PID - M1
As the water flows through the flume into the grid separation chambers, the flow rate is analyzed by the flow meter, and the flume flow meter provides an analog signal back to the PLC. High flow rates greater than 1200 gpm, will provide an alarm. Solenoid valves SSV-M1-01 & 02 will be activated by the flow meter. The solenoid valves provide hot water to wash the screens when the flow rate flows less than 100 gpm the solenoid valves will be shut off. The grit separator is operated by a local control panel including the mixer, the transfer pump and the conveyor. "Digital-in" signals are provided back to the PLC for status of operation and overload conditions to the PLC. A level control of slop oil tank LS-01 provides an alarm status signal to a PLC, activated on high level only. Sludge pump P-2 driven by solenoid valve SV-M1-01 is operated by a switch in the main control panel. The pH monitor pHA, mounted in the flume, senses pH providing an analog signal back to the PLC. There will be an alarm set on the pH if it is too high or too low to alert the operator of the off-spec condition.

PID - M2
The water flows out of the headworks into equalization tank #3 through air activated valve, M2-09. The level of water in equalization #3 is sensed through the pressure transmitter PIM2-03 providing analog signal to the PLC. When the water level rises in tank #3 to a predetermined height approximately 5’ above the overflow elevation (20 feet), air activated valve M2-10 will open providing outlet of the water to the dissolved air flotation unit. The rate of flow will be sensed through FITM-2-01 providing an analog signal to the PLC indicating the flow rate. An analog out signal from the PLC will drive the FCV flow control valve FCV-M2-01. The PLC will provide an analog signal to the flow control valve to adjust the flow rate to a preset level of 300 gpm. If the water rises above the 25’ height it will go to step 2. At step 2, transfer from equalization tank 1 & 2 will close. If the water level rises above the 30’ mark, air activated valve MV-M2-04 or MV-M2-05 depending on the status of the equalization tank 1 and 2 will open to divert a portion of the water into equalization tank 1 or 2, and will also sound an alarm to alert the operator who will then make a decision if he should increase the flow of the water to the DAF or bypass the DAF (to be discussed when we move to PIDM3 & 4).

The rate of flow from equalization tank 3 will be adjusted in 3 set increments of four specific cases preset into the PLC that regulates the flow control valve to a predetermined flow rate. The flow rate can be adjusted and proportioned to the level of the tank. Certain chemicals must be fed proportionately to the rate of flow.

Pressure transmitter M2-03 on equalization tank 2, and M2-01 on equalization tank 1 also supply analog signals to the PLC. The graphic screen of the PLC will graphically depict the level of water in each of these three tanks on a real time basis. When there is no operator present at the plant, the operator will turn off air activated valve M2-09 and divert the water to equalization tank 1 or 2. Their function can be automated on a 24 hour time cycle at the customer's option. The other equalization tank will be utilized for emergency storage during high flows (in rain event). pH meters M2-01, 02, and 03, are in the recirculating lines to each respective equalization tank providing an analog signal to the PLC to indicate off-spec water. Should the water reach an acidic state, an alarm will alert the operator, who will manually activate the supply of sodium hydroxide. The caustic is pumped by pump P-17 and PID-M3 and diverted to the proper equalization tank by an air activated valve M2-11 on equalization tank 3 and M2-07 on equalization tank 2 and M2-03 on equalization tank 1. One of these three valves must be opened and be indicated as open before the metering pump P17 will be activated. All three valves provide digital signals on their respective position to the PLC.

Return pumps P-12 and P-13 on equalization tank 3 are manually activated from the control panel to pump the wastewater back to the headworks. Switches on these pumps are off/auto with the auto position permitting the pump to be operated only when level is present within the tank. If low level is indicated the pumps will not be activated. Digital signals are provided to the PLC for status, both operating and overload, for P12 and P13.

Mix pumps P-11, P-4, and P-3 are operated by off auto switches. When the level controls indicate low level in each equalization tank the respective mixing pumps will not be allowed to operate.

