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Gurtler JB, Garner CM, Mullen CA, Vinyard BT. Minimum Concentrations of Slow Pyrolysis Paper and Walnut Hull Cyclone Biochars Needed to Inactivate Escherichia coli O157:H7 in Soil. J Food Prot 2024; 87:100210. [PMID: 38158047 DOI: 10.1016/j.jfp.2023.100210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Revised: 11/17/2023] [Accepted: 12/22/2023] [Indexed: 01/03/2024]
Abstract
Antimicrobial properties of biochar have been attributed to its ability to inactivate foodborne pathogens in soil, to varying degrees. High concentrations of biochar have reduced E. coli O157:H7 in soil and dairy manure compost, based on alkaline pH. Preliminary studies evaluating 31 different biochars determined that two slow pyrolysis biochars (paper biochar and walnut hull cyclone biochar) were the most effective at inactivating E. coli in soil. A study was conducted to determine the lowest percentages of paper and walnut hull cyclone biochars needed to reduce E. coli O157:H7 in soil. A model soil was adjusted to 17.75% moisture, and the two types of biochar were added at concentrations of 1.0, 1.5, 2.0, 2.5, 3.5, 4.5, 5.5, and 6.5%. Nontoxigenic E. coli O157:H7 were inoculated into soil at 6.84 log CFU/g and stored for up to 6 weeks at 21°C. Mean E. coli O157:H7 counts were 6.01-6.86 log CFU/g at all weeks between 1 and 6 in soil-only positive control samples. Populations in all soil amended with 1.0 and 1.5% of either type of biochar (as well as 2.0% of the walnut hull biochar) resulted in ≤0.68 log reductions at week 6, when compared with positive controls. All other concentrations (i.e., ≥2.0% paper and ≥2.5% walnut hull) inactivated ≥2.7 log at all weeks between 1 and 6 (p < 0.05). At the end of 6 weeks, E. coli O157:H7 declined by 2.84 log in 2.0% paper biochar samples, while concentrations of between 2.5 and 6.5% paper biochar completely inactivated E. coli O157:H7, as determined by spiral plating, at weeks 5 and 6. In contrast, 2.0% walnut hull biochar lowered populations by only 0.38 log at week 6, although 2.5-6.5% concentrations of walnut hull biochar resulted in complete inactivation at all weeks between 3 and 6, as assessed by spiral plating. In summary, ≥2.5% paper or walnut hull biochar reduced ≥5.0 log of E. coli O157:H7 during the 6-week storage period, which we attribute to high soil alkalinity. Amended at a 2.5% concentration, the pH of soil with paper or walnut hull biochar was 10.67 and 10.06, respectively. Results from this study may assist growers in the use of alkaline biochar for inactivating E. coli O157:H7 in soil.
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Affiliation(s)
- Joshua B Gurtler
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038-8551, USA.
