Water Quality Managements Developments: Nutrients and Bacteria
-
Upload
southeast-chapter-of-texas-awwa -
Category
Technology
-
view
902 -
download
0
description
Transcript of Water Quality Managements Developments: Nutrients and Bacteria
WQ Management DevelopmentsWQ Management Developments
Nutrients, BacteriaNutrients, Bacteria
Jim Davenport
Monitoring & Assessment Section
Water Quality Planning Division
Office of Water
Texas Commission on Environmental Quality
[email protected] tel. 512/239-4585
February 22, 2011
Nutrient Criteria: NationalNutrient Criteria: National
�EPA and numerical nutrient criteria:
- 1998 mandate: states to have criteria by 2004
- Allowed state development plans and schedules
- Established stringent national guidance criteria
○ Calculated from historical instream data
○ Separate for lakes, streams, reservoirs
○ Pooled for large, aggregate ecoregions
○ Criteria = 75th percentile of unimpacted sites
- Urged by EPA Inspector General, Aug 2009
- Lawsuits: Florida (Wisconsin, Kansas)
EPA Nutrient Criteria: FloridaEPA Nutrient Criteria: Florida
� Lawsuit from Florida Wildlife Fed. & others in 2008
� EPA promulgated criteria for Florida lakes & streams in Dec 2010 – in effect Mar 2012
� EPA estuary criteria – propose in Nov 2011
� New countersuits – Florida cities, Ag Comm., etc.
� Lakes TP: 0.01-0.05 mg/L TN: 0.51-1.27 mg/L
� Streams TP: 0.06-0.49 mg/L TN: 0.67-1.87 mg/L
� Potential long term costs?
- Regulated groups: $3 - $8 billion per year
- EPA: $135 - $206 million per year
Why Are Nutrient Criteria Difficult?Why Are Nutrient Criteria Difficult?
� Lack of clear “use-based” thresholds, for uses such as recreation & aesthetics, aquatic life propagation, drinking water sources
� Responses to nutrients are highly variable –e.g., effect of TN,TP on Chl a
� No consensus on how to derive criteria
� Independent criteria, or “weight-of evidence”?
� Insufficiencies in historical monitoring data
� Initial EPA guidance criteria were problematic
� High concern about regulatory impacts
TCEQ Nutrient Criteria: DevelopmentTCEQ Nutrient Criteria: Development
�Submitted plans to EPA in 2001, 2006
�Reservoirs, then streams & estuaries
�Convened advisory workgroup
�Separate criteria for each reservoir
�Set on historical conditions
�Adopted for 75 reservoirs – 6/30/10
�Based on Chlorophyll a
(suspended algae)
�New permitting procedures for nutrients
Nutrient Criteria: ExamplesNutrient Criteria: Examples
Reservoir Chl a (µg/L)
Stand-alone
TP (mg/L)
Not adopted
Transparency (meters)
Not adopted
Eagle Mtn 25.4 0.07 0.80
Cedar Creek 30.4 0.07 0.80
Livingston 23.0 0.16 0.67
Lewisville 18.5 0.06 0.60
[Houston –
not adopted]
[12.4] 0.18 0.28
Travis 3.7 0.03 3.13
2010 Nutrient Implementation Procedures2010 Nutrient Implementation Procedures
� In 2010 Standards Implementation Procedures
� Applied to increases in domestic discharges
� Sets framework for nutrient (TP) effluent limits
� Reservoirs – predict effects on “main pool”
� Relate TP to reservoir chlorophyll a criteria
� Streams and reservoirs – assess local impacts:
- Apply site-specific screening factors
- Level of concern – low, moderate, or high
- Assess “weight-of-evidence”
Nutrient Screening: Local Factors for StreamsNutrient Screening: Local Factors for Streams
- Size of discharge
- Instream dilution
- Sensitivity to attached vegetation – type of bottom
- Sensitivity to attached vegetation – depth
- Sensitivity to nutrient enrichment – clarity
- Sensitivity to aquatic vegetation – observations
- Sensitivity to aquatic vegetation – sunlight, tree shading
- Streamflow sustainability
- Impoundments and pools
- Consistency with other permits
- Listed as a nutrient concern in WQ inventory?
