High frequency monitoring needed to protect UK rivers!

29/06/2018
Nigel Grimsley from OTT Hydrometry describes relatively new technologies that have overcome traditional barriers to the continuous monitoring of phosphate and nitrate.

The science behind nutrient pollution in rivers is still poorly understood despite the fact that nitrate and phosphate concentrations in Britain’s rivers are mostly unacceptable, although an element of uncertainty exists about what an acceptable level actually is. Key to improving our understanding of the sources and impacts of nutrient pollution is high-resolution monitoring across a broad spectrum of river types.

Background

Green Box Hydro Cycle

Phosphates and nitrates occur naturally in the environment, and are essential nutrients that support the growth of aquatic organisms. However, water resources are under constant pressure from both point and diffuse sources of nutrients. Under certain conditions, such as warm, sunny weather and slow moving water, elevated nutrient concentrations can promote the growth of nuisance phytoplankton causing algal blooms (eurtrophication). These blooms can dramatically affect aquatic ecology in a number of ways. High densities of algal biomass within the water column, or, in extreme cases, blankets of algae on the water surface, prevent light from reaching submerged plants. Also, some algae, and the bacteria that feed on decaying algae, produce toxins. In combination, these two effects can lower dissolved oxygen levels and potentially kill fish and other organisms. In consequence, aquatic ecology is damaged and the water becomes unsuitable for human recreation and more expensive to treat for drinking purposes.

In its State of the Environment report, February 2018, the British Environment Agency said: “Unacceptable levels of phosphorus in over half of English rivers, usually due to sewage effluent and pollution from farm land, chokes wildlife as algal blooms use up their oxygen. Groundwater quality is currently deteriorating. This vital source of drinking water is often heavily polluted with nitrates, mainly from agriculture.”

Good ecological status
The EU Water Framework Directive (WFD) requires Britain to achieve ‘good status’ of all water bodies (including rivers, streams, lakes, estuaries, coastal waters and groundwater) by 2015. However, only 36% of water bodies were classified as ‘good’ or better in 2012. Nutrient water quality standards are set by the Department for Environment, Food & Rural Affairs (DEFRA), so for example, phosphorus water quality standards have been set, and vary according to the alkalinity and height above mean sea level of the river. Interestingly, the standards were initially set in 2009, but in 75% of rivers with clear ecological impacts of nutrient enrichment, the existing standards produced phosphorus classifications of good or even high status, so the phosphorus standards were lowered.

Highlighting the need for better understanding of the relationships between nutrients and ecological status, Dr Mike Bowes from the Centre for Ecology & Hydrology has published research, with others, in which the effects of varying soluble reactive phosphate (SRP) concentrations on periphyton growth rate (mixture of algae and microbes that typically cover submerged surfaces) where determined in 9 different rivers from around Britain. In all of these experiments, significantly increasing SRP concentrations in the river water for sustained periods (usually c. 9 days) did not increase periphyton growth rate or biomass. This indicates that in most rivers, phosphorus concentrations are in excess, and therefore the process of eutrophication (typified by excessive algal blooms and loss of macrophytes – aquatic plants) is not necessarily caused by intermittent increases in SRP.

Clearly, more research is necessary to more fully understand the effects of nutrient enrichment, and the causes of algal blooms.

Upstream challenge
Headwater streams represent more than 70% of the streams and rivers in Britain, however, because of their number, location and the lack of regulatory requirement for continuous monitoring, headwater streams are rarely monitored for nutrient status. Traditional monitoring of upland streams has relied on either manual sampling or the collection of samples from automatic samplers. Nevertheless, research has shown that upland streams are less impaired by nutrient pollution than lowland rivers, but because of their size and limited dilution capacity they are more susceptible to nutrient impairment.

References
• Bowes, M. J., Gozzard, E., Johnson, A. C., Scarlett, P. M., Roberts, C., Read, D. S., et al. (2012a). Spatial and temporal changes in chlorophyll-a concentrations in the River Thames basin, UK: are phosphorus concentrations beginning to limit phytoplankton biomass? Sci. Total Environ. 426, 45–55. doi: 10.1016/j.scitotenv. 2012.02.056
• Bowes, M. J., Ings, N. L., McCall, S. J., Warwick, A., Barrett, C., Wickham, H. D., et al. (2012b). Nutrient and light limitation of periphyton in the River Thames: implications for catchment management. Sci. Total Environ. 434, 201–212. doi: 10.1016/j.scitotenv.2011.09.082
• Dodds, W. K., Smith, V. H., and Lohman, K. (2002). Nitrogen and phosphorus relationships to benthic algal biomass in temperate streams. Can. J. Fish. Aquat Sci. 59, 865–874. doi: 10.1139/f02-063
• McCall, S. J., Bowes, M. J., Warnaars, T. A., Hale, M. S., Smith, J. T., Warwick, A., et al. (2014). Impacts of phosphorus and nitrogen enrichment on periphyton accrual in the River Rede, Northumberland, UK. Inland Waters 4, 121–132. doi: 10.5268/IW-4.2.692
• McCall, S. J., Hale, M. S., Smith, J. T., Read, D. S., and Bowes, M. J. (2017). Impacts of phosphorus concentration and light intensity on river periphyton biomass and community structure. Hydrobiologia 792, 315–330. doi: 10.1007/s10750-016-3067-1

Monitoring technology
Sampling for laboratory analysis can be a costly and time-consuming activity, particularly at upland streams in remote locations with difficult access. In addition, spot sampling reveals nutrient levels at a specific moment in time, and therefore risks missing concentration spikes. Continuous monitoring is therefore generally preferred, but in the past this has been difficult to achieve with the technology available because of its requirement for frequent re-calibration and mains power.