The return pumps P-12 and P-13 both have flow indicators in the line provided. The digital signal to the control panel must indicate flow, if not, an alarm will be given to the operator to show that the respective pump is inoperable.

When the liquid level is present in equalization tank 1 and 2 the operator will manually transfer the liquid to the treatment system in equalization tank 3. In the case of equalization tank 1, transfer pumps are P-6 and P-10. The operator manually operates air activated valve M2-01 on equalization tank 1 and then manually turns on transfer pump P-6. If after a 30 second delay the flow indicator in the line of P6 does not indicate moving liquid; P-6 will be turned off and an alarm will sound to the operator. Transfer pump P10 has the same type of service air activated valve MV-M2-06 at the bottom of equalization tank 2, which controls the delivery of water from equalization tank 2. Should tank 3 sense a high level, the transfer pumps will be turned off. Bleed pumps P-5 and P-9 utilized to transfer from equalization tank 1 and 2 through the air activated valve similar to the transfer pumps, slowly transfer the collected liquid into equalization tank 3. Flow indicators sense the flow. Should there be a loss of flow, pumping action will cease. The pumps will automatically turn off upon sensing low level in equalization tanks 1 or 2. The bleed pumps and the transfer pumps will sense low level in respective equalization tanks 1 or 2 depending upon which air activated valve M2-01 or M2-06 is open. When an air activated valve is opened, digital signals to the PLC will display the status, indicating if the valve is opened or closed. The color graphic monitor provides real time display of the status, opened or closed, of all air activated valves. Pumps P-7 and P-8 have an off/auto switch in the main control panel. The respective pumps will be operated from level controls in the sumps. If a high level is indicated in the sump an alarm will be given to the operator.

PID-M3
When flow through the air activated valve is permitted and indicated through the FIT (on M-2 drawing), the mixers in the waste conditioning tank, MX-2 3 & 4 will be activated. pH will be adjusted with sulfuric acid and caustic soda by metering pumps P-15 and P-16. Analog signals provided from the PLC progressively sense the pH and proportionately adjust the rate of flow of the required reagent pH so over-shoot does not occur. Pump P-14 supplying the ferric chloride will be preset at four different steps proportionate to the water flow as indicated from the FIT (drawing M-2). Polyelectrolyte is supplied through PM-M3-01 Polymixer with control by an analog signal from the PLC and will provide the rate of flow of polyelectrolyte. DAF #1 and #2 will be manually activated, the operator will select which DAF, 1 or 2 will be in operation by opening and closing the respective hand valves B-10 (located at the inlet of each DAF). When the operator initiates one DAF versus the second, he will then manually turn on the air activated bottom sludge removal, then from the central control panel activates a recycled pump. The recycled pump is controlled by the FIT. When flow is indicated from equalization tank 3, the respective DAF will be automatically activated. When recycle pump is activated the respective air compressor supplying the air will also operate and the collected sludges will be automatically drained from the bottom of the DAF. Flow indicators in the air line supply for each DAF will indicate an alarm, if no flow of air is indicated. Also, a flow indicator is in the recycle line and should loss of flow be indicated, an alarm will be given. Sludge from the top of the DAF flows by gravity to the sludge collection tank. When the level control in the sludge collection tank indicates a high level, the transfer pump P-21 will automatically be activated. The collected sludge will be pumped until the low level is sensed.

PID-M4
Level of water in tank T-47 is continuously analyzed and displayed on the color graphic monitor through PT-4-01. Transfer pumps P-22 and P-23 operated from hand/off auto switches within the central control panel will transfer the liquid from the surge tank to the air stripper. When the level of the tank T-47 indicates high level, the blower will start on the air stripper. After a delay of 15 seconds, FI-M4-02 will check the status of the blower, if air is flowing (FI-M4-02) is provided to alert the operator and will turn on transfer pumps P-22 or P-23 which will alternate. If the flow is not indicated, an alarm condition will sound. On sensing high high level in tank T-47 air activated valve (MV-M4-11) will open, transferring water directly to transfer tank T-48 bypassing the air stripper. Pressure differential indicator across the air stripper will automatically monitor the differential pressure giving an alarm if the air stripper is contaminated. An organic analyzer placed in the effluent from the air stripper line will automatically monitor the presence of hydrocarbons and should high level be indicated an alarm will be given.

