Upgrade of a Wastewater Treatment Facility to Meet ... · Upgrade of a Wastewater Treatment Facility to Meet Capacity and Nutrient Removal Requirements Angela R. Bielefeldt Department

ASSOCIATION OF ENVIRONMENTAL ENGINEERING & SCIENCE PROFESSORS

AEESP CASE STUDIES COMPILATION 2006 83

Upgrade of a Wastewater Treatment Facility to Meet Capacity and Nutrient Removal Requirements

Angela R. Bielefeldt Department of Civil, Environmental, & Architectural Engineering

Univ. of Colorado - Boulder Boulder, CO 80309-0428

Summary This case study illustrates the alternatives assessment process at a medium-sized municipal wastewater treatment facility that required upgrades for increased capacity and nutrient removal. Two different engineering consultants worked on this project over a three year period. The first consultant compared five different secondary wastewater treatment options using a weighted decision matrix, but their recommended option was rejected by the City. A second consultant was then hired to repeat the entire assessment process. They compared the recommended treatment approach from the first consultant with combinations of four newer types of biological treatment processes. The case study illustrates the subjective nature of decision making at this level, and the importance of listening to the client and stakeholder input. Complexity and uncertainty of facilities planning at this level is also apparent. Keywords: alternatives assessment, pre design, decision matrix Context and Logistics Learning Objectives

Through this case study, students will learn to: 1. illustrate the complex nature of environmental engineering design

problems, balancing an array of constraints and criteria; 2. illustrate the subjective nature of alternatives assessment to

determine optimal design approach; and 3. show the evolving nature of environmental engineering, and

innovative methods of secondary wastewater treatment (if the case study is used in a wastewater treatment course).



Accommodating Course(s) and Level

• junior, senior, or graduate level design courses; and/or • junior, senior, or graduate level wastewater treatment course.

Prerequisite Courses

• Sophomore/junior level environmental engineering course covering basics of wastewater treatment

Point of Use

• This case study can be used at the beginning of a capstone design course in environmental engineering to introduce students to the approach used in an alternatives assessment. It should make students more appreciate of the art of engineering judgment, since professional engineering firms recommended different solutions to the same problem.

Type of Activity

• Students can read the background information on the case prior to class. During class the instructor can break the students into teams to tackle each set of questions. Then the class can share their thoughts, the instructor can share the real recommendations of the consultants, and move to the next phase of the project and case. To do a complete job, I would recommend breaking across two class periods, allowing the students to do some brief research on wastewater treatment technologies between the first and second periods. Alternatively, the students can combine their out of class time in preparation for a longer in-class discussion period.

Level of Effort by Instructor

• Become familiar with the case study materials. About one to two hours. Lead in-class discussion. Two 50-minute class periods, or a single longer class period.

Level of Effort by Individual Student

• Read background on the problem and existing treatment facility prior to class: 1 hr. Participate in class discussion and in-class small group discussions: 1 hr. Research methods to achieve nutrient



removal from municipal wastewater outside class: 1-2 hrs. Participate in class discussion and in-class small group discussions: 1 hr.

Suggested Assessment Methods

• Evaluate the quality of student ideas and the discussion during class. Observe an increased level of student’s confidence in dealing with the complexities and uncertainties inherent in design. Ask students at the middle or end of the semester if the exercise was beneficial.

Introduction

For most environmental engineering consultants, the design process begins when they are hired by a client, such as a municipality or industry, to solve a problem. The problem is often stated in terms such as “design a process to treat our wastewater to applicable state and federal requirements.” It is therefore up to the consultant to work with the client and other stakeholders to define constraints and criteria for the design. From these, the consultant selects various options that satisfy the constraints and then evaluates these alternatives on how well they fulfill the criteria. Typically, there is no single best solution, but a variety of alternatives with trade-offs as to their strengths and weaknesses against the various criteria. The consultant works with the client and other stakeholders to find the solution that optimally meets the constraints and criteria of the project. This so-called “alternatives assessment” phase of the project is the most significant in terms of the overall costs and functionality of the final product. It is a creative process that couples technical information with engineering judgment. As a young engineer this process can seem daunting. In the real world, there are numerous examples of how teams of experienced engineers would recommend a different approach to solve the same exact problem given the same constraints. The case study below provides one specific example of a situation where this occurred. Students will follow the decision process used by the consultants and compare their ideas to each other and that of the actual consultants that worked on the project. The discussion will focus on the carbon and nutrient removal portion of the wastewater treatment process. The specific names of consultants and the project location have been changed to preserve the anonymity of the parties involved.



