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Monthly Archives:March 2017

Vortisand®

EcomuseumZoo: High Efficiency Filtration Reduces Turbidity & Maintenance Costs
The Project

​The Ecomuseum Zoo is home to the most impressive ambassadors of Quebec’s wildlife. All residents of the Ecomuseum Zoo are there for a special reason: orphaned, injured or born under professional human care, each of them could not return to the wild. Hence, they have found a forever home at the zoo.

The $1.4 million 6,000 square foot river otter habitat, first of its kind in Canada, is made up of vast land, river banks and a 250,000 litre (66,000 gallon) water basin; includes two port holes, an underwater tunnel and a 15 meter (50 foot) viewing window. In order to improve water clarity, a high efficiency submicron performance filtration system was required to fit in a 3 meter by 4 meter (10 foot by 14 foot) mechanical room.

With the need to filter contaminants and fine particles, engineering consultants had specified Vortisand® cross-flow filtration technology as the go to side stream filtration system.

Download PDF version of the case study here.

Montreal Ecomuseum Zoo Otter Water Basin

​The footprint of the mechanical room presented itself as one of the first challenges the Ecomuseum Zoo was faced with. With only a portion of the mechanical room space being dedicated to the water filtration system, the Vortisand team of application engineers were mandated to design a customized configuration. The natural outdoor environment of the habitat posed a second challenge for the Ecomuseum Zoo and engineering consultants. Over time the water basin acts as an air scrubber, absorbing airborne contaminants and debris as they brush along the surface of the water. These contaminants can buildup and create a film on various types of hard surfaces, potentially covering the viewing window and other surfaces found within the otter habitat. The airborne contaminants and debris also increase the risk of experiencing higher levels of water turbidity. Such high levels of turbidity will result in reduced water clarity, further limiting the learning experience for Ecomuseum Zoo visitors. Routine water basin cleaning would be costly, and the use of harmful chemicals are prohibited; ultimately requiring the removal of the fine particles before they have the chance of creating a concern. The Vortisand system was required to handle various types of contaminants and fine particulates, while yielding minimal maintenance and operational related costs.

The Solution

​Thanks to its compact design, the Vortisand H2F® system was installed within the current parameters of the maintenance room. Its submicron filtration performance and high efficiency capabilities helped remove the fine particles that would otherwise make it impossible for visitors to see the otters through the viewing glass, portholes and underwater tunnel. Most importantly, the Vortisand® system made it possible for the otters to go about their daily activities comfortably. With minimal maintenance and manual intervention required, the Ecomuseum Zoo employees were able to focus on nurturing and growing their family.

Upon start up a particle analysis test was conducted, showing that particles of 5 micron and less in size made up the vast majority of the particles within the otter water basin. The Vortisand system delivered 94% removal of particles less than 5 micron in size.

“Every effort is made to provide an exceptional level of care. Here at the Ecomuseum Zoo, we make animal welfare our number one priority, and this habitat is a faithful reflection of that choice. Nothing has been neglected to ensure that the River Otters in our care have a safe, soothing and stimulating environment. We are deeply satisfied with the work achieved by Vortisand systems. Being able to work with such a high level product means a lot for our team’s efficiency and our animals’ well-being, two of our main concerns.”

David Rodrigue, Executive Director of the Ecomuseum Zoo

MABR

MABRs (or membrane aeration bioreactors to you and me)

24 March 2017

The membrane aeration bioreactor (MABR) seems to be the new kid on the block, with just a few commercial technologies around and, it seems, just one or two full-scale installations (though there have been large-scale demonstration trials).

Except that it really isn’t that new. The term ‘MABR’ was first introduced around 20 years ago by Mike Semmens of the University of Minnesota. The large body of research on ‘regular’ aerobic, and subsequently anaerobic, MBRs at Cranfield University was actually preceded by a collaborative research programme on MABRs between Tom Stephenson of Cranfield and Semmens in the early 1990s.