High resolution SRP monitoring has been made possible in almost any location with the launch by OTT Hydromet of the the ‘HydroCycle PO4’ which is a battery-powered wet chemistry analyser for the continuous analysis of SRP. Typically, the HydroCycle PO4 is deployed into the river for monitoring purposes, but recent work by the Environment Agency has deployed it in a flow-through chamber for measuring extracted water.

The HydroCycle PO4 methodology is based on US EPA standard methods, employing pre-mixed, colour coded cartridges for simple reagent replacement in the field. Weighing less than 8kg fully loaded with reagents, it is quick and easy to deploy, even in remote locations. The instrument has an internal data logger with 1 GB capacity, and in combination with telemetry, it provides operators with near real-time access to monitoring data for SRP.

The quality of the instrument’s data is underpinned by QA/QC processing in conjunction with an on-board NIST standard, delivering scientifically defensible results. Engineered to take measurements at high oxygen saturation, and with a large surface area filter for enhanced performance during sediment events, the instrument employs advanced fluidics, that are resistant to the bubbles that can plague wet chemistry sensors.

Environment Agency application
The National Laboratory Service Instrumentation team (NLSI) provides support to all high resolution water quality monitoring activities undertaken across the Agency, underpinning the EA’s statutory responsibilities such as the WFD, the Urban Waste Water Directive and Statutory Surface Water Monitoring Programmes. It also makes a significant contribution to partnership projects such as Demonstration Test Catchments and Catchments Sensitive Farming. Technical Lead Matt Loewenthal says: “We provide the Agency and commercial clients with monitoring systems and associated equipment to meet their precise needs. This includes, of course, nutrient monitoring, which is a major interest for everyone involved with water resources.”

Matt’s team has developed water quality monitoring systems that deliver high resolution remote monitoring with equipment that is quick and easy to deploy. There are two main options. The ‘green box’ is a fully instrumented cabinet that can be installed adjacent to a water resource, drawing water and passing it though a flow-through container with sensors for parameters such as Temperature Dissolved Oxygen, Ammonium, Turbidity, Conductivity pH and Chlorophyll a. Each system is fitted with telemetry so that real-time data is made instantly available to users on the cloud.

Conscious of the need to better understand the role of P in rivers, Matt’s team has integrated a HydroCycle PO4 into its monitoring systems as a development project.
Matt says: “It’s currently the only system that can be integrated with all of our remote monitoring systems. Because it’s portable, and runs on 12 volts, it has been relatively easy to integrate into our modular monitoring and telemetry systems.

“The HydroCycle PO4 measures SRP so if we need to monitor other forms of P, we will use an auto sampler or deploy a mains-powered monitor. However, monitoring SRP is important because this is the form of P that is most readily available to algae and plants.”

Explaining the advantages of high resolution P monitoring, Matt refers to a deployment on the River Dore. “The data shows background levels of 300 µg P/l, rising to 600 µg P/l following heavy rain, indicating high levels of P in run-off.”

Nitrate
Similar to phosphates, excessive nitrate levels can have a significant impact on water quality. In addition, nitrates are highly mobile and can contaminate groundwater, with serious consequences for wells and drinking water treatment. Nitrate concentrations are therefore of major interest to the EA, but traditional monitoring technology has proved inadequate for long-term monitoring because of a frequent recalibration requirement. To address this need, which exists globally, OTT Hydromet developed the SUNA V2, which is an optical nitrate sensor, providing high levels of accuracy and precision in both freshwater and seawater.

The NLSI has evaluated the SUNA V2 in well water and Matt says: “It performed well – we took grab samples for laboratory analysis and the SUNA data matched the lab data perfectly. We are therefore excited about the opportunity this presents to measure nitrate continuously, because this will inform our understanding of nitrate pollution and its sources, as well as the relationship between groundwater and surface water.”

Summary
The new capability for high-resolution monitoring of nutrients such as phosphorus will enable improved understanding of its effects on ecological status, and in turn will inform decisions on what acceptable P concentrations will be for individual rivers. This is vitally important because the cost of removing P from wastewater can be high, so the requirements and discharge limits that are placed on industrial and wastewater companies need to be science based and supported by reliable data. Similarly, nitrate pollution from fertilizer runoff, industrial activities and wastewater discharge, has been difficult to monitor effectively in the past because of the technology limitations. So, as improved monitoring equipment is developed, it will be possible to better understand the sources and effects, and thereby implement effective prevention and mitigation strategies.

