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Miguel Agawin

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presentation

By Christine Hill and Jessica Marra, Cole Engineering

The backbone of all consulting engineering firms is a strong technical and design staff that has the expertise and experience necessary to problem solve. It wasn’t long ago that firms hired talented young staff and developed their skills and expertise over many years. But, changes in our industry have resulted in a loss of talented younger staff to the public and other sectors.

Some have left for work/life balance, while others have sought different opportunities. In addition, regular career and employment changes or job-hopping are now the norm with many workers, both young and older. Recent surveys (Globe and Mail, 2014) have identified that 51% of workers in Canada now stay in a role for less than two years, and that only 30% of workers in Canada stay in the same job for four years or more. The result is increased pressure on consulting firms to develop and maintain their key work forces, by providing career development opportunities, training and mentoring.

Multi-faceted programs that combine mentoring, formal training and exposure to a variety of business and practice areas can engage and encourage young graduates to continue as consulting engineers. These can include:

  • Exposure to different practice areas, enabling new graduates to find their passion within our industry;
  • Internal and external mentoring programs to provide technical, business and career advice;
  • Formal internal and external training programs that are individualized and build on the skills and attributes of the individual. These programs can also be tailored to meet the needs of individual engineers, identified through Professional Engineers Ontario’s PEAK program which requires ongoing training to maintain a level of knowledge and skill commensurate with safeguarding public interest.

Like many other companies within the industry, Cole Engineering (COLE) is facing challenges related to demographic changes. Knowledge transfer from retiring employees to younger project team members, as well as meeting the life/work balance that so many of our younger employees are looking for, are two of the most pressing challenges.

We have recognized the importance of developing younger engineers and have implemented comprehensive actions to support this. Following significant changes in our executive team and the development of a new Strategic Plan, COLE leadership engaged younger engineers. A new Young Professionals Group (YPG) was formed and broad consultation with younger employees was completed during the Strategic Plan development.

To gain input from younger employees, an anonymous survey was completed by 60% of the YPG. The survey asked YPG members to identify the most important issues in the workplace. The four most popular issues were opportunities for advancement, competitive compensation and benefits, promotion of life/work balance, and a strong office community and culture.

Figure 1
Figure 1: Issues of importance and dissatisfaction levels.

YPs also ranked their level of workplace satisfaction as part of the survey. Figure 1 shows the ranked issues of importance and also shows the percentage of staff dissatisfied with these issues.

On a more specific level, YPs also provided information on what gave them job satisfaction on a day-to-day basis. It was found that camaraderie with coworkers, followed by working on well-managed projects, were ranked as the most important factors. Based on level of dissatisfaction rankings, working on well-managed projects was identified as being a priority for areas of improvement. (See Figure 2)

Figure 2
Figure 2: Job satisfaction rankings.

Finally, YPs were asked to select three aspects of a manager/supervisor they saw as most important. Overwhelmingly, these were capabilities for mentoring, empowering workers and providing clear direction. COLE executives carefully reviewed the results and decided to implement the recommendations throughout the company.

As a result, the Strategic Plan addresses four key areas associated with the retention and development of its young professionals, including robust recruitment of new graduates, providing opportunities for social and team building, and professional development and training. Since the implementation of the Strategic Plan, achievements have been immediate and dramatic.

Graduate recruitment

The new graduate recruitment process was broadened and now includes young professionals. Together with Human Resources, our young engineers now attend career fairs, local association events and participate in student design competitions for universities and associations. COLE’s YPs judged final year design projects at the University of Guelph. COLE has been recognized for its efforts and won the University of Guelph’s Co-op Employer of the Year award.

We have recognized that not all new graduates have a clear idea of the type of work they would like to be doing in our industry. As a result, we launched a rotation program where new graduates rotate between four different technical groups during the first year of their employment. With the knowledge gained over their first year, these employees are better equipped to select the career direction and technical area they are best suited for.

Social and team building

The importance of team building has been expanded with more technical, professional and social events geared to all employees, including YPs. Weekly events, held during and after work hours encourage team building amongst employees. Some of our more popular social events have included snack and chat events, social hours and barbecue events. COLE is also a strong supporter of Water for People and has held well-attended Water for People charity events.

In 2017, we held our first company-wide conference and encouraged YPGs to present interesting technical projects to the company. “Collaboration” was about sharing ideas and experience amongst all staff and recognizing their accomplishments through a variety of awards. As part of the conference, outside speakers representing our clients, suppliers and contractors, were engaged to provide their knowledge and experience to the company.

Professional development and training

COLE is investing in its younger workers by providing training for key skills, encouraging involvement in industry associations, and providing comprehensive on-the-job training in a wide variety of technical areas. Regular training sessions on key business skills, such as business development, communications, presentation skills, proposal writing and networking, have been held.

In addition, YPs are encouraged to give presentations at conferences. Organized field trips have also been held to expose YPs to other business areas and demonstrate key aspects of projects, from planning and design through implementation.

Summary

Consulting firms depend on the knowledge and skills of our staff to meet our client commitments and to grow our businesses. We must meet the challenge of an increasingly mobile workforce by training, developing and retaining our staffs through robust multi-faceted programs that combine mentoring, formal training and exposure to a variety of business areas.

Christine Hill, P.Eng., is Business Development Leader and Jessica Marra, EIT, is Co-Chair of the Young Professionals Group, Cole Engineering. This article appears in ES&E’s December 2017 Issue.

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ISE cleaning
Cleaning the ion selective electrode should be done with a soft bristle brush.

By Rob Smith

Wastewater treatment plants rely on instrumentation to keep their facilities in compliance and running at optimum levels. Processes that have historically been labour-intensive and time-consuming, have in recent years become increasingly automated.

One such advancement is the use of ion selective electrodes (ISE) as part of an online monitoring and control system. ISEs are electrochemical sensors, incorporated into probes that can be placed directly in the process. This makes them ideal for continuous online operation. A pH probe is one type of ISE that has been used as part of online process monitoring systems for decades, to provide a general indication of the progress of wastewater treatment. But, capturing data for other parameters, such as ammonium and nitrate, has been relegated to laborious and offline methods of analysis, such as colorimetry used with grab samples.

It is only within the past 10 years or so that ISEs for measuring other more specific parameters have become available for incorporation into an online process. The primary advantage of using ISEs online is to obtain meaningful data about individual parameters, using an economical technology that does not require replenishment of reagents.