The original work was based on a pure oxygen fed technology, which attracted the interest of gas suppliers like Air Products. As with the most recent technology, pretty much all of the oxygen introduced to the bioreactor via the membrane is utilised by the microorganisms because it is introduced in molecular (or ‘bubbleless’) form. Because a biofilm is formed on the membrane itself, the oxygen seems to go straight into biomass; the usual mass transfer limitations, which limit the standard oxygen transfer efficiency to somewhere between 10 and 40% in conventional fine bubble diffuser aeration (FBDA), no longer apply.

So, what’s not to like? The ~100% efficiency of oxygen utilisation is the big selling point of the technology. Even if air is used as the feed instead of oxygen – which means five times as much gas is pumped but it is a free source rather than coming with a price tag – there is bound to be some aeration energy cost saving compared with FBDA.

There are a few things to consider when the membrane is used for aeration.

Firstly, and most obviously, using the membrane in this way means that there is no longer any membrane-based biomass separation. If the perm-selectivity properties of the membrane are needed to produce a clarified effluent, an additional membrane separation stage is required for this.

Secondly, even given the significant reduction in membrane cost over the past 25 years or so, membranes are unlikely to ever cost less than a simple FBD – which is not so different to something that would be dropped into a fish tank – or even the more advanced high-shear aeration devices.

Thirdly, membranes have a finite life – as, indeed, do FBDs but the latter are cheaper so the replacement cost is less onerous. Since commercial membrane aerators are still fairly new and there are few and only very recent installations, the membrane life is currently unknown.

Fourthly, FBDA does more than just oxygenate the mixed liquor. The fine bubbles also provide a degree of mixing, which is lost when the oxygen is introduced in molecular form. Membrane aerators must therefore always require supplementary mechanical mixing, though this doesn’t necessarily add greatly to the cost since mechanical mixers are often used in conjunction with FBDA. However, FBDA is effective in limiting the collection of solids at the base of the aeration tank.

Lastly, a key aspect of the MABR is the growth of a biofilm on the membrane surface, which expedites the high oxygen utilisation. The biofilm cannot be allowed to grow in an uncontrolled manner since it would eventually fill the membrane channels, clogging them. The membranes must therefore be regularly cleaned. Again, this isn’t exactly a showstopper: both conventional MBR biomass separation membranes and FBDs require cleaning, but it is another consideration.

So, will membranes displace FBDs? Will ceramic membranes displace polymerics? I’m asked these and similar questions on a fairly regular basis and the response is always: if I knew the answer to such things, do you think I’d be doing this job? The answer to thatquestion is much more straightforward.  No, I’d be reclining on a beach somewhere in the Maldives, sipping iced diet cola, with Mrs Judd sat next to me (probably checking the analytics on her web site).

Simon Judd

Simon Judd

Author Bio

Simon Judd, author of The MBR Book, Watermaths, and Industrial MBRs, offers observations on membrane technology.

Contact Simon at simon@juddwater.com.

http://www.thembrsite.com/blog/mabrs-or-membrane-aeration-bioreactors-to-you-and-me/

Evoqua’s Memcor® and Mempulse® at core of Europe’s largest MBR

The beaches of the Adriatic Sea, along the coast of Italy on the famous “Riviera Romagnola”, are among the most beautiful in the world. Keeping them that way is a key goal of the regional government in Rimini, Italy. Rimini is the heart of a region that is historic, scenic and fragile.

Densely populated to begin with, the area receives a huge population influx every tourist season that puts a strain on the region’s aging water resources. Rimini needed to expand its Santa Giustina wastewater treatment plant from serving 220,000 people to a maximum of 560,000, absorbing and demolishing two existing treatment plants in the area. The overall goal – eliminate discharges to the Adriatic Sea by 2020 and preserve the beauty of this legendary seacoast region.

The new Rimini wastewater treatment facility is a benchmark for the world in terms of operational efficiency and effectiveness. The facility utilizes Evoqua Water Technologies’ Memcor® Mempulse® MBR. Mempulse is a sub-brand within the Memcor family.