Nutrient Screening: Example of Local FactorNutrient Screening: Example of Local Factor
� Factor: Instream dilution in streams
Concern level Percent effluent in dry weather
Low < 10 %
Moderate 10 to < 25 %
High > 25 %
Nutrient Criteria: The Road AheadNutrient Criteria: The Road Ahead
� Reconvene nutrient advisory committee
� Review data and academic research; and
survey criteria development state-by-state
(joint project with U. of Houston Clear Lake)
� Continue special stream surveys (> 100 so far)
� Develop criteria options for streams & estuaries:
(1) Historical levels at reference sites
(2) Relate TP,TN to D.O., algae, biological indices
� Consider in part for next standards revisions
Revised Recreational Standards (6/30/10)
< Previously: Almost all water bodies primary contact
< 303 water bodies not meeting bacteria criteria (2010)
< Expand recreational categories
< Implement new use-attainability analyses
< Require bacteria limits in discharge permits
- in addition to chlorination (11/4/09)
Recreation Uses Indicator Bacteria
Geometric Mean Criteria (colonies/100 ml)
E. coli (FW) Enterococci (SW)
Previous Standards:
Contact recreation 126 35
Noncontact rec. 605 168
Adopted Standards:
(6/30/2010)
Primary contact 126 35
Secondary contact 1 630 175
Secondary contact 2 1030 --
Noncontact rec. 2060 350
Recreational Use-Attainability
▸ Uses other than primary contact may be appropriate for some water bodies
▸ TCEQ has new recreational UAA procedures
▸ Surveys include physical & flow characteristics, + observed evidence of recreation
▸ Local input (interviews) important
▸ Initiated 124 recreational UAAs
▸ Involves major coordination effort
and public participation
Effluent Bacteria: Houston TMDL Studies Effluent Bacteria: Houston TMDL Studies
Minor municipal facilities(114 data points)
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 5 10 15 20
residual chlorine (mg/L)
E.
co
li (
log
of
#/1
00 m
l)
E. coli log
Single samplemaximum log (2.6)
Geometric mean log(2.1)
SummarySummary
� National interest in nutrient criteria is increasing, partly in response to new EPA criteria for Florida.
� TCEQ adopted criteria (Chl a) for 75 reservoirs, but EPA has not yet approved them.
� TCEQ is developing draft criteria with multiple options for streams and rivers, and for estuaries.
� TCEQ has adopted expanded recreational categories and criteria
� Numerous UAA reviews of individual small streams
is continuing
� Questions?
Bacteria Requirements
Bacteria Limits
in TPDES Domestic Permits
Agreement with EPA
� Interim: bacteria limits in certain permits
� Bacteria limits in all permit actions issued after 1/1/10.
� Permits issued under interim agreement may see frequency adjustment in next permit
Implementation
� Next permit action
� New
� Renewal
� Amendment
� No compliance schedule
� Recommend evaluating now
Bacteria Limits� Standard
� E coli
� 126 avg
� 394 max
� Enterococci
� 35 avg
� 89 max
Measurement FrequenciesFlow Chlorine Ultraviolet Natural
>10 5/wk Daily Daily
5—10 3/wk Daily 5/wk
1—5 1/wk Daily 3/wk
0.5—1.0 2/mo Daily 1/wk
0.1—0.5 1/mo 5/wk 2/mo
<0.1 1/qtr 5/wk 1/mo
Continued Need for Chlorine Testing
� Retain
� 4.0 mg maximum
� 0.1 mg dechlor
� Regular check between bacteria samples
Chlorine Contact Chambers
�Recommend evaluating now
� If undersized or short-circuiting, violating current regulations
� 21-day retention time
� Recommend evaluating
� Capacities
� Sample Locations
� Wildlife impacts (birds, nutria, etc)
� Compliance schedule for new construction
Pond Systems
Laboratory Issues
� In-house testing without NELAC
� Contract lab must be NELAC certified
� Proximity to plant
� Increased workload
Sample Holding Times
� Standard Methods
� Holding time – 6 hours
� Set-up time – 2 hours
� Travel time issues
Reporting Units
� Colony Forming Units
� CFU
� Most Probable Number
� MPN
� Both Acceptable!
Nutrient Removal
Chapter 217:
Design Criteria for Wastewater Systems
Current Regulations
� “A facility design that proposes advanced
nutrient removal is innovative and
nonconforming technology and is subject to
217.10(b)(2) of this title (relating to
Innovative and Nonconforming
Technology).” - 217.163
Results
� Wide variety of removal processes yielding eco-regionally dependent results
� Problems-
� Variability of ego-regional conditions in Texas
� One treatment process with several different performance reports
Design Criteria Changes
� Engineer’s report must include detailed design calculations correlating the proposed removal process with the anticipated effluent concentration.
