY, USA) was a pelletized charcoal product sold as a soil conditioner and it was claimed to and itimprove was claimed to improve drainage drainage and adsorb harmfuland adsorb harmful impurities accordingimpurities according toThe to the manufacturer. the WBmanufacturer. (Wakefield The WB (Wakefield Agricultural Carbon LLC, Columbia, MO, USA) was a USDA-certified soil Agricultural Carbon LLC, Columbia, MO, USA) was a USDA-certified soil conditioner and it was conditioner and it was mainly claimed to contribute to healthier soils and improve drought resistance mainly claimed to contribute to healthier soils and improve drought resistance according to the according to the manufacturer. The WB was not a pelletized product and it was much finer than other manufacturer. The WB was not a pelletized product and it was much finer than other two carbon two carbon products. All carbon materials were analyzed for pH (1:80 solid to solution ratio) using a products. All carbon materials were analyzed for pH (1:80 solid to solution ratio) using a pH meter pH meter (Extech Instruments, Waltham, MA, USA) and elemental composition via Energy- (Extech Instruments, Waltham, MA, USA) and elemental composition via Energy-dispersive X-ray dispersive X-ray spectroscopy equipped in ZEISS EVO LS10 Scanning Electron Microscope (Hitachi, spectroscopy equipped in ZEISS EVO LS10 Scanning Electron Microscope (Hitachi, Japan). The results Japan). The results for elemental composition were expressed in weight % (Table 1). for elemental composition were expressed in weight % (Table 1).
Environments 2017, 4, 70 3 of 7 Environments 2017, 4, 70 3 of 7 Figure 2. Pyrogenic carbon materials tested in this study. Figure 2. Pyrogenic carbon materials tested in this study. Table 1. pH and elemental composition (weight %) of pyrogenic carbon materials Table 1. pH andCarbon Material elemental pH C(weight composition (%) O (%) %) ofFepyrogenic (%) Al (%) carbon materials. Activated carbon 8.03 73.1 11.6 13.7 1.6 Hoffman biochar 7.88 86.7 13.3 0 0 Carbon Material pH C (%) O (%) Fe (%) Al (%) Wakefield biochar 10.23 89.8 10.2 0 0 Activated carbon 8.03 73.1 11.6 13.7 1.6 Hoffman 2.2. Batch biochar Adsorption Experiment 7.88 86.7 13.3 0 0 Wakefield biochar 10.23 89.8 10.2 0 0 Batch sorption experiments were conducted in 50-mL centrifuge tubes at room temperature. Nitrate solution was prepared in deionized (DI) water containing 50 mg L−1 as potassium nitrate (KNO3). The 2.2. Batch Adsorption carbon materials (0.45 g) were weighted to the tubes and equilibrated with 36 mL of the Experiment nitrate solution. The concentration of nitrate at 50 mg NO3− L−1 were equivalent to 11.3 mg L−1 NO3-N in elemental Batch sorption basis. Samples were experiments with sand or pumice only conducted were included in 50-mL as experimental centrifuge tubes control. at room Thetemperature. tubes were shaken for 1 h on an end-to-end shaker at 90 oscillations min−1, and supernatants − 1 were Nitrate solution was prepared in deionized (DI) water containing 50 mg L as potassium nitrate filtered through 0.2-µm membrane filters. It is important to note that the 1 h reaction time in this (KNO3 ). Thestudycarbon materials may have (0.45 not reached g) were a chemical weighted equilibrium to the of nitrate tubes onto adsorption andtheequilibrated with 36 mL of carbon materials. Our previous the nitrate solution. Thezinc (Zn) adsorption of concentration experiment nitrate with at 50biochars mg NO up to− 48-h L −1equilibration were showed that equivalent to 11.3 mg L−1 3 54–98% of Zn adsorption occurred after 1 h relative to the amount of Zn adsorbed after 48 h . The NO3 -N in elemental basis. Samples with sand or pumice only were included as experimental control. filtrates were analyzed colorimetrically using a HACH UV–vis spectrophotometer (DR3900, The tubes were shaken Loveland, CO, for USA)1according h on antoend-to-end dimethylphenol shaker methodat for90 oscillations nitrate min− (HACH method 1 , and supernatants 10206). The were filteredamount through of nitrate adsorbed 0.2-µm by the testedfilters. membrane materialsIt(q)is was calculated byto important Equation (1): the 1 h reaction time note that in this study may have not reached a chemical q = (C0Vequilibrium – CV)/M of nitrate adsorption onto (1) the carbon materials. Our where previous zinc (Zn)ofadsorption C0 is the concentration nitrate in inputexperiment solution (mg L−1with biochars ), V is the volume ofup to (L), liquid 48-hC isequilibration showed thatthe