The composition of waste water from food processing and
other plants varies with time. A composite sample composed of
smaller samples taken at different times will represent an average
condition of these flows. The sampling system described in
this paper will gather subsamples over a 24-hour or longer
period and keep the composite sample frozen until ready for
laboratory analysis. This system will work equally well on
pressurized pipelines or ponded water. The parts cost per controller
is approximately $80.00 plus the price of a freezer,
associated plumbing, and a pump if the water sample is not
in a pressurized pipeline

Fisher, H.D.

Smith, J.H.

USDA - ARS - NWISRL

Reprinted from the Soil Science Society of America ProceedingsVolume 39, no. 2, March-April 1975877 South Segoe Rd., Madison, Wis. 53711 USAAN AUTOMATIC SYSTEM FOR SAMPLINGPROCESSING WASTE WATERH. D. FISHER AND J. H. SMITHPurchased by the Agricultural Research Service, U. S. Department of Agriculture, for official useAN AUTOMATIC SYSTEM FOR SAMPLINGPROCESSING WASTE WATER'H. D. FISHER AND J. H. SMITH2AbstractThe composition of waste water from food processing andother plants varies with time. A composite sample composed ofsmaller samples taken at different times will represent an aver-age condition of these flows. The sampling system described inthis paper will gather subsamples over a 24-hour or longerperiod and keep the composite sample frozen until ready forlaboratory analysis. This system will work equally well onpressurized pipelines or ponded water. The parts cost per con-troller is approximately $80.00 plus the price of a freezer,associated plumbing, and a pump if the water sample is notin a pressurized pipeline.Additional Index Words; Water quality, biological oxygendemand, chemical oxygen demand.rilOOD PROCESSING INDUSTRIES produce large volumes of_r water in which the amounts of suspended solids andconcentrations of inorganic constituents including nitrogenand phosphorus vary considerably with time (1, 2). InContribution from the Western Region, Agricultural Re-search Service, USDA; Idaho Agricultural Experiment Stationcooperating. This research was supported in part by a grantfrom the Potato Processors of Idaho Association, Inc. Received8 Aug. 1974. Approved 23 Dec. 1974.= Electronics Engineer and Soil Scientist, respectively, SnakeRiver Conserv. Res. Cen., Kimberly, Idaho 83341.order to obtain representative samples of the waste watereffluent stream, the water must be sampled periodically overan extended period of time. The only feasible way of obtain-ing this type of sample is with an automatic sampling systemsuch as the one outlined in this paper.This automatic sampling system was used to sample apressurized pipeline carrying water from a potato (Solariumtuberosum L.) processing plant which was then evaluatedfor organic and inorganic nutrient content. A report on thefirst phase of the 'project was made by Smith, (J. H. Smith.Treatment of potato processing waste water on agriculturalland. Invitational paper presented at Pacific NW PollutionControl Ass., Vancouver, B.C., 10 October 1973.)This sampler collects samples at fixed intervals in time,regardless of outflow rate. This may result in a smallertotal sample if effluent is not flowing at the time of sam-pling. Making the sampling rate proportional to the flowrate may result in more accurate samples, but was too com-plicated and expensive for the results desired here. The con-troller can be made to simulate a flow-proportional samplerif enough information is available on the typical flow varia-tions from a source, This can be done by adjusting the sam-ple timer to take more samples during peak flows andfewer during lower flows.Although the authors used this system on pressure pipe-lines, the operation of the controller is such that it can alsobe used with a pump on nonpressurized waste water, suchas lagoons or open waterways.382Motor Bypass samara ter Coil24 VACPower SupplyController383Waste WaterWin LineSolenoidValve A Union	 Valve 8	 Valve CTo WasteSolenoidVolvo 0FreezerNC NONO NC NO4 L o4NONOTESFigure 1 is a schematic layout of the waste water sam-pling system as used on these pressure lines. At each locationwhere the sampling equipment is used, valve A and one-half of a pipe union are permanently installed on the wastewater line. To obtain samples at a particular location, thesampling valve system is installed by attaching the matinghalf of the pipe union. Valve A is opened and the systemcycled manually once. The sampling system is then readyfor operation. Solenoid valve 13 delivers the water to thesampling system; valve C is adjusted to produce enoughbackpressure to allow flow through solenoid valve 13 whichdelivers the actual sample to the sample container.In operation, solenoid valve B opens at the start of a sam-pling cycle. This purges water retained in the system fromthe previous sampling cycle. After a fixed time interval setby a time-delay relay, solenoid D opens and delivers thesample to the sample container. Both solenoid valves 13 andII then close, deactivating the system until the next watersample is programmed to be taken.In the authors' application, the outlet in Fig. 2 providedfor the motor actually controlled solenoid valve B to supplywater to the system. The time delay of relay A controllingthe bypass outlet established the flushing time for the sys-tem, although a bypass valve was not used. Time-delayrelay B controlled solenoid valve D and its time delay estab-lished the sampling period.Because of the variation in pressure in waste water linesbetween locations, the system is calibrated for each installa-tion