Case Study Basic Problem

Due to rapid population growth in the Front Range area in Colorado, the existing municipal wastewater treatment plant (WWTP) in City, Colorado, needed to be upgraded from a 5 MGD facility to around 15 MGD to handle the additional flow anticipated over the next 20 years. It was also expected that under new Total Maximum Daily Load (TMDL) regulations for the Creek that nitrogen removal would be required. The City hired a consultant to do an Alternatives Assessment and recommend the treatment processes needed to upgrade the facility. History of Consultant Involvement

A medium-sized local consulting firm, ABC, was hired and began the project in June 1998. ABC had worked on previous projects for the City wastewater facility. They held approximately four meetings with clients, including two that were attended by an external advisory group, and two meetings with the public. This was designed to ensure buy-in from all key stakeholder groups. In particular, in August 1998 a workshop was held by ABC Consulting to gather stakeholder input to rate the importance of various decision criteria. This discussion was led by four engineers representing the consultant and attended by the Superintendent of the wastewater treatment plant, a City council representative, a regional Front Range planning representative, wastewater treatment plant operators, two citizen neighbors, three industrial dischargers, and one academic expert. This process resulted in a list of 11 weighted non-cost decision criteria to be used to compare alternative methods of wastewater treatment. Five methods for secondary biological wastewater treatment were compared. Each option went through preliminary sizing, and a layout of the proposed facilities was developed to illustrate fit within the available land area. The consultants then compared the outcome of using 30, 50, and 70% cost weight and 70, 50, 30% non-cost criteria weight, respectively. This information was presented at a public meeting held in October 1998 to discuss the Wastewater Treatment Improvements. The two best options of the five were then analyzed further to develop more detailed cost estimates. The recommended treatment approach was given to the client in Nov. 1998. Subsequent discussions revealed that the wastewater treatment plant operators and Superintendent were uncomfortable with the recommendation of the consultant. They were primarily concerned with operational difficulties and not convinced that they could operate the



biological process in a stable manner to reliably achieve anticipated future regulated levels of effluent nitrogen.

In Spring 2000, a different large consulting firm, XYZ, was hired by the City and repeated the wastewater treatment alternatives assessment. The second consultant tended to consider more “innovative” options. They split the project into Phase 1 to reach 8 MGD maximum month WWTP capacity, Phase 2 to reach 12 MGD maximum month WWTP capacity, and considered a future Phase 3 to 16 MGD (although costs were not developed for this phase). They conducted a more detailed cost and technical analysis, where 5 different biological treatment approaches were used in various combinations for phase 1 and 2 to comprise a total of 11 options evaluated. One of the options evaluated included the “recommended” best approach by ABC Consultants. XYZ conducted a very complete cost assessment for each option. The option they recommended had never been used full-scale at a municipal wastewater facility in the U.S., thus they brought a manufacturer-supplied pilot plant on-site to rigorously evaluate its treatment effectiveness and to determine design variables. The recommendation of XYZ consultants has since been constructed and is operating at the City. Existing Plant Data

The existing plant was a traditional mechanical secondary treatment plant with an approximate design capacity of 5.4 MGD (max. month). Residential areas grew up around the facility, such that its current land area is limited and neighbor concerns are significant. Specifically, the facility had received odor complaints from residents in the new housing development directly north of the WWTP. An aerial view of the site location and layout of existing facilities are shown in Figures 1 and 2, respectively. More specific information on the main unit operations at the facility are provided in Table 1.

Since many of the unit operations were constructed at different times, the “capacity” of each varied. Estimated treatment capacity for each indicated a need to upgrade the primary clarifiers, sludge handling facilities, and UV disinfection for the higher flowrates. Therefore, space to accommodate these facilities was needed in addition to the focus on the secondary treatment processes.



