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Water & Wastewater

Evoqua – WateReuse Project of 2017

Evoqua Water Technologies and Air Products, a Los Angeles based hydrogen production facility, installed a brine recovery reverse osmosis technology to reduce water and wastewater impact by up to 75 million gallons a year.

Flint’s water crisis

Pre-trial hearings loom for the former emergency manager and the director of public works of Flint, Michigan. Both have been charged with involuntary manslaughter over their roles in a public-health scandal.

The nearly bankrupt Midwestern city had switched to a cheaper water source, the Flint river. Officials repeatedly dismissed complaints by residents about the brownish, smelly water that came from their taps.

Flint did not treat the river water with an anti-corrosion chemical; when pumped through ageing pipes it exposed the lead, allowing the metal to leach into drinking water.

Babies in particular suffer from exposure to lead, which can lead to learning disorders, hearing loss, aggressive behavior, anemia, kidney damage and lowered IQ. As many as 9,000 children may have been affected.

Flow & TMP Modeling – Ultrafiltration (UF) modules

We know more flow enters at the top of the module than at the bottom. But how much more? Can we determine a set of equations to answer this question?

How about the pressure drop, known as TMP (trans-membrane-pressure)? How does the TMP varies along the height of the hollow fiber?

The answer is positive. Yes we can, and have already done so. Please see below and follow the link at the end of this post to find out the answers.

In brief, by using a second order differential equation, we determined the flow distribution and trans-membrane pressure function of (x).

As an example, using the above Q(x) expression, the following graph demonstrates the significant difference between the flow rate entering at the bottom of the module compared to the top of module (i.e. 0.18 usgpm vs. 1.5 usgpm). Approximately 8 times more flow passes into the fiber lumen of a clean ultrafiltration module at the top of the module than at the bottom.

Several factors are at play, most notably the fiber diameter. When the fiber diameter is reduced in half, the TMP increases sharply from 3.28 psi to 13 psi.

The model can help designers and process engineers better understand the inner workings of the ultrafiltration module; ultimately, designing a better module by optimizing the different variables, such as lumen diameter, number of fibers per module, porosity, height, etc.

Read the full paper in pdf format: Mathematical Model of TMP vs Flow Rate, Viscosity

Please drop us a line to receive a follow-up paper on the correlation between the temperature correction factor determined mathematically and actual test results.

Here’s a quick pick.



Top award for cooling tower steam capture

MIT’s Infinite Cooling won the top Cleantech University Prize at the 10th annual Massachusetts Institute of Technology Clean Energy Prize (MIT CEP), the nation’s largest student-run, clean energy-focused business plan competition.

Infinite Cooling’s innovative, patent-pending technology can reduce power plant water consumption by capturing steam escaping from cooling towers and reintroducing the resulting water into to the cooling system.

This novel technology can potentially save power companies millions per year in water costs.

Not a number to tweet about

Government infrastructure spending in the second quarter fell to 1.4% of GDP, the lowest level on record.

According to Thompson Reuters, investment by American municipalities in the first seven months of this year, at 50.7bn, was 20% below the same period in 2016.

Private-sector infrastructure funds show a similar trend.

The downward trend in both public and private investment suggests the administration’s lack of action has had an additional cooling effect.

Unless the federal government leads the way, there is unlikely to be much new activity.

Cornell tests smart, resilient underground infrastructure


The future looks “smart” for underground infrastructure after a first-of-its-kind experiment testing advanced sensors was conducted June 6 at the Cornell Geotechnical Lifelines Large-Scale Testing Facility. The test was the first use of the advanced sensors for the purpose of monitoring buried infrastructure, and gave an unprecedented look at the pipe’s ability to elongate and bend while being subject to ground failure.

Cornell tests ‘smart,’ resilient underground infrastructure (Cornell Chronicle)

Wastewater Treatment Basics – Video

UF System Design

UF municipal application example (direct filtration, no coagulation)

Design a pressurized Ultrafiltration (UF) system capable of supplying 20 MLD (5.28 MGD) of drinking water (net permeate) from a lake water source characterized by low levels of dissolved organics (< 2 mg/L) and low turbidity (1 NTU typically, with spikes up to 10 NTU).

The system should have a minimum of two (2) trains. One (1) of the trains shall be redundant.

