Embed Size (px)
Citation preview
CALIFORNIA POLYTECHNIC STATE UNIVERSITY
Task 3: Treatment of Wastewater for Reuse
Removal of Phosphorous
Team Members:
Claire Crocker
Tyler Dery
Justin Garcia
Andrew Kaneda
Toan Le
Shea Oades
Noe Varela
Advisors:
Dr. Tracy Thatcher
Dr. Rebekah Oulton
1 Task 3
Table of Contents
EXECUTIVE SUMMARY ................................................................................................................ 2
1.0 INTRODUCTION ................................................................................................................. 3
2.0 CHEMICAL PROCESSES ................................................................................................... 4
3.0 DESIGN CONSIDERATIONS ............................................................................................. 5
3.1 Alternatives ....................................................................................................................... 6
3.2 Bench Scale ..................................................................................................................... 7
3.2.i Design of Filter ................................................................................................................. 7
3.2.ii Size of Iron Filings .......................................................................................................... 8
3.2.iii Materials Used ............................................................................................................... 8
4.0 TESTING PROCEDURE ..................................................................................................... 9
5.0 RESULTS ........................................................................................................................... 10
6.0 FULL SCALE DESIGN CONSIDERATIONS .................................................................... 12
6.1 Location In Treatment Train ....................................................................................... 12
6.2 Full Scale Design ........................................................................................................ 13
7.0 ECONOMICS ..................................................................................................................... 14
8.0 ENVIRONMENTAL IMPACTS ........................................................................................... 15
9.0 SAFETY ............................................................................................................................. 16
10.0 WORKS CITED .................................................................................................................. 18
2 Task 3
EXECUTIVE SUMMARY
The corporate mission of Clear Water Consultants is to facilitate high environmental quality using
modern engineering techniques. This report outlines CWC’s response to the Waste-Management
Educational Research Consortium’s (WERC) request for a cost-effective, efficient, and robust 100
gpm water treatment system to treat a known wastewater contaminant from a treated waste water
stream meant for reuse in the community.
CWC proposes the implementation of pure elemental iron or iron-heavy recycled “scrap” metal
into existing sand filters in wastewater plants to create an efficient method of removing excess
phosphate from wastewater. The fact that the iron or scrap metal can be directly implemented into
filters that are already built makes it a cost-effective method of treating high levels of phosphate.
CWC has analyzed that 2% iron by-weight sand filters have been able to remove upwards of 94%
of phosphate levels in wastewater; the same removal efficiency was seen in filter built with scrap
metal.
Assuming the lifetime of the iron is 3 years, the annual cost of the proposed system is
approximately $21,000, considering filter media replacement, labor, and operating costs. This is
considerably cheaper than the industry standard of lime/HDS treatment, which can cost as much
as $127,000.
CWC proposes a proactive approach to health and safety for the workers and the residents. Proper
monitoring and disposal of backwash and iron(III) phosphate precipitate will need to be
considered. CWC has considered legal and regulatory issues, health standards, and economic
obligations in selecting the best alternative to recommend to WERC. This proposed design meets
WERC’s design criteria while maintaining low construction and operation costs.
3 Task 3
1.0 INTRODUCTION
Phosphorus is a prominent pollutant that can affect water quality and harm aquatic habitats.
Commonly found in agricultural fertilizers, manure, and industrial effluents, phosphorus can be
introduced to bodies of water by direct discharge or runoff. High levels of phosphorus in bodies
of water due to humans result in cultural eutrophication, which can encourage algae blooms.
Subsurface algae blooms block aquatic plants from receiving sunlight, causing the aquatic plants
to die. As the algae and other plants begin to die, decomposition by microbes reduces the amount
of dissolved oxygen in the water, sometimes to the point of creating anoxic dead zones. If left
unchecked, the phosphorus that enters a body of water can have drastic impacts on plant and animal
life[1].
Many wastewater treatment plants currently remove phosphorus using lime to precipitate out
phosphorus, a practice which leads to a solid waste issue. As water demand and population
continue to increase, water reuse will need to be implemented as a best management practice. The
maximum contaminant levels for pollutants, such as phosphorus, are expected to decrease to raise
the purity of water being used by community members and landowners. An alternate practice for
phosphorus removal is needed to preserve the health of the ecosystem and prevent further solid
waste challenges.