concentration 54–98% of Znofadsorption nitrate in solution after 1-h equilibration, occurred and M isto after 1 h relative drythe weight of carbon amount ofmaterial Zn adsorbed after (kg). Nitrate adsorption (removal) capacity of the carbon materials was calculated in % relative to the 48 h . The filtrates were analyzed colorimetrically initial amount of aqueous nitrate added (1.8 mg NO3 ). − using a HACH UV–vis spectrophotometer (DR3900, Loveland, CO, USA) according to dimethylphenol method for nitrate (HACH method 10206). The amount 2.3. Column Experiment of nitrate adsorbed by the tested materials (q) was calculated by Equation (1): A total of 16 columns (metal cylinder in 7.62-cm diameter by 7.62-cm depth) were packed to a depth of 4.56 cm with sand or pumice. Sixteen columns corresponded to our experimental treatments q = (C0 V − CV)/M (1) consisting of two geomedia and four different carbon amendments, including control in duplicates. During our initial trials, maximum amounts of sand and pumice needed for packing the columns where C0 is the (i.e.,concentration control columns) of nitrate were in input determined solution to be 318 (mg g and 165 L−1 ), V isThese g, respectively. the given volume were (L), C is the of liquid amounts concentrationdetermined of nitrateto inhave a bulk density solution of 1.67 after 1-h g cm for sand −3 equilibration, and columns M is and dry 0.86 g cm−3offor weight pumicematerial (kg). carbon columns. Sand or pumice with and without carbon amendment (5% by weight) was dry-packed into Nitrate adsorption (removal) capacity of the carbon materials was calculated in % relative to the initial the columns (Table 2). The bottom of each column was covered with cheese cloth to prevent the amount of aqueous geomedianitrate loss. added (1.8 mg NO3 − ). 2.3. Column Experiment A total of 16 columns (metal cylinder in 7.62-cm diameter by 7.62-cm depth) were packed to a depth of 4.56 cm with sand or pumice. Sixteen columns corresponded to our experimental treatments consisting of two geomedia and four different carbon amendments, including control in duplicates. During our initial trials, maximum amounts of sand and pumice needed for packing the columns (i.e., control columns) were determined to be 318 g and 165 g, respectively. These given amounts were determined to have a bulk density of 1.67 g cm−3 for sand columns and 0.86 g cm−3 for pumice columns. Sand or pumice with and without carbon amendment (5% by weight) was dry-packed into the columns (Table 2). The bottom of each column was covered with cheese cloth to prevent the geomedia loss.
Environments 2017, 4, 70 4 of 7 Table 2. The amount of geomedia used for column packing with and without carbon amendment (5% by weight). Environments 2017, 4, 70 4 of 7 Column Sand or Pumice (g) Amendment (g) Table 2. The amount of geomedia used for column packing with and without carbon amendment (5% by weight) Sand only 318 0 Sand + amendment 302 16 Pumice Column only Sand or 165Pumice (g) Amendment 0 (g) Sand only Pumice + amendment 318 157 0 8 Sand + amendment 302 16 Pumice only 165 0 Each column received 500 Pumice mL of DI water for initial + amendment 157 flushing on the 8 first day (day 1). The water was irrigated by 100 mL increments manually through a circular plastic pan that was placed on the top of column. The plastic Each column pan500 received hadmLmultiple small of DI water forholes, initial allowing flushing on uniform the first dripping day (day 1).of The the water water and was irrigated minimizing by disturbance surface 100 mL increments on themanually geomedia.through On the a circular secondplastic pan that day (day was placed 2), columns on the were leached top of column. The plastic − pan1 had multiple small holes, allowing uniform dripping with nitrate solution (50 mg L ) five times by 100 mL increments, totaling 500 mL of aqueous nitrateof the water and minimizing throughput. Thesurface amount disturbance of nitrateonapplied the geomedia. was 25 Onmg theinsecond total.day On(day the 2), columns third were leached day (day 3), columns with nitrate solution (50 mg L−1) five times by 100 mL increments, totaling 500 mL of aqueous nitrate were leached again with DI water only (100 mL increments, totaling 500 mL of DI water) to assess throughput. The amount of nitrate applied was 25 mg in total. On the third day (day 3), columns desorption of the nitrate. Collected column effluents were analyzed for nitrate in the aforementioned were leached again with DI water only (100 mL increments, totaling 500 mL of DI water) to assess method. The effluent desorption samples of the nitrate. werecolumn Collected also determined effluents were foranalyzed turbidityforusing nitrateNEP in the260 turbidity probe aforementioned (McVan Instruments, method. Melbourne, The effluent samples Australia) in nephelometric were also determined turbidity for turbidity usingunits NEP(NTU) and forprobe 260 turbidity pH using a portable (McVan pH meter (Extech Instruments, Instruments, Melbourne, Waltham, Australia) MA, USA). in nephelometric turbidity units (NTU) and for pH using a portable pH meter (Extech Instruments, Waltham, MA, USA). 