Hello HeadsUp Readers,
At Headworks International, our focus is on the continuing improvement of the processes, technologies and equipment needed to treat water and make it once again reusable. Water is a limited resource, and the very best environmentally sustainable approach we can take towards the reserves we have is to recycle water efficiently, economically and effectively.
There are a number of methods available. Some are more appropriate in a given set of circumstances than others. Although the methods we specialize in are extremely flexible and can be implemented in virtually any industry, not just in municipal sewage treatment, our team of process engineers is devoted to advising our customers on how they should proceed, even if the best choice of technology is not part of our portfolio. It is this dedication to wanting only the best for our customers which sets us apart from our competition. This month, we include a tale of two cities, highlighting two very different applications of one of our technologies, “IFAS”, including an explanation of how it works.
We are just a few short weeks away from WEFTEC 2019. This is our 25th Exhibition at the largest water-related tradeshow in North America. Frankly, it is hard to believe that so many years have gone by. Our first WEFTEC experience was in Chicago with our industry-changing bar screen and our 3-month-old baby daughter. As our daughter is now 25, it must be true that a quarter of a century has passed… You’ll find the team this year again in Chicago. Come by and say hello at Booth 3442, see our equipment, and talk with our awesome engineers!
Extreme weather events are happening in many countries. While writing this issue of HeadsUp, Hurricane Dorian is only starting to leave the Bahamas, which it slammed into on Sunday as a Category 5 hurricane. Having lived through several hurricane events in Houston, none of them good, it is clear to us that the hurricane suddenly stopping over the islands for more than a day was the worst outcome possible. Although it is now a Category 2 hurricane, it has expanded in size as it inches away from the Bahamas on its way to the United States. Our prayers and thoughts are with everyone in the path of such a storm. As an independent commonwealth, having gained independence from Great Britain in 1973, we hope the world comes quickly to their aid. The Red Cross is already ready to help as word comes in that whole communities have been wiped out and Nassau is still three feet under water, including all hospitals, after twenty feet of water was pushed across the Grand Bahamas by the force of the storm.
Meanwhile, a quarter of the world’s population is running out of water. Some of these are naturally arid countries, but many are countries where their precious water resources are being wasted unnecessarily. An August article in the NY Times maps out for us the areas in high stress. You can see on the map that India is particularly widely hard hit, but no continent is immune. Additionally, the Wall Street Journal ran an article a week ago entitled “India is Running Out of Water: We Can’t Waste a Drop.” As our populations continue to explode, adding additional pressure to the finite resources on the planet, responsible planning and actions should be the focus of each local government. Lack of water, food and the opportunity to create a safe and fruitful life drive people to extreme measures, from fleeing from everything they know to a foreign location in order to survive, to choosing violence as a way to control the chaos around them. Our team can convert wastewater to reusable water, but if there is no water in the region, reusable water could be non-existent. Better water management, including recycling used water, is imperative.
October 23rd is the fifth annual Imagine a Day Without Water campaign. For one whole day, people around the world will be focused on this essential resource with community and school events, editorials, company events, and other creative ways to educate people on the value of water. Our readers all understand water’s value, obviously, and are well positioned to bring this awareness to their communities. What will you do on October 23rd? There are many ideas at the website link above. Hopefully, you will take the time to register and start your own mini-campaign to highlight the value of water. This issue needs to be at the forefront of our environmental dialogues as we consider how we will be a more sustainable inhabitant of this lovely Planet Earth.
As we hear at the end of beer commercials, drink [water], but responsibly!
And please donate what you can to the people in the Bahamas.
Warm regards from Houston,
Headworks International Inc.
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Successful treatment of mixed industrial wastewater in Dubai and municipal wastewater in Costa Rica.
Learn more here.
A Tale of Two Cities:
Headworks Bio Successful & Diverse IFAS Process Installations
Headworks Bio has installed numerous Moving Bed Biofilm Reactor industrial and municipal treatment plants throughout the world. This article highlights two very diverse plants: one at the Dubai Industrial Park treating high concentration wastewaters from an assortment of industries and the other in Puntarenas, Costa Rica treating municipal wastewater. Both installations were expansions of existing systems which had little or no room to grow. How did we resolve their two very different treatment challenges? With Integrated Fixed Film Activated Sludge (“IFAS”).
So, before we dive into the details of these two case studies, what is this seemingly magical process that can deliver consistently stellar results in any location for any type of biologically contaminated water?
How Does the IFAS Process Work?
IFAS is a media-based process which is a hybrid between suspended growth and fixed film processes such as Moving Bed Biofilm Reactors (“MBBR”). IFAS, thus, takes advantage of both classes of biological treatment. Its main difference from MBBR is that it is accompanied by a return activated sludge (RAS) stream in addition to the waste activated sludge (WAS) from the mixed liquor solid-liquid separator (“MLSS”). The mixed liquor in an IFAS reactor is a combination of biomass from sloughed off cells from attached growth on the media as well as that from the suspended growth population. The mixed liquor from IFAS has better sludge settling properties than the effluent from MBBR and is very amenable to settling in a gravity clarifier. Typically, the Sludge Volume Index (“SVI”) values of reactor effluents from conventional activated sludge (CAS), IFAS and MBBR reactors can be graded as <100, 100 – 150 and >150 mL/L, respectively.
The treatment in an IFAS system is normally split with BOD removal occurring in the suspended phase and nitrification in the attached media phase.
