acwa – recycle research presentation to the acwa national convention august 2009
TRANSCRIPT
ACWA – RECYCLE RESEARCH
Presentation to the ACWA National ConventionAugust 2009
ACWA – RECYCLE RESEARCH
• ACWA applied for a grant to study the risks associated with water recycling in car washes
• Smart Water Fund of Victoria provided $244,000 for the research
• Management Committee of ACWA members, government and environmental/biological scientists
• Ecowise Environmental appointed technical consultant
• Characterisation of source water quality• Assessment of pathogen risk in source
water and final effluent• Evaluation of currently available
treatment systems• Validation of a risk management protocol • Establish a guideline for water recycling
systems
EXPERIMENTAL OBJECTIVES
EXPERIMENTAL METHODOLOGY
• Initial Screening of multiple sites for each system• Detailed monitoring of one site for each system• Source water sample collection and test
• E. coli, total organic carbon, pH, turbidity, total petroleum hydrocarbons and total metals
• Final effluent sample collection and test• Heterotrophic plate count, E. coli, Legionella, total
organic carbon, pH, turbidity, total petroleum hydrocarbons and total metals
• Questionnaire• Site characterisation / operation and maintenance
SITE SELECTION
• Found 12 recycle systems or system designs to test
• Initial screening with random selection of 3 sites per system
• 34 sites tested
• Urban, regional and all east coast states
METALS – SOURCE WATER
Source Water
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Silv
er
Alu
min
ium
Ars
en
ic
Bo
ron
Ba
riu
m
Ca
dm
ium
Ch
rom
ium
Co
pp
er
Iro
n
Me
rcu
ry
Ma
ng
an
es
e
Mo
lyb
de
nu
m
Nic
ke
l
Le
ad
An
tim
on
y
Se
len
ium
Zin
c
Metal
Me
tal
Co
nc
en
tra
tio
n (
mg
/L)
ADWG
Median
Aluminium and Iron guidelines are aesthetic based only (not health based)
Initial Screening
METALS – FINAL EFFLUENT
Aluminium and Iron guidelines are aesthetic based only (not health based)
Final Effluent
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Silv
er
Alu
min
ium
Ars
en
ic
Bo
ron
Ba
riu
m
Ca
dm
ium
Ch
rom
ium
Co
pp
er
Iro
n
Me
rcu
ry
Ma
ng
an
es
e
Mo
lyb
de
nu
m
Nic
ke
l
Le
ad
An
tim
on
y
Se
len
ium
Zin
c
Metal
Me
tal
Co
nc
en
tra
tio
n (
mg
/L)
ADWG
Median
Initial Screening
TURBIDITY
• Median turbidity removal was 34 % removal• Turbidity is being removed by the systems currently on the market
Turbidity
0
5
10
15
20
25
30
35
< 25 25 - 50 50 - 75 75 - 100 > 100
Turbidity Range (NTU)
Pe
rce
nta
ge
of
Sit
es
Turbidity - Source Water
Turbidity - Final Effluent
Initial Screening
E COLI IN SOURCE WATER BY ORIGIN
• Statistical analysis showed a significant increase from water sourced from Self Serve
• Auto median170 org/100mL
• Auto & SS median1,650 org/100mL
E. Coli in Source Water
0
10
20
30
40
50
60
70
80
<10 10 - 100 100 - 1000 >1000
E.coli concentration range (org/100mL)
Per
cen
tag
e o
f si
tes
From Auto Bay
From Auto Bay& Self Serve
Initial Screening
E. COLI IN FINAL EFFLUENT DISINFECTION
• This graph shows the disinfection performance observed with regards to the E. Coli concentrations in treated water
E. Coli - Final Effluent
0
10
20
30
40
50
60
70
80
90
< 10 10 - 100 100 - 1000 > 1000
E. Coli concentration range (org/100mL)
Pe
rce
nta
ge
of
sit
es
Chlorine
Non Chlorine
No Disinfection
Initial Screening
QUALITATIVE RESULTS
• Qualitative data was obtained through questionnaires• Data will be useful for refinement of risk assessments
Qualitative Results
0
10
20
30
40
50
60
70
80
Yes No Yes No Yes No Yes No
Manuals On-Site Alarms Water Recirculation Animal Trailers /Spray units
Pe
rce
nta
ge
of
Re
sp
on
se
s
Initial Screening
• Chemical contaminant risks acceptable
• Largest risk are pathogens in treated water due to:• Source water• Treatment process• Operational quality – variations between the same
system types due to operation and maintenance differences
RISK ASSESSMENT
Initial Screening
CONCLUSIONS
• Metals concentrations acceptable
• Effective turbidity removal is occurring in some systems tested to a small degree.
