Various WWTP's
Various States
A common problem encountered by traditional activated sludge systems involves failure
to develop biomass that separates efficiently from the liquid, leaving behind a clear
effluent that is low in BOD5 and suspended solids. Another problem is the bleed-through
of ammonia due to low detention time in the aeration tank. Oftentimes, failure may be
attributed to high return sludge flow rates (RSF) that affect not only clarifier hydraulics,
but also the growth of bacteria in the system. In order to promote efficient separation and
nitrification, system conditions should be maintained that favor the growth of flocforming
bacteria and nitrifiers over nuisance microorganisms that may include filaments.
Favorable conditions are encouraged by a regime of higher detention time and feast and
famine experienced by the bacteria in the system. By viewing system operation through
this lens, the following paper proposes that many activated sludge treatment systems can
achieve significant operational improvement through reduction in RSF. This paper
further provides a method for minimizing RSF and presents examples of successful
application of this method.
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Posted: May 20th, 2011 | Filed under: 100K-500K, 500K-1M, 50k-100k, Waste Water Treatment | Tags: Improved Effluent Quality, Improved Plant Efficiency, Maximized Feast/Famine Conditions, Maximized Nitrification, Reduced Return Sludge Flow Rates | No Comments »
Indianapolis Department of Public Works
Indianapolis, Indiana
The City of Indianapolis Department of Public Works (DPW) constructed eleven real-time
controls (RTC) in the operation of the collection system between 1995 and 2004 to reduce
combined sewer overflows (CSO). These eleven RTC facilities are part of the Early Action
Projects (EAP) to reduce CSO frequency and volume. In 2009, DPW completed a hydraulic
performance evaluation of each RTC facility using a computer hydraulic model simulation of
RTC operations, and successfully quantified their environmental benefits in CSO volume
reduction. This evaluation helped DPW to demonstrate the feasibility of utilizing RTC in the
collection system to reduce CSOs. This evaluation of the RTC facilities provided a basis for
DPW to further investigate additional CSO control projects that can utilize RTC. This technical
paper provides a case study on quantifying the environmental benefits of RTC in a large sewer
collection system.
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Posted: May 20th, 2011 | Filed under: 500K-1M, Sanitary Sewer, Stormwater, Waste Water Treatment | Tags: Enhanced Operational Efficiency, Environmental Improvement, Improved Plant Reliability, Reduced Combined Sewer Overflows | No Comments »
Council Bluffs Water Pollution Control Plant
Council Bluffs, Iowa
The Council Bluffs Water Pollution Control Plant (WPCP) added a high-rate, integrated, fixedfilm,
activated sludge (IFAS) process in 2007 to increase the organic removal capacity of their
conventional trickling filter plant. Plant staff uses an innovative approach to estimate the fixed
biomass on the IFAS media through strategically placed miniature textile-media coupons. These
coupons were used to evaluate the performance of the high-rate IFAS system at design
conditions during cold-weather operation in 2009. Results showed that the system could operate
within permit limits at design conditions; however, the effluent quality was less than predicted
target values. Results also showed that the average IFAS media biomass loading was only 40%
of the manufacturer’s design value. Additional testing is needed to evaluate options for
improving effluent quality at design conditions such as increased mixed liquor, increased solids
retention time (SRT) or even increased hydraulic retention time (HRT).
KEYWORDS: Trickling Filter; Integrated, Fixed-Film, Activated Sludge; IFAS
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Posted: May 20th, 2011 | Filed under: 50k-100k, Waste Water Treatment | Tags: Achieve Permit Limits, Improved CBOD Removal, Increased Plant Capacity | No Comments »
J.D Phillips Water Reclamation Facility
Colorado Springs, Colorado
The COD:TKN ratio in the influent wastewater to the J.D Phillips Water Reclamation Facility
(WRF) in Colorado Springs is too low to allow sufficient denitrification to meet the discharge
limit for pH. To reduce the reliance on adding caustic to the effluent to raise the effluent pH,
Colorado Springs Utility (CSU), began a search of local industries to find a source of local
supplemental carbon to increase denitrification, and hence alkalinity recovery. Simultaneously, a
local dairy approached CSU requesting relief from significant monthly excess BOD and TSS
surcharges. The dairy manufactures cottage cheese, producing acid whey as a waste. A full scale
pilot test was initiated at the WRF to investigate the opportunity to use whey as a supplemental
carbon source to enhance denitrification. During this test, it was discovered that fermented whey
provided superior results to unfermented whey.