A comparison of IFAS sludge SVI vs MBBR sludge SVI is illustrated below:
Another key parameter in designing IFAS systems is the approach velocity, this should remain between 30 – 35 m/hr max, to allow the carriers to stay evenly distributed through-out the reactor. At higher velocities (e.g., >35 m/h), the carriers will tend to migrate and stack against the media retention sieves at the effluent outlet of the reactor tank which results in high headloss, creating an unacceptable condition. This “bunching” is a common issue in an IFAS treatment plant and, if not properly designed, can lead to failure.
A schematic view of IFAS process is presented below:
IFAS enjoys the benefits of both MBBR and conventional activated sludge (CAS) processes. The basic intent of an IFAS process is to provide additional biomass within the reactor volume of an activated sludge process. Adding media to grow fixed film and increasing the biomass population in a CAS reactor can essentially increase the effective MLSS of the reactor by 150 to 200%. Because the biomass is fixed on a media system, the suspended growth mixed liquor concentrations are not increased, and the performance of the downstream final clarifiers is not negatively impacted by an increase in the solids loading rate. In fact, in many cases, clarifier performance is improved by a reduction in the SVI, as a result of the fixed film growth. Correspondingly, it enhances the solids retention time (SRT) in the reactor without adding any volume. Thus, IFAS requires less reactor volume, quantity of media and footprint area than CAS and MBBR processes for the same level of treatment.
Solids loading to the secondary clarifier does not increase significantly by converting the activated sludge process to IFAS. Hence, in most cases, the existing gravity clarifier also does not need any upgrade or expansion resulting from conversion of an activated sludge treatment process to IFAS.
IFAS is a very good choice for utilities faced with an upgrade requirement resulting from high flows due to population growth and/or to comply with a change in regulation calling for nutrient control. The media, and the biomass it supports, allows the aerobic treatment process to be completed within a reduced volume and, thus, allows a portion of the existing tank volume to be converted to an anoxic zone or to incorporate an anaerobic zone for biologically enhanced phosphorus removal. This is a very attractive feature of IFAS to the utility managers.
Advantages of IFAS systems include the following:
Disadvantages of IFAS systems include the following:
Headworks supplies its own proprietary media specially designed with high density polyethylene (HDPE) and with specific surface areas and shapes ideal in an IFAS upgrade. The surface area ranges are available from ~402 to 680 m2/m3. Each media contains specific advantages and the media fill fraction are kept between 30 – 54% within the IFAS reactor.
Headworks International has successfully implemented over 20 IFAS projects globally. Two of the recent installations by Headworks are presented below.
Case Study 1
Costa Rica Institute of Aquaducts and Sewers (AyA), the government agency responsible for sewage treatment in Costa Rica, considered IFAS technology for upgrading the Ptar El Roble wastewater treatment facility at Puntarenas. The CAS (Conventional activated sludge plant) at Puntarenas was originally designed for 3.5 MLD. With a substantial growth in population, as well as contributions from industrial and commercial sources, the plant needed to double the capacity in order to meet BOD and TSS limits. Due to land constraints and budget limitations, new aeration tanks were not feasible. Therefore, AvA decided to go with IFAS technology.
Ptar El Roble is the first ever IFAS plant in Costa Rica. This project was implemented by Headworks Bio in 2014 and it started up in 2015. Since the operation of the IFAS plants are very similar to the operation of CAS plants, the transition was very smooth. Because of the availability of two parallel trains, the plant was running without interruption during construction.
Existing clarifiers were previously overloaded. By implementing the IFAS process, the MLSS and solids loading actually was reduced to much more manageable levels. After the implementation of the IFAS process, the facility eliminated sludge bulking and washout conditions as much of the biomass moved to the biofilm from the suspended phase. Most importantly, the effluent from the plant consistently meets effluent limitations throughout the year. Flow, influent and effluent characteristics are as presented in Table 1.
Table 1: Flow and Characteristics at Ptar El Roble WWTF, Puntarenas, Costa Rica
Case Study 2
The Dubai Investment park is a special Industrial zone in the United Arab Emirates. It is a unique complex operated by the Dubai Investments Park Development Company LLC, consisting of a mix of commercial, residential and industrial zones. To complicate the wastewater further, the industrial zone includes a variety of industries ranging from food and beverage production, plastic fabrication, power generation, utilities, printing press to building materials. All of these industries require wastewater treatment. The initial treatment process was provided by a CAS system.
The existing system was designed to handle 5,000 m3/d. Growth demand required an expansion to double that capacity with little or no extra footprint. Another challenge was the high incoming COD and BOD of up to 3,000 mg/l and varying temperature. MBBR and IFAS processes were studied by Dubai Investment Park due to their self-regulating nature along with their ability to handle influent load variations. The cost effectiveness, low OPEX and easy implementation led the Dubai Investment Park Development Company to conclude that the IFAS system is an ideal solution to their problem.
Headworks Bio was awarded the project to upgrade the existing CAS to an IFAS system. It was implemented by employing Headworks’ proprietary ActiveCell 450 media for the IFAS reactors.
Flow, and influent and effluent characteristics are as presented in Table 2.
Table 2: Flow and Characteristics at Dubai Investment Park, Dubai, UAE
In conclusion, IFAS is a robust and very cost-effective technology to upgrade existing CAS-based treatment plants for handling higher loads and flows. Headworks Bio has a long history and the right experience in implementing such projects globally. Our internationally located team of process engineers would be delighted to help you and your engineers with your application, big or small. Contact your local manufacturers’ representative or the experts at Headworks Bio at email@example.com or +1.713.647.6667.
We celebrate our 25th WEFTEC September 23rd through the 25th.
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