To address the issue of targeted phosphorus treatment in wastewater, Clear Water Consultants
propose the use of an iron enhanced sand filter. In an iron enhanced sand filter, the iron reacts with
phosphate and the product (FePO4) remains in the filter as a precipitate. After treatment in the sand
filter, the water should be used for non-potable reuse: landscape irrigation, fire hydrants, industrial
use, etc[2].
4 Task 3
2.0 CHEMICAL PROCESSES
The phosphate solution used during testing was monopotassium phosphate (MKP), KH2PO4. If
pure MKP is mixed with pure iron, no reaction occurs. However, considering the environment of
the sand filter and impurity of iron filings, the reactions between iron and KH2PO4 can occur
because iron atoms can transfer their electrons to other cations appearing in the sand and the iron
filings itself by the following reaction series:
Fe → Fe2+ + 2e-
Fe2+ → Fe3+ + 1e-
X2+ + 2e- → X
Y+ + e- → Y
X and Y are usually Cu, Mg, and Zn. Iron cations will then be available to react with dihydrogen
phosphate as follow:
Fe2+ + H2PO4- → Fe(H2PO4)2
Fe3+ + H2PO4- → Fe(H2PO4)3
However, dihydrogen phosphate (H2PO4-) also has the tendency of binding to free OH- in the
solution to form a more stable form of phosphate PO43-. Phosphate ions will then react with excess
iron cations to form iron (II) phosphate (Fe3(PO4)2) and iron (III) phosphate (FePO4).
H2PO4- + 2OH- → PO4
3- + 2H2O
Fe2+ + PO43- → Fe3(PO4)2
Fe3+ + PO43- → FePO4
5 Task 3
Iron (II) and iron (III) compounds make the mixture have a blue-green color. Excess iron cations
can also react with oxygen to form different kinds of iron oxides. These iron oxides are also a
source of iron cations that can react with phosphate ions.
3.0 DESIGN CONSIDERATIONS
The iron enhanced sand filtration system proposed was modeled after the “Minnesota Filter.”
According to Erikson et al, “The City of Prior Lake, Minnesota installed two iron enhanced sand
filtration (called the “Minnesota Filter”) trenches along the perimeter of a wet detention basin in
Prior Lake, MN in January and February, 2010. . . . The storm water flows through the mix of iron
and sand, through a layer of pea gravel, and into a perforated pipe underdrain where it is captured
and conveyed to the outlet structure of the wet detention basin”[3]. The “Minnesota Filter” used
7.2% and 10.7% iron by weight in their two trenches. Each trench was about 12 meters long, 1.5
meters wide, and 0.6 meters deep[3]. The filter was reported to remove between 29% and 91% of
phosphate when the influent water had concentrations between 0.026 and 0.14 mg PO43- - P/L. The
data showed that in most runs phosphate removal was more than 50%. Researchers concluded,
“For most rainfall events, the iron enhanced sand filtration trenches are expected to capture
approximately 85-90% of the phosphates”[3].
The proposed system shares many features with the “Minnesota Filter.” CWC’s proposed system
uses a traditional rapid sand filter, with one layer of sand containing iron filings (Figure 1). Based
on experimental results, there was equally effective phosphate removal between the 10%, 5%, and
2% iron enhanced sand filters. Each small scale filter was able to remove around 90% of phosphate.
Based on experimental results, a 2% iron by mass filter was determined to be most efficient as
increasing iron concentration did not significantly increase removal.
6 Task 3
Figure 1: Bench scale design of proposed iron enhanced sand filter.
