Proposal by Lithuania for deletion of the Hot Spot No 51 Kaunas WWTP

Transcription

1 Proposal by Lithuania for deletion of the Hot Spot No 51 Kaunas WWTP 1. Name of the Hot Spot Kaunas wastewater treatment plant 2. No. of the Hot Spot Location Kaunas, Lithuania 4. Reason for being the Hot Spot Absence of wastewater treatment. Kaunas, the second largest city of Lithuania, is situated at the confluence of two largest Lithuanian rivers, the Nemunas and the Neris. Until the end of 1999 all municipal wastewater from Kaunas was discharged into receiving waters without any treatment at all. Population in Kaunas was about , and about 86 % were connected to sewage system (approx inhabitants). It was calculated that Kaunas was discharging 90 % of all untreated wastewater of Lithuania into these rivers. 5. Reason to delete the Hot Spot. In 1995 in collaboration with consultants and international financiers the Kaunas Water Company developed a fouryear priority investment program. It had a budget of 80 million USD. The construction of wastewater treatment plant had been the largest constituent part of this project. The plant was built as a separate construction and until 1995 was financed from Lithuanian national budget with subsidies from the Swedish Government. The starting date of the treatment plant was September of Although only primary treatment with chemical precipitation was installed, the BOD 7 was reduced by 60 %, suspended solids by 80 % and phosphorus by 75 %. In 2008 biological wastewater treatment plant with nitrogen and phosphorus removal started to operate. At present Kaunas WWTP consists of primary treatment facility, biological treatment plant and excess sludge treatment and biogas production facility. The capacity of WWTP is m 3 per day or P.E. All processes and devices are fully automated. 2 methane tanks (volume 8800 m 3 each) and 2 sludge reservoirs (volume 4500 m 3 each) are used for sludge treatment. The sludge is being treated in mezophylic conditions (34 35 o C). Any methane tank is compatible with any type of heat exchangers (sludge/sludge or sludge/water). Each day about 7800 m 3 biogas is produced. Biogas is diverted to gasholder (capacity 1200 m 3 ) after removal of humidity and sludge particles. Biogas is mainly used for the needs of Kaunas wastewater and sludge treatment facility. In 2008 two generators also were installed. The output of generators is 310 kilowatt of electric power and 440 kilowatt of heat power each. Part of biogas is being sold. For example m 3 of biogas was produced in ,7 % of biogas was sold, other part was consumed by facility. Generators produced 4074 megawatthours of electric power and 6900 megawatthours of heat power. 6. Compliance with relevant HELCOM's recommendations and EU requirements. Parameters of treated wastewater at the outlet and heavy metals in sewage sludge are in compliance with HELCOM recommendation 28E/5 and EU requirements (See Attachment 2). 7. Investment costs. The total investments in the construction of Kaunas biological WWTP with nitrogen and phosphorus removal amounted to 18,03 million EUR. 12,8 million EUR was allocated from EU Cohesion fund and 5,23 million EUR from national budget.

2 Attachment 1

3 The figure 3 shows, that after installation of biological treatment in 2008 (introduction of secondary and tertiary wastewater treatment) the discharges of BOD 7, nitrogen and phosphorus significantly decreased.

4 Attachment 2 Compliance with relevant HELCOM's recommendations and EU requirements for parameters of wastewater at the outlet Parameters of wastewater at the outlet Reached by the plant Required by Year Concentration, mg/l Reduction, % HELCOM EU BOD ,36 159,54 15 mg/l or 80% ,40 67, ,78 76, ,78 71, ,09 65, ,13 74, ,83 72, ,00 71, ,43 79, ,09 87, ,35 97, ,09 97,02 N mg/l or 7080% , , , , , , , , , , ,2 86,98 25 mg/l or 7090% 10 mg/l or 70 80%

5 Parameters of wastewater at the outlet P ,18 19,96 0,5 mg/l, or 90% ,63 76, ,40 82, ,30 79, ,50 79, ,80 74, ,34 78, ,21 76, ,15 76, ,68 82, ,37 95, ,28 95,53 1 mg/l or 80% Concentrations of BOD 5, total phosphorus and total nitrogen are in compliance with Lithuanian national regulations, requirements of HELCOM recommendation 28E/5 and EU Directive 91/271 EEC concerning urban wastewater treatment. The effectiveness of Kaunas WWTP is significantly higher than required by above mentioned legal acts.

6 Average concentracion of heavy metals in sewage sludge (mg/kg d.w.) Heavy metal Concentration of heavy metals in sludge Limit values of heavy metals concentration in sludge according to national legislation Limit values of heavy metal concentation in sludge for use in agriculture according to Directive 86/278/EEC Lead Cadmium 1,2 1,3 1, Chromium Copper Nickel Zinc Mercury 1,46 1,3 1, Data in this table shows that last year concentration of heavy metals in sewage sludge was in compliance with Lithuanian national regulations (except for chromium) and requirements of EU Directive 86/278 EEC..