Pressure indicator (PT-M4-02) on tank T-48 will continuously monitor the liquid level, providing a signal to transfer pumps T-24, T-25 and T-26. The three pumps will alternate with the second and third automatically being turned on as the liquid level increases in transfer tank T-48. Flow indicator (F1-M4-01) in the air line to the VOC unit will continuously monitor the status of the air movement and should the air flow cease a visual and audio alarm will be provided to alert the operator. Temperature indicator in the air line continuously monitors the temperature and opens or closes steam valves (SSD-M4-01) providing the required steam. The air blower will be operated from the main control panel with a hand switch.

Level controls in tank T-49, desorbate surge tank, will provide the level controls to turn on pump P-89 transferring desorbate to the decant tank. Level controls in decant tank (T-49) will sense the level of the liquid on the water side of the baffle and turn on pump P-27 to transfer the accumulated water directly to the headworks. Periodically the operator will manually turn on pump P-28 to transfer the accumulated hydrocarbons to the oil storage tank.

PID-M5
Liquid coming from the transfer tank T-48 is directed into tank T-1 or T-2 through respective air activated valve depending on the liquid level in each tank. The level control indicators on both tanks T-1 and T-2 continuously monitor the status of the level providing alarms if high level is indicated and open the corresponding air activated valve on the stand-by tank.

The operator must manually tell the system through a switch which treatment train A or B shall be operated. Activating train A or train B opens air activated valve AV-M5-03 or AV-M5-04. Upon opening these valves the entire system would be put into a ready state to process liquid should either pump P-29, P-30 or P-31 be activated from the level indicators in the storage tank. When T-1 and T-2 are at low level and the pumps deactivated, the entire train shuts down, the sand filter turns off and after the system is off for a period of 30 minutes, fresh water is flushed through the sand filter for a predetermined period of time to flush the carbonates from the sand. Treatment train B operates the same as treatment train A. When train A or B is in operation, the final pH adjustment mixer will be in operation and the pH will be adjusted. When the system turns off the final pH adjustment tank it will remain active for a period of approximately 30 minutes to allow accumulated water to drain through the treatment train. The pH in final pH adjustment tank is adjusted by an analog signal. Water overflows from the pH adjustment tank to the surge tank. The surge tank has a pressure transmitter providing a real time graphic display of the liquid level. The pumps on M-6, P-86 and P-87 are activated by the liquid level in the surge tank. These three pumps will alternate.

The sludge that accumulates in the sludge thickener will be pumped to the filter press. A low hydraulic pressure sensor within the filter press senses clamping pressure. The filter press will not permit P-83 to pump unless adequate clamping pressure is maintained. When the compacting pump (P-83) starts, timers in the control panel activate three solenoid valves providing a progressive pumping pressure. The first stage is set at 20 psig, the second stage is set at 40 psig, and the third full compaction pressure at approximately 90 psig. When the liquid flow through pump P-83 reduces to a preset low flow the flow indicator of the pump M5-05 provides a press full signal to the PLC. The PLC upon sensing low flow will sound an alarm to alert the operator that the press is full.

PID-M-6
The operation of P-85, P-86 and P-87 was previously discussed on PID 5. Two air activated valves AV-M-6-01 and AV-M6-02 determine where the pumps will transfer the liquid. If M6-01 is opened, the liquid will be pumped through the GAC absorbers 1 and 2. If M6-02 is opened the water will be directed to the sewer without passing through the GAC absorbers.