3.1 Alternatives
Treatment options for phosphorus filtration falls into three categories: physical, chemical and
biological. Physical treatment options include membrane and filter technologies, chemical
methods include precipitation, and biological treatment utilizes algae and plant growth. The most
common method of phosphorus removal is chemical precipitation, using calcium, aluminum, or
iron compounds[4]. Flocculation and sedimentation follows the addition of these chemicals, which
leads to the production of large amounts of sludge[1]. According to the Minnesota Pollution Control
Agency, a sludge increase of as much as 40% occurred with chemical precipitation in a typical
wastewater treatment plant. Some advantages of chemical treatment are its removal efficiency,
reliability, and cost effectiveness over biological treatment. However, the significant amounts of
sludge waste that are produced are a significant drawback of the method.
7 Task 3
Biological treatment utilizes communities of microorganisms, known as phosphorus accumulating
organisms (PAOs). During an anaerobic process, phosphorus is released. Subsequently, during an
aerobic process, the PAOs take up phosphorus[4]. Biological treatment can achieve phosphorus
concentrations lower than 0.1 mg/L; however, it is difficult to consistently achieve reductions that
low[4]. Biological treatment methods produce much less sludge than chemical treatment, but are
less reliable and more complicated to run and maintain. Until biological methods are improved,
they are typically a less desirable option.
Physical methods alone, such as sand filters, can remove as much as 43% of phosphorus (Figure
3). However, when physical and chemical processes are combined, like in iron enhanced sand, as
much as 97% can be removed (Figure 3). In addition to their success at removing phosphorus, iron
enhanced sand filters are reliable, simple to design and operate, and have much less sludge waste.
3.2 Bench Scale
3.2.i Design of Filter
The bench scale model consists of eight 2.5-foot sections of capped Triplewall drainage pipe, each
with an inner diameter of 4 inches and with eleven ¼ inch holes in the cap to allow the water to
flow through. The cap is sealed with PVC pipe wrap tape (Figure 1). The filter consists of the
following four layers, from bottom to top: large gravel, ~1-in diameter, pea-sized gravel, coarse
white pool sand, and iron enhanced fine sand. Each gravel layer is 5 cm deep and each sand layer
is 21 cm. This design was modeled after a column reported in the article, “Capturing Phosphates
with Iron Enhanced Sand Filtration,” by Erickson, Gulliver, and Weiss[3] (Figure 2). Initially 8
columns were made with varying concentration of iron filings: two with 0% iron by weight, two
with 2%, two with 5%, and two with 10%.
8 Task 3
Figure 2: Diagram of test column from Erikson et al.
3.2.ii Size of Iron Filings
The scope of this project did not include testing particle size. However, the total surface area of
the iron filings is expected to influence the amount of phosphorus removed, assuming that the
reaction is surface area limited. The smaller the individual pieces of iron, the more surface area
there is to interact with the aqueous phosphate. As the size of the filings increases when mass is
held constant, there is less surface iron for the phosphorus to react to.
3.2.iii Materials Used
The iron filings used in the experiment were purchased in a 1 lb. package from Educational
Innovations Inc., with part number M-600. The “scrap metal” that is referred to in the rest of the
report consists of iron- and steel-based dust that was collected from the metal shops on the Cal
Poly University campus. The sand was from 50 lb. Quikrete Play Sand Premium packages. About
4 packages of iron filings and 2 packages of sand were used throughout the experiment. After a
9 Task 3
period of approximately three years, the iron within the filter will need to be replenished as it will
react and deplete over time.
Phosphorus contaminated samples were made by mixing monopotassium phosphate (MKP) 0-52-
34[5] with tap water to achieve 6 mg/L of concentration. The purpose of using a solution composed
of tap water and MKP was to test the phosphate removal capacity of the filter, eliminating
variability that could be introduced if other contaminants are present in the water.
In later testing, reclaimed water from the San Luis Obispo Water Reclamation Facility was used
to simulate water that would be run through the filters in a treatment plant. The reclaimed water
was measured to contain 24 mg/L of phosphate.
4.0 TESTING PROCEDURE
The testing procedure consisted of two phases. The first phase was primarily concerned with
testing the ability of the iron enhanced sand to remove dissolved phosphate from the filtered water.
This was done by creating 2%, 5%, 10%, and 0% iron-by-weight sand filters in duplicate. Tap
water containing 6 mg/L MKP was run through the filter until five liters of water was collected.