3. Results and Discussion 3. Results and Discussion 3.1. Batch Adsorption of Nitrate 3.1. Batch Adsorption of Nitrate Only AC had ability to adsorb nitrate up to 41% (Figure 3) while biochars showed none Only AC(negative to even release had ability%)to adsorb nitrate of nitrate up to from (0.93% 41% (Figure HB and3) while 0.13% biochars from showed WB). DInone to even water extracts release (negative %) of nitrate (0.93% from HB and 0.13% from WB). DI water extracts (1:80 (1:80 solid-to-solution ratio) with the carbon materials (i.e., DI water only with no aqueous nitrate) solid-to- solution ratio) with the carbon materials (i.e., DI water only with no aqueous nitrate) confirmed that confirmed that an appreciable concentration was found for HB (1.46 mg NO3 − L−1 ) and WB (1.55 mg an appreciable concentration was found for HB (1.46 mg NO 3− L−1) and WB (1.55 mg NO3− L−1). NO3 − L−1 ). Commercial pumice for gardening use is often claimed to hold nutrients but it was not Commercial pumice for gardening use is often claimed to hold nutrients but it was not the case in the the case in adsorption batch the batch adsorption with 1time, with 1 h reaction h reaction time,for accounting accounting only 1.3% for only 1.3% of nitrate of nitrate adsorption. Sandadsorption. also Sandshowed also showed limitedlimited adsorption adsorption ability ability (1.2%), (1.2%), indicating indicating a lacksurfaces a lack of reactive of reactive surfaces for nitrate. for nitrate. 50 40 Nitrate adsorption (%) 30 20 10 0 -10 Sand Pumice AC HB WB Figure Figure 3. Adsorption 3. Adsorption from from aqueousnitrate aqueous nitrate affected affected by by geomedia geomediaand andcarbon materials. carbon ErrorError materials. bars bars represent standard error of the mean. represent standard error of the mean. It is often claimed that biochar can be used as a soil amendment to retain nutrients in soils [16,17]. It is often the However, claimed that biochar biochartested materials can be usedstudy in this as a showed soil amendment to retain no adsorption (evennutrients release) ofinnitrate soils in [16,17]. However, the biochar a batch-scale materialsOur experiment. tested in this result is instudy showed agreement noYao with adsorption (evenwho et al. (2012) release) foundoflimited nitrate in a adsorption batch-scale of nitrateOur experiment. (
Environments 2017, 4, 70 5 of 7 removing cationic species from solution as most biochars were found to have a net negative surface charge . While both AC and biochars have carbonaceous materials as feedstock materials and convert them to stable carbon through pyrolysis, AC typically receives an additional activation process where it undergoes oxidation to increase adsorptive capacities . It is important to note that feedstock materials for the biochars were plant-based while Environments 2017, 4, 70 5 of 7 the AC was produced from selected coal according to manufacturer. Detailed information on the feedstock types andnegative surface chargeprocesses manufacturing . While of both AC and these biochars have commercial carbonaceous products materials as feedstock are proprietary and unknown. materials and convert them to stable carbon through pyrolysis, AC typically receives However, it was notable that the AC contained substantial amount of Fe (13.7%) and Al (1.6%) in its an additional activation process where it undergoes oxidation to increase adsorptive capacities . elemental composition (Table 1), indicating mineral inclusion of Fe and Al and possibly leading to It is important to note that feedstock materials for the biochars were plant-based while the AC better adsorption was produced offrom nitrate. Thecoal selected Feaccording mineralstosuch as hematite, manufacturer. goethite, Detailed and on information iron-oxide have been the feedstock found to increase types oxyanion adsorption