North American Municipal Wastewater Treatment Plants Update
December 2017
We continue to pursue decision options for the systems and components used in municipal wastewater treatment. This month we are focused on biological treatment systems and their impact on blower requirements. We are also analyzing the individual blower options. If you are a system designer, you need to consider all the system options and then consider the blower options for each system alternative. One question is whether advances in blower technology will affect system decisions? Full text from which some of the following articles were written is included in the Municipal Wastewater Intelligence System.
Biological Treatment and Aeration
Two Questions Relative for and about Organica
They have a system using growing plants to compete with activated sludge. A number of wastewater plants in China and other parts of Asia and Europe have installed systems. Blower energy requirements are said to be 30 percent less. We need to pursue this further. Also, we need to assess their ability to remotely monitor and optimize their biological treatment system. Here is a summary and a link to the full text which is in the intelligence system.
The Organica Process Control System is a combination of instruments, input/output units, PLCs, operator stations and SCADA system to collect, analyze and display real time operational information and control the operation of a unique alternative to activated sludge processes for biological treatment.
Efficient operation requires quality data. Recognizing this important fact, Organica has developed an industry-first analytical software (designed by market-leading inCTRL solutions) to maximize data reliability, instantly evaluating and scrubbing “noise” from collected data. Based on a precise set of calculations and process models, this platform ensures accurate data reporting and documentation. Accessing this precise data, Organica can perform regular process simulations to identify improvements in operational strategy, and apply them remotely through the same software platform. These strategy changes often include set point adjustments, while the platform also supports remote PLC programming to acquire the most effective results.
Blower Technology Options
Juan Loera of Carollo compared blowers for sewage aeration pointing to the high efficiency of single stage high speed turbo. It also is equal to or has more turndown than others except multi stage centrifugals. Rotary blowers have the lowest capital cost for at least smaller installations. The main question posed by him seven years ago was long term reliability. We need input on this subject given the passage of time. He also compares the different high-speed turbo designs based on bearings (air or magnetic), impeller design (milled or cast), cooling system (self-contained or external), controls (single point vs dual). How important are these differences? ®Juan was not accessible at Carollo on LinkedIn. So, we need some input from whomever is pursuing this at Carollo as well as input from others who review the very detailed slide deck in the intelligence system.
Biological Aerated Filter comparison at San Diego
In 2005 a pilot study determined the potential to install either a Suez, Infilco Degremont BIOFOR® or a Veolia Kruger BIOSTYR®. Several choices included use of high rate clarifier thickeners and use the BAF to treat the effluent, mix BAF solids with primary sludge and treat with anaerobic digestion. Another alternative was to use the BAF to treat the chemically treated primary effluent to a secondary level. Both units had high solids yields but some differences were identified. Also, the BIOSTYR air scour rate was higher. A breakthrough of TSS in the BIOFOR unit indicated the importance of automatic backwash. The tests established the ability of the systems to meet the goals. The BIOFOR had somewhat better effluent quality.
The study was conducted by Brown & Caldwell, we will be pursuing the latest insights from them and find out about their most recent experiences.
Aerzen Comparison of Blowers
The paper presents four types of blowers: two dynamic and two positive displacement machines. Since each technology has its place, a comparison is made specifically based on the treatment of wastewater. Taken into account are the daily and seasonal swings in oxygen demand, fouling and aging of diffusers, air flow control and turndown capabilities, total blower efficiency and energy consumption over time, mode of operation, blower accessories, and plant set-up. Each technology has its place and blanket efficiency statements cannot be taken at face value. With professional due diligence, the engineer will select the aeration blower technology based on a comparison of real operating data over time while being mindful that any machine must be capable of operating safely under extreme site conditions and at the highest pressure ratio over the entire flow range. With pragmatism and common sense, the engineer will also be mindful of the actual operation of the plant and the management of its processes.
AECOM Tests BAF vs MBBR with DAF at Portsmouth
AECOM conducted pilot tests at the City of Portsmouth relative to secondary treatment options. The Moving Bed Bioreactor (MBBR) process uses floating plastic carriers (media) within the aeration tank to increase the amount of microorganisms available to treat the wastewater compared to conventional secondary treatment. To provide clarification, the effluent from the MBBR reactor flows to a Dissolved Air Flotation (DAF) system. DAF systems inject air into the wastewater to create small bubbles. A polymer is added to help the biological microorganisms and other particles attach to the air bubbles and rise to the surface, where a skimmer removes them. Clarified water passes under the biomass on the surface, and then it flows out of the DAF unit.
