The document discusses membrane bioreactor (MBR) systems for wastewater treatment. It provides common ranges for key design parameters like membrane flux rates, mixed liquor suspended solids concentrations, and aeration requirements. The text indicates MBR systems require careful design to prevent fouling and ensure integrity. It also notes TCEQ may require a pilot study or 2-year performance bond for non-standard MBR proposals.

1. WQ Management Developments
Nutrients, Bacteria
Jim Davenport
Monitoring & Assessment Section
Water Quality Planning Division
Office of Water
Texas Commission on Environmental Quality
jdavenpo@tceq.state.tx.us tel. 512/239-4585
February 22, 2011

2. Nutrient 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)

3. EPA 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

4. 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

5. TCEQ 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

6. Nutrient Criteria: Examples
Reservoir Chl a (µg/L) TP (mg/L) Transparency
Stand-alone Not adopted (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 – [12.4] 0.18 0.28
not adopted]
Travis 3.7 0.03 3.13

7. 2010 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”

8. Nutrient 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?

9. Nutrient 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 %

10. Nutrient 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

11. 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)

12. 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

13. 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

14. Effluent Bacteria: Houston TMDL Studies
Minor municipal facilities
(114 data points)
5
4.5
E. coli (log of #/100 ml)
4
3.5 E. coli log
3
2.5
Single sample
2
maximum log (2.6)
1.5
1 Geometric mean log
0.5 (2.1)
0
0 5 10 15 20
residual chlorine (mg/L)

15. Summary
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?

16. Bacteria
Requirements
Bacteria Limits
in TPDES Domestic Permits

17. 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

18. Implementation
Next permit action
New
Renewal
Amendment
No compliance schedule
Recommend evaluating now

19. Bacteria Limits
Standard
E coli
126 avg
394 max
Enterococci
35 avg
89 max

20. Measurement Frequencies
Flow 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

21. Continued Need for
Chlorine Testing
Retain
4.0 mg maximum
0.1 mg dechlor
Regular check
between bacteria
samples

22. Chlorine Contact Chambers
Recommend evaluating now
If undersized or short-
circuiting, violating current
regulations

23. Pond Systems
21-day retention time
Recommend evaluating
Capacities
Sample Locations
Wildlife impacts (birds, nutria, etc)
Compliance schedule for new
construction

24. Laboratory Issues
In-house testing
without NELAC
Contract lab must be
NELAC certified
Proximity to plant
Increased workload

25. Sample Holding Times
Standard Methods
Holding time – 6 hours
Set-up time – 2 hours
Travel time issues

26. Reporting Units
Colony Forming Units
CFU
Most Probable Number
MPN
Both Acceptable!

27. Nutrient Removal
Chapter 217:
Design Criteria for Wastewater Systems

28. 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

29. 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

30. 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

31. 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

32. Specific effluent standards are still
considered on case-by-case basis in each
permit

33. Contact Info
Louis C. Herrin, III, P.E.
louis.herrin@tceq.texas.gov
512.239.4552

34. Membrane Bioreactors (MBR)
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

35. 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

36. Membrane Bioreactors (MBR)
Expected Performance
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

37. Membrane Bioreactors (MBR)
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

38. 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

39. 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

40. 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

41. 217.157 Membrane Bioreactors
Treatment Systems (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