The costs of implementing and operating advanced aeration control systems have to be justified
by the reduction in energy consumption and/or improvements of the effluent quality. Control
measures should also not introduce operational problems like foaming or bulking or higher green
house gas emissions (mainly N2O). In addition to the effluent pH issues, as with all utilities, CSU
is faced with reducing operating costs as much as possible. The effluent ammonia limit for the
WRF varies on a monthly basis, which raised the question – “With the use of on-line analyzers,
could the activated sludge process be operated to produce an effluent just below the permit limit
to save aeration power?” A desktop analysis using BioWin™ and the BioWin™ Controller was
performed to predict which of feed-forward or feed-back control would provide the best control.
On-line ammonia and nitrate probes were installed at various locations and programmed into the
aeration blower and mixed liquor recycle pump control systems to determine if aeration blower
airflow and whey feed rates could be optimized. This paper will summarize the results achieved
through the full scale pilot test, list future activities at the WRF and briefly discuss the outcome
of the pretreatment permit negotiations with the dairy.
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Posted: May 20th, 2011 | Filed under: 100K-500K, Waste Water Treatment, Water Treatment | Tags: Cost Savings, Enhanced Denitrification, Enhanced Nitrogen Removal, Enhanced Phosphorus Removal, Increased Effluent pH, Increased Treatment Reliability, Supplemental Carbon | No Comments »
Back River Wastewater Treatment Plant
Baltimore, Maryland
For several decades deep bed downflow denitrification filters have proven reliable as tertiary
treatment for achieving low effluent nitrogen levels. The majority of these facilities are operating
in the southeastern region where wastewater temperatures are generally warmer. In recent years,
a number of facilities have also been installed in the mid-Atlantic region to meet nutrient
reduction requirements. While wastewater temperatures are comparably colder in this region
most of these facilities are either operating in seasonal denitrification mode (low flow, warm
period), or operating in filtration mode only (no external carbon addition) where the plant’s
upstream process is capable of meeting current total nitrogen requirements. Also, it is found that
many of these facilities are operating at lower loading conditions and therefore reported
performance data may not be representative of design conditions. In an effort to confirm the
design criteria for typical mid-Atlantic cold weather operation and year-round performance to
meet limit-of-technology (LOT) levels (TN < 3 mg/L, TP < 0.3 mg/L) required for treatment
plants in Maryland, as well as other jurisdictions within the Chesapeake Bay watershed, the
Maryland Department of the Environment (MDE) and the City of Baltimore collaborated on a
denitrification filter pilot testing program. Testing was conducted at the Back River WWTP
from January through July of 2009 and the results are presented in this paper, and compared with
performance observed at full-scale facilities.
In summary, the cold weather testing demonstrated the system’s ability to achieve effluent
objectives (for nitrate removal) at loading rates from 40-50 lbs nitrate/1,000 ft3/day. The average
hydraulic loading rates were up to 3.0 gpm/ft2, with 80-90% removal efficiency at average
wastewater temperatures of about 13 oC. During warmer weather testing the nitrate mass removal
capacity increased and the system was able to achieve lower effluent concentrations at loadings
similar to or higher than those for cold weather testing. The filter system was also hydraulically
tested during warmer weather at peak-day loading rates up to 9 gpm/ft2 (at a loading near 100 lbs
nitrate/1,000 ft3/day) while still achieving about 80% nitrate removal, demonstrating the system’s
ability to handle peak flows and loads without significant reduction in effluent quality.
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Posted: May 20th, 2011 | Filed under: 500K-1M, Waste Water Treatment | Tags: Cost Effective Treatment, Nutrient Removal, Tertiary Denitrification | No Comments »
Annacis Island Wastewater Treatment Plant
Vancouver, British Columbia (Canada)
Annacis Island Wastewater Treatment Plant which is operated by Metro Vancouver, is leading
the way in working within a carbon based regulatory environment. British Columbia has
instituted carbon reduction legislation province wide, a leader in North America. As a result
public entities, such as Metro Vancouver, must be carbon neutral by 2012. In response the utility
is holistically investigating different approaches to achieve the required GHG reductions. One
approach now being actively pursued is the implementation of co-digestion at Annacis Island.
Having developed a the scope for a full co-digestion program at the plant, a pilot facility was
constructed to provide further process controls as well as a start at reducing emissions by codigesting
material at the plant. This project also provided Metro Vancouver a basis of handling
its own sludges from other wastewater treatment plants on an emergency or planned basis by
dual tasking the receiving facility to receive both sludges and co-digestion substrates.
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Posted: May 20th, 2011 | Filed under: 500K-1M, Waste Water Treatment | Tags: Cost Savings, Energy Production, Environmental Impact, Improved Plant Performance, Improved Plant Sustainability, Reduced Carbon Footprint, Reduced Greenhouse Gas Emissions | No Comments »
Milwaukee Metropolitan Sewerage District (MMSD)
Milwaukee, Wisconsin
Significant opportunities exist to increase renewable energy production using existing municipal
anaerobic digesters. Many wastes can be added to co-digest more carbon and produce more
methane. The objectives of this study were to identify and compare potential co-digestates,
determine synergistic, antagonistic and neutral co-digestion outcomes, quantify performance of
co-digestion for selected wastes and estimate economic benefits. Over 80 wastes were identified
from 54 facilities within 160 km of an existing municipal digester. The most promising wastes
(26 wastes) were characterized by biochemical methane potential (BMP) and other testing. A
simple economic comparison identified the greatest benefits for seven co-digestates.