The biomass is removed and returned to the plant’s solids handling process for further treatment. The MBBR process can be configured to provide secondary treatment as well as nitrogen removal. For nitrogen removal, the aeration tank is partitioned into different zones with different levels of oxygen, which allows the microorganism to remove nitrogen.
Reported Advantages Over Conventional Secondary Treatment Technology
- Stable under varying amounts of wastewater
- Small footprint due to larger biomass volume
- Low concentration of solids in treated effluent
- Easily expanded by increasing media fill percentage
- Simple to operate
Potential Disadvantages/Concerns
- Higher energy consumption and chemical costs than conventional clarifier
- DAF typically performs best at constant flows, concern about varying performance with daily flow variation
The pilot system was furnished by Water Works. A BaF system supplied by “Veolia-Kruger was also tested.
Tertiary Treatment provides Water for Cooling at Minnesota Power Plant
A pretreatment strategy was the approach applied in the growing city of Mankato, Minn. The city installed a new water reclamation facility (WRF) to treat effluent from its wastewater treatment plant (WWTP), which would supply the cooling tower needs of an electrical generation plant.
In addition to providing quality reuse water for the energy center, the WRF needed to meet new state phosphorus removal regulations. The solution involved two products from Veolia.
1. The Hydrotech Discfilter is a mechanical, self-cleaning filter that offers a large filter area in a small footprint.
2. Efficient Filter: The BIOSTYR process combines biological treatment and filtration intoone compact system, removing ammonia and a majority of wastewater solids. The BIOSTYReffluent is then gravity fed into theDisc filters, which provide an ideal filtrationsystem for solids removal above 10 microns,thus producing much cleaner water needed for use in plant operations.
High Speed Turbos and Positive Displacement Blowers with VSD are Most Common Recommendations
A PG&E survey polled design engineers/vendors the question of “How often do you recommend the following types of blowers to your municipal WWT customers:
• positive displacement (constant-speed)
• positive displacement (variable-speed)
• multi-stage centrifugal
• single-stage centrifugal (constant-speed)
• single-stage centrifugal (variable-speed)
• high-speed turbo blower
The results for the surveyed vendors/distributors were as follows:
• Designers: High Speed Turbo Blowers and Positive Displacement Blowers with VSD were the more common blowers, typically recommended ~50% of the time to customers, but unclear whether customers selected this for installation
• Vendors: High Speed Turbo Blowers and Positive Displacement Blowers with VSD were the more common blowers, typically recommended ~50% of the time to customers, but unclear whether customers selected this for installation
Pacific Gas & Electric offers Incentives to replace Blowers
PGE is offering up to $150,000 at 8 cents/kwh for energy improvements at wastewater plants. Single stage blowers with variable inlet vanes and variable discharge diffusers can allow for flow adjustments while maintaining constant impeller speed. VFDs may also be appropriate for application to aeration blowers. This compares to the base case with multi stage centrifugals to set the incentive amount.
Rohm and Haas reduces Aeration Costs through Optimization
Rohm and Haas Company was able to drastically reduce O&M costs for their Aeration System by focusing on Reliability Engineering and Optimization at their WWTP. The costs reductions were a team effort and have resulted in a wide variety of benefits for Rohm and Haas and for the people associated with the WWTP. This initiate also revealed several interesting points relating to the design and operation of WWTPs: • Good data, particularly D.O., air flow and blower amps can help optimize operations and reduce energy costs. Without this data, plants may be wasting energy unnecessarily by adding to much air. • Existing blowers may be operating very inefficiently even if they are throttled or controlled to maintain D.O. setpoints. • If plants are designed for conservatively high present or future peaks loadings, the result will be an inefficient operation with oversized components unless good turndown is incorporated into the design. If designing for peak conditions, the use of different size blowers is strongly recommended. (see the intelligence system for this older article which was included because it has very detailed discussion of the individual initiatives employed)
Wastewater Aeration Blower Integration
Stephen Horne of Kaeser, writing in Blower & Vacuum Best Practices, discussed the approach to integration. System integration comes from relying on a system master controller to properly control individual blower packages. The advanced master controller is programmed with the performance information on each blower and it then selects the most efficient combination of blowers to meet the current demand. It can also rotate packages to balance load hours, spreading out preventive maintenance intervals.
