Reconstruction of WWTP Liptovský Mikuláš

Reconstruction of WWTP Liptovský Mikuláš

Reconstruction of WWTP Liptovský Mikuláš

Date of completion: 2012

WWTP Liptovký Mikuláš had started operating in 1975 as a mechanical and biological WWTP. In 1989, the biological level was extended and the sludge and gas treatment was built.

A complex reconstruction of the WWTP took place in 2011 and 2012. The capacity of the reconstructed WWTP is 126 400 PE. It is a mechanical and biological WWTP with elimination of nutrients and chemical precipitation of phosphorus with the use of ferric sulfate. The sludge treatment includes anaerobic stabilization of sludge while the produced biogas is used for the needs of the plant.

The mechanical treatment is made up by gravel trap, screens, two aerated sand and fat traps and two primary sedimentation tanks (radial and longitudinal tanks). Rain water is partly diverted into the recipient before the mechanical treatment and also after the mechanical pre-treatment before entering the biological treatment

The biological treatment is made of cascade activation with a sludge regeneration tank. Cascade activation is organized into three back-to-back levels of denitrification/nitrification with the inflow of waste water into each level in various amounts (20%, 25%, 55%). A device for dosing organic substrate is installed for the support and effective denitrification process. Waste water flowing into the WWTP Liptovský Mikuláš is typical by a high share of industrial water mainly from the leather industry and from gelatine production of pork, beef and fish origin. Due to this uncharacteristic composition of waste water arises the need to dose phosphorus (phosphoric acid) in certain periods during the year.

Oxygen is supplied by a rotating air blower depending on the measured concentration of soluble oxygen or the concentration of ammonia nitrogen. Treated waste water is led from four radial clarifiers into the recipient, Liptovská Mara.

Sludge treatment is made of two sludge anaerobic stabilization tanks (10 600m3) operated in mesophilic conditions, mechanical thickening of primary sludge, the sludge from biological treatment and dewatering of anaerobic stabilized sludge. The stabilization process in the sludge anaerobic stabilization tanks is either on a single stage (tanks are adjoined in a parallel) or on two stages (tanks are adjoined in a sequence). Sludge anaerobic stabilization tanks are also stirred pneumatically using rotating compressors powered by biogas in addition to hydraulic stirring.

In gas management, the produced biogas is accumulated in a dry double-membrane gasholder in anaerobic stabilization tanks. The gasholder consists of two membranes made of highly resistant polyester texture coated with PVC. Biogas is used, apart from pneumatic mixing, for heating sludge in the anaerobic sludge stabilization tank. Heat used for heating up the buildings in the winter is produced in boiler rooms from biogas. Excess biogas is burned on the biogas gas burner.

Measuring and regulating of main technological processes is ensured mainly by on-line ammonia nitrogen measurements, nitrate nitrogen, phosphate phosphorus, soluble oxygen, insoluble substances in the biological treatment or in the treated waste water on the outlet of clarification tanks.

Our company supplied WWTP technological equipment in the amount of 2 333 000 €.