• TOC removal by most systems tested is minimal. Ozone is used, high levels of TOC removal occur.
Initial Screening
• E. coli in source water is more of a concern when the source water is drawn from self serve bays.
• Pathogen risks need more investigation as the final effluent from many sites did not meet limits for E. coli in the ANZECC Guidelines;
• No firm conclusions on effects of specific detergents used with the recycling system performance
• Disinfection performance between similar systems was variable
CONCLUSIONSInitial Screening
RECOMMENDATIONS
• Develop a validation protocol against which to test the performance of recycle systems. – operation and maintenance – pathogens – set out the number of required validation sampling events and
the frequency
• Develop a risk-based management template to ensure that operation and maintenance issues are addressed
• Develop a Guideline for car wash water recycling• Detailed monitoring with sites that represent each
system type using all of the above processes
Initial Screening
VALIDATION PROTOCOL
• Microbial Risk Assessment– Sewerage E coli concentration 10 million org/100ml. – Greywater E coli concentration 1,000 org/100ml– Stormwater non human microbial indicators– Australian Guideline for Recycled Water
• Stormwater with 10% sewerage content
• Required 92% reduction in E coli for safe recycled water
Detailed Monitoring
RISK MANAGEMENT TEMPLATE
• Recycling system information including major technologies and support;
• Sketch a process flow diagram of the system• Individual sections dedicated to the major critical
control points • Operating procedures for start up, normal
operation, shut down and emergency shut down of the system;
• Maintenance procedures • Incident reporting procedures• Training log.
Detailed Monitoring
CHEMICAL PARAMETERS IN FINAL EFFLUENT
pH BOD
(mg/L) Suspended
Solids (mg/L) Turbidity
(NTU)
Minimum 7.0 1 1 0.05
Maximum 10.6 490 240 330
Median 7.8 60 30 40
Detailed Monitoring
DISINFECTION
Disinfection Type
0
10
20
30
40
50
60
70
80
90
< 10 10 - 100 100 - 1000 > 1000
Final Effluent E. coli (org/100mL)
Per
cen
tag
e o
f si
tes
Chlorine (n=30)
Ozone (n=25)
Detailed Monitoring
RECYCLING WATER TREATMENT SYSTEMS ASSESSED
System Process Description
A Coarse and fine filtration, chlorination
B Flocculation, clarification, filtration, and chlorination
C Flocculation, clarification and filtration with chlorine and ozone disinfection
D Electroflocculation, media, bag, membrane and activated carbon filtration with chlorination
E Aeration and bioreactor
F1 Hydrocyclone and aeration
F2 Hydrocyclone, aeration, ozone and bag filtration
G Filtration, hydrocyclone and ozonation
H Filtration and aeration
I Hydrocyclone, biobed, filtration and ozonation
J Hydocyclone, filtration, and ozonation
K1 Filtration and chemical dosing
K2 Hydrocyclone, UV and aeration
L Aeration, chlorination, flocculation, clarification, filtration and chlorination
Detailed Monitoring
E COLI REMOVAL
Auto Feed Combined Feed Overall
Initial Screening
(n=21)
Detailed Monitoring
(n=40)
Initial Screening
(n=8)
Detailed Monitoring
(n=20)
Initial Screening
(n=32)
Detailed Monitoring
(n=60) Maximum (org/100mL) 24,000 16,000 48,000 24,000 48,000 24,000 Median (org/100mL) 100 42 3,250 1,650 290 325 Mean (org/100mL) 1,880 1,074 19,114 4,694 7,515 2,281
Auto Feed Combined Feed Overall
Initial Screening
(n=21)
Detailed Monitoring
(n=40)
Initial Screening
(n=8)
Detailed Monitoring
(n=20)
Initial Screening
(n=32)
Detailed Monitoring
(n=60) Maximum (org/100mL) 5,800 9,200 24,000 2,000 24,000 9,200 Median (org/100mL) 5 6 120 98 97 18 Mean (org/100mL) 905 489 4,869 557 1,998 512
Influent
Effluent
Detailed Monitoring
CONCLUSIONS
• The source water E. coli were comparable to those obtained in initial screening
• Operation and maintenance of the recycling systems is an important factor in reducing risks
• Site specific risk management plans were effective – engage car wash owners and operators with risk management– improve operations and maintenance;
• Microbial re-growth in stored treated water is a concern if a disinfection residual cannot be maintained
• Water quality monitoring is highly variable making a test protocol with a “pass/fail” outcome difficult.