Minimum interval between CIP events shall be 30 days (monthly frequency).

Minimum interval between Maintenance Clean (MC) events shall be 2 days.

The first step is to select a suitable flux rate given the raw water quality and cleaning frequencies at design conditions.

Based on experience, piloting and full scale applications, on similar water quality, a typical flux rate (instantaneous) at design conditions is 50 gfd (85 lmh).

Assuming a UF module with a filtration area of 500 ft^2, each module can process 50 gfd x 500 ft^2 = 25,000 gpd (gallons per day) which is equivalent to 25,000 gpd : 1440 minutes/day = 17.36 usgpm/module (US gallons per minute per module).

In order to supply the desired net capacity of 20 MLD or 5.28 MGD, at least 212 modules are required, per the following:

5,280,000 gpd : 1440 mins/day : 17.36 usgpm/module = 3,666.6 usgpm : 17.36 usgpm/module = 211.2 ~ 212 modules.

The above calculation assumes the system is online 24 hours per day and no additional water has to be processed (filtered) for cleaning (backwash and maintenance clean).

In order to estimate the actual online time (OLT), the following assumptions are made:

a) backwash frequency is once every 30 minutes and takes 2 minutes b) maintenance clean frequency is once every two days and takes approximately 1 hour c) CIP downtime is not included in calculations, as one extra train is provided for redundancy d) 20 minutes are required for the daily integrity test (IT).

The online time can be calculated as follows: OLT = 1,440 minutes – 60 minutes (MC) – 2 x 2  x 23 (BW) – 20 (IT) = 1,440 – 60 – 92 – 20 = 1,440 – 172 = 1,268 minutes per day (approximately 21 out of 24 hours).

The online time percentage (OLT%) is therefore: 1,268 : 1,440 = 88%.

Assuming a recovery rate of 95%, approximately 2.5% (half of the reject or backwash water) represents permeate used for backwash and maintenance clean (MC) operations.

The number of modules would have to increase in order to maintain the same design flux rate (50 gfd), while producing 2.5% more permeate in a shorter amount of time, 1,268 minutes, rather than 1,440.

N_required = 212 x 1.025 : 0.88% = 247 modules (a 16.5% increase).

Next, the above number of modules would have to be divided over the number of duty trains, minimum 2.

The goal is to reduce the number of trains to a minimum, keeping in mind that minimizing the number of duty trains would result in a larger redundant train (more modules overall and higher cost).

My preference would be for a 3 duty + 1 redundant (4 x 33%) design to minimize the number of modules and the flow fluctuations when trains is taken offline for cleaning.

Since it is preferable to choose the number of modules per train in multiples of four, one could select either 80 modules per train (3 x 80 = 240, resulting a 3% higher flux rate), or 84 modules per train (3 x 84 = 252, 2% lower flux).

Considering N_selected84 modules per train, the total number of modules, including those installed on the redundant train, would be: 4 x 84 = 336 modules. Should we have selected only two (2) duty trains, the total number of modules would have been: 252 : 2 x 3 = 378 (42 extra modules).

In actual production, all four trains are online producing permeate (drinking water). Based on an average flow rate, usually half of the design capacity (10 MLD or 2.64 MGD), the average flux rate becomes approximately 18 gfd (36% of our original design flux of 50 gfd).

In the next post, we will evaluate the capital and operating cost of such system, along with the life cycle analysis over a 20-year horizon.

Should you have any questions regarding UF sizing and design, please feel free to drop me a line at:




ADI-BVF® reactor helps Ohio cheesemaker reduce sludge, energy and operational requirements

Location: Middlefield OH, USA • Sector: Food & Beverage

The Client:

Since 1956, Rothenbühler Cheesemakers has been producing delicious cheese using all natural ingredients and 100 percent Grade A milk. Formerly known as Middlefield Cheese, the family-owned company is one of the largest Swiss cheese manufacturers in the United States. Its plant in Middlefield, Ohio, USA, produces five Swiss cheese varieties, as well as high-quality whey ingredient products.

The Client’s Needs:

Rothenbühler Cheesemakers prides itself on adhering to strict environmental practices, blending the cheese making artistry of the past with modern day innovation. The company’s USDA-approved, SQF (Safe Quality Foods) certified facility was already using ecofriendly “green” initiatives to recycle on-site resources. The company wanted an on-site solution to anaerobically pre-treat raw wastewater, thereby remaining environmentally-responsible and reducing its carbon footprint.