The resulting solution is one of the largest MBR wastewater treatment facilities in Europe. The new expanded MBR has an average daily flow that varies from approximately 55 million liters to more than 76 million liters. The target of the MBR is to achieve an effluent with a quality higher than the stricter Italian legislation for reuse. Membranes are installed in tanks fed by gravity that can switch on/off according to need in order to ensure maximum flexibility.

In total, the membrane filtration area is approximately 150,000 square meters and includes nearly 4,000 Memcor MBR modules. Because the Mempulse MBR system eliminates the need for secondary clarifiers and tertiary treatment, it results in superior effluent quality in a smaller footprint.

With the system in full operation, the plant is meeting or exceeding all of the strict requirements for discharge into surface water. The effluent is fully compliant with reuse requirements and energy consumption is below industry benchmarks.

Most importantly, because of the compact footprint of the MemPulse MBR technology, Rimini was able to complete the upgrade without acquiring and developing new real estate, preserving the beauty and heritage of the land as well as the sea in this special part of the world. As a result, the region is well on its way to achieving its goal to completely eliminate discharges to the sea by 2020.

 

Three-stage modified Bardenpho process for BNR

The overall objective of wastewater treatment is to treat waterborne waste to a degree that it may be discharged at an environmentally acceptable level, prevent the pollution of surface waters and protect downstream users.

This is done by reducing the concentration of nutrients and trace chemicals, and by eliminating heavy metals that may be present in the waste stream. Disinfection of the clarified effluent (by UV for example) reduces the chances of disease by eradicating pathogens and viruses.

This three stage activated sludge process – in sequential anaerobic, anoxic, and aerobic zones – removes both nitrogen and phosphorus from the wastewater and achieves a high carbonaceous BOD removal.

The modification of having the ability to add a small portion of Primary Effluent (PE) to the anaerobic zone and the rest split between the anoxic zones is known as the Westbank Process.

Primary clarifier effluent enters the bioreactor and is diverted into the anaerobic and anoxic zones.

Primary effluent that enters the anaerobic zone mixes with the RAS from the secondary clarifier before flowing into the anaerobic zone. Primary effluent has a high BOD (biochemical oxygen demand) content and will readily take up oxygen in almost any form. This eliminates any nitrates that may be present in the RAS before entering the anaerobic zone – which must be free of oxygen.

The primary reason for returning activated sludge (RAS) to the anaerobic zone is to reintroduce microorganisms into the process. The RAS maintains the population in the bioreactor by returning mixed liquor (sludge containing microorganisms) that has settled to the bottom of the secondary clarifier.

The remaining flow enters the anoxic zones and is used as a carbon source for the microorganisms.

Suitable conditions such as food, dissolved oxygen and temperature allow the bacterium (mixed liquor) to reproduce and increase in concentration. To maintain a balanced population, some of the organisms are taken out of the process as waste activated sludge (WAS). The WAS pumps withdraw mixed liquor from the last aerobic zone and pump it to the DAF tank for thickening.

Anaerobic Zone

The anaerobic zone is the first zone in the bioreactor and ideally is devoid of oxygen and nitrates. The wastewater entering the anaerobic zone is:

  • High in BOD.
  • High in ammonia, with little to no nitrates present.
  • Nutrient rich with phosphorus.

The purpose of the anaerobic zone is to make the microorganisms release phosphorus stored in their cells. In this environment, the microorganisms are deprived of oxygen and nitrate and prompted to transport orthophosphorus across their cells while taking up substrate (VFA) from fermentation process.

The phosphorus release into the wastewater is crucial for the uptake of phosphorus in the aerobic zone. The phosphorus that is released by the microorganisms is 4 – 6 times the amount of phosphorus that is contained in the raw wastewater.

Anoxic Zone

As mentioned previously, a portion of the primary effluent flow is directed into the anoxic zones to provide an additional organic carbon source (food), since most of the carbon was taken up in the anaerobic zone.

The anoxic zone receives nitrates through the internal recycle of mixed liquor from the aerobic zone. This wastewater is high in ammonia, nitrates and phosphorus, while being low in dissolved oxygen (<0.10 mg/L DO). Mixers keep the mixed liquor in suspension.