by adjusting the backpressure with valve C and the timedelay relay controlling solenoid valve D so that the correctamount of water is passed into the sample container at eachsampling period.From the valve system, the water passes into a 4-literplastic jug inside a small freezer. In the authors' application,Fit 1—Schematic of sampling system used an pressure pipe-nes.water samples were taken at a frequency of approximately2 samples/ hour for 24 hours to obtain a composite sample.Individual samples usually freeze between samplings and astratified sample is obtained. The composite sample is keptfrozen, until analyses are desired, at which time the sampleis thawed, mixed, subsampled and analyzed.An inlet heater prevents freezing of the sample in thedelivery tube inside the freezer. This heater consists of in-sulated nichrome wire (constantan wire can also be used)wound around the delivery tube and powered from a 24-VAC source with a series-dropping resistor so that the+24VDC	Time Delay A	Time DelayNCNCNC NO	 NC NOI NC NOMOI14101Cornn	 1""Pass	 SampleOutletsFig. 2—Electrical schematic of sampling system controller.n AMotorPonarrdWasteWaterSampleBypassTo WasteVACr SupplyFreezerPumpContreiter384	 SOIL SCI. SOC. AMER. PROC., VOL. 39, 1975Fig, 3—Schematic of system used on ponded water.heater dissipates approximately 1 W. Enough resistancewire is used so that the total resistance of the heater isapproximately 2 a The delivery tube is a 0.6-cm (1/4-inch)diameter brass tube. Glass should not be used for this deliv-ery tube because it will not conduct enough heat from theheater and the water inside will freeze.The controller for the sampler (Fig. 2) has three electri-cal outlets that supply 115 VAC for three separate func-tions. The first outlet from the controller can operate asmall motor-driven pump, if required when sampling waterthat is not under pressure. This outlet is activated continu-ally during the sampling cycle. The other two outlets oper-ate sequentially to control two sampling functions. Whenthe sampling cycle is complete, all three of the outlets aredeactivated until the beginning of another sampling cycle.Figure 3 shows all the outlets in operation to samplenonpressurized water.A modified time switch from which all the electrical con-tacts have been removed controls sample timing. A 13-cmdiam disc attached to the underside of the timer face hasa series of holes drilled around the circumference at 5° cen-tral angle intervals to accept No. 2 machine screws. Thismodified timer is mounted on the outside of the box inwhich the controller is constructed. The machine screws inthe disc actuate a miniature snap-action switch with a leveractuator mounted on the box. With screws in each of theholes in the disc, samples can be obtained at 20-min inter-vals for 24 hours during the day. Other arrangements ofscrews in the disc will produce samplings at intervals whichare multiples of 20 min. The snap-action switch on thetimer actuates a 24-VDC relay which supplies both 115VAC to the points of the next two relays and 24 VDC tothe coil of time delay relay A. Relays A and B are delay-on-actuate time delay relays.When the relay controlled by the time switch actuates,115 VAC is available to the bypass outlet through this relayand the normally closed (NC) points of time delay relay A.The motor outlet is powered through a set of NC contactson time delay relay B. When time delay relay A actuates,it deactivates the bypass outlet and applies 24 VDC to thecoil of time delay relay B. One set of normally closed pointson this relay, in turn, supply 115 VAC to the sampleoutlet. When relay B actuates, it deactivates both the sam-ple and motor outlets.Because of the location of these units, voltage fluctua-tions on the 115-VAC line are quite probable. To eliminatethe effects of these fluctuations on relay actuation time, thetime delay relays are powered from a 24-VDC regulatedsupply (Fig. 2) with sufficient storage capacity that shortoutages can be tolerated without interrupting the samplingcycle.The parts cost per controller is approximately $80.00.This results in a sample controller which can be pro-gramed to sample a maximum of once every 20 minthroughout the day, and which has easily adjustable bypassand sampling periods. This enables the user to programthe system to fit the type of installation he is interested insampling, whether it be a pressure system or one in whicha pump is required for sampling.List of Major ComponentsCONTROLLER1	 Paragon Model 4003-0 time switch,1	 Potter-Brumfield XAP-11DG relay-24-VDC coil,2	 Potter-Brumfield CHD38-30003 time delay relay,1	 Triad F-45X filament transformer,1	 Encapsulated fullwave bridge rectifier,1 each 2000 of 50 V, 60 /if 50 V capacitors,1	 2N3026 transistor, and1	 1N3030 zener diode.SAMPLER AND COLLECTOR1	 115 VAC centrifugal pump and motor,2	 115 VAC solenoid valves in size of pipe used,2	 Gate valves in size of pipe used,1	 5 cubic-foot freezer, and1	 Triad F-45X filament transformer for inlet heater.Literature Cited1. Knapp, C. E. 1970. Agriculture poses waste problems.Environ. Sci. Technol. 4:1098.2. Pearson, G. A., W. G. I. Knibbe, and H. L. Worley. 1972.Composition and variation of waste water from food-proc-essing plants. USDA ARS-41-186. Washington, D.C.

An Automatic System for Sampling Processing Waste Water

Northwest Irrigation & Soils Research Laboratory Publications

https://eprints.nwisrl.ars.usda.gov/id/eprint/268/1/304.pdf

An Automatic System for Sampling Processing Waste Water

Abstract

Similar works

Full text

Available Versions

USDA - ARS - NWISRL

Northwest Irrigation & Soils Research Laboratory Publications