The Solution:

ADI Systems was selected to design, install, and commission an anaerobic wastewater treatment system for Rothenbühler Cheesemakers’ plant in Middlefield. The system consists of a 230,000 gallon equalization (EQ) tank, which pumps wastewater into an in-ground 6.8 MG ADI-BVF® reactor. Anaerobic effluent is discharged by gravity to the existing downstream membrane bioreactor (MBR) system for aerobic polishing. The project also included construction of a control/electrical equipment building.

The large volume of the BVF® reactor provides a robust and diverse anaerobic microorganism community, making the system resilient to variations in influent characteristics such as organic load, influent solids concentrations, pH, temperature, and alkalinity. As wastewater passes upward through the sludge blanket, microorganisms digest the majority of the organic load, reducing chemical oxygen demand (COD), total suspended solids (TSS), and fats, oils, grease (FOG). The low-rate system is designed to treat 600,000 gpd of wastewater. The anaerobic digestion process continuously produces biogas, which is collected beneath the reactor cover and delivered to a standard biogas flare and/or utilization system.

The Results:

The wastewater treatment system that ADI Systems engineered for Rothenbühler Cheesemakers has simplified and improved process efficiency. The BVF® reactor can directly digest raw wastewater (no DAF or other FOG or TSS removal is required), and requires very little electrical horsepower, helping lower operational costs. Aeration energy and chemical requirements for the existing aerobic system have also been reduced.

We are thrilled to be able to process our wastewater responsibly. The BVF® reactor supports our vision of a well-ordered, efficient, and technically advanced system,” says Gary Schoenwald, CAO, Rothenbühler Cheesemakers. “The wastewater treatment system reduces our electrical consumption, provides biogas to supplement our existing plant heating, reduces bio-solids production, and ultimately reduces our carbon footprint.

The BVF® reactor at Rothenbühler Cheesemakers is designed to remove approximately 90 percent of the influent COD. The reactor’s long solids retention time (SRT) and hydraulic retention time (HRT) ensure complete biodegradation of the raw organic compounds, thus higher biogas production can be achieved. At design conditions, approximately 320,000 ft3 (9,000 m3) of biogas is captured per day. This biogas is utilized at a new dual-fuel boiler in the production plant, further minimizing costs for the cheesemaker.

This project was a success due to the attention to detail that we experienced from ADI Systems’ staff—everything from the concept drawings through to installation and startup,” says Schoenwald. “We have seen significant savings in our electrical consumption and expect exceptional savings as well from the use of the biogas.

Balfour Beatty, Atkins, Mott MacDonald and WSP Strategic Partnership

Balfour Beatty, the international infrastructure group, today announces the formation of a collaborative UK Strategic Design Consultant Partnership with Atkins, Mott MacDonald and WSP.

This mutually beneficial partnership will foster a new level of openness, collaboration and innovation never before seen within the construction industry.

The Partnership will focus Balfour Beatty’s procurement of design consultants for its projects towards Atkins, Mott MacDonald and WSP with standard terms and conditions. A community of practice will bring designers and engineers from the four companies together to find solutions in key areas such as health and safety through design, value engineering and the use of more cost-effective design resources.

Customers will benefit from earlier engagement with a co-ordinated collaborative team and improved, consistent working practices which will ultimately reduce construction and programme costs.

The Partnership will be led by Balfour Beatty’s newly-appointed Strategic Design Consultant Partnership Director, Robin Bashford. Robin will be responsible for implementing the Partnership working with the three design consultants to deliver increased value to customers. Prior to his appointment, Robin held a senior work winning role within Balfour Beatty’s Major Projects business and has been with the company since 2013.

Stephen Tarr, Managing Director for Balfour Beatty’s Major Projects business and Executive Committee Sponsor for the Partnership, said:

This newly formed Strategic Design Consultant Partnership represents collaboration in its purest form. Providing a new and refreshed way of working between contractor and designer, I am delighted to announce that we are joining together with Atkins, Mott MacDonald and WSP to deliver the very best of the industry’s ability and capability to provide a complete, refined and Expert offering to our customers.