Denitrification takes place in the anoxic zones. Denitrification is the reduction of nitrate to nitrogen gas. Pseudomonas and Bacillus are primarily responsible for the denitrification process.

The BOD is also reduced in the anoxic zones as a result of the oxidation of organic matter through anaerobic respiration.

The degree of nitrogen removal is controlled by the rate of the internal recycle flow.

Aerobic Zone

The flow from the anoxic zones flows hydraulically into the aeration zones. The air is dispersed to the aerobic zones through a grid of fine bubble diffusers. The movement of the bubbles from the diffusers also acts to keep the solids fully mixed.

The wastewater is high in phosphorus and ammonia and low in nitrates. Dissolved oxygen levels are kept greater than 1.0 mg/L DO, and vary according to plant operations (typically ranges from 1 to 2 mg/L DO).

The aerobic zones are responsible for two types of biological processes – luxury uptake of phosphorus and nitrification.

Luxury Phosphorus Uptake is the excessive uptake of phosphorus by Acinetobacter that takes in more phosphorus (PO) then is required for the metabolic activity of the cell.

This reaction takes up the surplus of phosphorus that was expelled in the anaerobic zone. The phosphorus is synthesized (combined) and stored as a poly-phosphate. The result is a phosphate rich sludge of which a portion is removed from the end of the aerobic zone.

Nitrification Processnitrifying bacteria are able to oxidize ammonia to nitrate (and other oxidized nitrogen compounds). This process is known as nitrification and takes place in an aerobic environment.

There are two subgroups of nitrifiers – the ammonia (NH3) oxidizers and the nitrite (N02-) oxidizers. Ammonia oxidizing bacteria (AOB), most commonly Nitrosomonas, convert ammonia to nitrite. This is a rate limiting step that relies on temperatures above 8°C to proceed.

The nitrite oxidizer that converts the nitrite to nitrate is Nitrobacter.

The rate at which nitrifiers grow is slow because of the way they obtain their energy, which is relatively inefficient. These chemolithotrophs must oxidize simple inorganic compounds, such as ammonia and nitrite, and used dissolved carbon dioxide to make sugars for cell material.

What does a tonne of CO2 look like?

Wondering how much volume 1 metric tonne of CO2 takes?

The art installation was created by Millennium ART in partnership with the United Nations Department of Public Information, Google and YouTube. The 3-story-tall cube was made from used shipping containers and had two sides covered draped with screens projecting images and videos. The idea was to help people visualize exactly what one tonne of CO2“looks like” in volume: 27 feet or 8 m cubed! (Photo above by PUSH_ARCHITECTURE.)

Interesting facts:

  • The government of Canada has pledged to reduce national emissions by 30% from 2005 levels by 2030 – that is, to 524 megatons (Mt) of CO₂ emissions annually by 2030 (compared to 732 Mt of CO₂e emissions in 2014).
  • U.S. energy-related carbon dioxide emissions increased by 0.9% in 2014 to 5,406 Mt of CO₂.
  • Every year the United States emits a 30.5 cm (1 ft) high blanket of carbon dioxide over its land area.
  • The U.S. economy is 10 times larger than the Canadian economy in terms of GDP and releases 7 times as much GHGs than its counterpart.
  • The U.S. economy grew from 16.77 T (trillions) in 2013 to 18 T in 2015, while the Canadian economy shrank from 1.83 T to 1.55 T in the same period, most likely due to the drop in oil prices.