The next step was to then test the lifespan of the filters. Two new filters were made: one consisting
of the most efficient iron-filing percentage by weight, and another filter of the same percentage,
but made of scrap metal instead of the iron filings. Reclaimed water from the San Luis Obispo
Water Reclamation facility was used during this part of testing to simulate water that would be run
through the filters at a treatment plant. The reclaimed water was run through the filters for two
hours at a time, collecting samples of the filtered water every eleven minutes. The data collected
from this testing allows a visual representation of the lifespan of the filters by graphing the percent
removal versus the time of running
10 Task 3
5.0 RESULTS
Various concentrations of iron were tested to determine the most cost effective design in regards
to phosphorus removal performance. The addition of iron to sand filters increased phosphorus
removal from 40% to greater than 90% (Figure 3). However, increased iron concentration did not
directly correspond to an increase in phosphorus removal. Therefore, the 2% by weight iron
enhanced sand mixture design is more cost-effective than the 5% or 10% designs. Further testing
comparing the efficacy of the iron filings and the scrap metal on phosphate removal was conducted
using a 2% by weight iron filing/scrap metal enhanced sand mixture.
Figure 3: Percent phosphorus removal vs. iron concentration
After initial testing to find the most effective iron concentration, a new 2% iron filing filter and a
2% scrap metal filter were tested for longevity. Breakthrough curves for iron filings and scrap
metal were analyzed to determine the more cost effective iron resource. The breakthrough curves
showing their longevity can be seen below (Figures 4 and 5).
11 Task 3
Figure 4: Breakthrough curve for 2% iron filings filter.
Figure 5: Breakthrough curve for 2% scrap metal filter.
The lifetime of our bench-scale filters varies from forty minutes in the iron-filing filter to about
seventy minutes for the scrap-metal filter. When the iron/scrap metal lose their effectiveness, the
curve breaks to about 0.3 to 0.35 efficiency. The control filter with no sand-enhancement (Figure
1) reached 43% efficiency. Therefore, iron/scrap metal enhanced filters will have one of two
12 Task 3
breakthroughs: one for when the metal in the system is used, and a second for when the sand is
completely saturated. Upon analysis, the scrap metal filter appeared to be more efficient in
removing phosphate from the water than the filter enhanced with iron filings. Impurities in the
scrap metal and the smaller size of the filings may have provided more surface area for the
reactions previously explained to occur, resulting in an increased phosphorus removal.
6.0 FULL SCALE DESIGN CONSIDERATIONS
6.1 Location In Treatment Train
For implementation in a wastewater treatment plant, the iron enhanced sand filter would most
likely be co-located within the filtration section of the treatment train (Figure 6). Filtration and
phosphorus treatment are considered tertiary treatment, usually taking place near the end of the
water treatment process prior to disinfection. Implementation into existing sand filters would be
simple, inexpensive, and would not impact the existing infrastructure of the plant. Creating the
new iron enhanced sand filter would only require mixing the iron into an existing sand filter’s fine
sand layer.
13 Task 3
Figure 6: A standard treatment train for a wastewater treatment plant[6]
6.2 Full Scale Design
The 4-inch diameter scale model filter using 2% iron by mass achieved an average flow rate of
0.10 gallons per minute (gpm). To achieve a flow rate of 100 gpm, the total filter area required is
720.8 ft2. This area is achieved in the full scale design by using ten 9 ft. x 9 ft. filter beds. Nine
filter beds are needed to achieve a flow rate of 100 gpm and the tenth allows one basin to backwash
at any time. The system will use flow splitters to control the flow rate into each filter bed.
Perforated pipes beneath the filter media will drain the treated water.
When the filter is backwashed, water will be forced upward and filtered particles will be removed.
The backwashed water will be removed using wash troughs that are placed high enough above the
sand layer that the sand will not be carried out. After backwashing, the densest particles will settle
first. To ensure that the layers settle with minimal mixing, the two sand types should differ in
14 Task 3
density with the more dense sand placed lower in the filter. The iron is nearly five times as dense
as the sand in the mixed layer; therefore, the average particle diameter of the sand containing the
iron should be close to three times greater than the average diameter of the iron filings to ensure
the layers remain mixed. Filter backwash frequency will be determine based on pressure drop
through the filter. Additional research is needed to determine how often the filter will need to be
backwashed.