Cost savings

Having real-time and reliable data on monitoring specific substances, like ammonia and nitrate, is critical for plant operators. Using an online system that ties the data directly into the facility SCADA to help control the process can be a real asset. As an example, wastewater treatment plants typically address nitrification by turning on or turning up aerators, or address denitrification by adding chemicals to anoxic zones. Whatever adjustments need to be made, there is money spent on energy or chemicals, and it can add up significantly over the course of a year.

Using ISEs as part of an online solution provides reliable real-time data, and can lead to substantial savings by fine-tuning and controlling the process. Reliable data can also help a wastewater plant stay in compliance, avoiding steep fines from regulating authorities.

Reliable data versus accurate data

Years ago, accurate measurement of ammonia and nitrate in the wastewater lab provided useful data for the facility. Continuous measurement of ammonium and nitrate concentrations with online ISEs is an important transition for facilities to make, as it creates process control opportunities. It is important to note that with process sensors, repeatability is the objective, not necessarily accuracy.

Published accuracy specs for process sensors are not relevant once the sensor is out of the box. Accuracy is very dependent on the sample matrix, which varies with the application. Therefore, users should focus on obtaining reliable data with repeatable results.

Achieving reliable measurements

To ensure reliable measurements with online process ISEs, it is important to take the necessary steps to set up and install the sensor correctly, and to provide proper and routine maintenance over the life of the instrument. This typically includes routine verification measurements which can be determined with a second method, e.g., colorimetry in the lab.

If the difference between the sensor and the lab measurement is greater than an acceptable tolerance, e.g., +/– 10% or +/– 0.2 mg N/L, depending on the application, a matrix adjustment is required. The matrix adjustment is a typical procedure for correcting the ISE sensor calibration, and is required as part of commissioning the measuring system and as necessary thereafter.

Matrix adjustment execution varies with the manufacturer, but the basic procedure consists of matching the online sensor measurement with a reference laboratory measurement on a grab sample as follows:

1. Clean the electrodes. Electrodes in wastewater are especially prone to biological fouling. Routine manual cleaning is essential even with supplemental automatic air cleaning devices installed. The best cleaning agent is process water. Soaps, detergents, and even deionized water can damage the membrane and shorten electrode life. Scrub the electrode surface with a soft bristle brush (a toothbrush is perfect). The probe body can be cleaned with warm water and a brush.

2. Take notes. Record the sensor values just prior to sampling for comparison to reference measurements. Recorded data should include both concentration in mg/L and the raw signal in mV. Some monitoring systems will store the value of the raw signal for each electrode and automatically match them to new reference concentrations determined in the lab. These values are entered manually, or uploaded into the monitoring system.

3. Sampling. Using a sample dipper, collect a sample as near to the position of the electrodes as possible. Rinse the dipper a couple of times before sampling to remove contamination from previous sampling events. Immediately filter the sample through a 0.45-micron filter into a clean, disposable sample vial to remove bacteria, which will quickly alter sample composition. A delay of even 10 minutes can alter the composition of the sample and invalidate reference measurements, especially in warm water.

Ammonia and nitrate are dissolved and will pass through the filter. Collect a filtered volume sufficient to allow measurement of each parameter with a suitable laboratory method. Generally, this will be less than 30 mL.

4. Measurement and evaluation. Analyze filtered samples in the lab for ammonia and potassium (for compensation) and nitrate and chloride (for compensation) as necessary, using appropriate methods, e.g., colorimetry. It is tempting to skip verifying the compensation parameters. However, these measurements are critical for monitoring system performance. Evaluate duplicate or triplicate measurements as necessary to determine the most likely concentration.

5. Update and check. Enter the new reference values and matching sensor values into the monitoring system. Compare the concentrations and values of raw signals from previous calibrations to evaluate the matrix adjustment and gain insight into the status of the electrodes. The concentration should vary proportionately with the signal.

Changes in the wastewater matrix, errors in sampling and analysis, and aging and contamination of the electrode can cause the raw signal (mV) to drift independently from changes in the measured concentration. Some monitoring systems do the math automatically and record the information as part of the calibration history.

Frequency of matrix adjustments depends on the application, the design of the sensor, the age and history of the sensor, and the veracity of reference measurements. Typical intervals vary from weekly to every three months or longer.

Rob Smith, PE, BCEE, PhD, is with YSI, a Xylem brand. This article appears in ES&E Magazine’s December 2017 issue.

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The Greenway wastewater treatment plant in London, Ontario.

Sludge dewatering is achieved using two centrifuges that operate continually, while one is in standby mode.
Sludge dewatering is achieved using two centrifuges that operate continually, while one is in standby mode.

By Daniel Lakovic

Located along the Thames River, London Ontario’s Greenway wastewater treatment plant takes in sludge from six other city treatment facilities. Upon arrival, sludge dewatering is achieved using two C7E Flottweg centrifuges.

In 2012, the Greenway plant decided to replace its belt presses with Flottweg centrifuges.

“Sludge dryness can greatly affect overhead,” said Geordie Gauld, division manager at the Greenway plant. By increasing sludge dryness from 24% to 25%, the plant was able to burn it in incinerators without the aid of natural gas. This results in an annual savings of about $700,000. “The centrifuges are also producing cleaner and more consistent centrate,” said Gauld.

The plant currently treats approximately 17,000 dry tons of sludge per year. After it is burned, left over ash is hauled to a nearby landfill.

“Odour control was an issue,” said Angelo Marcoccia, maintenance manager at the Greenway plant. “With a centrifuge, everything is contained, which greatly reduces odour. This also cuts down on the mess that resulted with the belt presses, which frequently spilled.”

There are three C7E Flottweg centrifuges reside in the plant. Two operate continually, while one is in standby mode. The machines are rotated into standby on scheduled intervals, at which point they are taken through preventative maintenance.

Flottweg’s engineering staff analyzed the plant’s process and incorporated ancillary equipment into the control system provided. For example, the sludge feed pumps and polymer feed systems are controlled by Flottweg controls.

The changeover from belt presses to centrifuges was not entirely seamless. For example, polymer consumption increased and centrifuge parts tend to be more expensive than belt press parts.