Pump P-88 transfers accumulated water in a reuse storage tank to back flush the GAC absorbers. The manual back flush has an automatic interlock to pump P-88. Should low level be indicated in the storage tank, the pump will no longer transfer liquid. Flow indicators are located in the lines to the GAC absorbers to indicate which absorber is in the primary mode and which one is in the secondary mode. PID indicators are installed across each gas absorber to indicate the pressure differential required to drive the liquid through the beds. When the preset high pressure level is attained and is exhibited on the PLC, an alarm will sound to alert the operator of the internal back pressure.

PID-M-7
Cyanide wastewater accumulates in cyanide equalization tank T-25. The pressure transmitter provides real time indication of the level in the tank, graphically displaying the level on the color graphic monitor. Upon sensing a preset level, transfer pump P-55 is activated transferring accumulated waste to cyanide oxidation stage 1 and stage 2. When the liquid is being transferred the mixer MX-19A and MX-19B are activated and chemicals may be added as determined by the pH and the ORP instrumentation. When liquid does not flow through the cyanide oxidation tanks pH and ORP instruments will monitor the condition but chemicals will not be added. Treated cyanide waste accumulates in lift tank T-28 as sensed by the three level controls M7-M-01, M-02 and M-03. Upon sensing the level either P-56 or P-57 are automatically activated to pump the treated water to the equalization tanks in the metal treatment area, P-56 and P-57 will alternate. Should high level be indicated an alarm will sound and the secondary pump will be activated and transfer of liquid from tank T-25 will cease.

PID-M-8
Water will be permitted to accumulate in tank T-30 acid batch equalization and T-30B alkaline batch equalization. Pressure transmitters on each tank will continuously monitor the presence of the liquid and provide a real time graphic display of the level to the color graphic monitor. When high level is indicated on either of the tanks, P-62 or P-63 will be activated to transfer accumulated liquid to the batch treatment tanks. Water will continue to be transferred into the batch tank until a high level is indicated in the batch tank. The respective pump will be discontinued. The system will be locked out from transfer until the waste has been treated and transferred. pH and ORP instruments provided for each tank will provide analog inputs to the PLC. Automatic programs are set in the PLC to treat either cyanide waste or chromate waste or neutralization waste. A switch on the local control panel has a selection switch so the operator can select the treatment process that he desires. Example: If cyanide is to be treated pH will be raised with sodium hydroxide, hypochlorite will be added to a preset ORP reading held for one hour, pH will be dropped to 8, additional hypochlorite will be added and then the pH will be raised to preset level, polymer will be added, the mixer will operate 10 minutes after the polymer is added, then it will shut itself off. After 2 hours of settling time, an alarm will sound to indicate to the operator that it is time to drain the tank. Conversely the chromate treatment cycle is also programmed into the treatment system. Sludge will be transferred to the local sludge thickener and the compacting 5 cubic foot filter press (through pump P-73).

Controls to the filter press for low hydraulic pressure, "press full" and progressive pressure steps will be identical to the filter press located in the metal treatment area.

Tanks T-33 and T-34 both have water fill circuits. A level control built into the tank provides a low level which sounds an alarm to indicate to the operator it is time to fill the tank. He presses a local push button switch which allows water to fill into the tank until the high level is attained. He then manually turns on the mixer and adds chemicals as required to mix up the batch.

PID-M-9
Lime silo has an ultrasonic level control which provides a signal to the PLC. The quantity of lime remaining in the silo is graphically displayed on the screen.

The liquid lime slurry or "milk" is automatically prepared. Upon sensing low level in the lime make-up slurry tank, fresh water is added to raise to the high level. At the same time the conveyor starts transferring lime into the mix tank. The vane feeder on the bottom of the lime silo is activated to deliver lime at preset rate. At the completion of the preset time cycle, the vane feeder turns off. The conveyor is allowed to run an additional 5 minutes to purge itself of all lime. While the lime is being transferred from the silo an air slide system at the bottom of the silo is activated to shift the lime to the center outlet. Both vane feeder and conveyor provide digital signals back to the PLC indicating the status of either overload condition or operation.