Performance was investigated using bench-scale digesters receiving synthetic primary sludge
with and without co-digestates. Methane production rates in co-digesters were as much as 180%
greater than anticipated from the additional chemical oxygen demand (COD). Therefore,
significant synergism was observed. The VS destruction efficiencies were 49 and 33% higher
when co-digestates were present. Co-digestion is one method to increase renewable energy
production via anaerobic digestion.
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Posted: May 20th, 2011 | Filed under: >1M, Sanitary Sewer, Stormwater, Waste Water Treatment | Tags: Cost Savings, Environmental Impact, Improved Plant Performance, Improved Plant Sustainability, Increased Biogas Production, Reduced Carbon Footprint, Reduced Greenhouse Gas Emissions | No Comments »
Stormwater discharges from an industrial aerospace complex located in Ventura County,
California require substantial treatment in order to meet the stringent NPDES permit
limits. Overflows are generated during heavy rain events when onsite storage pond
capacities are exceeded. Multiple treatment configurations have been tested to remove the
constituents of concern (COCs) below the permit limits. Past experiences have indicated
that chemical treatment with rapid clarification consistently produced water quality close
to the permit limits. Therefore, additional treatment is required to fully meet the treatment
goals. Ultrafiltration (UF) membranes were tested for this effect during a pilot study
conducted to determine performance of a submerged membrane unit. Effluent from the
rapid clarification unit (i.e., Kruger’s ACTIFLO) was further treated with multimedia
filters and used as influent to the membrane pilot. The submerged UF membrane was
able to remove approximately 99% of the influent turbidity. Ultimately, the submerged
UF membrane proved to be a viable treatment alternative that consistently removed
COCs below their NPDES permit limits, which in this particular case are even more
stringent than drinking water limits for certain COCs.
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Posted: May 20th, 2011 | Filed under: Stormwater, Waste Water Treatment | Tags: Improved Filtration Effectiveness, Improved Plant Reliability, Improved Total Suspended Solids Removal, Meet Regulatory Constraints, Turbidity Control | No Comments »
The current NPDES permit of an industrial aerospace complex located on Ventura
County, California requires to provide treatment to any stormwater overflows originated
at the complex typically during storm events. These overflows occur when the individual
capacities of a series of storage ponds located at different points of the site are exceeded.
A stormwater treatment system (STS) is required to avoid exceedances of certain
constituents of concern (COCs), especially certain heavy metals (iron, manganese,
copper, mercury, lead) and organics (dioxins and volatile organic compounds – VOCs),
that may washout from the soil during storm events. Coarse filtration (sand and
multimedia filters) was the basis of the STS, but did not achieve the required removal of
COCs to meet the permit. Additional analyses were required to increase filtration
effectiveness. Fractionation of the solids present in the water revealed the presence of
large fractions of silts and clays, which are too small to be removed by coarse filtration.
These small solids also had a significant fraction of the total COCs attached to them,
which prompted the exceedances of the permit limits. This analysis highlighted the need
for coagulation chemicals to clump these small particles together and form flocs that may
be further removed by coarse filtration while meeting permit limits. This analysis also
allowed to better characterize the raw water from different storage ponds and select the
location with the best water quality to feed the STS.
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Posted: May 20th, 2011 | Filed under: Stormwater, Waste Water Treatment | Tags: Improved Filtration Effectiveness, Improved Plant Reliability, Meet Regulatory Constraints | No Comments »
Pump stations are an integral part of wastewater collection and treatment systems. Their
applications can be quite varied: lift stations in the collection network pump raw sewage up to a
level where gravity can take over; pumping systems within the treatment plant move effluent
through various treatment stages or deliver it from the plant to agricultural users and others.
While wastewater pumps have a common function––moving fluid where gravity can’t––the
design of any individual pump station can depend on many factors.
Choosing the right pump station design for the application is a matter of balancing personal
preference with the requirements of the job, the necessity for energy efficiency and the need for
pump station reliability. This presentation examines three very different pumping system
designs, and weighs the advantages and disadvantages of each in the context of real-world
applications.
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Posted: May 20th, 2011 | Filed under: Stormwater, Waste Water Treatment | Tags: Efficient Lift Station Design, Energy Efficiency, Improved Plant Performance, Improved Plant Reliability, Improved Wastewater Pumping | No Comments »