@OTTHydrometry @EnvAgency @CEHScienceNews #Water #Environment

Pressure Transducer Delivers water level monitoring in emergency tank shower!

24/11/2014

Applied Measurements were recently contacted by spill control and containment manufacturer Empteezy, to provide a sensor to be used within an emergency tank shower.  The emergency tank shower is ideal for use in locations where a constant water supply and adequate water pressure cannot be guaranteed.

Emergency_showerThe Challenge 
To ensure the emergency tank shower is able to provide a flow of 75.7ltrs per minute of water for 15 minutes, fulfilling the ANSI Z358.1 regulations for emergency tank showers.

The Problem 
Once a gravity fed shower is switched on and the water level within the tank drops, both the water pressure and the flow rate at the shower head decreases.  In order to achieve the flow rate of 75.7ltrs per minute of water for the full 15 minutes, the emergency tank shower needs to contain a minimum of 2000ltrs of water within the tank.

The Solution
Applied Measurements provided Empteezy with a Pi600 series pressure transducer.  The pressure transducer was connected and calibrated to the digital readout scale on the front of the shower, giving an accurate reading of the litres of water remaining in the tank.  When the water level falls below the minimum safety level, a signal is sent to the sounder strobe alarm on the front of the shower.  This signal has a dual function. Firstly, alerting safety personnel that the water level has dropped below the minimum, notifying them to refill the shower to achieve the required flow rate and water pressure. Secondly, that the shower has been operated and an injured employee may need assistance.

Pi600The Pi600 Series of Pressure Transducers
The Pi600 series of pressure sensors are designed for the measurement of gas and liquid pressure across a wide range of general purpose and industrial applications such as hydraulics, medical, research and development, meteorology and food processing.  Constructed from stainless steel with a ceramic diaphragm and viton ‘O’ ring seal as standard, they are designed to be extremely rugged, yet compact in design.

Key Features Include:

  • Ranges 0-50mbar up to 0-700bar
  • Wide Variety of Outputs: mV/ Volts / mA
  • Can be Offered Calibrated in Metres Water Gauge
  • Sealed to IP65 (plug & socket) or IP66/68 (Cable)
  • Accuracy: <±0.25%/FS (0.1% option)
  • Gauge or Absolute Versions
  • Various Pressure Port Options (G1/4” male as standard)
  • Excellent Chemical and Abrasion Resistance
  • Rugged Construction
  • Full Customisation Possible

These pressure transducers come in pressure ranges of 0-50mbar and 0-700bar in absolute or gauge versions, with a wide choice of electrical output signals from its ASIC-based amplifier circuit.  These outputs include, 4-20mA, 0-5Vdc & 0-10Vdc, 1-6Vdc and 10mV/V, as well as a ratiometric 0.5-4.5Vdc signal that requires a 5Vdc supply to suit most data loggers.  The Pi600 series of pressure transducers can also be supplied with any of our wide range of instrumentation to give you a complete calibrated system.

In addition, the series can be completely customised to suit your application including; custom process connections, alternate case and ‘O’ ring material for applications where aggressive media is present, and higher IP ratings for more challenging environments.

The Pi600 series of pressure transducers have proved vital in Empteezy’s emergency tank shower units, enabling engineers to guarantee the water pressure and flow rate of the units.  We are always looking for new and exciting challenges so contact our technical sales team today on +44 (0) 118 981 7339 or info@appmeas.co.uk to discuss your application.


Accelerating development of smart, power-efficient IoT applications!

28/07/2014
Delivering intelligent connectivity starting at the network edge

B&B Electronics has introduced its Wzzard™ Intelligent Sensing Platform.    Wzzard is an easy to use, complete wireless sensor connectivity platform for the rapid deployment of scalable, intelligent, reliable Internet of Things (IoT) networking in remote and demanding environments.   Wzzard was designed to help integrators, VARs and service providers efficiently develop and deploy secure, smart, self-powered, and scalable IoT applications.

BBWzzardUnlike a traditional SCADA application where sensors and edge devices are simply passive conduits for raw data, edge decision making delivers a more effective network.  Using iterative control limits and gateway data aggregation to support applications closer to the network edge, the Wzzard Intelligent Sensing Platform brings this intelligence to the network starting at the sensor, creating a more responsive, reliable and efficient network.

There are several key components and technologies that comprise B&B Electronics’ Wzzard Intelligent Sensing Platform, as demonstrated here: B&B Smart Sensing Wzzard Platform

First, Wzzard Intelligent Edge Nodes will connect, via conduit fitting cable gland or M12 connector, to any industry-standard sensor. General-purpose analog inputs, digital input/output and thermocouple interfaces are included. B&B has already integrated internal temperature and accelerometer sensor options, and can integrate other application specific sensors upon request.

The Intelligent Edge Nodes are easily configurable, using Android or IoS smartphones or tablets and the Wzzard app over Bluetooth LE 4.0. They can be configured to communicate only data outside specified thresholds, reducing the cost on cellular networks, as well as to associate other useful information (geo-location, device name, and up-time) with the collected sensor data for upstream analytics applications.   Control time synchronization is used to maximize battery life, exceeding 5 years for many applications.   Nodes are IP67 rated for outdoor use and include both magnetized and screw mount options.