Figure 1. Aerial photo, USGS. Oct. 4, 1999 (terraserver.micosoft.com) Table 1. Existing main unit operations at City Wastewater Treatment Plant Unit Operation Number and size Details Screw pumps, enclosed 3 @ 8.6 MGD ea 60 hp motors

Mechanical bar screen 16.9 MGD; 4’ w x 5’ h Vulcan front rake; 16 MGD manual

back-up Parshall flume 1 @ 0.3 – 21 MGD Aerated grit basin 2 @ 39,300 gal

Primary clarifier 2 @ 70 ft dia octagon 10’ depth; 261,800 gal ea; 3500 ft2 surf area

Biotower 82.5’ dia x 14’ media depth; 75,000 ft3 media

taken out of service due to odor complaints

Activated sludge 2 basins @ 275,959 gal ea; 2 @ 328,725 gal ea

ceramic dome diffusers 700 ea ceramic dome diffusers 816 ea

Secondary clarifiers 2 @ 60’ dia x 10’ depth 1 @ 85’ dia x 12’ depth

UV 6 modules w/ 40 lamps ea.

4-ft deep trough with 15-sec contact time

Residential area

Blue line is approximate site boundary

Creek (receiving water)

Biosolids Lagoon

Flow EQ

Admin Bldg

Aeration basins

PCs

Anaerobic Sludge Digesters



Figure 2. Drawing showing layout of existing facilities on site. (ABC Consultants)

Water quality parameters of the inlet, outlet, and National Pollutant Discharge Elimination System (NPDES) permit are shown in Table 2. Future effluent limits for nitrate-N and phosphorus could be added due to TMDL issues, water rights, and potential for water reuse; however, these would take effect after 2005 at the earliest. State facilities planning requirements specify a 20-yr design life making this possibility important. The two different consultants handled this regulatory uncertainty somewhat differently as they evaluated treatment options.



Figure 3. Flow schematic of the City WWTP (ABC Consultants). Table 2. Regulatory discharge limits and current wastewater quality

Parameter

Current Discharge

Limits 30 d avg/7 d

avg

Future Discharge

Limits Anticipated

Average Inlet

Average Effluent

BOD5, mg/L 30 / 45 30/45 186 5.6 TSS, mg/L 30 / 45 30/45 186 7.6 Fecal coliform, no/100 mL 2000 / 4000 2000 / 4000 not meas <200

Total residual Chlorine 0.022 / 0.038 0.022 / 0.038 0 (UV used)

pH 6.5 – 9 6.5 – 9 NM Total ammonia, mg/L as N none 3 in August

6.6 in June * 28 not measured

Nitrate-N (mg/L) none 10 † 3.2 not meas Total phosphorus (mg/L) none 0.1 †‡ 5.7 ~0.2 +

Turbidity (NTU) none 3 †‡ not meas not meas * varied monthly based on aquatic life requirements and in-stream dilution available † not included by ABC Consultants; added in 2000 by XYZ Consultants ‡ added for ~6 MGD of flow from Phase 1 going to Reservoir due to water rights or direct reuse + due to ferric chloride addition at the inlet junction box for odor control

A critical feature of the upgraded treatment facility is the ability to treat wastewater flows, with a State-required 20-yr planning period. Thus,



estimating the increase in wastewater flowrates and changes in water quality characteristics is needed. Population projections from the City were 4.7% increase annually. Currently the flowrates are about 117 gallons/day/capita. Estimated flow rates from each consultant are shown in Table 3. Table 3. Estimated wastewater flow rates. ABC Consultant XYZ Consultant Year Population Ave Annual

MGD Max Month

MGD Ave Annual

MGD Max

Month MGD

1998 34,400 3.9 5.3 4.3 4.9 2000 4.9 5.8 2005 49,100 5.7 7.6 6.4 7.7 2010 61,800 7.1 9.6 7.5 9.0 2015 77,700 8.9 12.1 8.4 10.1 2020 97,800 11.2 15.2 9.2 11.1 Questions 1. How are the flow rate estimates of the two consultants similar or different?

Discuss likely reasons for differences. How important are these differences likely to be in the alternatives assessment and final designs?

2. List the constraints that are important in the wastewater treatment plant

upgrade. 3. List non-monetary decision criteria that you would use to select optimal

treatment processes; what weights seem appropriate? Which of these criteria are probably common to all municipal wastewater plants? Which criteria are specific concerns or more important at this City than is typical?

4. Given the list of constraints and criteria that were developed, select five

secondary wastewater treatment methods that you would evaluate in detail and compare.

5. Rate each of these five options against the criteria matrix. What

difficulties are there in assigning scores? Which criteria lend themselves to quantitative evaluation versus those that are more subjective? Which treatment alternative seems optimal?