However, these added costs were more than offset by the natural gas savings and the fact that there are fewer wear parts in a centrifuge, which makes repairs faster, lowering labour costs. The biggest offset is that the centrifuges remove more moisture, which in this case reduces incinerator demand.

During startup, the plant did experience a bearing failure on a centrifuge. With Flottweg’s help, it was determined that the culprit was an incorrectly sized centrate line. Since the plant installed a larger line, the machines have been running without issue.

In the past, energy consumption was a big concern with centrifuges. However, the electric motors driving centrifuges have become more efficient. Also, centrifuge technology has evolved to harness spin to create more spin. One such innovation was Flottweg’s Recuvane® which was introduced in 2012.

Within a centrifuge, energy is required to accelerate the separation medium to operating speed. The liquid separated from the solid is normally discharged without pressure. This means the energy contained in the liquid is lost. The Recuvane system enables this rotational energy to be recovered by targeted centrate discharge, thus supporting the main drive and reducing energy consumption. It is possible to save 10% to 20% of the work energy, depending on the pond depth and sludge composition.

Water mills and turbines also use this principle to harness flowing water energy to perform work.

Further centrifuge improvements include the optimization of the drive system, or more specifically, the differential speed between the decanter bowl and decanter scroll. Differential speed determines the length of time the solid remains in the bowl, and thus has a significant influence on the separation process. The bowl and differential speeds can be adjusted independently of one another during ongoing operation. This control is only possible with a special transmission mechanism.

In 1995, Flottweg invented this special transmission mechanism and called it the Simp-Drive® (i.e., special planetary epicyclic gear unit).

Conclusions

The change from belt presses to centrifuges helped the Greenway plant regain reliability and consistency of the system and is expected to cover demand for the next 20 years. The system has helped reduce costs and simplify operations. According to Marcoccia, the C7E machines are much easier to work on from a maintenance perspective.

Daniel Lakovic is with Flottweg Separation Technology. This article appears in ES&E Magazine’s October 2017 issue.

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Pump impellers come in a variety of configurations.

Combined pump station for stormwater and wastewater.
A combined pump station for stormwater and wastewater.

By Mehran Masoudi

Solid and fibrous materials in wastewater streams can block or clog pumps, valves and piping systems. Abrasive materials, such as sand, can cause premature wear in pump components.

Large flow variations, especially those that are encountered in pump stations that need to deal with a combination of wastewater and stormwater, can make it impossible to keep pumps running in their most efficient operating range. Low velocity flows in pipes and tank structures can lead to solid wastes settling out into hard-to-move masses, while very high-velocity flows can cause air entrapment and cavitation at pump intakes.

While it is impossible to prevent all such problems, there are ways to prevent some of them.

Screens are the first line of defence

Clearly, the best way of dealing with solid materials in the waste stream is to intercept and remove them before they can get into the wastewater treatment process. Screens are very effective at this task and care should be taken to keep them clear and in good repair.

Settling basins near the plant intake are also very valuable, since they allow dense, fine-grain solids, such as sand, to settle out before they come into contact with machinery.

Chose the right pump configuration for the job

Some pump/impeller combinations are better at handling solids-laden wastewater streams. Pumps with large free passages can pass relatively large solid objects without becoming blocked. Special impellers, such as the KSB’s D-impeller, have specially contoured leading edges to help avoid becoming clogged with tangles of fibrous materials. Vortex, or free-flow impellers, such as KSB’s newly-designed F-Max model, offer large free passages and are effective when pumping fluids with high levels of dissolved gases.

A key to optimizing pumping efficiency is to match pump characteristics to local operational requirements. Manually clearing blocked pumps can be very time and resource consuming. Pumps intended to handle raw or minimally screened sewage should be selected with good anti-clogging characteristics in mind. Pumps installed at the later stages of the wastewater treatment cycle are less likely to encounter solid materials and can be fitted with impellers that deliver good energy efficiency.

“Chopper”, “grinder” or “cutter” impellers are designed to break up solids into smaller pieces that can pass through the pump without causing blockages. However, when solids are broken into smaller bits, they can more easily pass through screens. This means that they become harder to separate from the waste stream and can cause problems with downstream biological digestion processes.

Keep things moving

In many pumping applications, low flow rates are regarded as a good thing, since they reduce friction losses. For wastewater though, low flows can lead to sludge material settling out in tanks, wells, or in awkward places in the piping system. Careful design of pump stations and related piping systems can keep flow rates high enough that solids are kept in motion. Low flow rates, which implies running on the far left side of the pump’s characteristic curve, can cause cavitation at the discharge nozzle.

Very rapid flows can also cause problems, such as excessive turbulence, the formation of vortices and the entrainment of air in the stream of water entering the pump station. These can create uneven, two-phase flows near the pump suction nozzle and result in rough running and damage due to cavitation.

Avoiding these flow-related problems requires careful design of pump station structures and piping systems.

Stormwater plus wastewater?

Facilities designed to handle a combination of wastewater and stormwater can be difficult to design, considering the extreme variation in flow rates between “normal” and “peak storm” conditions. They should be designed with separate sewage and stormwater sections. The sewage section is relatively small, designed to deal with the lower “normal” wastewater flows and maintain minimum flow velocities. The stormwater section is large enough to handle extreme conditions. Incoming water normally enters the sewage section. It only flows into the stormwater section when volumes exceed the capacity of the sewage section.

A “dissipation chamber” in the stormwater section allows turbulent inflows to settle before they reach the pump intakes. Splitter plates between the pumps keep turbulent flow conditions that might become established near one pump intake from affecting neighbouring pumps.
Multiple pumps make it easier to manage highly variable flow rates. The number of pumps turned on would depend on the volume of water that must be handled. Each running pump would be operated near to its best efficiency point.

Mehran Masoudi is a Project Engineer with KSB Pumps Inc. This article appears in ES&E Magazine’s October 2017 issue.

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Water and wastewater systems have hundreds or even thousands of painted assets, including: pipes, pumps, valves, actuators, motors, etc.

By Paul Makar

Oxidizing and neutralizing chemicals, as well as misty, wet and damp conditions, contribute to an aggressive corrosive environment in water treatment plants. In wastewater treatment plants, there is also a corrosive cocktail of bacterial decomposition of fecal and other matter and varying pH levels.

Water and wastewater systems have hundreds or even thousands of painted assets, including: pumps, valves, actuators, motors, process skids, stairways, pump stations, piping systems, elevated potable water towers, standpipes, above ground reservoirs, etc.