and manufacturing processes ofsuch theseascommercial arsenite and arsenate products in the Fe-impregnated are proprietary and unknown. carbon materials thoughit surface However, was notablecomplexation betweensubstantial that the AC contained the Fe-O surface amount ofand oxyanion Fe (13.7%) and[20,21]. Al (1.6%) in its elemental composition (Table 1), indicating mineral inclusion of Fe and Al and possibly leading to 3.2. Nitrate betterLeaching in Column adsorption of nitrate.Experiment The Fe minerals such as hematite, goethite, and iron-oxide have been found to increase oxyanion adsorption such as arsenite and arsenate in the Fe-impregnated carbon Overall turbidity materials though in effluent surface samples between complexation were 3- the to 4-times greater Fe-O surface and in pumice oxyanion columns (17 to 27 NTU) [20,21]. compared to sand columns (5 to 7 NTU) (Table 3). Coarse grains in pumice were likely to contribute to 3.2. Nitrate the higher turbidityLeaching in Column by eluting fineExperiment suspended solids from pumice and the carbon materials. The pH values in column Overall effluents turbidity inranged effluentfrom 7.6 were samples to 8.73- and the columns to 4-times greater inamended with WB pumice columns showed (17 to 27 the highestNTU) pH (7.9compared to 8.7),toindicating sand columns the (5 to 7 NTU) presence (Table 3).ash of mineral Coarse grains in the WBin.pumice were likely to contribute Under to theinput the pulse higherof turbidity by eluting nitrate solution (50fine mgsuspended NO3 − L−solids from in 1 ), nitrate pumice columnandeffluents the carbon increased materials. The pH values in column effluents ranged from 7.6 to 8.7 and the columns amended − 1 with with nitrate solution throughput (leaching event 1–5 in Figure 4) up to 11 mg L in both sand and WB showed the highest pH (7.9 to 8.7), indicating the presence of mineral ash in the WB . pumice columnsUnder the(Figure pulse 4). The input lowestsolution of nitrate concentration (50 mg NOwas found with sand column amended with 3− L−1), nitrate in column effluents increased AC (7 mg − 1 L−to1 ), suggesting withLnitrate ) and pumice solution column(leaching throughput amended eventwith AC 1–5 in (8 mg Figure 4) up 11 mg L−1 in bothACsand outperformed and biochars in thecolumns pumice flow-through (Figure 4). experiment as well. Under The lowest concentration wasthe desorption found with sand stage column(leaching amended event with 6–10), AC (7 the nitrate mg L−1) and pumice concentrations columndecreased gradually amended withwithAC AC (8 amendment mg L−1), suggestingin bothAC geomedia outperformed being the biochars in the − flow-through experiment as well. Under the desorption stage (leaching event 6–10), 1 lowest (1 to 3 mg L ) suggesting that AC amendment was more effective than biochar amendment in the nitrate concentrations gradually decreased with AC amendment in both geomedia being the retaining nitrate during desorption stage. lowest (1 to 3 mg L−1) suggesting that AC amendment was more effective than biochar amendment in retaining nitrate during desorption stage. Table 3. Average pH and turbidity (mean ± standard error) in column effluents over the entire leachingTable events. 3. Average pH and turbidity (mean ± standard error) in column effluents over the entire leaching events Column a pH Turbidity (NTU) Column a pH Turbidity (NTU) 7.84 ± 0.18 Sand only Sand only 7.84 ± 0.18 7.29 ± 0.85 7.29 ± 0.85 Sand + AC 7.92 ± 0.06 5.38 ± 0.59 Sand + HB Sand + AC 7.92 ± 0.06 7.93 ± 0.08 5.38 ± 0.59 7.43 ± 0.56 Sand + WB Sand + HB 7.93 ± 0.08 8.73 ± 0.16 7.43 ± 0.56 7.35 ± 1.72 Pumice onlySand + WB 7.60 8.73 ± 0.08 ± 0.16 7.35 ± 1.72 23.86 ± 5.57 Pumice + ACPumice only 7.60 7.50 ± 0.06 ± 0.08 23.86 ± 5.57 24.61 ± 4.22 Pumice + HB 7.58 ± 0.05 26.80 ± 3.80 Pumice + AC 7.50 Pumice + WB ± 0.06 7.91 ± 0.17 24.61 ± 4.22 17.41 ± 2.46 Pumice + HB 7.58 ± 0.05 26.80 ± 3.80 a AC = activated carbon; HB = Hoffman biochar; WB = Wakefield biochar. Pumice + WB 7.91 ± 0.17 17.41 ± 2.46 a AC = activated carbon; HB = Hoffman biochar; WB = Wakefield biochar. 12 12 Sand only Pumice only 10 (a) Sand + AC 10 (b) Pumice + AC DI Sand + HB Pumice + HB NO3- (mg L-1) water Sand + WB Pumice + WB NO3- (mg L-1) 8 8 DI water 6 6 50 mg L-1 4 4 2 50 mg L-1 2 0 0 0 2 4 6 8 10 12 0 2 4 6 8 10 12 Leaching event Leaching event Figure Figure 4. Concentrations of nitrate (NO3−))in incolumn effluents: (a) sand and (b) pumice. − 4. Concentrations of nitrate (NO 3 column effluents: (a) sand and (b) pumice.
