Automation and visualization (SCADA) of Talsi city waste water treatment plant (Talsi city)

Used controller: General Electric Fanuc, Versa Max.

Used visualization program: based on General Electric Cimplicity .

treatment 01 1

Purification devices of the Talsu city were commissioned this year. Construction of the devices as well as its technical equipment was performed with the support of PHARE financial means and the main contractor for the performance of these works was JSC "U. Pilena birojs".

Purification devices ensure purification of the sewage received from the pumping stations. Purification process consists of pre-purification, aeration, re-circulation of the mixed environment, re-circulation of sludge and separation from floating substances. All devices that are realizing this process are controlled with the help of General Elektric Fanuc or Versa Max controllers. Information about the process procedure and device statuses is observable in the process visualization program, which has been designed on the basis of General Electric program Cimplicity.

Program allows controlling process from the computer, by changing positions and regulation modes of the devices. Given visualization program is the main everyday working instrument of the device service operator. Operator goes to observe particular device if an alarm has been received. Program also records all operator activities. For example, it is possible to find out alarm emerging time, as well as when operator has read it and when he has given confirmation about its prevention. Apart from all standard service opportunities offered by this program, it also issues messages about necessity to perform preventive maintenance and maintenance of the device or its elements. Link with the pumping stations is ensured via radio modem. In that way uninterrupted data stream about status in the pumping houses with option to ensure remote switching on/switching off/ commutation of the pumps is provided.

Sewage received from the pumping stations is diverted further for purification. Purification process consists of pre-purification, aeration, re-circulation of mixed environment, re-circulation of sludge and separation from floating substances.

Separation of drainage with conveyer, septic drainage station (Distribution VS3)

Fine racks and conveyer

Incoming sewage in the beginning is purified from the waste and other larger components, by using two fine racks and a conveyer. Operation cycle of the fine racks happens as follows - fine rack 1, switches on and switches off when reaches the dog, consequently, fine rack 2, switches on and switches off when reaches the dog, consequently the conveyer starts up, which turns off after previously set amount of time.

Analogue level sensor in the channel, located straight before fine rack is used for controlling of fine rack cycle. Fine racks switch on when water level in the channel reaches previously adjusted guide-mark. Next cycle consequently will be started straight after conveyer will switch off, in case if level in the channel would not be below that guide-mark. If level in the channel has decreased during the previous cycle and at the time when cycle finishes, would not have reached the adjusted guide-mark, then this cycle will be started as soon as level will reach this guide-mark, but not later than after previously set time interval. This time interval has been determined purposely, so that in cases if level in the channel is low, and when fine racks could remain turned off for a long period of time, they should be switched on in order to preserve them from blocking or other damages.

Apart from the analogue sensor two floats are used in the channel for detection of critically high and critically low sewage level. If critically high level is reached, both, fine racks and conveyer are switched on straight a way, and keep operating until level returns to normal (signal about critically high level is not received any more).

treatment 01 2


Sand catcher activators, sand pumps and sand washer.

After fine racks there are two sand catcher activators (4 and 5) that are operated without interruption.

Pumps 6 and 7, as well as sand washer is used for pump-down and separation of sand. Operating cycle of these devices starts by switching on sand pump 6 and operating it for a certain amount of time and then by switching on and operating pump 7. After certain amount of time (during this time the sand settles), when sand pumps have stopped, operation sand washer 8 turns on and operates for a certain amount of time. After that the cycle starts from the beginning. Time from start up of the first pump until start up of sand washer is maintained equal, with respect whether only one or both pumps are operating. If none of the sand pumps has been switched on (they are in the manual mode or a device error has occurred during start up), then sand washer is not turned on.

treatment 01 3


Anauxic and anaerobic chamber mixers 10, 11, 12, 13, 14, 15 usually are kept in a turned on position.

