污水处理厂
Silver Springs is a small community near Reno inwestern Nevada. As with many small towns with septic tanks,fecal coliform is appearing in drinking water wells. To counteractthis problem, SilverSprings has built a new waste water treatmentfacility with aerated lagoons. The Silver Springs projectis innovative in that it sends the treated, aseptic water tofarmers for reuse in irrigation rather than releasing the waterunused into a river or back to the groundwater via aninfiltration system. Another innovative aspect is that the systemis set up so that the necessary parties can control and monitorplant operation and retrieve archived data remotely. Operators and engineers access the computer remotely to con-figurethe system and provide updated software and CR10X programs. The newfacility consists of head-works with a spiral drive andagitator, controls for grit removal and screening, three lagoons, aclarifier, two sand filter beds, a chlorine contact basin, and atreated water effluent storage pond.
污水处理厂
As oxygenation is critical to break down complex organicsubstances, aeration is an integral part of the system.(Biologicalreactor pond at the Silver Springs Wastewater Treatment Facility.)
A number of pumps circulate water and activated sludge whileaerators operate in three of the lagoons on a rotating basis. TwoCR10X dataloggers with AM416multiplexers monitor status andflow throughout the plant. Each CR10X/AM416 monitors thestatus of the head-works lift spiral and agitator, theclarifier arm, the traveling bridge filters, aerator/blower motors,pumps, and door intruder switches. The dataloggers monitorpulse and 4-20 mA signals representing pump speeds and flow ratesat various points in the system as well as a small weather stationon the top of the control building. An SDM-CV04 current outputmodule allows one CR10X to control the speed of chlorine dosing andactivated sludge movement in proportion to plant flow. Each CR10Xuses an SDM-CD16ACrelay driver to control pumps and a valve. Theeffluent storage pond level is measured using a pressuretransducer. The dataloggers automatically turn off theirrigation effluent pumps in the event of freezing temperatures,excessive wind speed, or low storage pond level. After shutting down the pumps, the dataloggers call the irrigationdistrict to notify them.
One CR10X uses a COM300 for voice synthesizer alarmcallouts. The irrigation district can restart the effluentpumps over the COM300 telephone modem by listening to voicemessages on pond level and weather conditions, then pressing phonekeys to turn the pumps on remotely. The other CR10X is connected toa computer in the facility office via an ethernet connection (NL100network inter-face.) The dataloggers share significant datavia a serial link using control ports. Thus, real-time data andcontrol are avail able both on the computer monitor and over thevoice modem. Campbell Scientific’s LoggerNet soft-ware communicatesover the network link to retrieve data from the CR10Xs and dis-playit on a monitor in the facility office. Grapher, part of theControl Panel LoggerNet client, allows graphical trend-ing ofreal-time or historical data from the LoggerNet data cache. LoggerNet’s Baler client periodically retrieves historicaldata over the network. The data is imported into MS Accessusing Visual Basic for Applications (VBA) scripts and is usedto generate monthly reports required by the EPA. Datacritical to these reports are retained for months in the CR10Xsincase of communications or computer problems