Next is the communications component. B&B chose SmartMesh IP® wireless sensing technology from Linear Technologies Dust Networks.  SmartMesh IP is based upon the wireless IEEE 802.15.4e standard and creates full-mesh networks, sometimes referred to as “mesh-to-the-edge” networks.  SmartMesh IP networks use a triple-play of wireless mesh technologies—time diversity, frequency diversity, and physical diversity—to assure reliability, resiliency, scalability, power source flexibility, and ease-of-use.  At the core the technology is an intelligent mesh network with advanced algorithms and power saving technologies that enable powerful features not available from other WSN providers including:

• Ultra low power consumption

• Deterministic power management and optimization

• Auto-forming mesh technology for a self-healing and self-sustaining network

• Dynamic bandwidth support, load balancing and optimization

• Network management and configuration

• Zero collision low power packet exchange

• Scalability to large, dense, deep networks

wzzard_groupWzzard’s Intelligent Edge Nodes can join the mesh network at any time without gateway interaction.  Nodes attach automatically, and the SmartMesh IP technology dynamically self-configures to re-form the mesh network. To ensure data always reaches the gateway, nodes will determine their optimal RF paths to other nodes and back to the gateway. The SmartMesh IP protocol implemented within the edge nodes includes advanced network management functions and security features such as encryption and authentication. For more information: B&B Smart-Sensing What is Smartmesh

Wzzard also uses the lightweight, publish/subscribe messaging transport MQTT protocol for sensor communications.   MQTT is an extremely simple messaging protocol created for M2M and IoT applications over wireless networks. Its efficient distribution of information to single or multiple receivers, low power usage and minimized data packets make it ideal for mobile or remote locations. Unlike older SCADA protocols such as Modbus, MQTT places few restrictions on the volume or type of data that can be communicated. This facilitates a meta-data approach where multiple IoT applications can act upon the information simultaneously without having to know its origin.

Finally, B&B’s programmable, industrial-grade Spectre router serves as Wzzard’s Intelligent Gateway. Spectre can connect equipment and other devices to the Internet or Intranet over either wired Ethernet or wireless cellular connections. Spectre is built for plug-and-play simplicity with extensive remote management, deployment and customization options.  It is a robust, flexible gateway designed for easy deployment in demanding environments and the cellular version creates secure connections in locations where cable connections are impractical.

Processed information from the sensor nodes is published through the Spectre Gateway up to the customer’s IoT application using MQTT transport protocol.

SeeControl is one of the first IoT platform providers to leverage the Wzzard Intelligent Sensing Platform and MQTT protocols to develop applications. (More information at: B&B/SeeControl Partnership)

“Today, most business analytics can only describe what has happened and why,” said Parthesh Shastri, SeeControl’s vice president of customer success and strategy.  “The industry can move past descriptive to predictive and even prescriptive analytics using IoT technologies such as B&B’s Wzzard that applies edge decision making and processes information collected from sensors before transmitting relevant, as opposed to raw data, up to SeeControl’s SaaS remote management platform. Cloud-based big data analytics is then better able to derive meaning from the data, and prescribe specific courses of action, to drive more intelligent applications.”

Jerry O’Gorman, CEO of B&B Electronics explained, “The Wzzard platform’s technologies, protocols and hardware work together to reduce the complexity, expertise and time it takes for integrators to develop scalable IoT solutions.   We developed Wzzard to facilitate the coming world of connected intelligence, where smart machines and systems will collaborate, inform and make decisions on the intelligence gained from each other with little or no human supervision. Humans will program these smart networks, but then they have the ability to run efficiently and autonomously, sometimes for years, until there’s data reported that requires human intervention.”

Possible Applications:

  • Flood and water level monitoring
  • Smart car parks; vehicle counting, air quality
  • Smart irrigation systems monitoring soil moisture, environmental conditions, leaks
  • Mechanical condition monitoring/preventative maintenance
  • Energy measurements and audits on a per system or machine basis
  • Data center environmental monitoring
  • Tank and lift stations
  • Condition monitoring and optimization in industrial environments
  • Traffic monitoring of over-height vehicles for tunnels and bridges

Celebrating twenty years abnormality!

21/07/2014

This year the Abnormal Situation Management (ASM®) Consortium  is celebrating 20 years of thought leadership in the process industry. The ASM Consortium grew out of a grassroots effort begun in 1989 by ASM to address alarm floods. Honeywell spearheaded the development of a proposal to the US NIST, Advanced Technology Program to form a Joint Research & Development Consortium.

Background on the ASM ConsortiumasmThe ASM Consortium was started in 1994 to address Process Industry concerns about the high cost of incidents, such as unplanned shutdowns, fires, explosions, emissions, etc. The term, Abnormal Situation Management®, was used to describe it. Matching funds from NIST enabled the consortium to spend several years researching and developing highly-advanced concepts to address the problem of abnormal situations. Since then research has continued and increasing effort has been put into development and deployment of solutions that incorporate ASM knowledge.The basis of the ASM Consortium is collaboration and information-sharing. By working together, members achieve far more than they could working alone. Research results are published for members, and often further shared by means of webinars, seminars and workshops. User members also guide Honeywell in selection and development of product solutions that incorporate ASM knowledge. Non-members can benefit from ASM Research as ASM Effective Practices Guidelines for Alarm Management, Display Design and Procedural Practices are available for purchase on Amazon.com.

