Accepted Manuscript Decay of enteric microorganisms in biosolids-amended soil under wheat (Triticum aestivum) cultivation K.R. Schwarz, J.P.S. Sidhu, D.L. Pritchard, Y. Li, S. Toze PII:
S0043-1354(14)00227-9
DOI:
10.1016/j.watres.2014.03.037
Reference:
WR 10562
To appear in:
Water Research
Received Date: 5 November 2013 Revised Date:
15 February 2014
Accepted Date: 17 March 2014
Please cite this article as: Schwarz, K.R., Sidhu, J.P.S., Pritchard, D.L., Li, Y., Toze, S., Decay of enteric microorganisms in biosolids-amended soil under wheat (Triticum aestivum) cultivation, Water Research (2014), doi: 10.1016/j.watres.2014.03.037. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Decay of enteric microorganisms in biosolids-amended soil under
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wheat (Triticum aestivum) cultivation
3 K.R. Schwarz 1, J.P.S. Sidhu2*, D.L. Pritchard1, Y. Li3 and S. Toze2, 4
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Department of Environment and Agriculture, Curtin University, GPO Box U1987 Perth, Western Australia 6845, Australia. 2CSIRO Land and Water, EcoSciences Precinct, 41 Boggo Road, Dutton Park, Queensland 4102, Australia. 3CSIRO Animal, Food and Health Sciences, Queensland Biosciences Precinct, 306 Carmody Road, St Lucia, QLD 4067, Australia. 4School of Population Health, University of Queensland, Herston Road, Herston, Brisbane, QLD, Australia, 4006.
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Running title: Pathogen decay in biosolids-amended soil
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*Corresponding author: Dr Jatinder Sidhu. Mailing address: CSIRO Land and Water, EcoSciences Precinct, 41 Boggo Road, Brisbane 4102, Australia. Tel: +617 3833 5576; Fax: +617 3833 5503. E-mail address:
[email protected]
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ABSTRACT
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There is a growing need for better assessment of health risks associated with land-applied
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biosolids.
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Salmonella enterica, Escherichia coli, and bacteriophage (MS2) in biosolids-amended soil
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under wheat cultivation. The biosolids seeded with microorganisms were placed in decay
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chambers which were then placed in the topsoil (10 cm depth) at three different sites. Sites
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were selected in arid wheat-growing regions of Australia with loamy-sand soil type (Western
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Australia) and sandy soil (South Australia). Seeded E. coli and S. enterica had a relatively
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short decay time (T90 = 4-56 days) in biosolids-amended soil compared to un-amended soil
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(T90 = 8-83 days). The decreasing soil moisture over the wheat-growing season significantly
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(P180 days) during the winter in biosolids-amended soil. The stability
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of adenovirus suggests that consideration towards biosolids amendment frequency, time, rates
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and appropriate withholding periods are necessary for risk mitigation.
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This study investigated in-situ decay of seeded human adenovirus (HAdV),
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Keywords: Human adenovirus, Salmonella enterica, MS2, pathogen decay, biosolids-
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amended soil.
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ACCEPTED MANUSCRIPT 1. Introduction
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Recycling of biosolids as a low-grade fertilizer and soil amendment, to improve the chemical
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and physical properties of soil, is increasingly favored over un-sustainable landfill disposal
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options worldwide. In Australia, over 330,000 tonnes per year of dry solids are produced and
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are predominantly used for agricultural purposes (ANZBP 2013). There is a recognized
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pathway for transfer of enteric pathogens such as hepatitis A virus, adenovirus, S. enterica,
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Campylobacter spp., E. coli O157:H7, Cryptosporidium and Giardia, to humans from
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biosolids-amended soil, through contamination of water and food chain (Gerba and Smith
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2005, Pepper et al. 2006, Sidhu and Toze 2009).
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Enteric pathogens may accumulate in the soil under favorable conditions depending on the
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frequency and rate of biosolids application (Gerba and Smith, 2005; Viau and Peccia, 2009).