The sand filters should be placed as tertiary treatment in a wastewater facility to remove
phosphorus from the water. In addition to targeting phosphorus, the filter will be able to remove
other contaminants that can be removed by a traditional rapid sand filter. Particle loading in the
wastewater stream will increase the frequency with which backwashing is required.
According to Erickson et al, in “Capturing Phosphates with Iron Enhanced Sand Filtration,” “As
iron oxidizes to form rust, phosphates bind to these iron oxides by surface adsorption”[3]. Iron can
only bind with a specific amount of phosphate before it become ineffective at treating phosphate.
The true lifetime of iron in the sand filter will need to be determined; however, the effective
lifetime of iron in the filter can be approximated as 3 years as estimated for the “Minnesota Filter.”
The full-scale filters will have the same cross sectional layers as the bench scale model.
The ten basins will require approximately 0.55 tons of iron fillings and 27.8 tons of each sand
types. Approximately 7 tons of both small and large gravel will be needed.
7.0 ECONOMICS
Iron fillings filtration has already been used for treating phosphorus contaminated storm water by
the Ramsey Washington Metro Watershed District of Minnesota[7]. Based on the scale model test
results, with 2% iron filings and above, the filters showed an increase in phosphate removal from
45% to over 90% compared to a normal rapid sand filter. When cost of materials is considered,
the 2% iron filings filter yielded the best ratio of cost/effectiveness. Since pure iron filings can be
15 Task 3
purchased for approximately $285/100lb, it would cost approximately $3000-$4000 for enough
iron to install filters that can treat a 100 gallon/minute input. About $800-$900 for each sand layer
is required to build the rapid sand filter, with sand price is about $30/ton. Since mandated
particulate removal would likely be present where phosphorus removal is required, the plant’s
current filter media could be replaced with that of the proposed system with no detriment to the
filtration capacity. If the plant had no sand filter stage, capital costs of building a standard rapid
sand filter would need to be addressed. Over time the proposed filter media will need to be
replaced. The approximate life of iron in a similar filter to the system proposed by CWC is 3-5
years[3]. Assuming the lifetime of the iron is 3 years, the annual cost of the proposed system is
approximately $21,000. This includes filter media replacement, labor, and operating costs. All
construction costs assumed to have a 20% markup. An alternative to the proposed system is a
lime/HDS treatment plant which would have an approximate cost of $127,900 per year for reacting
chemicals alone in a 100 gpm plant[8]. The overall annual cost of the proposed design is far less
than the cost of only reacting materials in a comparable lime/HDS plant. By implementing the
proposed system into a pre-existing rapid sand filtration system, the annual cost of phosphorus
treatment is significantly less than a lime/HDS alternative. Assuming the system can consistently
run at 100 gpm, the cost of treatment due to the proposed system will be $0.002 per 100 gallons
treated.
8.0 ENVIRONMENTAL IMPACTS
To evaluate the environmental impact of this treatment design, all chemicals used must be taken
into consideration. These are iron and iron (III) phosphate.
The iron used in the treatment process comes from two sources. Some of the iron is supplied from
Cal Poly’s mechanical engineering scrap metal waste. This source is favored environmentally,
because of the fact that it is recycled. Recycled scrap metal is not readily available cheaply as a
fine powder, so it cannot be relied on as the primary source. The scrap metal can be ground up,
and the iron filings can be used. The other source of iron was purchased as iron filings. Less than
0.05 mg/L of iron was introduced during testing from the sand filter. This minimal increase in iron
16 Task 3
does not pose an environmental threat since sample effluents iron concentration did not exceed the
EPA secondary standard of 0.3 mg/L.
Iron (III) phosphate is insoluble in water so the precipitate will remain in the sand filter until
backwashing. During backwashing, the iron (III) phosphate will be removed from the filter as a
solid waste and has no restriction on disposal location. However, proper lab analysis should be
conducted to determine if site-specific backwash is hazardous waste.