The proposal addressed the challenging problem of abnormal situation management. In preparing for this proposal effort, Honeywell and its collaborators created the Abnormal Situation Management (ASM) Joint Research and Development Consortium (referred to as ASMC) under the U.S. Cooperative Research and Development Act. In November 1994, the ASM research joint venture began its research with $16.6 million (€12.27m) in funding for a three year study program, including $8.1 million (€6m) from ATP and industry cost-sharing of $8.5 million (€6.29m).

This year, ASM Consortium members have met twice for a week-long Quarterly Review Meetings (QRM) , once at Houston, Texas (USA) in April and then again at Antwerp (B) in June. Along with its normal business, the Consortium discussed plans to celebrate the Consortium’s 20 year of service to the Process Industry. The Quarterly Review Meetings are a platform for the ASM Consortium members to share the benefits gained from the ASM practices and products, and to discuss new challenges faced in plant operations. Members of the Consortium besides Honeywell include industrial manufacturers, a human factors research company, and universities that collaborate to research best practices for managing abnormal situations in industrial facilities.

To celebrate its 20th year, ASM Consortium will be spreading further awareness about managing and mitigating abnormal situations in process industries by publishing journal articles, white papers at leading industry conferences, and a planned video.


Ensuring that necessary dredging mantains water quality!

07/07/2014

Last winter brought unprecedented weather conditions both in Ireland and Britain. In the Read-out offices we were hit by a thunder and lightening storm which played havoc with our electronic equipment and elsewhere in the region the rough seas did incredible damage. In the south-west of England the farms and homes in the Somerset Levels and Moors, a sparsely populated coastal plain and wetland area of central Somerset, was severely hit with incredible flooding. Indeed the effects of this will be felt in the area for many years to come.

levels

This shows the incredible extent of last winter’s flooding with superimposed map showing location of the Somerset Levels and Moors.

A special monitoring system is helping protect water quality on the Somerset Levels and Moors where a major dredging operation is under way following this severe flooding. The system, which was supplied by OTT Hydrometry and installed by Wavelength Environmental, is designed to protect the river ecology by issuing email alerts if water quality deteriorates beyond pre-set conditions. Any such alerts would immediately be relayed to the project team and an assessment of conditions would then be undertaken, so that working practices can be reviewed and continued.

The flood caused extensive damage to properties in the area and many residents had to leave their homes.  Approximately 170 homes and businesses were affected. The Environment Agency estimated there were more than 65 million cubic metres of floodwater covering an area of 65 square kilometres.

Dredgers commenced work at the end of March 2014

Dredgers commenced work at the end of March 2014

On Monday 31st March 2014, three months after the flooding began, dredging work started on the banks of the river Parrett between Burrowbridge and Moorland, just a few minutes from Junction 24 of the M5 in the south west of England. Costing £1 million per mile, 5 miles of river bank will be dredged (3 miles of the river Parrett and 2 miles of the river Tone), based on restoring the river channels to their 1960’s profile and improving their drainage capability.

In recent years, an accumulation of sediment has narrowed the river channel and this is believed to be just one of the reasons for the severe flooding that took place. A network of mobile real-time water quality monitors is therefore being deployed to continuously monitor water quality upstream and downstream of the dredgers. This work complements the Environment Agency’s wider environmental monitoring.

Adcon Telemetry plus Hydrolab WQ sonde.

Adcon Telemetry plus Hydrolab WQ sonde.

The monitors consist of Hydrolab water quality ‘sondes’ and Adcon telemetry systems which transmit near-live data during the dredging operation that is due to run until the Winter of 2014. The monitors are anchored to the river bed and suspended in the river by means of two small buoys. Each sonde is fitted with sensors for the measurement of dissolved oxygen (DO), ammonium, temperature, pH, conductivity and turbidity. A short cable connects each sonde to an Adcon telemetry unit on the bank, which transmits data via GPRS every 10 minutes. The sondes contain internal dataloggers, however the transmitted data is available to project staff in near real-time via a web-based data portal. If water quality meets the pre-set alert conditions (for temperature, dissolved oxygen or ammonium), email messages are issued via the telemetry units. It is important to note that poor water quality can be caused by a number of factors including low flow levels and high nutrient levels arising from many sources in the area.

Downstream monitoring!

Downstream monitoring!

The project plan has allowed for up to eight dredging teams, and the monitors are being installed approximately 50 metres upstream and 100-150 meters downstream of the dredgers – to allow sufficient mixing.

Simon Browning from Wavelength Environmental has been monitoring the data from the sondes and says: “The monitors are quick and easy to deploy, and have performed very well; however, portability is extremely important because the instruments have to be moved and redeployed as the dredging work proceeds.