Slowing down and ultimately stopping the corrosion process is certainly achievable and affordable, provided sound steps are taken.

Specific coating systems selected for their bonding, overcoating and moisture-tolerant attributes must be the first priority. These are somewhat more expensive, but will outperform and outlast conventional coating systems, resulting in a savings in both labour and material costs. The selection of a quality coating system will slow down the corrosion process.

If the coating system is left unattended and not periodically maintained on any and all components, hundreds of thousands of dollars will ultimately need to be spent to refurbish and restore them.

With periodic inspections, good record keeping that tracks the coating deterioration over specific time frames, and scheduled maintenance painting, there will be substantial savings. However, keeping track of coatings and corrosion issues is a daunting task of inspection, setting priorities for areas of concern, and managing costs for remediation within an annual budget.

PW Makar Coatings Inspection Ltd. has developed a coatings and corrosion assessment program, specifically tailored to water, wastewater and water transmission system facilities for municipal, private and industrial operators.

Selected areas within water, wastewater and water transmission system facilities are audited annually for their coatings and corrosion “condition levels”. The coatings and corrosion assessment program will inspect all painted assets located in the selected buildings, rooms, galleries, chambers, and elevated towers. This is a yearly program and assets inspected will be re-inspected every three to five years, depending on location and level of exposure to corrosion-causing factors.

A coatings and corrosion condition level is assigned to each painted asset. This format helps to identify assets that are in a newly painted state, ready for minor maintenance painting touchups, or a more aggressive surface preparation and the utilization of a multi-coat painting system. It will even identify safety issues, such as an asset that has lost enough metal due to corrosion to render it unsafe for further use.

The type of coating system, the colour of the top coat, the amount of dry paint film thickness and whether or not the asset has lead in its pigment can also be identified for a painted asset. Any environmental issues are noted. Is the area damp and wet? Does the area get flooded? Is the HVAC system working properly? Are there any contamination issues, i.e., oil, grease or fuel on the surface of the painted asset?

If a painted asset’s coating system has failed, an explanation as to the root cause of the failure is determined. Each asset is then photographed, which helps to visually identify the type and size of the asset and the health of its coating and corrosion tolerance.

Information gathered from the painted asset field audits are downloaded into a customized database program, where the painted assets are organized and prioritized from “pristine” to “complete failure” and requiring immediate remediation based on a percentage of deterioration. The database program assigns paint specifications to each asset based on the assigned paint condition level. The estimated labour and material cost to repaint and bring each asset to a “like new” state is also assigned.

The coatings and corrosion assessment program report package is delivered to the client, facilities managers and supervisors. It consists of hardcopy binder reports and electronic copies, which have all of the painted assets identified and categorized. A summary of the painted assets from that year’s audit is outlined in key performance indicators such as “paint health” and “general plant health”, utilizing charts and graphs.

These methods highlight where to focus resources to combat coating deterioration and corrosion issues, and demonstrate overall deterioration trends.

For the first time, water and wastewater managers have a tool to show where they have spent maintenance budget money, why they need more, and to demonstrate how well they are doing in the battle to fight corrosion and keep control of costs.

Before a coatings and corrosion assessment program can be implemented, a data collection and labeling program must be conducted. Each asset must have a specific numerical identifier assigned to it, which clearly defines one asset from another. This data collection process can be quite simple for small rural facilities in which only critical operating equipment has data and labeling assigned to it. Data collection can be much more robust for facilities which have thousands of painted assets.

A team of data collection specialists catalog and label each asset. That captured asset is then downloaded into a sophisticated computerized database program that identifies the make, model and operating parameters of that asset.

A scheduled preventative maintenance inspection plan is assigned to the labeled asset, which is routinely inspected and maintained to ensure that it is in ready-for-service condition.

With the continuing use of aging infrastructure, the “paint it and maintain it” philosophy maintains plant heath, saves maintenance dollars, frees up staff time, extends the life of the asset, and flags corrosion deterioration issues before metal failures and unsightly rust blemishes can occur.

Paul Makar is with PW Makar Coatings Inspection Ltd. This article appears in ES&E Magazine’s October 2017 issue.

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Schematic of a bio-electrode system.

By Dr. Colin Ragush, Dr. Patrick Kiely and Jack Ambler

Bio-electrode sensors (BES) are an emerging technology for the monitoring of water quality. They allow the user to put their finger on the pulse of the metabolic activity of a microbial community. The concept of BES technology is not new, with the research into microbial fuel cells dating back over a century.

Thanks largely to technical advancement and cost-effective components, the technology is only now becoming attractive for wastewater applications. The most recognizable BES technology is the microbial fuel cell that harnesses the energy produced by exo-electrogenic bacteria when they consume organic compounds to produce electrical energy.

The basic architecture of a BES system is an anode/cathode pair, with a resistor positioned between them. Exo-electrogenic microbes on the anode oxidize organic material in the wastewater and the electrons are transferred to the cathode through the circuit. Protons (H+) created at the anode migrate to the cathode to recombine with the electrons which have travelled through the circuit, creating a complete electrical circuit. Electrons travelling through the resistor are measured and logged.

Protobacteria, such as those from the Geobacter genus, typically colonize the anode and oxidize organic carbon material. Through metabolic pathways that evolutionarily predate the presence of atmospheric oxygen, these bacteria can use the metallic anode as an electron receptor.

Monitoring of the microbial derived electrical current provides novel real-time insight into biological treatment rates and efficiencies. The data generated can also provide rapid insights into water quality characteristics.

Standard BES probe and data acquisition system used for this study.
Standard BES probe and data acquisition system used for this study.

BES sensors are attractive because they have low power and maintenance requirements, and provide novel data on microbial activity that can be leveraged in wastewater process optimization. They can be installed in a similar fashion to a standard wastewater probe (either submerged in a tank or installed in a pipe). All that is required for maintenance of a pre-inoculated probe is a regular supply of soluble organic material for the resident microbial populations. Therefore, the probes must be maintained in a proprietary synthetic wastewater when not being used for measurement.

Output from the sensor is a voltage measurement, which is typical of other sensors such as pH, conductivity or ORP. The standard signal output being a voltage signal allows for BES sensors to be easily integrated into an existing data acquisition system or a developed SCADA system. In addition, the low power requirement means that BES sensors are attractive for remote locations or in situ water quality monitoring.