Detailed Monitoring
RECOMMENDATIONS
• Move away from testing system performance against a chemical and pathogen targets and produce a guideline document outlining best practice in recycle management. – A risk management plan template
– A non-mandatory, indicative Water Quality Testing Guideline;
• Evaluate which systems performed consistently against the Water Quality Testing Guidelines,
Detailed Monitoring
GUIDELINES FOR WATER RECYCLING IN COMMERCIAL CAR WASH FACILITIES
• Regulatory requirements for water recycling in Australia
• Relevant questions to ask in selecting a recycle system
• Parameters for risk management • Monitoring and performance expectations • Risk management plan template • Non-mandatory indicative water quality guidelines • Sampling guide.
• Does the system incorporate a disinfection stage?• Is treated water stored prior to use or is it continually recirculated
without any final storage? If it is stored, is a disinfectant residual maintained in the final storage tank to reduce the risk of microbial re-growth?
• Does the system incorporate any monitoring equipment and/or alarms to help assess disinfection performance? If not, how is disinfection performance monitored?
• Are there any alarms to indicate failure of the disinfection process? • Does the system utilise any online turbidity monitoring to indicate
that there is a shock load, or one of the system barriers has failed (filters etc)?
• Does the system have processes that remove BOD, Suspended Solids and turbidity? Is there any monitoring data to prove this?
• Does the system have pH correction? How does it maintain a safe and workable pH in the final effluent given the varying input pH’s from car wash chemicals?
GUIDELINES FOR WATER RECYCLING IN COMMERCIAL CAR WASH FACILITIES
Supplier Questions
• Site Characteristics– System diagram with explanations– Manufacturer maintenance contact details
• Critical control points– Template for each element in each system type– Points of system control that may fail with how risks
should be managed• Operation and maintenance plan• Incident Reporting• Training
GUIDELINES FOR WATER RECYCLING IN COMMERCIAL CAR WASH FACILITIES
Risk Management Plan
GUIDELINES FOR WATER RECYCLING IN COMMERCIAL CAR WASH FACILITIES
Hazards Associate
d with Bag
Filters
Assessment of Management of Risks Associated with Bag
Filter
Risk Management Details
Does your system incorporate bag filtration?
□ Yes (if yes, continue with this section)
□ No (if no, move on to next section)
Does you bag filter/s have any alarms in place? □ Yes □ No
If yes, what triggers the alarm? If no, what measures are in place to identify bag failure and to determine when to replace bags?
Are all staff trained in maintaining bag filters? □ Yes □ No
If no, what measures are in place in the case of bag filter failure in the presence of an untrained operator? Is this adequate?
How often are bag filters replaced?
Carry over of solids and carry over of pathogens
Is regular inspection of your bag filters part of your maintenance program? □ Yes □ No
If no, how will you manage the risk of bag filter failure?
Other issues associated with bag filters?
Risk Management Plan
GUIDELINES FOR WATER RECYCLING IN COMMERCIAL CAR WASH FACILITIES
Analyte Source
Water
Final Effluen
t
Interpretation Guide Water Quality Guidelines
E. coli Yes Yes There should be a reduction in E. coli between source water and final effluent
92% Reduction
Heterotrophic Plate Count (HPC)
Yes Yes
There should be a reduction in HPC between the source water and final effluent. Higher HPC in final effluent can indicate microbial re-growth through the treatment system.
-
Free Chlorine Residual
- Yes
A positive chorine residual should be observed in final effluent if chlorine is used as a disinfectant
Target effluent concentration of greater than 0.1 mg/L if chlorine is used as a disinfectant
Turbidity Yes Yes There should be a reduction in turbidity between source water and final effluent
-
Suspended Solids
Yes Yes
There should be a reduction in suspended solids between source water and final effluent
Target effluent concentration of 10mg/L.
Biological Oxygen Demand
Yes Yes There should be a reduction in BOD between source water and final effluent
Target effluent concentration of 10mg/L.
pH Yes Yes pH should be stable and close to neutral through the treatment process
Target in effluent of 6.5 – 8.5
Analysis Parameters and Results Interpretation
• Risks associated with car wash water are more akin to risks in stormwater than sewerage and grey water
• Combined auto and self serve feed is higher risk than auto alone
• Recycling to self serve is higher risk – not recommended
• Generally chlorine does a more satisfactory job at removing microbes than ozone or UV
• Storage of recycled water is higher risk
• Testing water to defined parameters is useful but not exacting
• Creating and following a Risk Management Plan is the most essential element in controlling risks from recycling car wash water
• We now have a tool kit which will be on the ACWA web site
– Guideline for Water Recycling in Commercial Car Wash Facilities
– Risk Management Plan template
ACWA – RECYCLE RESEARCH
What have we learned
ACWA – RECYCLE RESEARCH
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