Components
Salem solves Wipes Clogging of Lift Station with Barnes Solids Handling Pump from Crane Fluid Systems
The Town of Salem is a small, rural community located in southeast Wisconsin. The municipality manages 25 lift stations. Lift station #18 is a triplex station and was clogging weekly mostly due to flushable wipes. Crane Pumps & Systems provided a Barnes 4SHVA 30HP Solids Handling pump as a demo replacement for the station in September 2013. The pump was installed a month later. The next time the pump was pulled was October 2014 for its annual maintenance. Today’s non-biosolid laden wastewater requires new technology to keep the stream flowing. The Barnes SH Series with its non-recessed vortex impeller was the easiest, and it turned out to be the best option for Salem. It is estimated that the pump paid for itself in the first six months of operation.
The pump continues to be clog-free for over a year
Aerzen has Remote Monitor with Alerts
The Aerzen iAir Remote Monitoring System (RMS) is a comprehensive monitor that can be attached to any blower or compressor to capture real-time activities and conditions. Based on industrial cellular technology, the RMS can function in any location with cellphone coverage for both indoor and outdoor applications. The iAir Remote System reviews the actual usage of the equipment and sends alerts and reminders via text or email directly to the user.
Sage is supplying Thermal Mass Flow Meters to replace Orifice and Vortex Meters
A successful aeration control system is dependent upon the efficient operation of its system components. The components for each region may include an air flow valve, air flow meter and DO (dissolved oxygen) meter. The valve, commonly a butterfly valve, is usually installed downstream of the flow meter. Much of aeration control is predictive, as there is a nonlinear relationship between the airflow and dissolved oxygen content which creates a lag time to reach equilibrium. Three technologies are used to measure aeration airflow: orifice plates, vortex shedding, and thermal mass flow meters. The thermal mass flow meter is the preferred method to measure airflow at wastewater treatment facilities. They require lower maintenance, are easier to install and save on energy costs. As older aeration systems with vortex and orifice meters are being replaced or upgraded, thermal mass flow meters are being integrated into the systems.
Flowseal high performance butterfly valves are a standard in many industries including heating, ventilating and air conditioning, power generation, hydrocarbon processing, water and waste water treatment and marine and commercial shipbuilding. Their products are also installed in applications as diverse as food and beverage processing, snowmaking and pulp and paper production. Configurations are available for harsh conditions as well as applications requiring nominal pressure and temperature ratings.
New APG-Neuros Turbo Blower Remote Monitoring System
APG-Neuros, the leading manufacturer of high-efficiency turbo blowers offers the Remote Monitoring System to its customers for monitoring blower operation through real-time data using a VPN or a dedicated router. The system can be installed at the managed communication/Ethernet switch at an individual blower, master control panel or SCADA level to fit different plant needs and configurations. The Remote Monitoring System is easy to deploy with minimal to no interruption to the plant’s system or operations. The real-time data is streamed through secure network to the cloud or APG-Neuros’ servers for monitoring and diagnostics of operational issues. All the parameters are monitored remotely by APG-Neuros engineers to ensure optimized aeration system and blower operation, analyze trends and detect any abnormalities.APG-Neuros demonstrated energy efficiency by replacing competitor’s blowers in Nice, France, Narragansett Bay Commission, and Lowestoft, U.K. (Anglian Water).
With approximately 1,000 units installed and over 100 on order, their installations enjoy the highest success with large cities including Washington D.C., NYC, London (U.K.), Vancouver (B.C.) and Mexico City
EDI and BioChem Partnership provides Holistic Approach to Aeration Control
BioChem introduced its patented Bioprocess Aeration Control System (BACS) in 2009.
Since then it has proven its effectiveness, efficiency and reliability in dozens of applications as a standalone subsystem to control the production and distribution of the aeration process. BACS is not the standard proportional integral (PI) loop utilizing high speed trial and error based control actions to chase the desired set-point. Rather BACS is an intelligent system which actually calculates the volume of air required to maintain the DO setpoint by analyzing the process metabolism in real-time. In fact, because of system response times, it is necessary to know what the oxygen demand will be 15 minutes from now in order to effectively maintain the proper DO concentration. BACS does this. It has a Predictive element in its nature.