9.0 SAFETY
CWC proposes a proactive approach to health and safety issues during the construction of the sand
filter and at the treatment plant where it will be implemented. While compiling the scrap metal to
be used in the filter, it is important to ensure that other materials that could be covering the metal
(grease, paint, etc.) be cleaned off. Depending on the source of the scrap metal, specific measures
should be taken: power-washing, alkaline cleaners for grease/oils, acidic cleaning solutions for
rust, etc. Afterward, precautions should be taken specific to the cleaning method to ensure
hazardous runoff does not occur. During sand-enhancement, the workers must wear safety glasses,
proper outer clothing, approved/certified dust respirators, and gloves. When dealing with iron (III)
phosphate solid, mouth, eye, and hand protection must be worn to prevent skin irritation.
Safety training will be conducted on a regular basis. The training will cover both the danger of the
materials being used, such as the flammability of the iron being used, as well as the necessity of
following all enforced safety measures such as handling the chemicals used throughout the
process. Operators will be trained on all processes to ensure no unauthorized discharges of
untreated water.
Maintenance of the filter will be similar to that of traditional sand filters. Loss of metallic iron
should not occur during backwashing as the density and diameter of sand and iron are selected to
promote equal settling rates and prevent loss of filter media. As iron loss is a possibility, it will be
important to direct the backwash effluent to a safe container and monitor the iron levels in the
discharge. Backwash effluent concentrations of metallic iron and iron (III) phosphate should be
17 Task 3
monitored through laboratory testing to categorize it as a possible hazardous waste, and finally
dispose of it accordingly based on state and federal ordinances and laws.
This system does introduce iron into the effluent water in excess of EPA secondary drinking water
standards. As tertiary treatment, the system does not add any new contaminants, and serves to
increase the overall quality of the water as other contaminants are treated during filtration.
Effluents should meet all standards for non-potable reuse before being used as such. The iron
enhanced sand filter system does not act as a detriment to water quality and poses little individual
health risk.
18 Task 3
10.0 WORKS CITED
[1] "Enhanced Nutrient Removal - Phosphorus." Onsite Wastewater Treatment Systems
Technology Fact Sheet 8. EPA, n.d. Web.
[2] "California Code of Regulations, Title 8, Section 3363. Water Supply."California Code of
Regulations, Title 8, Section 3363. Water Supply.N.p., n.d. Web.
[3] Erickson, Andrew J., John S. Gulliver, and Peter T. Weiss. "Capturing Phosphates with
Iron Enhanced Sand Filtration." Water Research 46 (2012): 3032-042. Science Direct. Web. 17
Oct. 2015.
[4] Strom, Peter F. "Phosphorus Removal." Rutgers Water Resources Program. Web. 3 Mar.
1996.
[5] "Greenway Biotech, Inc." Greenway Biotech, Inc. N.p., n.d. Web.
[6] Davis, Mackenzie Leo. Water and Wastewater Engineering: Design Principles and
Practice. New York: McGraw-Hill, 2011. Print.
[7] Minnesota Pollution Control Agency. "Phosphorus Treatment and Removal
Technologies." (2006): n. pag. Web. <https://www.pca.state.mn.us/sites/default/files/wq-wwtp9-
02.pdf>.
[8] Golder Associates. “CHINO CLOSURE/CLOSEOUT PLAN 2007 UPDATE.” Web. 17
Mar. 1996.
[9] "Sand." Acme Sand Gravel. N.p., n.d. Web.
Proposed System Sand Filter media replacement every 3 years.
Item Cost (USD) Description NotesSand Filter Components $6,720 sand and pure iron filings for filter Assuming a material mark‐up of 20%
Labor $20,000
4 workers for 4 days at $75/hour. Includes roughestimate of 2 earth mover rentals for 4 days
Sub Total $26,72015% Mark‐up $4,008.00
Operating Costs
0.25 mgd Mixed media filter operating cost $32,700
Lodson et al. (n.d.). Capability and Cost of Treatment Technologies for Small Systems. AWWA.
