Construction at Latvijas Piens

Pre-treatment at dairy company Latvijas Piens

Cheese production company Latvijas Piens is discharging its wastewaters to Jelgavas Udens municipal wastewater treatment plant. Average daily amount of wastewater is 450 m³. The wastewater contains high concentration of COD and nutrients. Pre-treatment and better process control of these effluents was needed within the dairy company´s production facilities to enhance the treatment results at municipal WWTP. To solve the problem, the dairy company invested in flocculation-flotation pre-treatment installation. Before the investment there was no pre-treatment in place.

Timeframe of implementation of the solution was 4th quarter of 2018 – 2nd quarter of 2020.

Components installed in the solution

  • Raw wastewater pumps with level control in main pump pit;
  • Buffer tank 600 m3 equipped with level control, air blowers and aeration system;
  • Odor removal system;
  • Flocculator equipped with basket filters, flow meter and feed pumps;
  • Coagulant tank 30 m3 equipped with dosing unit;
  • Neutralizer tank 30 m3 equipped with dosing unit;
  • Flocculant dosing unit equipped with automatic flocculant make-up station for powder polymer;
  • Flotation unit equipped with skimmer system for floating sludge, aeration system and recirculation pump;
  • Sludge tank with level control and pump for mixing / truck loading
  • Effluent pump pit equipped with pumps and level control

Operational mode

Site is located next to the dairy company. Total area of the site is 5 400 m2. It consists of:

  • Main pump pit;
  • Pre-treatment building 138 m2, with height of 8.25 m. The Coagulant and Neutralizer filling station are located at the building.
    Following components are installed in the building;
  • Flocculator;
  • Coagulant and Neutralizer tanks with equipment;
  • Flocculant dosing unit;
  • Flotation unit;
  • Sludge mixing / truck loading pump and valves
  • Control cabinet
  • Buffer tank, volume 600 m3;
  • Air blower building, located next to buffer tank 37,43 m2;
  • Sludge tank;
  • Effluent pump pit;
  • Biofilters.


Wastewater from dairy plant is directed to existing main pump pit from where it is pumped to the buffer tank for equalization of the pollution concentration and its flow. After buffering the wastewater stream is pumped to flocculation flotation system for insoluble TSS, fat, oils and greases removal. Pre-treated stream is directed to the effluent pit no.2 and the sludge is pumped to sludge storage tank.

Performance of the system in July 2020
Parameter Limit Influent Effluent
pH 6,8-8,5 4,9 6,8
COD [mg/l] 625
(max 935)
3 008 867
TSS [mg/l] <410 1 470 96
TP [mg/l] <23 27,7 4,1


Sludge will be utilized by an external company in biogas production.

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