This Partnership will draw on decades of industry experience and combine it with the modern-day technological expertise of our engineers and designers to deliver a truly Lean, Expert, Trusted and Safe way of working together as an industry.

Mike McNicholas, Managing Director of Atkins’ Infrastructure division, said:

Infrastructure investment continues to be a high priority for the UK, but clients couldn’t be clearer in their message to industry that we need to deliver it differently to provide better value and outcomes for them, their end users and those funding the projects. A greater use of technology is widely acknowledged as one way of doing this, but equally as important will be industry leading companies coming together to innovate and collaborate more effectively. This Partnership is an exciting step forward in achieving these goals.

Stephen Lawrence, Mott MacDonald’s Design Partnership Director said:

Our collaboration with Balfour Beatty goes back nearly 35 years and we’re looking forward to building an even stronger working relationship. We’ve worked together to successfully deliver some of the UK’s most well-known infrastructure such as Heathrow T2B, A3 Hindhead and London Underground’s Jubilee Line Extension, and our joint venture Balfour Beatty Mott MacDonald continues to provide service excellence in the highways maintenance industry.

This strategic partnership will provide access to our global network of experts to offer new ideas, drive value and efficiency into the design process and fully support their ‘Build to Last’ transformation programme, Stephen added.

Alistair Kennedy, WSP’s Executive Director responsible for the new partnership said:

We are delighted to have been selected by Balfour Beatty as a strategic partner. Our two companies already work closely together across a wide spectrum of projects and WSP is excited to have the opportunity to be part of this innovative and collaborative approach. We look forward to working together to challenge the status quo for design build contracting in the UK.

Balfour Beatty

Balfour Beatty (www.balfourbeatty.com) is a leading international infrastructure group. With 30,000 employees, we provide innovative and efficient infrastructure that underpins our daily lives, supports communities and enables economic growth. We finance, develop, build and maintain complex infrastructure such as transportation, power and utility systems, social and commercial buildings.
Our main geographies are the UK, US and Far East. Over the last 100 years we have created iconic buildings and infrastructure all over the world including the London Olympics’ Aquatic Centre, Hong Kong’s first Zero Carbon building, the National Museum of the Marine Corps in the US and the Channel Tunnel Rail Link.

Atkins (www.atkinsglobal.com) is one of the world’s most respected design, engineering and project management consultancies, employing some 18,300 people across the UK, North America, Middle East, Asia Pacific and Europe. We build long term trusted partnerships to create a world where lives are enriched through the implementation of our ideas. You can view Atkins’ recent projects on our website.

Mott MacDonald

Opening opportunities with connected thinking. Mott MacDonald is a US$2bn engineering, management and development consultancy. We’re involved in:

solving some of the world’s most urgent social, environmental and economic challenges
helping governments and businesses plan, deliver and sustain their strategic goals
responding to humanitarian and natural emergencies
improving people’s lives
Our expertise by sector includes buildings, communications, defence, education, environment, health, industry, mining, oil and gas, power, transport, urban development, water, wastewater and more. Our skills encompass planning, studies and design, project finance, technical advisory services, project and programme management, management consultancy and beyond. For every project, we create the blend of talent needed to create the right result – appropriate; cost, carbon and resource-efficient; safe, easy and swift to deliver and operate; reliable and resilient; delivering great outcomes.

Engineering. Management. Consultancy. mottmac.com


WSP is one of the world’s leading engineering professional services consulting firms. We are dedicated to our local communities and propelled by international brainpower. We are technical experts and strategic advisors including engineers, technicians, scientists, architects, planners, surveyors and environmental specialists, as well as other design, program and construction management professionals. We design lasting solutions in the Property & Buildings, Transportation & Infrastructure, Environment, Industry, Resources (including Mining and Oil & Gas) and Power & Energy sectors as well as project delivery and strategic consulting services.

With 7,000 talented people in the UK (including Mouchel Consulting) and 36,000 globally, we engineer projects that will help societies grow for lifetimes to come. WSP has been involved in many high profile UK projects including the Shard, Crossrail, Queen Elizabeth University Hospital, Manchester Metrolink, M1 Smart Motorway, the re-development of London Bridge Station, and the London Olympic & Paralympic Route Network. www.wsp.com/uk