| | - Christina M Garner
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038-8551, USA
| | - Charles A Mullen
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038-8551, USA
| | - Bryan T Vinyard
- U.S. Department of Agriculture, Agricultural Research Service, Northeast Area, 10300 Baltimore Ave., Bldg. 003, BARC-West, Beltsville, MD 20705-2350, USA
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Teshnizi FA, Ghobadinia M, Abbasi F, Hallett PD, Sepehrnia N. Biochar and flow interruption control spatio-temporal dynamics of fecal coliform retention under subsurface drip irrigation. JOURNAL OF CONTAMINANT HYDROLOGY 2023; 253:104128. [PMID: 36603302 DOI: 10.1016/j.jconhyd.2022.104128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 12/14/2022] [Accepted: 12/27/2022] [Indexed: 06/17/2023]
Abstract
Applying wastewater in subsurface drip irrigation helps address water shortage in arid and semi-arid environments. Microbial contamination may result, but soil amendments such as biochar could help protect soil and water resources. To improve understanding, this study investigated spatio-temporal dynamics of fecal coliform retention in a biochar-treated soil under subsurface drip irrigation. Two dripper discharges rates of 2 and 4 l hr-1 containing fecal coliforms (3.99 ± 1.4 × 105 CFU ml-1), three maximum allowable depletion levels (MAD; 30, 50, and 70%), and three biochar levels (0, 0.5 and 1%, w/w) were used. The lysimeters were filled with biochar-treated soil and had drippers located at 20 cm depth. Three irrigations were performed for either Q, and soil samples were taken after each irrigation at different times at the lysimeter centre at 5, 15, 25, and 50 cm depths and at the edge at 20 cm depth (labeled 20 L). Soils containing biochar had much greater recovered coliforms from soil than the unamended controls. The greatest retention was at 15 and 25 cm depth (within 5 cm of the dripper) for 1% biochar, with the recovered cells about 70% for 2 l hr-1 discharge and 60% for 4 l hr-1 discharge. The greatest concentration occurred immediately after irrigation, but over 10 days the number of coliforms gradually decreased and inactivated. Therefore, the coliform residence time, soil depth, and biochar rate all influenced coliform retention if the discharge rates and MADs were considered. We recommend slower subsurface dripper rates with high MAD and biochar amendment to minimize fecal coliform contamination from subsurface field wastewater irrigation.
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Affiliation(s)
- Forough Abbasi Teshnizi
- Department of Water Engineering, Faculty of Agriculture, Shahrekord University, Shahrekord, Iran.
| | - Mahdi Ghobadinia
- Department of Water Engineering, Faculty of Agriculture, Shahrekord University, Shahrekord, Iran
| | - Fariborz Abbasi
- Agricultural Engineering Research Institute (AERI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
| | - Paul D Hallett
- School of Biological Sciences, Cruickshank Building, St Machar Drive Aberdeen, AB24 3UU, Scotland, United Kingdom
| | - Nasrollah Sepehrnia
- School of Biological Sciences, Cruickshank Building, St Machar Drive Aberdeen, AB24 3UU, Scotland, United Kingdom.
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Characteristics and Applications of Biochar in Soil–Plant Systems: A Short Review of Benefits and Potential Drawbacks. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12084051] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The available literary data suggest the general applicability and benefits of different biochar products in various soil–plant–environment systems. Due to its high porosity, biochar might generally improve the physicochemical and biological properties of supplemented soils. Among the direct and indirect effects are (i) improved water-retention capacity, (ii) enhanced soil organic matter content, (iii) pH increase, (iv) better N and P availability, and (v) greater potential uptake of meso- and micronutrients. These are connected to the advantage of an enhanced soil oxygen content. The large porous surface area of biochar might indirectly protect the survival of microorganisms, while the adsorbed organic materials may improve the growth of both bacteria and fungi. On the other hand, N2-fixing Rhizobium bacteria and P-mobilizing mycorrhiza fungi might respond negatively to biochar’s application. In arid circumstances with limited water and nutrient availability, a synergistic positive effect was found in biochar–microbial combined applications. Biochar seems to be a valuable soil supplement if its application is connected with optimized soil–plant–environment conditions. This work aims to give a general review of the potential benefits and drawbacks of biochar application to soil, highlighting its impacts on the soil–plant–microbe system.