Total Cost/ 3 years $63,428
Total cost/year $21,142.67
WERC_EHS Audit_2016
March 13, 2016
Andrew I. Kaneda Clear Water Consultants California Polytechnic State University 1 Grand Avenue San Luis Obispo, CA 93401 RE: Safety Audit for Clean Water Consultants - WERC Environmental Design Competition Report for Task 3: Treatment of Wastewater for Reuse Removal of Phosphorous
Dear Mr. Kaneda, Per your request, I have completed a review of Clear Water Consultants’ (CWS) WERC Environmental Design Competition Report and have prepared my comments on environmental, safety and health considerations. The objective of this review was to contribute to the improvement of environmental, health, and safety within the team’s large scale and bench scale design by identifying and evaluating the product’s exposures to risks.
Bench Scale Comments
1. Spent filtration media should be characterized prior to disposal to determine proper management and disposal requirements. When a change out is required the media waste should be characterized through laboratory analysis to determine if it is hazardous or non-hazardous waste. Storage, handling and disposal of hazardous wastes shall be managed according to state and federal regulations.
2. According to the SDS for the “Iron Metal” by Science Lab, the following PPE is required when handling the material: Safety glasses; lab coat; an approved/certified dust respirator or equivalent; gloves.
3. Since the “Iron Metal” material is flammable, ensure all it is stored in a tightly closed container. Keep container in a cool, well-ventilated area.
4. Ensure all team members are trained on the proper handling and spill response for all chemicals used.
Large Scale Comments
1. The report does not specify the non-potable application in which the reclaimed water will be used. Many additional management, planning, and regulatory compliance considerations must be made depending on the intended use and geographical location of the application of reclaimed water.
a. For a more comprehensive proposal I recommend identifying one or more possible applications for your proposed reclamation system in the report.
b. Discuss the various environmental, health and safety compliance considerations and economic planning associated with your application(s) and whether the reuse is restricted or unrestricted by States. I suggest selecting an example State for the purpose of this discussion.
Andrew I. Kaneda, California Polytechnic State University Page 2 of 3
WERC_EHS Audit_2016
i. e.g. Reuse needs, permitting requirements, treatment and water quality requirements, distribution system requirements, public awareness and signage, back-flow prevention devices, training.
c. Review State and local municipality environmental regulations
2. If backwash water is being collected as a waste it will need to be characterized to determine if it is a hazardous or non-hazardous waste. If backwash waste is expected to be hazardous, the facility may need to obtain proper hazardous waste storage and treatment permits from the regulating authority. Depending on the location of the treatment system, the hazardous waste tanks may need to be designed and certified by a licensed professional engineer.
3. Proper management and disposal of the spent filtration media should be considered. When a change out is required the media waste should be characterized through laboratory analysis to determine if it is hazardous or non-hazardous waste. Storage, handling and disposal of hazardous wastes shall be managed according to state and federal regulations
a. Recommend including media disposal in the economic analysis.
4. Report states that the system introduces iron into the effluent water in concentrations that exceed the EPA secondary drinking water standards. Iron concentrations in reclaimed water should be evaluated to determine appropriate application for reuse. Significant concentrations of iron in reclaimed water use for irrigation or agriculture applications, for instance, may contribute to increased iron contamination in stormwater runoff which may lead to future compliance issues.
5. Consider specifically how the scrap metal will be cleaned. Specific equipment may be necessary to ensure traces of iron or cleaned material do not enter the environment or are exposed to personnel.
6. Operators must ensure that no unauthorized discharges of the untreated water will occur. Operators should be trained on proper use of the system as well as the locations of storm drains, outlets, and all surrounding surface water locations at the facility.
7. Operators must be trained annually on spill reporting requirements.
General Safety Comments
1. Safety training for treatment system personnel should be defined and conducted on a regular basis.
2. All operators should be familiar with the hazards of the system.
3. Personnel should be trained in the proper selection, use, and maintenance of personal protective equipment.
Overall the system design proposed is a suitable treatment solution and meets the task requirements. I was especially impressed by your use of scrap metal for the filter. I thought it was very innovative. It is apparent that your team has worked diligently on this proposal with accurate research, successful testing, and professionalism. With more consideration into the specific application and planning of the large scale system and evaluation of local,
Andrew I. Kaneda, California Polytechnic State University Page 3 of 3
WERC_EHS Audit_2016
State and federal requirements, I am confident in your team’s ability to produce an excellent presentation at the competition. If you have any questions or comments regarding this review please do not hesitate to contact me at [email protected] or (415) 505-4080. Good luck in New Mexico.