Pump of the local pumping station 37 is usually kept in a turned on position. Feedback provided by this pump means that it is " prepared for operation" respectively- glowing of a pilot lamp does not mean that pump is in operation. Switching on/off of the pump happens separately, by using especially incorporated float.

Pump 9 of the septic waste collection well is supposed for use in exceptional cases, when tank is filled up. Septic waste collection well is equipped with analogue level sensor and floats for detection of critically high and low levels. If pump is operating in the automatic mode, it starts up when float of critically high level switches on, and it switches off when level decreases until it reaches float of critically low level.

Aeration (Distribution VS4)

A simplified solution, which considers basin supply with oxygen without automatic control is used before the optimum aeration mechanisms are establisheds.

Three air compressors 16, 17 and 18 are used for oxygen supply in the basin. Air compressor16 is connected with VFD device, which allows controlling its operation capacity. During automatic control mode, air compressor 16 is permanently in an operating position and it ensures set up capacity (power). Only one of the rest compressors is used, which after 24 hours is replaced by another.

Air valves 19 and 20 are not controlled automatically.

Mixed environment re-circulation, sludge scraper, waste separation (Distribution VS5)

Re-circulation pumps

In each of three basins there are two re-circulation pumps that ensure circulation of the water volumes from channel aeration end zone back to the initial part of the anauxic chambers. Only one of the two pumps, so called operation pump is used for operation. Operation pump is operated for 24 hours non-stop. As soon as this amount of time has passed pumps parallely switch, in that way, for the next 24 hours pump that was turned off becomes the operation pump. Significance of the pumps also changes if the operating pump goes wrong, the automatic control mode is switched off or its safety switch has been turned off.

Re- circulation pumps (21 and 22) in one channel are operated in capacity load. Pumps (23, 24, 25 and 26) in the rest two channels are operated by using VFD that ensures revolutions of the pump appropriate for the discharge capacity of re-circulation channel.

Two sludge re-circulation pumps 27 and 28 are used for re-circulation of sludge. Automatic control mode determines that only one pump is used for basic operation, however, the other pump is used as reserve pump and in the cases when water level is increased.

Start up and shutdown of the pumps is controlled, by using pumping tank floats, altogether six, that signalize about the water level in the tank. Basic operating pump starts up when 4th float is reached. If the level continues to rise and it reaches the 5th float reserve pump switches on. If level decreases and falls beneath the 3rd float reserve pump is switched off, in that turn when level falls under the 2nd float basic operating pump is turned off.

If level is lower than the underneath, 1st float or higher than the upper 6th float it is considered that there is a critically high or critically low level in the tank.

treatment 01 4


After every 24 hours basic operating pump and reserve pump roles switch over. Roles also switch in cases when automatic mode of the actual sludge re-circulation pump used for basic operation is turned off or the safety switch is turned off (for example when performing maintenance of the device) position, as well as if other pump is operable in automatic control mode.

Skippers 29, 30, 31 are usually kept in a turned on position.

Floating substances collectors 32, 33, 34 work cyclically. In the beginning of cycle, floating substances collector #1 performs scooping and spilling. Afterwards the same operation is performed by floating substances collectors #2 and #3. Interval is kept between the spilling of last floating substances collector and scooping of the first collector. Interval is also kept between scooping and spilling of floating substances collector, during which the inflow of the floating substances takes place. Interval is also kept between the operation of floating substances collectors #1 and #2, as well as #2 and #3. During the time of it instant water in the collector flows till floating substances pump tank.

treatment 01 5


PFloating substances pump 35 is operated using four tank-floats. Floating substances pump is turned on if pump tank level exceeds level of the 3rd float, but it is turned off if the level falls below 2ndfloat level. 1st and 4th floats are used to receive information about emergency level in the tank- accordingly critically low and critically high levels.





Further come fragments of the process visualization program:





treatment 01 7
treatment 01 9
treatment 01 10
treatment 01 11


treatment 01 12











You are here Application examples Waste water treatment equipment Automation and visualization (SCADA) of Talsi city waste water treatment plant