Environments 2017, 4, 70 6 of 7 Environments 2017, 4, 70 6 of 7 Cumulative amount of nitrate leached (Figure 5) showed a clear separation of AC-amended sand Cumulative amount of nitrate leached (Figure 5) showed a clear separation of AC-amended sand or pumice geomedia being the lowest (3.6 to 4 mg as NO3− − ) after the entire leaching event. In both or pumice geomedia being the lowest (3.6 to 4 mg as NO3 ) after the entire leaching event. In both sand and pumice columns, HB resulted in higher nitrate leaching (6.3 mg) than control columns sand and pumice columns, HB resulted in higher nitrate leaching (6.3 mg) than control columns (5.2– (5.2–5.3 mg)while 5.3 mg) while WB-amended WB-amended columns columns showedshowed similarofamount similar amount of nitrate nitrate leached withleached with control control columns. columns. The higher amount of nitrate leached from the columns amended with HB was in agreementagreement The higher amount of nitrate leached from the columns amended with HB was in with with the thegreater greaterrelease release ofof nitrate nitrate from from batch batch adsorption adsorption (Figure (Figure 3). There 3). There was nowas no substantial substantial difference difference in in thethe amount amountof ofnitrate nitrate leached betweensand-only leached between sand-only (5.3(5.3 mg)mg) andand pumice-only pumice-only columns columns (5.2 mg). (5.2 mg). 7 7 Sand only 6 Sand + AC (a) 6 Pumice only (b) Pumice + AC NO3- leached (mg) NO3- leached (mg) Sand + HB Pumice + HB 5 Sand + WB 5 Pumice + WB 4 4 3 3 2 2 DI water DI water 1 1 50 mg L-1 50 mg L-1 0 0 0 2 4 6 8 10 12 0 2 4 6 8 10 12 Leaching event Leaching event Figure Figure 5. Cumulative 5. Cumulative amount amount ofof nitrate (NO33−))leached nitrate(NO leachedinin column effluents: column − (a) sand effluents: and (b) (a) sand andpumice. (b) pumice. 4. Conclusions 4. Conclusions Results in this study suggested that sand and pumice geomedia amended with biochars (5% by Resultswere weight) in this notstudy suggested as effective thatamended as those sand and pumice with AC. Thegeomedia presenceamended of Fe and Al with biochars in the AC was (5% by weight) were likely not as effective to promote as those possibly nitrate adsorption amended with AC. through Thecomplexation surface presence of to Fesome and Al in the extent. AC was There likelywas to promote nitrate no substantial adsorption difference possibly between sandthrough and pumicesurface complexation columns to some in all carbon extent.types. amendment There was Our studydifference no substantial indicated that net negatively between sand andcharged pumice surfaces columnsofintheall biochars may be attributed carbon amendment types.toOur thestudy poor adsorption of nitrate anion due to electrostatic repulsion. To improve its efficacy indicated that net negatively charged surfaces of the biochars may be attributed to the poor adsorption for aqueous nitrateanion of nitrate removal, dueantoadditional process electrostatic during biochar repulsion. production To improve is desirable its efficacy fortoaqueous create acid functional nitrate removal, groups (which have a positive charge) that can protonate surface –OH group in biochars [23,24]. It is an additional process during biochar production is desirable to create acid functional groups (which important to note that while biochar may not be effective in reducing nitrate leaching, it can provide have a positive charge) that can protonate surface –OH group in biochars [23,24]. It is important to other benefits such as increasing the N use efficiency by plants and decrease nitrous oxide (N2O) note emission that while biochar may not be effective in reducing nitrate leaching, it can provide other