Island Water Technologies recently launched the first commercial BES platform, SENTRY-AD™. It monitors microbial activity in anaerobic digesters to aid in process optimization and stability. For this research project a standard SENTRY-AD probe was used in a bench-scale setting to determine if there was a relationship between the signal generated by the probe and carbonaceous biochemical oxygen demand (CBOD5) of a wastewater sample.

The project’s hypothesis was that the metabolic activity recorded from the exo-electrogenic bacteria, as measured by the BES, would be directly correlated to the presence of biologically oxidizable organic carbon in a water sample. Traditionally, the biologically oxidizable organic carbon is quantified by the consumption of oxygen in Wheaton bottles over five days (the CBOD5 test). It was hypothesized that a BES sensor’s output would be an analogous means of measurement of CBOD5.

In this study, the relationship between BES output and CBOD5 concentration was confirmed, and a strong linear relationship (R2 = 0.98) between the total charge transferred and the CBOD5 concentration (standard Wheaton bottle method) was identified.

Replacement of the current standard method is of interest because it requires five days and skilled lab personnel to obtain precise and accurate results. Also, setup of the test is relatively time-consuming (two hours) which makes the test less practical when regularly running a small quantity of samples, and impractical in remote locations. A BES sensor that is effective for quantification of CBOD5 would liberate the measurement from a lab setting, and the real-time quantification would create the potential for optimization of wastewater treatment trains, based on real-time influent and effluent water quality.

In this experiment, the sensors were run as batch reactors with regular flushing of the probe with buffered solution between each test. The response of the sensor was recorded until it fell to background levels (deemed to be caused by endogenous respiration). After this period, a feed synthetic wastewater was put in the cup to sustain the microbial community until another sample was prepared.

Bench-scale testing was performed on a synthetic wastewater with sodium acetate as a source of CBOD5, and on domestic wastewater samples collected directly from the septic settling tank at Dalhousie University’s Bio-Environmental Engineering Centre. Wastewater at the collection site has already undergone settling and is low in solids (5 concentration was created from the domestic wastewater samples by diluting samples in phosphorus buffer with the addition of minerals and nutrients.

Two metrics were used to create a relationship with CBOD5: total charge transferred (integrated current); and max current. A strong linear relationship between charge transferred and CBOD5 concentration was found, with the domestic wastewater relationship having an R2 of 0.98. A relationship between the maximum current CBOD5 was also apparent. However, it was non-linear and only a maximum measurable concentration of 25 mg/L CBOD5 when sodium acetate was the carbon source and 80 mg/L CBOD5 with domestic wastewater. The limitation on the quantification of CBOD5 is a satiating response (biological limitation). However, when using total charger transferred to quantify CBOD5 there were no identifiable limits for total charge response.

Analytical processing times for max current output were near-instantaneous after inserting a sample. The relationship of max current output with CBOD5 concentration suggests that further BES development has the potential to provide continuous real-time measurements of CBOD5 from an in situ installation. Using this sodium acetate based, synthetic wastewater, the satiating response in maximum current was identified at approximately 25 mg/L CBOD5, representing the maximum biological uptake rate for this exo-electrogenic biofilm.

A Monod-type relationship was examined as a fit for the max current data but it was a poor fit, suggesting that the response limitations are not a simple substrate limitation. More in-depth analysis of the relationship will provide avenues of investigation to improve BES sensor architecture.

Analysis time for total charge transfer for the domestic wastewater was linearly dependent on CBOD5 concentration with an R2 = 0.95. This was an anticipated result as the measurement of charge transfer is complete when the organic substrates are consumed.

The results of this work are very encouraging for the potential of BES to act as real-time tools for monitoring CBOD5 concentrations in wastewater streams. The data shows a strong correlation between both the instantaneous current and charge transfer with CBOD5. Improvements of the architecture and operation of the BES technology will focus on reducing the time required for CBOD5 quantification and improving the quantifiable range of the max current relationship.

The team at Dalhousie University and Island Water Technologies are interested in installing a demonstration bioelectrode sensor technology for real-time BOD quantification at municipal wastewater treatment facilities across Canada and the U.S. The technology could be used for monitoring end-of-pipe wastewater being discharged from the facility or wastewater streams internal to the treatment process.

Dr. Colin Ragush, P.Eng. is with the Centre for Water Resource Studies Dalhousie University. Dr. Patrick Kiely and Jack Ambler, P.Eng. are with Island Water Technologies. This article appears in ES&E Magazine’s October 2017 issue.

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By Edgar Tovilla

Cumulative effects assessment (CEA) is a concept that requires further understanding and analysis. This article examines the regulatory framework for CEA in Canada, particularly as it relates to the metal mining sector, which is highly regulated and scrutinized.

A regulatory scan was recently completed on federal and provincial water environmental protection policy, with a focus on Ontario, Quebec, Newfoundland and Labrador, British Columbia, Manitoba, Nunavut and the Yukon (NRC, 2014). Ninety-five percent of metal mining and exploration activity occurs in these jurisdictions.
The Canadian government and provincial/territorial jurisdictions recognize the need for CEA, but have no binding policies. There is ambiguity surrounding the term “cumulative effects” from a regulatory perspective.

The Canadian Environmental Assessment Agency (CEAA) defines cumulative effects as “the effect on the environment which results from effects of a project when combined with those of other past, existing, and imminent projects and activities. These may occur over a certain period of time and distance.”

Within this context, the associated effects from other activities are difficult to define and predict. CEA and management techniques are not fully developed to date and as a result they are not always effective.

CEA involves three dimensions of scale: spatial extent, level of detail, and temporal scale. It can cover extensive areas such as watersheds, typically encompassing several jurisdictions. It should also consider a time scale beyond a project lifespan, typically measured in hundreds of years, and examine specific effects on the environment to a meaningful level of detail. CEA provides an integrated and more strategic level to a site-specific environmental assessment process in that it addresses how the receiving environment “is affected by the totality of plans, projects and activities, rather than on the effects of a particular plan or project” (Therivel and Ross, 2007).