“We have also started fitting GPS units to the telemetry systems so that we can keep track of the monitoring locations. This is important because each dredging team is constantly moving, so the monitors have to be moved regularly.”

Matthew Ellison, a telemetry specialist from OTT Hydrometry, was delighted to be involved in this high profile project and recommended the Adcon systems because they are extremely small and therefore portable, and have been designed to run on very low power, which means they can be left to run in remote locations for extended periods of time with just a small solar panel.

In January, Owen Paterson, the Environmental Secretary of State in England, asked for a 20 year Action Plan to be developed to look at the various options for the sustainable management of flood risk on the Somerset Levels and Moors. The plan is supported by a £10m investment from the Department for Transport with a further £500k from the Department for Communities and Local Government, on top of the £10m previously announced by the British Prime Minister. The plan has been published and is available here on the Somerset County Council website!

Whilst the plan recognises that it will not be possible to stop flooding completely, it has 6 key objectives:

  1. Reduce the frequency, depth and duration of flooding.
  2. Maintain access for communities and businesses.
  3. Increase resilience to flooding for families, agriculture, businesses, communities, and wildlife.
  4. Make the most of the special characteristics of the Somerset Levels and Moors (the internationally important biodiversity, environment and cultural heritage).
  5. Ensure strategic transport connectivity, both within Somerset and through the county to the South West peninsula.
  6. Promote business confidence and growth.

“Dredging is one of the one things the local community has really been pressing for and people are going to check the Environment Agency is doing the work properly. The water quality monitoring undertaken by the mobile monitors and by our own static monitors will help provide assurance that the environment is not compromised by this work,” said Graham Quarrier for the Environment Agency.


Final effluent monitors protect wastewater treatment efficiency

20/05/2013
Richard Reeves, Principal Process Scientist, Southern Water, and David Ballinger, Optimisation and R & D Manager, Southern Water discuss this application. Southern Water supplies water and wastewater services for Kent, Sussex, Hampshire and the Isle of Wight in the south of England.
Authors

Richard Reeves

Richard Reeves

David Ballinger

David Ballinger

Southern Water operates 370 wastewater treatment plants (WWTP), many of which are unmanned for most of the time and most have numeric environmental permits, so a network of online monitors has been established to improve treatment and protect discharge compliance. This has involved the installation of final effluent monitors at over 300 sites in a programme that has lasted for more than ten years.

The online monitors are comprised of a Hach Lange turbidity probe with sensors for temperature and level (to show when the turbidity probe is out of the water) and mounted on a plastic ‘spade’ which holds the sensors in position at the final effluent monitoring point.

Using turbidity to estimate BOD & TSS
As a measure of clarity, turbidity provides extremely useful data; a cloudy final effluent suggests poor treatment and possible discharge permit failure.

In 1993 Southern Water conducted an extensive research project to demonstrate that effluent clarity, as measured by turbidity, can be related on a site by site basis to permitted BOD (Biological Oxidation Demand) and TSS (Total Suspended Solids).

The constituents of final effluent are such that biological slimes and algae are prone to develop on optical surfaces, and the trials therefore concentrated on the most efficient method of probe cleaning. Probes with no automatic cleaning were therefore eliminated. The technically preferred monitor was the Hach Lange Solitax turbidity probe, which incorporates a silicon rubber wiper, which sweeps over both optical surfaces at a programmable frequency. Southern Water also found that the cleaning efficiency was improved by the addition of an air purge which blows away the loosened solids.

The Solitax probes use a single LED light source with three detectors, one for light intensity and two for light scatter. Hach Lange’s Clive Murren says “This provides reliable colour-independent readings with a low maintenance requirement. However, we have a contract to routinely visit each site to service and calibrate the turbidity sensors.”

Hach Lange has confirmed that their SC200 and SC1000 controllers and the SOLITAX sc turbidity probe were awarded MCERTS certification on 1st November 2012. MCERTS is the Environment Agency’s monitoring certification scheme and currently only a small number of analytical instruments have achieved this award. However, an MCERTS certificate demonstrates that equipment has met or exceeded the stringent performance requirements of the scheme.

Solitax Wiper

Solitax Wiper

The monitor control unit is mounted in a separate cabinet which also houses the air compressor. When the plc calls for a clean, the wiper operates followed by two air purges which release the algae/biofilm. A further wipe then removes any remaining material.

Cleaning is initiated every hour and, when a clean is called for, the last recorded turbidity reading is held in the monitor for 5 minutes, to avoid recording the false turbidity generated by the loosened material.

Design and Installation
Linton Electrical Contractors (Kent) Limited has a longstanding relationship with Southern Water and was responsible for the final design and installation of the final effluent monitoring systems. Subject to prior approval by Southern Water, the installations incorporate the latest Hach Lange instrumentation as it becomes available.

Linton Electrical is now installing as standard the 110V MKV SC200 controller and occasionally the MKVI SC1000. Each system is complete with conductivity sensor, level sensor, temperature probe and air cleaning system; all of which is mounted on a PVC spade.

Linton’s Mark Pendry says “The project has been very successful because we have established the skills, tools and spares to ensure that every installation is conducted quickly and efficiently and the quality of the HACH LANGE instruments ensures reliability and accuracy.”