With BioChem's EDI partnership a new more holistic concept to process design and control was introduced. This new concept called Symphony considers all the critical subsystems required to control the biological treatment process utilizing digitized intelligence throughout. The goal is to achieve unprecedented economy and performance while providing practical, actionable information to manage the plant by incorporating such features as fault detection and isolation (FDI) and Reliability Centered Maintenance (RCM).
EDI, headquartered in Columbia, Missouri has been a leader in the development, manufacturing, and installation of advanced aeration products and solutions for over 40 years.
EDI's Chairman, Charles Tharp provided this rationale for the partnership: "This represents a major expansion of EDI's capability to deliver superior aeration mixing solutions for biological treatment systems. The combination of predictive aeration logic and premium EDI aeration hardware will deliver unprecedented levels of performance in biological and aeration systems."
George Lee, BioChem's longtime CEO and the father of its innovative technologies, and newly appointed CTO stated: "BioChem will continue to expand its knowledge and apply its core competencies in the complex and nuanced bio-chemical dynamics in the wastewater segment. The partnership with EDI for the distribution of our control solutions allows us to more quickly realize our shared goals and vision; which is to essentially transform the way wastewater treatment systems are built and operated, so as to incorporate the most advanced, efficient and effective wastewater treatment strategies that modern technology allows.
Florida Wastewater Plant saves $20,000 /yr with Predictive Aeration Control
The Camelot WRF located in the City of Kissimmee Florida was upgraded from a 3 MGD MLE process to a 5.5 MGD (average annual daily flow) facility.
To extend the facility's aeration capacity, the plant installed a bank of four 125 hp turbo blowers - each theoretically capable of delivering 2650 SCFM at 8 PSI with a rise to surge of 1.5 psi. The facility is unmanned at night and requires robust automation and remote monitoring capabilities. Additionally, the facility experiences a hydraulic and ammonia loading peaking factor of approximately 1.5 and 1.6 respectively, presenting an excellent opportunity for a DO/aeration control system. To accommodate these requirements and opportunities, the Bioprocess Aeration Control System (BACS) was integrated into the plant's existing SCADA network and commissioned over a 1-week period.
The BACS adjusts the valve position of each of Camelot's six aeration control zones and trims the blowers up and down in order to maintain the plant's user defined zone specific DO setpoints using BioChem's patented Oxygen Uptake Rate Factor (OURf) technology and energy saving field tested Most Open Valve logic.
The data reveals an aeration savings of approximately 23.8% over a manual control baseline. Given the facility's electricity cost of .11 $/kWh, this translates to a savings of approximately $21,300 annually.
Wide Variety of Valves for Water and Wastewater Treatment Plants
Some of the articles in this Update reference butterfly valves used to control air in the aeration processes. Valves used for air and gases are small in number compared to the many valves involving liquids in a wastewater plant. We are including the water line valve specifications for the City of Pearland in the intelligence system. This eight-page listing includes details on gate valves in various different size ranges. Here is just the specification for the small valves.
Gate Valves 1-1/2 Inches in Diameter and Smaller: 125 psig; bronze; rising-stem;
single-wedge; disc type; screwed ends; such as Crane No. 428, or approved equal.
Coatings for Gate Valves 2 Inches and Larger: AWWA C550; Indurall 3300 or
approved equal, non-toxic, imparts no taste to water, functions as physical, chemical,
and electrical barrier between base metal and surroundings, minimum 8-mil-thick,
fusion-bonded epoxy. Prior to assembly of valve, apply protective coating to interior
and exterior surfaces of body.
The specification also includes plug valves, butterfly valves, air release and pressure reducing valves. Many of these valves are general performance valves sold primarily by price. However, a number of valves used in slurry lines and for sensitive control are high performance valves sold on the basis of lowest total cost of ownership. We will endeavor to identify those applications and pursue cost of ownership aspects for them.
McIlvaine Company
Northfield, IL 60093-2743
Tel: 847-784-0012; Fax: 847-784-0061
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Web site: www.mcilvainecompany.com