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Gurtler JB, Mullen CA, Boateng AA, Mašek O, Camp MJ. Biocidal Activity of Fast Pyrolysis Biochar against Escherichia coli O157:H7 in Soil Varies Based on Production Temperature or Age of Biochar. J Food Prot 2020; 83:1020-1029. [PMID: 32438397 DOI: 10.4315/0362-028x.jfp-19-331] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 02/11/2020] [Indexed: 11/11/2022]
Abstract
ABSTRACT Soils in which fresh produce is grown can become contaminated with foodborne pathogens and are sometimes then abandoned or removed from production. The application of biochar has been proposed as a method of bioremediating such pathogen-contaminated soils. The objectives of the present study were to evaluate three fast-pyrolysis-generated biochars (FPBC; pyrolyzed in house at 450, 500, and 600°C in a newly designed pyrolysis reactor) and 10 United Kingdom Biochar Research Center (UKBRC) standard slow-pyrolysis biochars to determine their effects on the viability of four surrogate strains of Escherichia coli O157:H7 in soil. A previously validated biocidal FPBC that was aged for 2 years was also tested with E. coli to determine changes in antibacterial efficacy over time. Although neither the UKBRC slow-pyrolysis biochars or the 450 and 500°C FPBC from the new reactor were antimicrobial, the 600°C biochar was biocidal (P < 0.05); E. coli populations were significantly reduced at 3 and 3.5% biochar concentrations (reductions of 5.34 and 5.84 log CFU/g, respectively) compared with 0.0 to 2.0% biochar concentrations. The aged 500°C FPBC from the older reactor, which was previously validated as antimicrobial, lost efficacy after aging for 2 years. These results indicate that the biocidal activity of FPBC varies based on production temperature and/or age. HIGHLIGHTS
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Affiliation(s)
- Joshua B Gurtler
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Food Safety and Intervention Technologies Research Unit, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038-8551 (ORCID: https://orcid.org/0000-0001-5844-7794 [J.B.G])
| | - Charles A Mullen
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Sustainable Biofuels and Co-Products Research Unit, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038-8551
| | - Akwasi A Boateng
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Sustainable Biofuels and Co-Products Research Unit, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038-8551
| | - Ondřej Mašek
- UK Biochar Research Centre, School of GeoSciences, University of Edinburgh, Crew Building Alexander Crum Brown Road, Edinburgh EH9 3FF, UK
| | - Mary J Camp
- U.S. Department of Agriculture, Agricultural Research Service, Northeast Area, 10300 Baltimore Avenue, Building 003, BARC-West, Beltsville, Maryland 20705-2350, USA
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Schmidt HP, Hagemann N, Draper K, Kammann C. The use of biochar in animal feeding. PeerJ 2019; 7:e7373. [PMID: 31396445 PMCID: PMC6679646 DOI: 10.7717/peerj.7373] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 06/28/2019] [Indexed: 12/24/2022] Open
Abstract
Biochar, that is, carbonized biomass similar to charcoal, has been used in acute medical treatment of animals for many centuries. Since 2010, livestock farmers increasingly use biochar as a regular feed supplement to improve animal health, increase nutrient intake efficiency and thus productivity. As biochar gets enriched with nitrogen-rich organic compounds during the digestion process, the excreted biochar-manure becomes a more valuable organic fertilizer causing lower nutrient losses and greenhouse gas emissions during storage and soil application. Scientists only recently started to investigate the mechanisms of biochar in the different stages of animal digestion and thus most published results on biochar feeding are based so far on empirical studies. This review summarizes the state of knowledge up to the year 2019 by evaluating 112 relevant scientific publications on the topic to derive initial insights, discuss potential mechanisms behind observations and identify important knowledge gaps and future research needs. The literature analysis shows that in most studies and for all investigated farm animal species, positive effects on different parameters such as toxin adsorption, digestion, blood values, feed efficiency, meat quality and/or greenhouse gas emissions could be found when biochar was added to feed. A considerable number of studies provided statistically non-significant results, though tendencies were mostly positive. Rare negative effects were identified in regard to the immobilization of liposoluble feed ingredients (e.g., vitamin E or Carotenoids) which may limit long-term biochar feeding. We found that most of the studies did not systematically investigate biochar properties (which may vastly differ) and dosage, which is a major drawback for generalizing results. Our review demonstrates that the use of biochar as a feed additive has the potential to improve animal health, feed efficiency and livestock housing climate, to reduce nutrient losses and greenhouse gas emissions, and to increase the soil organic matter content and thus soil fertility when eventually applied to soil. In combination with other good practices, co-feeding of biochar may thus have the potential to improve the sustainability of animal husbandry. However, more systematic multi-disciplinary research is definitely needed to arrive at generalizable recommendations.