One tonne of greenhouse gas emissions is equal to:

  • Heating a home for 4 months – By far the single biggest emissions source in Canadian households is for space heating. It accounts for 63% of all household energy use. The high demand for heat means a single Canadian household will produce 3 tonnes of GHG emissions in a year from space heating alone. Canadian residential space heating accounts for 39 Mt of CO₂e emissions in a year, mostly over the winter months.
  • 7 months powering a home – In Canada, households rely heavily on electricity. One of the biggest single electricity users is water heating systems which accounts for approximately 50% of an average Canadian’s household electricity. Big household appliances, like refrigerators and clothes washers, use almost as much. Collectively they contribute 4.4 Mt of CO₂e emissions in a single year.
  • A year’s trash from 1 household – Compared to other countries with similar levels of disposable household income and urbanization, Canada has one of the highest levels of municipal waste production per capita. This is the result of two significant factors: the increase in the overall waste Canadians make and the lack of comprehensive municipal waste diversion programs. Organics waste is one of the biggest contributors to municipal waste GHG emissions especially when sent to landfills. About 35% of Canadian waste, measuring up to 10 Mt of CO₂e emissions annually, comes from food waste alone.
  • Driving 4500 km – Transportation is the second biggest GHG contributor in Canada. Within the sector, 53% of emissions are produced by personal vehicles. In 2012 the Pembina Institute estimated that Canadians living in metro or suburban areas (the majority) commute an average of 45 km a day for work. At that rate, Canadian drivers produce 1 tonne of GHG emissions from just four and a half months of commuting. Personal vehicles driven in Canada contribute a yearly total of about 70 Mt of CO₂e emissions.
  • Raising a cow for 6 months – Cows produce an exceptionally high level of GHG emissions. Canadians also consume more beef than almost any other type of animal protein. This means cows are a big part of Canadians’ GHG footprint. GHG emissions associated with beef are 4 times those associated with chicken, and 18 times higher than for beans and lentils. Cheese production contributes double the emissions of chicken and 9 times the emissions of beans and lentils. The emissions equivalent of raising a cow for 6 months is enough to produce beef and cheese to satisfy the average consumption of one Canadian for a year. The total emissions of cattle raising in Canada contributes 24 Mt of CO₂e emissions in a year.
  • Manufacturing 46 bags of cement – Cement is the binding ingredient of concrete. Concrete is used in a multitude of ways in urban and industrial development. 46 bags of cement is enough to construct about 40 meters (or 125 feet) of concrete city sidewalk. The average concrete and steel commercial building, the predominant choice for most mid- and high-rise buildings constructed in the last century, uses 200 times that much cement. In Canada, the energy intensive cement industry contributes 10 Mt of CO₂e emissions annually.
  • Extracting 15 barrels of oil – Extracting oil from the ground produces emissions even before it is refined, transported, and used. The Canadian oil and gas sector produces 1.6 billion barrels of oil a year which is estimated to produce 104 Mt of CO₂e emissions at the point of extraction. These emissions are in many ways unaccounted-for life-cycle emissions for any oil based energy or products (which includes many daily-use household items), essentially doubling actual emissions for things like gasoline used in a car.

Evoqua’s 12.8 MGD Mempulse® MBR for Star City

Thursday, February 2, 2017 2:00 pm EST

PITTSBURGH & MORGANTOWN, W. Va.

Mayor Marti Shamberger and other local officials today celebrated the commitment of the Morgantown Utility Board to address the present and future wastewater treatment needs of the greater Morgantown community at a groundbreaking ceremony for improvements at the Star City Wastewater Treatment Plant.

The improvements at the facility include Evoqua Water Technologies’ Memcor MemPulse® MBR System which was pre-selected for its reduced footprint, operational simplicity, and ability to deliver consistent, high quality effluent. The $5.8 million project will include five Memcor MBR cells to treat 12.8 million gallons per day at peak flow of wastewater.

The design of the MemPulse® MBR System was a key factor in selecting Evoqua for this project as the city needed to increase capacity in the existing footprint and allow for future expansions. The unique space-saving, modular design of the system allows for more productivity in a smaller footprint. As a result, the city will be able to expand further in the future to treat a total of 20 MGD in the existing plant footprint, based upon its growth needs.

Evoqua’s Memcor® brand products have become an industry leader in the global water and wastewater treatment markets, with microfiltration and ultrafiltration solutions for drinking water, water reuse, wastewater, desalination pretreatment, and industrial process water. The products are in use in thousands of industrial and municipal plants across the world. For more information, visit www.evoqua.com/memcor.