Pump P-94 air diaphragm transfer pump, will transfer lime from the lime mixed tank to the lime slurry tank located in the metals treatment area. Upon sensing low level in the lime slurry tank, T-24 on PID-M10, pump P-94 is activated to transfer liquid lime. Upon the completion of the transfer by sensing the high level in the slurry tank, P-94 is stopped. Fresh water is added for a period of 30 seconds to the input side of the pump to flush the lime slurry from the pump and through the line to tank T-24 prohibiting the build up of lime in the lime transferred line.

Lime feed pump P-78 transfers lime to the sludge conditioning tank T-37, which occurs when solids are being transferred from either the DAF sludge tank or the sludge tank in the headworks. Upon completion of the transfer of the required lime, a fresh water flush valve opens flushing fresh water to T-78 prohibiting the build up of lime within the pump or the line.

Ferric chloride tank T-35 has a pressure transmitter on the tank providing the level of ferric chloride. Upon sensing a preset reorder level, an alarm will sound on the control panel and the tank will flash until reorder has been accomplished.

Pump P-79 will pump ferric chloride to the sludge conditioning tank. Transfer of the ferric chloride is done only when solids are being transferred from the DAF or the headworks.

An additional air diaphragm pump is located on the ferric chloride storage tank to transfer liquid ferric chloride to tank T-23 on PID-M10. The ferric chloride tank operates very similar to the lime. Upon sensing low level, ferric chloride is automatically transferred from the bulk tank to the day tank.

Add mix is supplied to the sludge conditioning tank by pump P-80. This is a hand-off-auto function. The operator must place it in the auto condition which will transfer add mix whenever solids are being transferred from the DAF to the headworks. The operator may also turn it on by hand to add additional add-mix. Conditioned sludge in T-37 flows by gravity into T-38 and then is pumped through P-81 and P-82 into one of the two large sludge thickeners. Level controls in T-38 indicate the level of the surge tank and turn on P-81 and P-82 as required. Transfer of sludge from the sludge thickeners to the filter press is a manual transfer. The filter press is equipped with a low hydraulic pressure similar to the two previous filter presses and a low pressure progressive pump step control and as well as low flow to indicate press full like the other two presses.

The filtrate exiting the filter press is transferred to tank T-41 which has three level controls providing digital inputs to the PLC to operate P-90 and P-91, to transfer the water to the headworks. T-39 hot wash tank has level controls to indicate the low level and solenoid valves automatically fill the water level back up to the high level.

The sludge dryer provides digital input signals for the status of the drive motor to the control PLC.

PID-M10
Low level signals are provided for T-17, T-18 and T-19. High and low level signals are provided for T-20, T-21, T-22, T-23 and T-24. T-24 lime slurry tank is automatically filled as we discussed from PID-9. Tank T-23 the ferric chloride day tank is also automatically filled as discussed on M-9. T-20 and T-22 have automatic fill circuits for the dilution water.

The lime slurry transfer pumps P-53 and P-54 have water flush circuits.

When the pump turns off fresh water is flushed through the pump and through the line to prohibit the accumulation of the lime in the transfer line or pump.

PID-M-11
The treated water collects in the treated water storage tank. When the tank is full the excess gravity flows to the industrial sewer. Pumps with hydropneumatic pressure reserves supply a continuous supply of pressurized water to be reused as non-potable "Treated Effluent Storage" (TES) or sent to the reverse osmosis unit (M-13) for further purification.

PID-M-12
A boiler is installed to provide steam regenerate for the gas phase carbon adsorption unit.

PID-M-13
A reverse osmosis unit is installed to remove the dissolved salts from the (TES) producing reusable demineralized water. The treated water initially flows through dual softeners to remove the alkaline earth metals. The soft water is then filtered and pumped through two array reverse osmosis membranes. The permeate is stored in the RO tank (reverse osmosis) and later reused as required. The reject, containing the concentrated dissolved salts, is sent to the industrial drain.