6. Compare and contrast the decision approaches used by the two

consultants.



Analysis (Instructor Information to facilitate the discussion of each of the questions above): 1. Differences may be due to Inflow & Infiltration, decreases in future per capita flowrates due to requirements of low water use toilets, etc. in new construction, assumed peaking factors, etc. Differences are fairly minor, and will affect facilities sizing and therefore cost to some extent. 2. Constraints: meet discharge limits; fit on available land; work with local climate. 3. Non-Monetary Decision Criteria and Weights from ABC Consultant Factor Weight Factor Weight Process stability and control 2.86 Reliability 2.38 Odor generation 2.63 Best use of existing facilities 1.88 Environmental impact 2.52 Truck traffic 1.71 Operational flexibility 2.43 Public acceptability 1.50

Modularity 1.50 Potential negative impact on processes

2.43 On site land requirements 1.14

Sept. 1998; weighting factors from 1 (less important) to 3 (very important) Typical criteria for WWTP upgrades listed in Metcalf & Eddy (1991) and Tchobanoglous & Schroeder (1985) are: environmental impacts, personnel requirements, energy requirements, chemical requirements, reliability, complexity, compatibility, and equipment availability. Odor generation is a concern whenever people live close to the WWTP, and is becoming a large concern in areas where rapid population growth has led to developments close to WWTPs. Note that the consultants didn’t have “truck traffic” on the original criteria list, but it was added during the meeting by the citizen neighbors. It is likely unique to this facility because there is an elementary school a few blocks away located on the only road that can be used to access the WWTP. The City WWTP in this example already had more than one Class A operator on staff, so personnel requirements weren’t a very big concern. At smaller plants that have been historically operated under a Class C or D license, facility upgrades that require a higher level of operator certification can be problematic. In Colorado, for example, there is a shortage of qualified WWTP operators, particularly at higher certification levels. These criteria weights seem very “specific” and similar because of the process used to develop them. Each of the August workshop participants



(listed on pg. 5) ranked the importance of each factor from 1 to 3. The consultant averaged the input from each person, so diversity of opinions evened out the resulting numbers. Citizen neighbors and wastewater treatment plant operators had equal say. This built buy-in among all stakeholders. However, the public cannot be expected to grasp the importance of some of the day-to-day operational issues and may over-value such aspects as odor while the wastewater operators are more likely to recognize the inter-relationship among factors. Thus the operators may rank process stability the highest, realizing this tends to result in low odors and other problems such as environmental impact.

The short list of options for secondary treatment evaluated by ABC Consultants was: 1) Activated sludge with on/off aeration capacity and step feed. High land requirement, sludge more difficult to dewater; good flexibility, power savings with on/off aeration, handles variable flow and loading 2) Activated sludge with anoxic/anaerobic selector, on/off aeration capacity and step feed. Same pros/cons as Alt. 1, plus: possible P removal, selector may improve sludge settling; (concept shown in Figure 4, with approximate layout on-site in Figure 5)

3) Roughing filters and activated sludge with on/off aeration capacity. Uses existing Biotower but requires retrofit for odor control, potential interference of sloughed biomass with UV disinfection, less flexible than other options. 4) Activated sludge with anoxic zone and nitrifying trickling filters (NTF). NTF poor performance at low temperatures, NTF poor response to variable ammonia loading, large secondary clarification needs, low flexibility; uses existing Biotower. 5) Activated sludge and BIOFOR™ nitrification/denitrification system (attached growth biofiltration; it is a type of biological aerated filter or BAF) process not well proven in US, may require pilot testing; removes P, best effluent quality, smaller area requirements, easy to operate, handles variable ammonia (for more information see: http://www.infilcodegremont.com/ biofiltration_1.html)



Figure 4. Activated sludge with anoxic/anaerobic selectors, On/Off aeration and step feed (ABC Consultants).

The decision matrix used by ABC Consultants is illustrated in Table 4. The decision matrix was used to narrow down from the five options to the two best options:

• Alternative 2: additional aeration basins with selector basins, on-off aeration, step feed capabilities, additional secondary clarifiers and DAF thickeners for WAS

• Alternative 5: BIOFOR™ nitrification and denitrification cells and DensaDeg® solids contact clarifier system

More detailed costs were developed for these options. The designs

were sized for a maximum monthly flow of 15.4 MGD (predicted in the year 2020). Inlet BOD was assumed as 190 mg/L and inlet TSS as 200 mg/L. Some of the non-cost criteria scores were also changed as the additional research needed to develop costs revealed new information (see Table 5). The revised layout for Alternative 2 is shown in Figure 6 (below; Nov. 1998 ABC Consultants).