One of the advantages of the SC controllers is the ability to add additional instruments and Clive Murren says: “The facility to add the Nitratax nitrate probe saves time and money when using this platform, because it utilises the same spade design as the turbidity sensor and several of the latest installations have also incorporated the nitrate probe.”

Processing of Data
The WWTP telemetry outstation scans all connected monitors every second. The outstation calculates 15 minute averages (or in the case of temperature takes a 15 min spot reading) and relays the data by a phone line to a central processing unit known as SCOPE. The SCOPE data is available to the Regional Control Centre and local PCs.

The System serves as a single source of process data with automatically generated performance indicators that allow exception notification and strategic analysis.

An important functionality of the System is Exception Reporting. This function compares the recently archived value with a limit value and generates an Exception Report if the value is out of range. The Exception Report, as an email, is sent to selected recipients.

An Operational Database has been designed to hold asset dimensions and other site details (current operational units and trigger (limit) values) which are used in the calculations.

Reporting of Data
A relationship has been established between the sum of the spot sample TSS + BOD and archived turbidity (see Figure 1).

Figure 1. The relationship between final effluent Turbidity and TSS+BOD - WWTP with standard Percolating Filters

Figure 1. The relationship between final effluent Turbidity and TSS+BOD – WWTP with standard Percolating Filters

The turbidity relationship is used to determine a turbidity level equivalent to the sum of the permitted BOD + TSS. This turbidity ‘permit’ equivalent is used by Southern Water in three ways:

  1. 80% of the ‘permitted’ turbidity is used in the outstation to generate an alarm in SCOPE if the 15 minute mean turbidity exceeds the ‘permitted’ turbidity for more than a chosen time span. This may be instantaneous or up to 2 hours depending on the environmental significance of the discharge. A high priority alarm is then issued to the site/standby Operator who will visit the site and take appropriate action.
  2. The Process Management System generates an Exception Report by email to selected recipients if the daily average turbidity held in the derived values archive exceeds 80% of the ‘permitted’ turbidity.
  3. Each Exception Report generated is investigated by the Process Scientist and an ‘Exception Reason’ is chosen from an agreed list of 43 operational and environmental causes of high turbidity – ranging from storm conditions and mechanical failure to equipment malfunction and vandalism. These reasons are then summarised and used for Business Intelligence purposes. In this way Southern Water is monitoring performance of all WWTPs against a continuously monitored parameter in addition to the compliance statistics generated by spot sampling.

Benefits of on-line monitoring

The installation of on-line monitors has encouraged a proactive response to system deterioration, which has resulted in a significant reduction in staff time associated with operational management of the wastewater assets. Non-routine site visits by Operational Staff have been reduced, and Wastewater Support Staff can target their site visits to WWTPs with poor performance as identified by on-line monitors.

The plant performance data has been improved with the use of 35,040 readings at fifteen minute intervals per monitor per year. The consequences have been protection of compliance and the identification of optimisation opportunities.

Routine final effluent sampling has been substantially reduced, resulting in considerable savings in sampling and analytical costs.

Real-time access to turbidity data also helps troubleshooting. For example, high turbidity values can indicate filter rotation problems, hydraulic/organic overload, final tank scraper failure, secondary treatment bypass or tertiary treatment failure.

In addition to the benefits from early warnings of poor quality effluent and the ability to show deteriorating trends, compliance levels have been maintained at around 98% since installation of the monitors began.


Remote monitors track river restoration success

10/05/2013
Remote monitoring of restoration work on beautiful English river using advanced sensing and telemetry technology.

Possibly one of the most unique areas of England is East Anglia; that part of the country north of London and south of the inlet known as the Wash. It encompasses the counties of Norfolk, Suffolk, Cambridgeshire and Essex, and is generally flat, stretching to the famous Broads, beloved of inland sailors and wildlife lovers. Water is an ever-present feature and this needs to be protected for environmental and biodiversity reasons.

The Norfolk Rivers Trust has installed a remote river monitoring station that has been tracking water quality and flow before and after river restoration work at an area of ecological importance on the River Nar (WIKI link!).

Picturesque view of the River Nar below Castle Acre! (Pic: Norfolk Rivers Trust)

Picturesque view of the River Nar below Castle Acre! (Pic: Norfolk Rivers Trust)

Rising in chalk hills to the east of the village of Tittleshall, the river flows south for 2.5 km until it reaches Mileham, then predominately west for 39.5 km through the villages of Litcham, Castle Acre, West Acre and Narborough until it reaches the tidal Ouse at King’s Lynn. The river rises on chalk and in its course to Narborough flows over chalk formations. In its lower course the underlying geology is more complex and consists of a progression from Narborough downstream through a series of clays and greensands, making it one of only a few remaining fenland chalk streams. In line with the requirements of the Water Framework Directive, the project is designed to ensure that the Nar maintains good ecological status by 2015 and in doing so it aims to improve the habitat for wildlife and promote biodiversity. The river monitoring station incorporates an Adcon GPRS telemetry unit from OTT Hydrometry, which automatically collects data and feeds a website, providing easy access for the project team.

