Process automation helps wastewater treatment operators keep treatment systems functioning and in compliance with permit requirements. Here are some of the latest innovations in tools for process monitoring, automated control, sampling, trend analysis, flow measurement and more.
Decentralized Automation
Meeting telecontrol application requirements, the 750-872 PFC controller from WAGO Corp. simplifies network access and remote data monitoring and collection. The IEC 61131-3 compliant modular system makes all fieldbus and input/output data available to wastewater treatment control systems, and provides access to more than 300 analog, digital and specialty modules.
Data acquisition or control protocols include Modbus TCP/-RTU, IEC 60870-5-101/-104, 3964R, RK512, and Ethernet/IP). System management and diagnostics protocols include HTTP, BootP, DHCP, DNS, SNTP, FTP, SNMP and SMTP. Users can place HTML pages on an internal server for Web-based monitoring or access programs via XML and ASP. The system also has library functions for e-mail, SOAP, ASP, IP configuration, and Ethernet sockets and file system.
Equipped with a 32-bit CPU, the multitasking system has a battery-backed, real-time clock for data logging. Access to IEC 60870-5-101 and -104 telecontrol protocol is through function blocks using CoDeSys. Users not wishing to write a PLC program can parameterize the telecontrol protocols within CoDeSys. 800/346-7245; www.wago.us.
Trending Tool
Wastewater operators can spot operational issues before they become serious with the Trending Tool from Sunapsys Inc. Users need only a Web browser to view predefined trends or time-based data from any database. They can map database field names to user-friendly names and export trends for sharing with others. The tool enables operators to plot levels, flows, pump status and more. Holding the mouse pointer over a trend reveals its actual point values. Features include scroll and zoom, drop-down lists, and pop-up calendars. 540/904-6862; www.sunapsys.com.
Constant Pressure Control
The H2O variable frequency drive (VFD) from SJE-Rhombus has integrated advanced pumping software that reads the discharge pressure and adjusts the pump speed to maintain a constant output pressure without a programmable logic controller or separate controller.
Automatically adjusting pump speed to correspond with lower demand reduces electric motor energy consumption by 20 to 50 percent. Available from 5 to 150 hp at 200 to 230 volts and 5 to 500 hp at 380 to 480 volts, the speed pumping application handles single- or multiple-pump operations. The standard VFD has a NEMA 1 enclosure with a pressure transducer, and can be customized for specific requirements including outdoor-rated enclosures, terminal blocks, door-mounted keypad, hands-off-auto switch, line and load reactors, dv/dt filters, IEEE-519 compliance, remote monitoring, and control (SCADA). 888/342-5753; www. sjerhombus.com.
Mass Flow Meter
The Model ST51 mass flow meter from Fluid Components International measures digester gas, biogas and other methane composition biofuel gases, including natural gas. Units are precision calibrated to match the gas composition and specific flow conditions of each digester system. Meters have a thermal mass flow element with flow accuracy to ±1 percent of reading from 0.3 to 400 SFPS (0.08 to 122 MPS), and repeatability of ±0.5 percent. The flow element works in 2- to 24-inch lines. Electronics are housed in a compact, explosion-proof transmitter that installs easily and requires little maintenance. 800/854-1993; www.fluidcomponents.com.
Ultrasonic Flow Meter
The Innova-Sonic Model 206 from Sierra Instruments Inc. includes a digital correlation transit-time device that has fewer upstream/downstream piping requirements and no moving parts. The meter has zero tracking with no damping, measures down to zero flow, and outputs in 4-20mA DC analog and RS 232.
PicoFly measurement technology processes the ultrasonic transit time in picoseconds (one trillionth of a second), enhancing resolution and low-flow detection. Reading accuracy is ±0.5 percent, and the unit can measure any clean liquid regardless of conductivity down to zero flow. The unit offers low power consumption, digital signal processing with advanced noise filtering, accuracy and repeatability of ±0.1 fps, -40 to 176 degrees F temperature range, and zero to 23 fps liquids bidirectional flow range.
Large-scale integration technology allows 10 times the component population compared to typical integrated circuits. The in-line spool design has a carbon steel flow body available with ANSI or DN 16 flanges. Easy to program, the meter has a readable 16-character-by-two-line backlit display. 800/866-0200; www.sierra instruments.com.
Compact Pressure Transmitters
The GC51 and GC52 gauge and differential pressure transmitters from Ashcroft Inc. offer an economical alternative to network process transmitters when a digital protocol is not required. The design has a 2.65-inch diameter NEMA 4X/IP65 enclosure and stainless steel wetted parts to accommodate wet or dry media. The GC51 has ranges from 0 to 7,500 psig and the GC52 has D/P ranges up to 400 inches of water.
A built-in LCD backlit display and 4-20mA output provide local indication and remote signaling. GC series transmitters measure fluid levels in tanks and differential pressures across membranes in water purification systems. Media isolators are available for sludge or caustic media installations. 800/328-8258; www. ashcroft.com.
