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Investments of PURE

In 2010, in order to estimate the investment needs of PURE partners, technical audits were conducted in the wastewater treatment plants of five water utilities – Brest (Belarus), Jurmala (Latvia), Kohtla-Järve (Estonia), Gdansk and Szczecin (Poland). The technical audits considered the current technical processes and necessary technology to decrease the concentration of phosphorus in purified wastewater to the HELCOM recommended level of 0.5 mg/l. The technical audits were carried out by Pöyry Finland Oy, hired by investment coordinator John Nurminen Foundation with PURE co-financing from the EU Baltic Sea Region Programme 2007-2013.

 

Results reported in partners’ technical audits:


Quite new wastewater plants of Gdansk, Jurmala, Kohtla-Järve and Szczecin had been achieving good results in nutrient removal, although occasionally exceed the limits for effluent concentrations. Common to these plants is large capacity with regards to the incoming wastewater load. Some of them were facing difficulties with bulking sludge, which could lead to escape of phosphorus with effluent solids. These problems could be minimized with sufficient process control.

At Gdansk and Szczecin wastewater treatment plants, no new investments were needed to reach the level of 0.5 mg/l phosphorus. The biological processes remove nutrients efficiently and the plants already had the needed equipment for precipitation chemical storage and dosing to ensure efficient phosphorus removal. At the time of the audits, Gdansk Wschod WWTP aeration basins were undergoing major reno-vation with the aim to enhance nitrogen removal. The auditors, however, questioned the relevance of this renovation work in their report.

On the left ZWiK Szczecin's Pomorzany plant, on the right Jurmala plant. Photos: ZWiK Szczecin and Jurmala Water.
On the left ZWiK Szczecin's Pomorzany plant, on the right Jurmala plant. Photos: ZWiK Szczecin and Jurmala Water.


At Jurmala wastewater treatment plant, the proposed PURE investment included an additional polymer station to improve sludge thickening, and new online measurement equipment to improve the process control and balancing. This would enable the plant operators to enhance nitrogen removal without jeopardizing phosphorus removal efficiency. The auditors gave several suggestions for further improvement of Kohtla-Järve wastewater treatment plant’s performance, dealing with, e.g. activated sludge mixing.

It was concluded that Brest municipal wastewater treatment plant lacked capacity for efficient biological nutrient removal. Introducing chemical precipitation of phosphorus was found as the quickest and most cost-efficient way to reduce the phosphorus load to the Baltic Sea from Brest. As the incoming phosphorus load to the plant was high, chemical precipitation was needed to reach the HELCOM recommendation even if the biological process would be refurbished in the future. PURE-financed chemical storing and dosing station was chosen to be built in old, unused pre-aeration basins. Also laboratory analysis equipment of phosphate and total phosphorus was decided to be purchased within PURE to optimize the treatment process.

Based on results of the technical audit, proposals for investments to be realized with PURE funding had been presented to Brest and Jurmala WWTPs. Riga Daugavgriva wastewater treatment plant, intending to purchase dosing equipment and flow meters for phosphorus removal and centrifuge for excess sludge management, was a pilot investor in PURE. Their investment needs were identified already prior to PURE.

Currently, all three of PURE investments have been successfully finalized.

  • In Riga, the phosphorus removal equipment - two electromagnetic flow meters and ferrous sulphate dosing container were put into operation already in May 2012. The centrifuge to improve sludge dewatering capacity was delivered and installed in early autumn 2012. More details of the investment process are available from the sub-page on implementing PURE investment in Riga.
  • In Jurmala new air flow meters and pressure sensor were supplied on 1 August and installed in November 2012. The polymer unit for improved sludge treatment was supplied and installed in August-September; it had been tested during mid-December 2012. Lowering the walls between anoxic and aerobic zones was completed in October 2012. It is possible to learn more about the investment process from the sub-page on implementing PURE investment in Jurmala.

  • In Brest, after the additional project implementation time, realization of the investments was finalized in September 2013. Construction works of the chemical storing and dosing station in the plant were completed in summer 2013. The purchase, delivery and installation of the chemical dosing and laboratory equipment took place in June-August 2013.to PURE. The investment process is described at the sub-page on implementing PURE investment in Brest.