Figure 5. Proposed On/Off aeration layout on site (Sept. 1998, ABC Consultants). Bold lines indicate new facilities, lighter lines are existing facilities.



Table 4. ABC Consultants’ decision matrix for secondary wastewater treatment options

Factor Aeration Basins

Selector Basins

Roughing Filters

Trickling Filters

BIOFOR™ Filters

Process stability and control 4 4 1 2 3

Odor generation 4 4 1 2 3 Environmental impact 2 3 4 1 4

Operational flexibility 2 3 4 3 4

Potential negative impact on processes

3 3 1 2 3

Reliability 2 3 3 1 3 Best use of existing facilities 4 4 3 3 3

Truck traffic 3 3 4 3 2 Public acceptability 3 4 1 1 5

Modularity 2 2 1 3 4 On site land requirements 2 3 4 1 5

Wt’d TOTAL 66.34 76.31 54.9 45.94 78.96 Non-cost Rank 3 2 4 5 1 Cost Rank (approx capital)

3 ($76.7M)

1 ($73.9M)

4 ($86.9M)

5 ($100M)

2 ($76.3M)

Sept. 1998; ABC Consultants; Scores from 1 (least favorable) to 5 (very favorable) Compared 30, 50, and 70% cost weight and 70, 50, 30% non-cost criteria weight Overall, BIOFOR™ best if 70% non-cost; otherwise, selector basins best Table 5. Detailed comparison of Alternatives 2 and 5 by ABC Consultants

Item Alternative 2: On/Off Aeration

Alternative 5: BIOFOR™

Capital cost $69,300,000 $101,956,000 Annual cost $6,260,000 $12,998,000 Present worth $150,735,000 $271,029,000 $/gal unit cost $9.79 $17.60 Changes in non-cost scores (old score) Potential negative impacts 4 (3) 3.5 (3) Reliability 3 2 (3) Best use of existing facilities 5 (4) 4 (3) Truck traffic 3 2.5 (2) Public acceptability 4 4 (5) On site land requirements 3 4 (5) Overall non-monetary wt’d score 80.62 (76.31) 77.89 (78.96)



Figure 6. Refined layout of On/Off aeration Alternative 2 (Nov., 1998, ABC Consultants.)

As a result of both lower cost and better non-monetary characteristics, ABC Consultants recommended on-off aeration – unpopular with operators who were concerned that the recommended biological treatment process would not be able to reliably meet the effluent nitrogen required. ABC Consultants had successfully used this design at another local WWTP, but were unable to overcome client concerns.

XYZ Consultants evaluated eleven secondary wastewater treatment options (see Table 6). These consisted of five different unit operations in different Phase 1 and Phase 2 combinations. The key driver for considering these processes was the need to achieve nutrient (N and P) removal in the limited area of land available. Many of these options were not yet commonly used in the U.S. at the time of the evaluation (Summer 2000).

N



Table 6. Comparison of biological treatment options by XYZ Consultants. Capital Cost (U.S. dollars) Option, Phase 1/Phase 2 Phase 1+2

Advantages Limitations

A) preanoxic/anaerobic, On/Off aeration basins

17,251,000 no recycle pumping of ww

no room for phase3; risk of filamentous bulking

B1) IFFAS / IFFAS 15,844,000 space for phase 3; phase 1&2 similar; P removal

B2a) IFFAS/ MBBR 17,516,000 space for phase 3; no backwash, nit/denit stable

MBBR cannot incorporate bioP removal

B2b) IFFAS/BIOFOR™ ~ (5) 16,695,000 added clarifier

not needed no bioP removal

B2c) IFFAS/BIOSTYR 16,223,000 no bioP removal; high op risk of simult nit/denit

C1a) MBBR/IFFAS 22,572,000 layout difficult with existing hydraulic profile

C1b) BIOFOR™ / IFFAS 19,741,000 need MeOH for denit

C1c) BIOSTYR/IFFAS 20,301,000 need MeOH for denit

C2a) MBBR / MBBR 24,245,000 no backwash req’d; no recycle pumping of ww

need MeOH for denit

C2b); 5) BIOFOR™ /BIOFOR™ 20,592,000

media longevity unknown no bioP removal

C2c) BIOSTYR/BIOSTYR 20,680,000 operation risk simult nit/ denit; no bioP removal

