Baigiamajame magistriniame darbe tirta Utenos nuotekų valymo įrenginių pirminio ir perteklinio veikliojo dumblo mišinio skirtingų polimerų ir geležies druskų anaerobiniam puvimo procesui įtaka. Analizėje nagrinėjama proceso metu išsiskiriančių biodujų tūris ir metano dujų koncentracija. Tyrime naudojamas anaerobinio pūdymo modelis „W8 Armfield Ltd“, kuris dirba kaip vienalaipsniai anaerobiniai reaktoriai su mezofiliniu režimu. Išbuvimo trukmė – 20 dienų, apkrova bepelenėmis sausomis medžiagomis (BSM) nuo 0,61–0,96 gBSM/l/d, tiekiamo dumblo mišinio sausų medžiagų kiekis (SM) – 4 %. Baigiamuoju darbu siekiama išanalizuoti dumblo tirštinimui naudojamo sintetinio arba natūralaus polimero ir dozuojamos druskos (geležies sulfato (Fe2(SO4)3) bei geležies chlorido (FeCl3)) įtaką anaerobiniam pūdymo procesui. Panaudojus anaerobinio pūdymo modelį buvo sukurtos anaerobinės sąlygos ir pūdomas iš Utenos nuotekų valyklos tiekiamas pirminio ir perteklinio dumblo mišinys. Naudojantis įrenginiu INCA 4000 T100 buvo kaupiamos biodujos ir analizuojama jų sudėtis. Darbe taip pat nagrinėjamas SM sumažėjimas ir BSM suskaidymas. Įvertinus visus analizuojamus kriterijus nustatomas efektyviausias metodas išsiskiriančių dujų efektyvumui ir kokybei pagerinti. Išanalizavus tyrimo rezultatus pateiktos išvados. Darbą sudaro šios dalys: įvadas, 4 skyriai, išvados, rekomendacijos, literatūros sąrašas. Darbo apimtis – 63 p. teksto be priedų, 32 paveikslai, 8 lentelės, 42 bibliografiniai šaltiniai. / Objective of this work was to investigate impact of different iron and polymer doses on anaerobic digestion process. Primary and waste activated sludge was obtained from Utena Wastewater treatment plant. Analysis shows the volume of biogas produced and percentage of methane. The work was carried out using high-rate anaerobic digestion model W8 (Armfied Ltd. UK) which operates in the mesophilic range. The solids retention time was 20 days. The volatile suspended solids loading rate ranged from 0.61 to 0.96 g VSS/l d.Sludge mixture feed concentration – 4%. The Purpose of this work is to analyse impact of synthetic and organic polymer also iron (III) sulphate (Fe2(SO4)3) and iron (III) chloride (FeCl3) on anaerobic digestion process. Primary and waste activated sludge was obtained from Utena Wastewater treatment plant. The biogas was collected and components were analysed using INCA 4000 T100 analyser. Analysis of TS reduction and VS destruction is also presented. The most effective method of improving off-gas efficiency and quality was determined considering all the criteria determined by analysis. Having analyzed the results of the research, conclusions have been made. This work consists of the following parts: pre-face, 3 sections, conculsions, recommendations, reference list. There are 63 pages of text without appendices, 32 figures, 8 tables and 42 bibliographical sources in this work.

The pulp- and paper industry (PPI) faces a great challenge in finding new ways to reduce its overall carbon emissions. Large quantities of water are used in the pulp- and paper making process. In this context, a more sustainable wastewater treatment with a lower carbon footprint is of relevance for the PPI. Applied to a pulp- and paper mill (PPM) in Norway, the ongoing demonstration project “EffiSludge for LIFE” lowers the wastewater treatments (WWT) energy consumption while turning residual waste (bio sludge) into energy by implementing a new wastewater treatment concept. The aim of this study was to evaluate the current carbon footprint from a hypothetical PPM WWT plant, the potential lowering of the carbon footprint when applying the EffiSludge concept and the benefits in a larger scale assuming EffiSludge would be applied at all of the PPMs WWT in the Nordic countries represented by Sweden, Norway and Finland. An estimation of a current and future carbon footprint from one example mill was provided through the construction of one baseline and two case scenarios. Results from a laboratory biomethane potential experiment together with the responses from a survey and contributions from one example mill provided relevant input to the scenarios. The major impact on carbon emissions in the scenarios came from reducing electricity needed to aerate the biological WWT step. The maximum current carbon footprint from the parts of the WWT process included in the baseline scenario was 9.6-13 kg CO2-eq/kg pulp and the estimated future carbon footprint when implementing the EffiSludge concept was estimated as 3.6-5.9 kg CO2-eq/kg pulp. A reduction of 6-8 kg CO2-eq/kg pulp could be expected by implementing the EffiSludge concept. If the EffiSludge concept was introduced in all of the WWTP connected with Nordic PPMs a reduction of the carbon footprint with 55-180 million kg CO2-eq could be expected each year. This would reduce the total carbon emissions from the European PPI with 0.2-0.5 % annually

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