Realization: 2011-2012
Number of PE: 25 000
Investor: Podtatranská water company, joint-stock company
Cost of electromechanical part: 2 075 000,– EUR
The project goal was the completion of existing WWTP for the town Stará Ľubovňa and the surrounding villages Nová Ľubovňa, Jakubany, Jarabina and it was realized within the years 2011-2012. The main goal was to utilize the existing object on site maximally. The project realization was followed in accordance of FIDIC – “red book” which meant that the Contractor built the project according the project documentation made by Client.
WWTP Stará Ľubovňa works as a mechanical-biological treatment plant with nutrients removal and with a chemical precipitation of phosphorus by ferric sulfate solution. Sludge management consists of anaerobic sludge stabilization and of utilization of produced biogas for the needs of the plant.
The mechanical step consists of mechanical coarse screenings, mechanical fine screenings and sand traps, a sand separator and a primary sedimentation tank. Storm waters are relieved to recipient after the mechanical step.
The biological step (3 714 m3) consists of pre-denitrification, nitrification sections and aerobic regeneration of return sludge. Phosphorus removal is provided by chemical precipitation with ferric sulfate solution. Return sludge is regenerated under the aerobic conditions in the regeneration tank of volume 600 m3. The air for nitrification and regeneration is delivered by rotary blowers (3400 and 800 m3/h) in dependency of on line measurement of dissolved oxygen concentration. After the nitrification sections biologically treated water with activated sludge flows to radial secondary clarifiers for separation. From secondary clarifiers is treated water pumped to pumping station and afterwards to recipient.
The sludge management consists of an anaerobic stabilization tank operated under mesophilic conditions, mechanical thickening of biological excess sludge and dewatering of anaerobically stabilized sludge. The anaerobic stabilization tank is mixed by pneumatic mixing with produced biogas by rotary compressors or alternatively by hydraulic mixing with a pump.
A biogas produced in anaerobic stabilization tank is stored in dry two membrane gasholder. These membranes are made of high resistant polyester fabric coated with PVC. The biogas is preferably used as a fuel to produce electricity in cogeneration unit for the needs of WWTP and created heat is used for the heating of sludge in anaerobic stabilization tank. In the boiler room is produced heat from the biogas to heat buildings in winter time. The excess biogas is burned in a gas burner.
The measurement and control of the main technological processes is ensured by an on-line measurement of ammonium nitrogen, nitrate nitrogen, dissolved oxygen and phosphate phosphorus in biological step or at the outlet of the WWTP.