The Problem
Agricultural runoff is a particular problem in the Anglian region because of the light sandy soils which are easily eroded during times of heavy rainfall. Fertilisers can add to the problem because they can be washed from the field and end up in water courses. As a result, many Norfolk Rivers contain high levels of nitrate and phosphate. Excessive levels of these nutrients can lead to eutrophication, symptoms of this can include vigorous growth of blanket weed; this change in water quality lowers dissolved oxygen levels in the streams and rivers, and harms wildlife.

In the past, the Nar channel has been made straighter, wider and deeper; initially to improve navigation, and later to improve drainage. However, this has had a detrimental effect on wildlife.

The River Nar also suffers from sediment deposition arising from point sources such as land drains, and from diffuse sources such as run-off resulting from cultivation in wet periods. This has affected species that rely on gravel beds for any stage in their lifecycle. For example, brown trout need sediment free gravel to lay their eggs.

The River Nar Project
Assisted by funds from WWF-UK, the Coca-Cola Partnership and the Catchment Restoration Fund, the Norfolk Rivers Trust has established a £609k  (€720k) river and flood plain restoration project to reduce pollution in the River Nar and improve the habitat for wildlife.

The project began in June 2012 and includes work to change the course of the river from a straight incised channel to a meandering route; reconnecting the river to the floodplain, which would create new habitats. This channel restoration project was completed in October 2012. The project also includes the creation of reed beds and other in-ditch options to trap sediment before it enters the River Nar. Currently four reed beds have been installed in different areas in the River Nar catchment which also includes the dredging of an existing pond.

Monitoring
Prior to the commencement of the project, the Norfolk Rivers Trust measured water quality by collecting weekly samples and transferring them to their laboratory for analysis. This was a time-consuming and expensive activity and only produced spot data for the moment that a sample was taken. Consequently, events that took place at night or between the sampling interval were not detected, so there were clear advantages to be obtained from continuous monitoring.

In order to establish a continuous monitoring station for water quality and flow, OTT Hydrometry provided a Hydrolab Minisonde water quality monitor and an Adcon A755 Remote Telemetry Unit (RTU). In combination with a bed mounted Doppler flow meter (provided by the Environment Agency), the station is able to provide a continuous record of the river’s condition.

narOTTThe Hydrolab Minisonde 5 takes measurements for turbidity, flow, conductivity, temperature and luminescent dissolved oxygen (LDO) every 15 minutes. The collected flow and water chemistry data is then stored and transmitted every hour via the RTU to an online server hosted by OTT Hydrometry. This allows information to be downloaded and analysed in the Trust’s office without the need for regular site visits. Data can be accessed at anytime from anywhere using the Adcon app.

Operating on extremely low power, and designed specifically for the collection and transmission of remote monitoring data, ADCON RTUs are able to utilise a variety of communication methods depending on site conditions. For example, radio represents a low-cost alternative in areas with poor GSM coverage and where line of sight is possible, with repeaters if necessary.

The monitoring site on the Nar has some GSM coverage, but the signal is poor, so an ADCON A755 RTU was chosen to communicate via GPRS. The A755 RTU has been developed specifically for areas with low signal, because it stores all monitoring data when signal strength is too low for transmission, and then sends the information when signal coverage improves, sending the backed up data first.

The monitoring equipment was installed at the end of July 2012 and restoration work began on 8th October 2012. Emphasising the importance of monitoring before and after the restoration work, project officer Helen Mandley says: “To be able to judge the success of the project it is essential that we are able to compare water quality data from the old river channel to the new river channel, because we need to improve water quality in order to improve the biodiversity of the river.”

Results
In addition to water quality and flow monitoring, ecological assessments have been undertaken for water voles and other small mammals, macrophytes, aquatic invertebrates, vegetation and fish. However, before a reliable assessment of the project’s success can be undertaken, it will be necessary to evaluate data over an extended period so that seasonal effects can be taken into consideration.

Pre- and post-restoration data on ecology, water quality and flow will be assessed in September 2013, and it is hoped that this will provide clear evidence that the project has had a significant effect on water quality and biodiversity.

Helen hopes to continue the project beyond 2013 commenting, “We currently monitor downstream of one of the new reed beds, but in the future we would like to place more monitoring equipment upstream of the reed bed to really see the differences, particularly in levels of turbidity and conductivity.”

The current phase of the project is due to run until the end of 2013, but a series of ‘restoration units’ have been identified by The River Nar Steering group that includes the Norfolk Rivers Trust, each applying restorative work to a specific section of the river. These units extend to 2027 but will be reliant on the availability of future funding.

Clearly, environmental monitoring is essential for the evaluation and ongoing management of remediation projects, and OTT’s UK Managing Director Simon Wills says: “This project is a good example of how simple and low-cost it can now be to create a monitoring station that is sufficiently flexible to collect and transmit data from a variety of monitors. “Advances in sensor, datalogging, communications and power management technology have combined to dramatically improve the effectiveness of remote data collection, which means that less site visits are necessary; thereby saving a great deal of time and money that can be spent on restoration.