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Jun 22, 2023 155 likes •291 views

Fecal Indicators and Microbial Fecal Indicators and Microbial Pathogens in Effluent Irrigated Pathogens in Effluent Irrigated Crops and Soil Crops and Soil 1 , Osnat Gillor 1 , Nirit Bernstein 2 , Woutrina Miller 3 , Ezra Orlofsky 1 , Osnat

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Fecal Indicators and Microbial Fecal Indicators and Microbial Pathogens in Effluent Irrigated Pathogens in Effluent Irrigated Crops and Soil Crops and Soil

Ezra Orlofsky Ezra Orlofsky1

1, Osnat Gillor

, Osnat Gillor1

1, Nirit Bernstein

, Nirit Bernstein2

2, Woutrina Miller

, Woutrina Miller3

, Karen Shapiro Karen Shapiro3

3 and Stefan Wuertz

and Stefan Wuertz3

1 Ben 1 Ben-

Gurion University, Israel

Gurion University, Israel 2 Agricultural Research Organization, Volcani Center, Israel 2 Agricultural Research Organization, Volcani Center, Israel 3 UC Davis, California. 3 UC Davis, California.

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Wastewater Wastewater-

Its not all waste

Its not all waste

Many countries, especially poor and developing

Many countries, especially poor and developing

nes, reuse wastewater in some way.
nes, reuse wastewater in some way.
Wastewater is cheap, high in nutrients and

Wastewater is cheap, high in nutrients and available even in countries with water scarcity available even in countries with water scarcity problems. problems.

There is a need to assess the risks associated

There is a need to assess the risks associated with wastewater usage, especially vis with wastewater usage, especially vis-

à-

vis agricultural application. agricultural application.

Adhesion to produce

Adhesion to produce

Survival/accumulation in soil

Survival/accumulation in soil

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Israeli Policy Israeli Policy

Zero tolerance

Zero tolerance

Barrier method

Barrier method

Irrigating trees/horticulture only

Irrigating trees/horticulture only

Reallocation of potable water to the sector

Reallocation of potable water to the sector that needs it most that needs it most

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Safety Guidelines Safety Guidelines

“Pathogens are rarely measured directly in Pathogens are rarely measured directly in wastewater, because their concentrations vary wastewater, because their concentrations vary and analytical procedures are often difficult or and analytical procedures are often difficult or expensive to perform. expensive to perform.” ”

– –Guidelines for the safe use of wastewater, excreta and greywater Guidelines for the safe use of wastewater, excreta and greywater, vol 2 (WHO, , vol 2 (WHO, 2006). 2006).

It is standard practice to assess microbial

It is standard practice to assess microbial contamination with indicator organisms contamination with indicator organisms

Total Coliform/E. coli

Total Coliform/E. coli

Enterococcus

Enterococcus

Viral indicators

Viral indicators

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Objectives Objectives

Comparing the effectiveness of the

Comparing the effectiveness of the “ “Indicator Indicator” ” method to predict a health risk in soil and crops method to predict a health risk in soil and crops irrigated with treated effluents. irrigated with treated effluents.

Direct, quantitative testing of pathogens using

Direct, quantitative testing of pathogens using both culture dependent and culture independent both culture dependent and culture independent methods. methods.

Water: Ultrafiltration with cut

Water: Ultrafiltration with cut-

off >35 KD
ff >35 KD
Quantitative testing of indicators according to

Quantitative testing of indicators according to standard means standard means

Water/Produce : EPA

Water/Produce : EPA

Soil: Microbiology literature

Soil: Microbiology literature

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Experimental Design Experimental Design

Effluent/ Potable water

5 Plots (N=5) Soil Sample Tomato Sample Water Sample

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Method validation Method validation – – Recoveries Recoveries from spiking studies from spiking studies

Protozoa are ~50% recoverable from all

Protozoa are ~50% recoverable from all matrices matrices

Culture dependent methods for bacteria

Culture dependent methods for bacteria show high replicability for water (70 show high replicability for water (70-

80%),

80%), but not for soil but not for soil

qPCR tends to show >100% recovery, but

qPCR tends to show >100% recovery, but within reason. within reason.

Standard methods for indicators are

Standard methods for indicators are replicable replicable

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Results Results-

Effluent Water

Effluent Water

Coliforms were always

Coliforms were always detected in high detected in high abundance abundance

Enterococcus and E.

Enterococcus and E. coli coli-

sometimes

sometimes

Salmonella was

Salmonella was detected (putatively) in detected (putatively) in the time 2, as well as the time 2, as well as

E. coli
E. coli
Protozoa was detected

Protozoa was detected at time 1 at levels that at time 1 at levels that approach the limit of approach the limit of detection detection

100 200 300 400 500 CFU/100 mL time 0 time 1 time 2

Effluent Water Characteristics

Coliforms Enteroccocus

E. Coli

Salmonella

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Soil Results Soil Results

In Soil, coliforms

In Soil, coliforms appear to be the appear to be the major indicator group major indicator group present present-

perhaps

perhaps environmental environmental

Salmonella (putative)

Salmonella (putative) was identified in both was identified in both treatment plots. treatment plots.

1 10 100 1000 10000 100000 Tap 0 Eff 0 Tap 1 Eff 1 Tap 2 Eff 2 Coliforms Enterococcus

E. Coli