Definitions • IFFAS = integrated fixed film activated sludge. A hybrid process in which

buoyant media is aerated and suspended along with mixed liquor in activated sludge (AS) basins. Ammonia oxidation is possible and the attached growth on the media enhances BOD removal in the same reactor volume compared to conventional AS. However, the attached growth does not increase solids loading to the secondary clarifiers. Returned sludge from the secondary clarifier is returned to the aeration basin. Separate anoxic and anaerobic basins without media can be



used for nitrate and phosphorus removal. For additional reading: http://www.brentwoodprocess.com/ifas.html

• MBBR = moving bed biofilm reactor. Buoyant plastic media is aerated

and suspended in a tank. Kaldnes media is one example. Oxic zones can remove BOD and ammonia, and anoxic zones can remove nitrate. Phosphorus removal will not occur in the bioreactor. Waste sludge sloughed from the media is collected in secondary clarifiers, similar to a trickling filter. More information at: http://www.anoxkaldnes.com/Eng/c1prodc1/mbbr.htm

• BAF = biological aerated filter. Aerated wastewater flows through media.

No secondary clarifier is needed as the media itself acts as a filter. Phosphorus removal cannot be directly incorporated into the bioreactor. Common media used includes plastic (Kruger’s BIOSTYR; http://www.krugerusa.com/Pages/Products/Biostyr.htm) or expanded clay (Infilco’s BIOFOR™).

XYZ Consultants recommended option B1 (Figure 7) based on lowest cost and consideration of non-cost factors. Due to lack of operational experience in the U.S., pilot plant tests were conducted to confirm the abilities of the treatment process to meet effluent limits and operational considerations. Conclusions

The design process is not exact. Engineering judgment plays a strong role. Therefore, previous experience can bias the consultant. Client and stakeholder views may also be less than fully objective and biased by previous experiences. Final Design Choice

By spring 2003, the integrated fixed-film/activated sludge (IFFAS) process, which involves adding plastic biomass carrier media to aeration tanks, was installed and operating in City, Colorado. The treatment capacity was increased from 5.4 to 8 mgd, and the addition of new anoxic and anaerobic zones ahead of the aeration basins enabled the plant to achieve denitrification and remove phosphorus. A new final clarifier was added to handle the additional flow.



Figure 7. Layout of Option B1 (left side represents North; XYZ Consultants). Learning Assessment

The full alternatives assessment and design for the City Wastewater Treatment Plant was a class project in the capstone design course at the University of Colorado in 1998 and 2000. These comprised semester-long team projects where the class shadowed the consultants, with eight teams in 1998 and one team in 2000. Since that time, the City WWTP project has been discussed informally in the capstone design class as the students express concern about the subjectiveness of the criteria development, criteria weighting, and alternatives ranking process. As this issue comes up every year, the use of this formal case study should enlighten the students as to the engineering judgment that is exercised by practicing consultants during the design process.

I have not used the case study to illustrate innovative biological wastewater treatment options, but given the options evaluated by XYZ Consultants, it could also be used for this purpose. In this case the

N



supplemental information (see attached) on each process should be provided or the students given additional time to research these processes. References ABC Consultants. 1998. City 201 Facility Plan/Utility Plan. Interim Report No. 1. Aug. ABC Consultants. 1998. City 201 Utility Plan. Interim Report No. 2. Sept. ABC Consultants. 1998. City 201 Utility Plan. Interim Report No. 3. Nov. Metcalf&Eddy. 1991. Wastewater Engineering, 3rd Ed. McGraw-Hill. New York. Tchobanoglous, G. & E. Schroeder. 1985. Water Quality. Addison-Wesley. Reading, MA. XYZ Consultants. 2000. City Workshop: Evaluation of Biological Treatment Alternatives.

Documents

Upgrade of a Wastewater Treatment Facility to Meet ... · Upgrade of a Wastewater Treatment Facility to Meet Capacity and Nutrient Removal Requirements Angela R. Bielefeldt Department