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Affiliation(s)
| | - Nikolas Hagemann
- Ithaka Institute for Carbon Strategies, Arbaz, Valais, Switzerland
- Environmental Analytics, Agroscope, Zurich, Switzerland
| | | | - Claudia Kammann
- Department of Applied Ecology, Hochschule Geisenheim University, Geisenheim, Germany
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Gurtler JB, Doyle MP, Erickson MC, Jiang X, Millner P, Sharma M. Composting To Inactivate Foodborne Pathogens for Crop Soil Application: A Review. J Food Prot 2018; 81:1821-1837. [PMID: 30320513 DOI: 10.4315/0362-028x.jfp-18-217] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Compost is organic material that has been degraded into a nutrient-stabilized humus-like substance through intense microbial activity, which can provide essential plant nutrients (nitrogen, phosphorus) to aid in the growth of fruits and vegetables. Compost can be generated from animal waste feedstocks; these can contain human pathogens, which can be inactivated through the heat and microbial competition promoted during the composting process. Outbreaks of infections caused by bacterial pathogens such as Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on fruit and vegetable commodities consumed raw emphasize the importance of minimizing the risk of pathogenic contamination on produce commodities. This review article investigates factors that affect the reduction and survival of bacterial foodborne pathogens during the composting process. Interactions with indigenous microorganisms, carbon:nitrogen ratios, and temperature changes influence pathogen survival, growth, and persistence in finished compost. Understanding the mechanisms of pathogen survival during the composting process and mechanisms that reduce pathogen populations can minimize the risk of pathogen contamination in the cultivation of fruits and vegetables.
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Affiliation(s)
- Joshua B Gurtler
- 1 U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038 (ORCID: http://orcid.org/0000-0001-5844-7794 [J.B.G.])
| | - Michael P Doyle
- 2 Center for Food Safety, University of Georgia, 350 Woodroof Drive, Griffin, Georgia 30223
| | - Marilyn C Erickson
- 2 Center for Food Safety, University of Georgia, 350 Woodroof Drive, Griffin, Georgia 30223
| | - Xiuping Jiang
- 3 Department of Food, Nutrition and Packaging Sciences, Clemson University, 217 P & A Building, Clemson, South Carolina 29634
| | - Patricia Millner
- 4 U.S. Department of Agriculture, Agricultural Research Service, 10300 Baltimore Avenue, Building 201, Beltsville Area Research Center-East, Beltsville, Maryland 20705, USA (ORCID: http://orcid.org/0000-0002-8585-0308 [M.S.])
| | - Manan Sharma
- 4 U.S. Department of Agriculture, Agricultural Research Service, 10300 Baltimore Avenue, Building 201, Beltsville Area Research Center-East, Beltsville, Maryland 20705, USA (ORCID: http://orcid.org/0000-0002-8585-0308 [M.S.])
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Abstract
The purpose of this review is to delineate means of decontaminating soil. This information might be used to mitigate soil-associated risks of foodborne pathogens. The majority of the research in the published literature involves inactivation of plant pathogens in soil, i.e., those pathogens harmful to fruit and vegetable production and ornamental plants. Very little has been published regarding the inactivation of foodborne human pathogens in crop soil. Nevertheless, because decontamination techniques for plant pathogens might also be useful methods for eliminating foodborne pathogens, this review also includes inactivation of plant pathogens, with appropriate discussion and comparisons, in the hopes that these methods may one day be validated against foodborne pathogens. Some of the major soil decontamination methods that have been investigated and are covered include chemical decontamination (chemigation), solarization, steaming, biofumigation, bacterial competitive exclusion, torch flaming, microwave treatment, and amendment with biochar. Other innovative means of inactivating foodborne pathogens in soils may be discovered and explored in the future, provided that these techniques are economically feasible in terms of chemicals, equipment, and labor. Food microbiology and food safety researchers should reach out to soil scientists and plant pathologists to create links where they do not currently exist and strengthen relationships where they do exist to take advantage of multidisciplinary skills. In time, agricultural output and the demand for fresh produce will increase. With advances in the sensitivity of pathogen testing and epidemiological tracebacks, the need to mitigate preharvest bacterial contamination of fresh produce will become paramount. Hence, soil decontamination technologies may become more economically feasible and practical in light of increasing the microbial safety of fresh produce.