benefits from N-rich soils. Our study included nitrate only under controlled leaching conditions and suchfuture as increasing the N study should use efficiency consider evaluatingbymultiple plants anions and decrease nitrous and/or cations foroxide (N2applications the field O) emission of from N-richgeomedia amended with pyrogenic carbon materials. In addition, future study investigating thestudy soils. Our study included nitrate only under controlled leaching conditions and future should consider synergistic evaluating effect multiple of the carbon anionsinand/or amendment geomedia cations for with combined the field redoxapplications of geomedia condition is needed to advance amended ourpyrogenic with understanding of biotic carbon and abiotic materials. processes of In addition, nitrate future retention study in stormwater investigating thecontrol synergistic effectmeasures. of the carbon amendment in geomedia combined with redox condition is needed to advance our understanding of biotic and abiotic processes of nitrate retention in stormwater control measures. Acknowledgments: We gratefully acknowledge UTRGV graduate assistantship from the School of Earth, Environmental and Marine Sciences, UTRGV work study program, and US EPA Border 2020 Program for the Acknowledgments: We gratefully acknowledge UTRGV graduate assistantship from the School of Earth, partial funding Environmental andofMarine this project. Sciences, UTRGV work study program, and US EPA Border 2020 Program for the partial Author funding of this project. Contributions: Kang supervised the overall project and wrote the manuscript. Davila and Mireles collected Author column andKang Contributions: batch supervised adsorption data, the respectively. overall projectHo contributed and wrotetothe manuscript preparation manuscript. Davilaand data and Mireles analyses. collected column and batch adsorption data, respectively. Ho contributed to manuscript preparation and data analyses. Conflicts of Interest: The authors declare no conflict of interest. The use of trade names in this publication does not imply Conflicts endorsement of Interest: of the products The authors declarenamed or criticism no conflict of similar of interest. Theones usenot of mentioned by these trade names organizations. in this publication does not imply endorsement of the products named or criticism of similar ones not mentioned by these organizations. References References 1. US Environmental Protection Agency. National Water Quality Inventory: Report to Congress: 2004 Reporting Cycle; USEPA, Office of Water: Washington, DC, 2009. 1. US Environmental Protection Agency. National Water Quality Inventory: Report to Congress: 2004 Reporting Cycle; USEPA, Office of Water: Washington, DC, USA, 2009. 2. Li, L.; Davis, A.P. Urban stormwater runoff nitrogen composition and fate in bioretention systems. Environ. Sci. Technol. 2004, 48, 3403–3410. [CrossRef] [PubMed]
Environments 2017, 4, 70 7 of 7 3. Camargo, J.A.; Alonso, Á. Ecological and toxicological effects of inorganic nitrogen pollution in aquatic ecosystems: A global assessment. Environ. Int. 2006, 32, 831–849. [CrossRef] [PubMed] 4. Chang, N.B.; Hossain, F.; Wanielista, M. Filter media for nutrient removal in natural systems and built environments: I—Previous trends and perspectives. Environ. Eng. Sci. 2010, 27, 689–706. [CrossRef] 5. Demiral, H.; Gündüzoğlu, G. Removal of nitrate from aqueous solutions by activated carbon prepared from sugar beet bagasse. Bioresour. Technol. 