Sincerely,
Laura Cremer Regional Environmental Specialist Praxair, Inc.
PROFESSIONAL AUDIT
California Polytechnic State University, San Luis Obispo
Clean Water Consultants
Task 3: Treatment of Wastewater for Reuse
Removal of Phosphorus
Reviewer: Justin Kraetsch, E.I.T. Staff Engineer Water Works Engineers
Review Date: March 13, 2016
This memorandum summarizes a professional audit performed for Clean Water Consultants’
proposed design of an iron enhanced sand filter for improved phosphorus removal from
tertiary treated wastewater intended for non-potable reuse. The following comments are in
regards to the economics of the proposed design.
1. Section 5.0 – Various concentrations of iron were tested to determine the most cost
effective design in regards to phosphorus removal performance.
2. Section 5.0 – Breakthrough curves for iron filings and scrap metal were analyzed to
determine the more cost effective iron resource.
3. Section 7.0 – Clarify if the $285/100lb for iron filings is from the scrap metal source or
pure iron filings.
4. Section 7.0 – When estimating costs at the preliminary design phase, a more
conservative approach should be used. With an approximate iron lifespan of 3 – 5 years,
3 years should be used to estimate the 30-year project cost instead of 5 years.
5. Section 7.0 – In Section 7.0 Economics, the following is stated, “…the present cost of
building and maintaining the filter media is approximately $10,000. This does not
include the construction of the system or the labor needed to replace and mix the iron
into the filter media.” These statements seem to contradict each other. The $10,000
estimate includes building and maintaining the filter media, so that should mean it
includes the construction of the system and the labor needed to replace and mix the
iron into the filter media. If the “system” refers to the entire filter and not just the iron
enhanced media, then state that in the section. Also, when estimating the cost for
maintaining the filter media, labor should be included along with the assumptions for
hourly labor costs and daily equipment rental costs. When preparing a cost estimate at
the preliminary design phase, it is always better to be more conservative and over-
estimate rather than under-estimate.
6. Section 7.0 – Clarify if the $10,000 estimate includes the contractor mark-up for
purchasing the iron filings, or if the wastewater treatment plant will purchase it.
7. The cost estimation spreadsheet should be provided as an appendix with assumptions
clearly stated.
March 14, 2016 To: CWC Clean Water Consultants From: Chris Wm Clark JD City & Regional Planning, Cal Poly Re: Proposal to remove Phosphorus from wastewater Team; I have reviewed your proposal and offer the following:
• Your system is a promising approach to phosphorus removal. While I have studied this issue in general, my expertise is in law and regulatory permitting, so I confine my comments to those.
• Wastewater treatment is carefully regulated under a number of statutes, and by a number of agencies. Each of these will need consultation, and many will require formal permitting. While I don’t believe your proposal needs to detail all of the regulations, it should acknowledge this regulatory regime.
• The California Environmental Quality Act (CEQA) would require an analysis of the effects of the treatment process. You address the amount of iron released into the environment. Testing of your system, and support in scientific literature would be necessary to substantiate the effects. In addition, the long-term effects of the system would need to be addressed.
• The federal Clean Water Act, and California’s Porter Cologne Act deal with water quality in the environment. The release of effluent from the system would put the project within the jurisdiction of the Regional Water Quality Control Board. While the Regional Board does not mandate the design of systems, it does establish waste discharge limits for all point source discharges. Your project would be subject to permitting requirements of the Regional Board.
• Depending upon the location of the treatment facility, it may also require review under the Endangered Species Act, the Clean Air Act, local zoning regulations, local health regulations as well as any requirements in a given locale.
Again, this is a very promising project. Best of luck with your submittal.