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Therefore, land application of biosolids is controlled via regulations that set out acceptable
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levels for pathogens and heavy metals in biosolids prior to the release onto land, along with
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other management practices to reduce human health risks and environmental contamination
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(DEC 2012; EU 2003; US-EPA 2003). Under the United States Environmental Protection
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Agency (US-EPA) regulations, biosolids which meet Class A or B classifications at the
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wastewater treatment plant are allowed for un-restricted and restricted land application,
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respectively. Similarly, under the European Union and Australian guidelines, treatment-
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based standards and monitoring for fecal indicators and pathogens in the finished product are
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required for risk mitigation (DEC 2012; EU 2002, US-EPA 2003).
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Fecal coliform numbers in the stabilized biosolids can be high, up to 105 g-1 dry weight
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(Davies et al. 1999, LeClerc et al. 2001, Vasseur et al. 1996, Zaleski et al. 2005).
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Furthermore, a significant number of enteric viruses such as adenovirus, polyomavirus (104 g-
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1
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et al. 2006, Chauret et al. 1999, Sidhu and Toze 2009). In the USA, Class B biosolids
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containing 180
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E. coli
Un-amended
Site C
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Microorganism
>180
NT = Not tested
796 797
Table 4. Recovery rates of seeded adenovirus in biosolids-amended and un-amended soil. Seeded virus
Sample ID
Site A - Unamended Site B - Amended
4.40 X 104
4.40 X 104
100
3.17 X 105
6.94 X 104
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2.10 X 105
1.33 X 105
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5.06 X 10
2
3.96 X 10
2
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5.44 X 10
4
3.27 X 10
4
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Mt Compass Site C - Amended
1.20 X 105
4.36 X 104
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4
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798 799
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Recovery rate (%)
(PDU mL-1)
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Recovered virus number
numbers (PDU mL-1)
Water Moora
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2.40 X 10
8.12 X 10
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800 801
35 mm
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Figure 1. A commercial 3.5 mL Microsep™ centrifugal device (35 mm x 10 mm) used as a
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sentinel chamber and; (bottom right) filled with the sample contents of soil, biosolids and
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laboratory-cultured microorganisms.
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Outside chamber
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In side chnamber
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Log10 cfu g ds
807 808 809 810 811 812
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0
40
80 120 160 Time (days)
200
813 814
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Figure 2.
Decay patterns of E. coli with SE bars, outside chambers (soil) and inside
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chambers in biosolids-amended soil and at Site B (Moora 2008).
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Site A
E. coli amended E. coli un-amended S. enterica amended S. enterica un-amended
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0 20
60
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100 120 140 160 180 200
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100 120 140 160 180 200
Site B
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0 20 10
40
60
Site C
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2 0 20
40
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100 120 140 160 180 200
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Figure 3. Decay patterns of E. coli and S. enterica with SE bars across three sites in
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biosolids-amended soil and un-amended soil.
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Site C
HAdV amended HAdV un-amended MS2 amended MS2 un-amended
8 6 4
10
20
40
60
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100 120 140 160 180 200
60
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100 120 140 160 180 200
60
80
Site B
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ds
0
0 10
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20
40 Site A
8 6
2 0 20
40
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100 120 140 160 180 200
825 826
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Days
Figure 4. Decay patterns of human adenovirus (HAdV) and MS2 with SE bars across three
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sites in biosolids-amended soil and un-amended soil.
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E. coli S. enterica Soil temperature Soil moisture amended Soil moisture unamended
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20 15 10 5 40
80 120 Time (days)
0 200
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Soil moisture (%) and temp. ( C)
10 9 8 7 6 5 4 3 2 1 0
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Log10 cfu g ds
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biosolids-amended (black symbols) and un-amended (clear symbols) soil in chambers, with
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changes in soil moisture in both soil types (inside chambers) and soil temperature.
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Adenovirus (HAdV) Bacteriophage MS2 Soil temperature Soil moisture amended Soil moisture unamended
45 40 35 30
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Log10 pfu/pdu g ds
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80 120 Time (days)
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Soil moisture (%) and temp. ( C)
Figure 5: Decay patterns of E. coli and S. enterica at Site B (Moora 2008) with SE bars in
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Figure 6. Decay patterns of MS2 and adenovirus at Site C (Mount Compass 2008) with SE
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bars in biosolids-amended (black symbols) and un-amended (clear symbols) soil in chambers,
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with changes in soil moisture in both soil types (inside chambers).
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Table 4. ANOVA results of individual factors influencing decay of enteric microorganisms in biosolids-amended soil and un-amended soil chambers.