2010, 101, 1675–1680. [CrossRef] [PubMed] 6. Ahmedna, M.; Marshall, W.E.; Husseiny, A.A.; Rao, R.M.; Goktepe, I. The use of nutshell carbons in drinking water filters for removal of trace metals. Water Res. 2004, 38, 1062–1068. [CrossRef] [PubMed] 7. Kazemipour, M.; Ansari, M.; Tajrobehkar, S.; Majdzadeh, M.; Kermani, H.R. Removal of lead, cadmium, zinc, and copper from industrial wastewater by carbon developed from walnut, hazelnut, almond, pistachio shell, and apricot stone. J. Hazard. Mater. 2008, 150, 322–327. [CrossRef] [PubMed] 8. Ippolito, J.A.; Laird, D.A.; Busscher, W.J. Environmental benefits of biochar. J. Environ. Qual. 2012, 41, 967–972. [CrossRef] [PubMed] 9. Ahmad, M.; Rajapaksha, A.U.; Lim, J.E.; Zhang, M.; Bolan, N.; Mohan, D.; Ok, Y.S. Biochar as a sorbent for contaminant management in soil and water: A review. Chemosphere 2013, 99, 19–33. [CrossRef] [PubMed] 10. Liang, B.; Lehmann, J.; Solomon, D.; Sohi, S.; Thies, J.E.; Skjemstad, J.O.; Wirick, S. Stability of biomass-derived black carbon in soils. Geochim. Cosmochim. Acta 2008, 72, 6069–6078. [CrossRef] 11. Ahiablame, L.M.; Engel, B.A.; Chaubey, I. Effectiveness of low impact development practices: Literature review and suggestions for future research. Water Air Soil Pollut. 2012, 223, 4253–4273. [CrossRef] 12. Ho, J.; Kang, J. Hydrologic impacts of bioswale porous media on parking lot drainage. Int. J. Civ. Struct. Eng. Res. 2017, 5, 23–30. 13. Gee, G.W.; Bauder, J.W. Particle-size analysis. In Methods of Soil Analysis, 2nd ed.; Klute, A., Ed.; Agronomy Monograph No. 9; ASA and SSSA: Madison, WI, USA, 1986; Part 1, pp. 404–408. 14. Venezia, A.M.; Floriano, M.A.; Deganello, G.; Rossi, A. The structure of pumice: An XPS and 27Al MAS NMR study. Surf. Interface Anal. 1992, 18, 532–538. [CrossRef] 15. Mireles, S.; Ok, Y.; Cheng, C.; Kang, J. Adsorptive and kinetic characterization of aqueous zinc removal by biochars. SDRP J. Earth Sci. Environ. Stud. 2016, 1, 1–7. 16. Beesley, L.; Moreno-Jiménez, E.; Gomez-Eyles, J.L.; Harris, E.; Robinson, B.; Sizmur, T. A review of biochars’ potential role in the remediation, revegetation and restoration of contaminated soils. Environ. Pollut. 2011, 159, 3269–3282. [CrossRef] [PubMed] 17. Lehmann, J.; Rillig, M.C.; Thies, J.; Masiello, C.A.; Hockaday, W.C.; Crowley, D. Biochar effects on soil biota—A review. Soil Biol. Biochem. 2011, 43, 1812–1836. [CrossRef] 18. Yao, Y.; Gao, B.; Zhang, M.; Inyang, M.; Zimmerman, A.R. Effect of biochar amendment on sorption and leaching of nitrate, ammonium, and phosphate in a sandy soil. Chemosphere 2012, 89, 1467–1471. [CrossRef] [PubMed] 19. Azargohar, R.; Dalai, A.K. Biochar as a precursor of activated carbon. In Twenty-Seventh Symposium on Biotechnology for Fuels and Chemicals; Humana Press: New York, NY, USA, 2006; pp. 762–773. 20. Hu, X.; Ding, Z.; Zimmerman, A.R.; Wang, S.; Gao, B. Batch and column sorption of arsenic onto iron-impregnated biochar synthesized through hydrolysis. Water Res. 2015, 68, 206–216. [CrossRef] [PubMed] 21. Cantu, J.; Gonzalez, L.E.; Goodship, J.; Contreras, M.; Joseph, M.; Garza, C.; Eubanks, T.M.; Parsons, J.G. Removal of arsenic from water using synthetic Fe7 S8 nanoparticles. Chem. Eng. J. 2016, 290, 428–437. [CrossRef] [PubMed] 22. Mukome, F.N.; Parikh, S.J. Chemical, Physical, and Surface characterization of Biochar. In Biochar: Production, Characterization, and Applications; Ok, Y.S., Ed.; CRC Press: Boca Raton, FL, USA, 2015; pp. 68–96. 23. Gai, X.; Wang, H.; Liu, J.; Zhai, L.; Liu, S.; Ren, T.; Liu, H. Effects of feedstock and pyrolysis temperature on biochar adsorption of ammonium and nitrate. PLoS ONE 2014, 9, e113888. [CrossRef] [PubMed] 24. Yang, J.; Li, H.; Zhang, D.; Wu, M.; Pan, B. Limited role of biochars in nitrogen fixation through nitrate adsorption. Sci. Total Environ. 2017, 592, 758–765. [CrossRef] [PubMed] © 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
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