While principles of CEA can be explored and examined on a regional basis, it is only at the federal level where policy tools exist under the Fisheries Act, such as the Metal Mining Effluent Regulations (MMER), or the Pulp and Paper Effluent Regulations. Environmental effects monitoring (EEM) reports are required to better understand the potential negative effects of site-specific effluents on fish, fish habitat, and the use of fisheries resources. The EEM is a science-based performance measurement tool that assists in determining the adequacy of current regulated requirements (EC, 2012).

Additional opportunities to explore CEA exist at the provincial level with site-specific rule instruments, where local assimilative capacity studies provide indicator values for the spatial and temporal dimensions.
Nunavut is the only jurisdiction with a clear policy towards cumulative effects. With only one operating metal mine in the Kivalliq region and significant exploration within the same area, Nunavut works in partnership with Inuit organizations to enhance capacity and knowledge sharing in the territory.

Among other objectives, the intent of this partnership is to build knowledge on baseline water quality in the Kivalliq region, where there is the potential for more mineral development. It is in the process of establishing a cumulative effects monitoring framework for the Baker Lake watershed (NCNC, 2013).

The governments of Canada, British Columbia, and Ontario do recognize the need for CEA but have no binding policies. At the federal level, assessment of cumulative effects may be required by legislation when a project is subject to a federal environmental assessment under the CEAA, or in regulations under the Fisheries Act. However, no provincial jurisdiction was found to have binding obligations at a sector level.

The MMER – EEM reports provide the spatial and temporal dimensions needed for CEA. The Environment Canada response to Mining Watch Canada (AGC, 2012) noted that “the scope of the MMER – EEM requirements is restricted to effects at individual mines, and there is no requirement for study designs to collect data to investigate cumulative effects over entire watersheds. Environment Canada has not collected additional data and conducted analyses specifically targeted to investigate relationships between observed metal mining EEM effects and geographic or climatic categories.”

There is evidence of public requests to provincial governments to address the need to have cumulative impacts assessments (ECO, 2006: 14; ECO, 2012: 56). However, no other province or territory has a requirement for CEA.

In Ontario, the Environmental Bill of Rights (EBR) requires the Ministry of the Environment and Climate Change (MOECC) to have a Statement of Environmental Values (SEV), specifically requiring that MOECC “considers the cumulative effects on the environment; the interdependence of air, land, water and living organisms; and the relationships among the environment, the economy and society” (MOECC-SEV). While CEAs are not required, SEV is typically addressed at a very high level through the environmental assessment process, and site-specific studies at a micro-spatial and temporal scale.

Technical guidance, such as the 2004 Stormwater Management Design Manual, requires project proponents to consider cumulative effects in their design criteria, but this is not a regulated requirement. The Ontario Toxic Reduction Act has requirements for bioaccumulation of toxic substances, but, due to its lack of enforceability, its effectiveness relies on a voluntary approach (MacDonald and Lintner, 2010).

In British Columbia, while there are no requirements for CEA, there are considerations for a provincial multi-agency approach to provide recommendations and analysis that may contribute to cumulative effects assessments (BC-MEM, 2013: 2-3). The BC Water and Air Baseline Monitoring Guidance Document for Mine Proponents and Operators (McGuire, and Davis, 2012) notes the ambiguity surrounding the term “cumulative effects” and cites the same definition by the CEAA.

The BC mining guidance document refers “specifically to the combined effects on the environment from separate activities, including activities that are not associated with the proposed mine.” The document notes that, despite the importance of cumulative effects, current assessment and management techniques are not fully developed with respect to these. As a result, they are not always effective (McGuire, and Davis, 2012).

The provinces of Ontario, British Columbia and Quebec have developed provincial water quality programs with the goal of ensuring that their waters are protected and are of a quality that sustains aquatic life, supports ongoing recreational activities, and protects drinking water sources for current and future generations. These provinces have water quality objectives or benchmarks with specific water quality criteria to support a healthy population of aquatic life and protect human uses of surface water.

These water quality criteria are assessed on a site-specific basis in order to obtain approvals. Site-specific assimilative capacity studies provide indicator values for the spatial and temporal dimensions needed for cumulative effects assessment.

The water-receiver assimilative capacity study is by far the only available tool currently being required that considers the receiver’s existing water quality upstream, proposed discharges, and consequently downstream impacts.

Climate change considerations have given a renewed impetus for a cumulative effects type of analysis, but the cumulative effects assessment will remain an area of further study to find innovative ways to define it and implement it.

Edgar Tovilla, P.Eng. is manager of wastewater operations at the Region of Peel and a PhD candidate at Ryerson University. This article appears in ES&E Magazine’s October 2017 issue.

References cited are available upon request.

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Probe type machine used to measure a sample.

By Pat Kennedy

In North America, there are many older pumping installations that are still in operation. It is not uncommon for centrifugal pumps commissioned in the 1950s, ’60s and ’70s to still be in service.

As this equipment ages, spare parts and replacement pumps become obsolete. In cases where parts are available, prices can be extremely high, and deliveries prohibitively long. At times, the original manufacturer no longer exists, making matters even more difficult.

When confronted with delivery and price problems, customers are forced to consider replacing the older pumps with current line offerings. This can be a costly option. In most situations, the new equipment will not have the same footprint as the existing. In order to install the new pumps, baseplate, motor and couplings will also need to be purchased. Piping and concrete work will also be required.

An alternative to outright replacement is to reverse engineer/duplicate existing parts. Major components or complete pumps can be manufactured this way by companies such as Emnor Mechanical Inc.

In recent years, there have been advances in technology that make the reverse engineering process more accurate than ever before. Portable coordinate measuring machines can be used to create 3D models of either new or worn cast parts. Enmor uses a probe type machine to measure samples. It generates a 3D model of the impeller. This is then checked for accuracy versus the sample part. In the case of used parts, the model will be adjusted to accommodate for wear.

For pump impellers, the following steps are taken:

  • The solid model is used to determine hydraulic geometry and vane angles.
  • Using the pump curve, inlet angles are calculated and compared to the solid model.
  • Head calculation based on speed, design flow and impeller exit geometry is compared to actual head.
  • The impeller solid model is then corrected for wear.

In a similar manner, when casings are worn, inlet area and inlet angles are calculated, and the solid model adjusted for wear.

Emnor also uses portable scanning equipment, either on its own or in conjunction with the probe device. The scanning equipment is helpful when making site visits to measure parts that cannot be sent out. It speeds up obtaining the cast profile shape.