Web-enabled Controller
The Model 5300 automation controller from Control Technology Corp. accesses remote sites via Ethernet or wireless communications. It supports CTC Web server technology, enabling users to securely monitor and control process variables, especially SCADA applications requiring 24-hour remote access.
Using webHMI software, operators can create graphical HMI projects and host them on the controller’s Web server, giving any browser-based device interactive HMI functionality. High-speed data logging stores time- and date-stamped measurements to internal or external files. Remote terminal units also support wireless communications.
Operators can choose from multiple CPUs and various input/output and motion modules. Up to 16 I/O or motion modules can connect to one CPU for a maximum of 512 I/O or 32 axes of motion in a single controller. Input/output modules come in 4-, 8-, 16- and 32-channel versions and plug into terminal blocks. The unit connects to color displays that are readable in full sunlight to total darkness.
The controller supports Modbus serial and Ethernet connections, and Modbus/RTU and Modbus/TCP in master or slave configurations. Operators can run multiple Modbus networks of different types simultaneously. 888/818-2600; www.ctc-control.com.
Self-learning Sampler
The refrigerated Quick Lift Sampler (QLS) from Quality Control Equipment Co. delivers an accurate, repeatable sample. A vacuum pressure pump lifts samples up to 28 feet without damaging or distorting them, and they are unaffected by horizontal runs of 125 feet or more. Strong purge capabilities eliminate cross contaminants in the intake line. The maintenance-free unit checks itself after each sample to verify the amount. If incorrect, it self-calibrates automatically. A programmable sample size of 20 to 500 ml in 1 ml increments allows the sampler to self-learn. 800/959-7232; www.qcec.com.
Digital Controller
The Digital Indicating Controller from Analytical Measurements configures to monitor and control pH or ORP (Redox). If recording is needed, operators can add a strip chart or circular chart. Manual temperature compensation is from 0 to 100 degrees C.
The instrument has a large digital display readable from more than 50 feet away and a two-point controller to activate pumps and alarms based on pH or millivolt setpoints. Options include a 4-20 mA output for remote monitoring and recording, and an ATC probe for automatic temperature compensation. The unit, protected in a NEMA 4X enclosure with clear plastic front-hinged panel, comes with a probe and buffer solutions for calibration. 800/635-5580; www.analyticalmeasurements.com.
Alarm Annunciator
The 725B stand-alone annunciator from RTK Instruments Ltd. uses Canbus communication technology and a multi-redundant design. Interchangeable ultra-bright white LEDs illuminate alarm windows. An optional integral 1ms event recorder and universal power supply that connect to 85-264V AC or 88-360V DC are available.
Modular construction allows units to be assembled in almost any size and shape from one to 256 channels in a single housing with choice of window sizes and colors. Up to 32 output relays can be configured as group, audible or diagnostic relays. Six pushbuttons and dual audibles cover almost all alarm applications. Each alarm channel is fully programmable using the supplied configuration utility and a standard USB port connected to a PC or laptop. 908/688-6709; www.rtkinstruments.com.
Monitors H2S Emissions
The Jerome 651 fixed monitoring system from Arizona Instrument LLC provides long-term, unattended monitoring of hydrogen sulfide levels from 0.003 to 50 ppm. A weatherproof, temperature-control-led box houses the Jerome X631 gold film sensor.
The box also has a control panel for on-site programming and a 2.4-GHz radio for remote programming and data downloading. Built-in software includes statistical analysis and graphing capabilities, extensive data storage, customizable reports, and high H2S-level e-mail alerts. For large sites, multiple units can be linked to form a com-prehensive perimeter or facility monitoring system. 800/528-7411; www.azic.com.
DO Sensor
The Triton DO8 dissolved oxygen sensor from Electro-Chemical Devices (ECD) delivers accurate measurement with low maintenance and low cost of ownership in municipal wastewater applications.
The unit uses intelligent microprocessor-based electronics and stores calibration data within the sensor. The maximum error rate is less than 2 percent, repeatability ±0.5 percent, and resolution 0.01 ppm or 0.01 percent saturation. It withstands pressures up to 145 psi.
A replaceable cap contains a circular layer of optically active, oxygen-sensitive molecules that is highly permeable to oxygen and rapidly equilibrates. Via digital communication, the unit sends DO data to ECD’s C-22 Controller, which provides a 4-20mA output signal to the treatment plant control room. The unit has no membranes, no electrolytes, and no anode/cathode assemblies. 800/729-1333; www.ecdi.com.
Process Control Software
Advantage from Total Systems Resources is a fully functional HMI/SCADA software program for Windows. It is a maintenance scheduler, remote alarm notifier, process or strategy simulator/tester, PID (process identifier) controller, report generator, and multiple poller. Online configuration, multiple security levels, math function library, and a pending optical particle counter (OPC) are included, all without third-party application appendages. 888/583-3001; www.TSR-Advantage.com.