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Affiliation(s)
- Joshua B Gurtler
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Food Safety and Intervention Technologies Research Unit, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038-8551, USA
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Gwenzi W, Chaukura N, Noubactep C, Mukome FND. Biochar-based water treatment systems as a potential low-cost and sustainable technology for clean water provision. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2017; 197:732-749. [PMID: 28454068 DOI: 10.1016/j.jenvman.2017.03.087] [Citation(s) in RCA: 124] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 03/23/2017] [Accepted: 03/27/2017] [Indexed: 05/22/2023]
Abstract
Approximately 600 million people lack access to safe drinking water, hence achieving Sustainable Development Goal 6 (Ensure availability and sustainable management of water and sanitation for all by 2030) calls for rapid translation of recent research into practical and frugal solutions within the remaining 13 years. Biochars, with excellent capacity to remove several contaminants from aqueous solutions, constitute an untapped technology for drinking water treatment. Biochar water treatment has several potential merits compared to existing low-cost methods (i.e., sand filtration, boiling, solar disinfection, chlorination): (1) biochar is a low-cost and renewable adsorbent made using readily available biomaterials and skills, making it appropriate for low-income communities; (2) existing methods predominantly remove pathogens, but biochars remove chemical, biological and physical contaminants; (3) biochars maintain organoleptic properties of water, while existing methods generate carcinogenic by-products (e.g., chlorination) and/or increase concentrations of chemical contaminants (e.g., boiling). Biochars have co-benefits including provision of clean energy for household heating and cooking, and soil application of spent biochar improves soil quality and crop yields. Integrating biochar into the water and sanitation system transforms linear material flows into looped material cycles, consistent with terra preta sanitation. Lack of design information on biochar water treatment, and environmental and public health risks constrain the biochar technology. Seven hypotheses for future research are highlighted under three themes: (1) design and optimization of biochar water treatment; (2) ecotoxicology and human health risks associated with contaminant transfer along the biochar-soil-food-human pathway, and (3) life cycle analyses of carbon and energy footprints of biochar water treatment systems.
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Affiliation(s)
- Willis Gwenzi
- Biosystems and Environmental Engineering Research Group, Department of Soil Science and Agricultural Engineering, Faculty of Agriculture, University of Zimbabwe, P.O. Box MP167, Mount Pleasant, Harare, Zimbabwe.
| | - Nhamo Chaukura
- Nanotechnology and Water Sustainability Research Unit (NanoWS), University of South Africa (UNISA), P.O. Box 392, UNISA, 0003, South Africa
| | - Chicgoua Noubactep
- Department of Applied Geology, Universität Göttingen, Goldschmidtstrase 3, D - 37077, Gottingen, Germany; Comite Afro-europeen, Avenue Leopold II, 41 - 5000, Namur, Belgium; Kultur und Nachhaltige Entwicklung CDD e.V., Postfach 1502, D - 37005, Gottingen, Germany
| | - Fungai N D Mukome
- William Jessup University, 333 Sunset Boulevard Rocklin, California, 95675, CA, USA
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Nicholson AM, Gurtler JB, Bailey RB, Niemira BA, Douds DD. Influence of mycorrhizal fungi on fate of E. coli O157:H7 and Salmonella in soil and internalization into Romaine lettuce plants. Int J Food Microbiol 2015; 192:95-102. [PMID: 25440552 DOI: 10.1016/j.ijfoodmicro.2014.10.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 09/29/2014] [Accepted: 10/02/2014] [Indexed: 11/16/2022]
Abstract