Once the solid models are finalized, the manufacturing process can begin. Most parts produced by Emnor are cast in sand foundries, and require pattern tooling. The pattern is used to create a cavity in a sand mould, into which liquid metal can be poured. After being poured, the casting is cleaned and heat treated if required.

The solid model of the part being manufactured is adjusted for foundry shrink, and machining allowance is added. Once this is done, the pattern tool can be designed. The tools are cut on computer numeric control machines. When the pattern is complete, it is inspected versus its solid model. Corrections are made if required.

Typical 3D printed core.
Typical 3D printed core.

Portable scanning equipment.
Portable scanning equipment.

In cases where parts need to be made quickly, a combination of 3D printed sand cores and single use tooling is used. When using this process, foundries can be working on moulds in one week.

Whether employing traditional or 3D core methods, Emnor uses melt simulation software. The program uses algorithms to predict liquid metal behaviour as it is poured into a mould. To detect and prevent possible casting flaws, velocity and solidification are checked. If problems are detected, the mould design is corrected. This technology helps eliminate common problems such as shrink and porosity.

One customer was operating two large double suction pumps that had been in service since the 1960s. The casings were badly worn. The cost to replace the pumps with current offerings was prohibitive due to civil, piping and motor requirements. Emnor manufactured two new casings and impellers, that were drop in replacements, at a much lower cost.

Portable advanced technology has made the reverse engineering process speedy, accurate, reliable and cost-effective. When considering whether to replace older equipment, manufacturing drop in replacements is a viable option.

Pat Kennedy is with Emnor Mechanical. This article appears in ES&E Magazine’s October 2017 issue.

The Duffin Creek Water Pollution Control Plant's fluid air blower coupled with steam turbine driving the blower.

By E. Ferguson, B. Dobson, K. Dangtran and L. Takmaz

Duffin Creek WPCP stack.
Duffin Creek WPCP stack.

The Duffin Creek Water Pollution Control Plant (WPCP) in Pickering, Ontario, is jointly owned by the Regional Municipalities of York and Durham. Both regions are experiencing significant population growth, which necessitated increasing rated plant capacity to 630 million litres per day (ML/d) through several process expansion projects.

Two fluid bed thermal oxidizer units were built back in the late 1970s by GL&V. Two additional reactors built by SUEZ were recently added to provide the facility with a firm solids processing capability of 270 dry tonnes per day. Identical to the original systems, the new oxidizers are also equipped with two waste heat recovery systems producing superheated steam to drive two steam turbines coupled with two fluidization air blowers.

Unit No. 4 fluidization air blower is connected to an electric motor (447 kW) and a steam turbine through a clutch mechanism. Unit No. 3 fluidization air blower is connected to only a steam turbine. A clutch mechanism between the fluidization air blower and the steam turbine enables the switching from turbine to electric motor during normal operation.

Once both units are operating at full capacity, the fluidization air blowers are driven by steam turbines during steady state operation. This unique design should be a template for future incineration systems. Each fluid bed unit has the capacity to incinerate 105 metric dry ton per day (MDTPD) total solids.

Each fluid bed unit is equipped with a dedicated heat recovery system employing a primary heat exchanger and waste heat recovery boiler. Primary heat exchanger (shell and tube design) is used to preheat fluidization air to minimize the auxiliary fuel usage during steady state operation. Each unit was designed to be autogeneous with a sludge feedstock composition of 68% volatile, 28% total solids and 5,560 kcal/kg sludge heat value based on volatile. Based on the feedback from the plant, both units are operating autogeneously even with a sludge feedstock content as low as 24%.

Flue gas from the fluid bed reactor is passed through a primary heat exchanger and then discharged into a waste heat boiler to generate superheated steam. From waste heat boiler, flue gas is sent to a wet scrubber to remove particulate and acid gas (SO2, HCl). The wet scrubber is not equipped with a caustic injection system.

Due to more stringent air requirements, a Kombisorbon mercury removal system is installed downstream of the multi-venturi wet scrubber to remove mercury, dioxins and furans. It includes a conditioner having a droplet separator to remove free water droplets from the clean flue gas discharged from the wet scrubber. The conditioner also has a heat exchanger to increase the saturated flue gas temperature about 20°C above the dew point temperature, to prevent moisture formation inside the fixed carbon bed adsorber.
Clean flue gas discharged from the wet scrubber flows through the cold side of the conditioner heat exchanger and the steam from the low pressure steam header is used as the heating medium for the hot side of the conditioner heat exchanger. Clean flue gas from the conditioner heat exchanger is sent to the Kombisorbon adsorber to remove mercury, dioxins and furans.

There is also an ID Fan installed before the stack to maintain vacuum conditions inside the waste heat boiler to prevent any potential flue gas leak into the building. The adsorber has three layers, with the first layer filled with regular carbon and the following two filled with activated carbon.

Operators can take carbon samples from the adsorber during normal operation and test the samples for mercury loading to determine the current condition of activated carbon. It is estimated that every two or three years, carbon bed material will need to be replaced. The actual life expectancy of the carbon is based on the mercury-loading rate at each facility. However, the Duffin Creek units do not have sufficient operating time on them at present to provide a definitive life expectancy.

Commissioning and performance testing

The Duffin Creek fluid bed incinerators went through start-up, commissioning and performance testing in 2013 and 2014. Unit No. 4 passed the performance testing in June 2013. Unit No. 3 passed the performance testing in February 2014. During the performance testing, sludge, ash and water samples were collected and analyzed.

The successful operation at Duffin Creek WPCP has shown that the improved thermal oxidizer design, incorporating enhanced air pollution control and energy recovery systems to reduce the operational expenditures, is an economical, environmentally friendly and cost-effective solution for sludge disposal. Duffin Creek WPCP fluid bed units have satisfied the sludge disposal needs of the plant, emission requirements of the Ministry of the Environment and Climate Change, and the future growth needs of the Regions of York and Durham.