� Process
� TP/TN Influent Characteristics
� TP/TN Effluent Characteristics
Desired Ranges
� Total Nitrogen < 8 mg/L
� Total Phosphorous
� Chemical Addition: 0.1 - 0.5 mg/L
� Membrane Filtration: 0.1 - 0.5 mg/L
� BNR: 0.2 - 0.3 mg/L
� Specific effluent standards are still considered on case-by-case basis in each permit
Compiled Surveys from Vendors of Membranes
� Huber, Koch, Kruger, Kubota, Siemens, Zenon
Results of Survey, Literature and Other State Regulations
Concerns
� Prevention of Fouling
� Adequate aeration at high MLSS concentrations
� Achievable rate of flow through membranes
� Adequate pretreatment i.e. fine screening
� Hydraulics
� Ensure Integrity
� Foam Control
� Warranty
� Nutrient Removal
Membrane Bioreactors (MBR)
Applicability
� Submerged
� Low-pressure, vacuum or gravity
� Ultrafiltration or microfiltration
� 217.8(b)(2) Approval of Nonconforming and Innovative Technologies
� May require pilot study and/or 2 year performance bond
Membrane Bioreactors (MBR)
� CBOD5 5 mg/l� TSS 1 mg/l� Ammonia 1 mg/l� Total Nitrogen (w/pre-anoxic zone) 10 mg/l� Total Nitrogen (w/pre-anoxic and
� post-anoxic zone) 3 mg/l� Total Phosphorus (with chemical addition) 0.2 mg/l � Total Phosphorus (with Bio-P removal) 0.5 mg/l� Turbidity 0.2 NTU� Bacteria up to 6 log removal (99.9999%)� Viruses up to 3 log removal (99.9999%)
If proposed design is for higher quality effluent,
Pilot Study or Data from Similar Facility
Membrane Bioreactors (MBR)Expected Performance
Membranes
Hollow fiber or Flat plate
Nominal Pore Size
Microfiltration 0.10 – 0.40 microns
Ultrafiltration 0.02 to 0.10 microns
Common Membrane materials
Pretreatment
Fine Screen - perforated plate or drum
Hollow fiber 1.0 - 2.0 mm
Flat plate 2.0 - 3.0 mm
No Bypass
Primary clarifier Evaluated for > 1 MGD
Grit Removal excessive I/I
Oil and Grease Removal 50 mg/l
Membrane Bioreactors (MBR)
Operation
Average Daily Net flux rate @ 20 C 12 to 20 gfd
Peak Daily Net flux rate @ 20 C 20 gfd
Two Hour Peak Daily Net flux rate @ 20 C 24 gfd
Operational Range for TMP
Maximum Operational TMP
Hollow Fiber 2.0 – 10.0 psi Max 12.0 psi
Flat Plate 0.3 - 1.5 psi Max 3.0 psi
Operational Range of MLSS Concentration
Bio Reactor 4,000 - 10,000 mg/l
Membrane Tank 4,000 – 12,000 mg/l
Operational control parameters
SRT 10 – 25 days
Membrane Bioreactors (MBR)
Operation
Amount of air used per square foot of membrane
0.01 – 0.04 SCFM / SF
Method of Integrity Testing : In-line Turbidity <=1.0 NTU
Hollow Fiber Pressure Decay Testing
Surface Wasting to Foam Control
Run in full manual mode or backup PLC
Aeration
alpha value of 0.5 or lower
anoxic 0.5 mg/l DO
aerobic 1.5 – 3.0 mg/l DO
membrane 2.0 - 8.0 mg/l DO
Nutrient Removal
deoxygenate recycle
recycle 300 – 600 percent
Membrane Bioreactors (MBR)
Redundancy
N+1, trains, units or storage. Show calculations
Peak Flow
Peak Ratio of 2.5 requires Equalization, off-line storage or reserve membrane capacity
RAS rate
200 – 400 percent of influent
Warranty
5 year on Membranes
May require a 2 year performance bond
Membrane Bioreactors (MBR)
� Engineering Report Required
� Common range of values
� Justification for using parameters outside the common range
� May be required to provide 2 year performance bond
217.157 Membrane Bioreactors
Treatment Systems (MBR)