The objectives of this study were to determine the influence of a symbiotic arbuscular mycorrhizal (AM) fungus on persistence of Salmonella and enterohemorrhagic Escherichia coli O157:H7 (EHEC) within soil, and survival within Romaine lettuce. Romaine seedlings were grown with or without AM fungi. Soil surrounding plants was inoculated with ca. 8 log CFU/plant of either Salmonella enterica or E. coli EHEC composites. Samples (soil, root, and shoot) were analyzed on days 1, 8, 15 and 22 for Salmonella and EHEC by direct plating and selective enrichment. Twenty-four hours after inoculation, populations of Salmonella and EHEC, respectively, were 4.20 and 3.24 log CFU/root, 2.52 and 1.17 log CFU/shoot, and 5.46 and 5.17 log CFU/g soil. By selective enrichment, samples tested positive for Salmonella or EHEC at day 22 at rates of 94 and 68% (shoot), 97 and 56% (root), and 100 and 75% (soil), respectively, suggesting that Salmonella has a greater propensity for survival than EHEC. Salmonella populations in soil remained as high as 4.35 log CFU/g by day 22, while EHEC populations dropped to 1.12 log CFU/g in the same amount of time. Ninety-two percent of all Romaine leaves in our study were positive for internalized Salmonella from days 8 to 22 and remained as high as 1.26 log CFU/shoot on day 22 in AM fungi+Romaine plants. There were no differences (P>0.05) between the survival of either pathogen based on the presence or absence of mycorrhizal fungi. Results of this study suggest that AM fungi do not affect the internalization and/or survival of either S. enterica or E. coli O157:H7 in Romaine lettuce seedlings. Our results should provide Romaine lettuce farmers confidence that the presence and/or application of AM fungi to crop soil is not a contributing factor to the internalization and survival of Salmonella or E. coli O157:H7 within Romaine lettuce plants.
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Affiliation(s)
- April M Nicholson
- College of Agriculture and Related Sciences, Delaware State University, 1200 N DuPont Hwy, Dover Delaware 19901, United States
| | - Joshua B Gurtler
- Food Safety Intervention Technologies Research Unit, U.S., Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038-8551, United States.
| | - Rebecca B Bailey
- Food Safety Intervention Technologies Research Unit, U.S., Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038-8551, United States
| | - Brendan A Niemira
- Food Safety Intervention Technologies Research Unit, U.S., Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038-8551, United States
| | - David D Douds
- Molecular Characterization and Foodborne Pathogen Research Unit, U.S., Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038-8551, United States
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Mohanty SK, Boehm AB. Escherichia coli removal in biochar-augmented biofilter: effect of infiltration rate, initial bacterial concentration, biochar particle size, and presence of compost. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:11535-11542. [PMID: 25222640 DOI: 10.1021/es5033162] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Bioretention systems and biofilters are used in low impact development to passively treat urban stormwater. However, these engineered natural systems are not efficient at removing fecal indicator bacteria, the contaminants responsible for a majority of surface water impairments. The present study investigates the efficacy of biochar-augmented model sand biofilters for Escherichia coli removal under a variety of stormwater bacterial concentrations and infiltration rates. Additionally, we test the role of biochar particle size and "presence of compost on model" biofilter performance. Our results show that E. coli removal in a biochar-augmented sand biofilter is ∼ 96% and is not greatly affected by increases in stormwater infiltration rates and influent bacterial concentrations, particularly within the ranges expected in field. Removal of fine (<125 μm) biochar particles from the biochar-sand biofilter decreased the removal capacity from 95% to 62%, indicating biochar size is important. Addition of compost to biochar-sand biofilters not only lowered E. coli removal capacity but also increased the mobilization of deposited bacteria during intermittent infiltration. This result is attributed to exhaustion of attachment sites on biochar by the dissolved organic carbon leached from compost. Overall, our study indicates that biochar has potential to remove bacteria from stormwater under a wide range of field conditions, but for biochar to be effective, the size should be small and biochar should be applied without compost. Although the results aid in the optimization of biofilter design, further studies are needed to examine biochar potential in the field over an entire rainy season.
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Affiliation(s)
- Sanjay K Mohanty
- Department of Civil and Environmental Engineering, Stanford University , Stanford, California 94305, United States
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