ParameterLimitTest Results for Unit No. 4 taken in June 2013Test Results for Unit No. 3 taken in February 2014
OxygenMinimum 4%8.70%7.70%
Total Hydrocarbons100 ppm (10 min. avg.)6.3 ppm4.1 ppm
20 ppm (30 min. avg)4.9 ppm3.2 ppm
Hydrogen Chloride30 ppm0.15 ppm0.517 ppm
Dioxins and Furans100 pg/m32 pg/m33.7 pg/m3
Total Suspended Particulate20 mg/m30.6 mg/m30.35 mg/m3
Arsenic99% Removal Efficiency100%100%
Cadmium89% Removal Efficiency99.90%99.90%
Chromium99% Removal Efficiency100%100%
Lead92% Removal Efficiency100%100%
Nickel99% Removal Efficiency99.90%99.90%
MercuryMax. 70 µg/m30.5 µg/m30.91 µg/m3

E. Ferguson is with York Region. 
B. Dobson is with the Duffin Creek Water Pollution Control Plant. 
K. Dangtran and L. Takmaz are with SUEZ. This article appears in ES&E Magazine’s October 2017 issue.

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Both stages were mounted on a temporary 150 mm PVC piping manifold and steel supports.

Municipalities and other government agencies are investigating methods to collect and store sufficient water for public distribution and consumption, including storage in underground aquifers.

One method under development to mitigate these supply issues consists of the capture of excess surface water from creeks, rivers or lakes during an area’s rainy season. Surface water is pumped through a filtration system and stored in underground aquifers via a well for later withdrawal, treatment and distribution.

In the summer of 2016, an aquifer storage recovery (ASR) pilot was performed to test the feasibility of this method. The system included a freshwater surface pump, booster pump, self-cleaning automatic filtration system, and an injection/withdrawal well containing a turbine pump. Monitoring included flow meters, conductivity meters, pressure transducers, and recording devices.

The ASR 3.8 megalitre per day pilot was supplied from a local creek next to a water treatment plant. The final filtration requirement was determined to be 10-micron, in order to protect the porosity of the underground aquifer. The creek water treatment consisted of two in-series stages of 25-micron and 10-micron before injection into the storage well at 75 PSI. There are two 25-micron Orival model ORG-060-LE filters, followed by four 10-micron model ORG-060-LE filters.

The rainy season turbidity averages between 4 – 6 NTU (nephelometric turbidity unit), with TSS (total suspended solids) grab sampling of less than 5 ppm to 200 ppm. The water treatment plant lab tested water from a sampling point inside the lab at a sink faucet that is connected to the plant piping system. Lab technicians stated that there was a difference in TSS concentration between equipment testing points, which indicated better quality than the actual water quality that entered the plant.

It was determined that water sampling should take place at the water pipe supply side of the ASR filtration systems in order to provide the best accuracy.

The filter elements are permanent multi-layer stainless steel weave-wire cylinders within a carbon steel, powder-coated housing. Each stage of filtration is operated by an independent controller that initiates a cleaning cycle. The cycle sequentially operates the rinse system inside each housing at a rate of 16-seconds per unit. Both stages were mounted on a temporary 150 mm PVC piping manifold and steel supports.

Wastewater from the cleaning cycle was sent to a cement lined holding pond for further processing and recycling.

Traditional filtration

Sand-media and multi-media filtration has been traditionally used for surface water sources. The configuration for high pressure systems involves a series of interconnected round tanks. Flushing a tank involves reversing the flow through each tank for one to two minutes at a rate slightly greater than the flow-through of other connected tank(s).

Reversing the flow allows the sand bed to be lifted, agitating the sand particles to release the collected solids. During agitation, sand particles hit each other, making their sharp edges smoother. Eventually, the sand media will need to be replaced because of this wear and some loss through flushing.

The particles that break off during the agitation process must either pass through to the piping system during the filtration process or be flushed out for a period of time to a wastewater collection area.

Preliminary startup

During a preliminary 24-hour operation of the filter pilot there were unexplainable large swings in the flushing frequency of the automatic self-cleaning filters, which characteristically indicated TSS water quality changes. In order to compensate for the flushing frequency of 2.5 to 5 minutes, the flow rate was reduced by the manual closure of a gate valve at the injection point at the well. The flow rates averaged 1,130 – 1,326 LPM and, on those occasions of higher than expected TSS values, flows were reduced.

During the first days of operation it was observed that filter flushing frequency increased in the mornings and then tapered off during the day and at night.

Finally, a correlation developed and it was determined that the morning increase of TSS occurred when city flood management utility workers would open up drainage canal gates, flowing water into the creek. In the late afternoon, the gates were set back into a lesser flow condition. Once this was discovered, the ASR operators established an operating protocol to address the TSS changes affecting the filters through flow regulation.

Suspended solids are collected on the screen element, forming a filter cake. Cleaned water flows outside the screen element and is discharged.
Suspended solids are collected on the screen element, forming a filter cake. Cleaned water flows outside the screen element and is discharged.

On occasion, the ASR filtration system was temporarily shut down for flood protection due to tropical storm activity. Full flow drainage of the canal network in the city caused the water turbidity to increase to 9 NTU.
When TSS levels reach this maximum concentration, any water flow into the 10-micron stage filters resulted in instant blinding of the screen elements. Such an event prompted a water sample to be collected and sent to a local lab for TSS testing and additional augmentation of the operating protocol.

The aquifer storage recovery pilot stored and withdrew water in the aquifer in two consecutive long-term tests. In each test, there were no adverse effects of pressure and flow into the porous underground formations. Conductivity meters were used during the withdrawal process to indicate the end of the stored water quantity. When the normal aquifer conductivity was reached, it signaled to the plant operators that the end of the stored water was met.

Summary

Although the sand media option was considered, there were several drawbacks for this application. Residual particles that break off during the back-flush process would have to be eliminated for fear of plugging the porosity of the aquifer. The long run-times for flushing and the elimination of the smaller particles to the waste collection area produce too much water volume to manage. The maintenance and replacement of the sand-media was a human resource scheduling and budget cost issue. The foot-print size of the sand media system was also much greater, requiring a higher capital investment.

The second underground storage test using the 25-micron filtration was only done to determine if a larger degree of filtration could be used to protect the porosity of the aquifer. The larger degree of filtration also allowed for a much smaller footprint and sequential cost of a permanent 5.7 Megalitre per day system.

The advantages of the self-cleaning automatic filter system include: a much smaller footprint size; less complexity; smaller maintenance personnel support; and a permanent media with a consistent required degree of filtration.

Due to the success of the aquifer storage recovery pilot, a permanent filtration system was designed and is scheduled for installation before the end of 2017.

This article appears in ES&E Magazine’s October 2017 issue.