Abstract In this work a manometric respirometric measuring system was applied to practical environmental cases related to wastewater management and biodegradation studies of oil-contaminated soils and materials used in landfill structures. Pollution of groundwater, surface water and soils is a worldwide problem. Therefore, tests simulating the biodegradation behaviour of organic compounds in water media and soils have become increasingly important. Respirometric methods provide direct measurement of the oxygen consumed by micro-organisms in biodegradation processes from an air or oxygen-enriched environment in a closed vessel. Biochemical oxygen demand (BOD) is a crucial environmental parameter used to measure the quality of water and treatment results in wastewater. Generally, BOD is measured with standardised methods, which are usually time-consuming as well as laborious. In this work the manometric respirometric test was compared with conventional BOD tests by determining the BOD of pulp and paper mills as well as domestic wastewater samples. The effect of different factors such as type, amount and pre-treatment of inoculum and the effect of dilution of a sample on the BOD values were also tested. A right dilution was noticed to be the most significant factor affecting the BOD values of the industrial wastewater samples. The mathematic estimation of the BOD7 values from the respirometric data was proved to work reliably after a 2–3 day incubation period. Characterisation of organic fractions of the pulp and paper mill wastewater was carried out with methods including filtration, long term BOD measurements and COD analyses. The most significant observation in characterisation analyses was that a remarkable part of the detected oxygen demand was consumed for the biotransformation of biodegradable fractions into new inert decomposition products, not only for mineralisation of the biodegradable COD fraction. Biodegradation behaviour of the peat samples with different decomposition rates was studied in order to evaluate the applicable peat types that can be used in landfill structures. Only minor (BOD/ThOD < 0.4%) biodegradation was observed with compaction peat samples, and the stable state, in which biodegradation stopped, was achieved during a two month period. The manometric respirometric method was also applied for the biodegradation studies in which the effect of the modification of soil properties on biodegradation rates of bio-oils was tested. Modified properties were the nutrient content and the pH of the soil. Fertiliser addition and pH adjustment increased both the BOD/ThOD% values of the model substances and the precision of the measurement. The manometric respirometric method was proved to be an advanced method for simulating biodegradation processes in soil and water media.

Abstract Biodegradation is an aerobic or anaerobic degradation reaction where bacteria use organic materials as an energy source. In the aerobic biodegradation reaction, bacteria need oxygen as an electron acceptor, whereas an anaerobic reaction takes place in the absence of oxygen. Compounds degrade totally or partially, and produce simple inorganic species, such as CO2, CH4, NH3, NO3−, and H2O, as well as by-products that may be non-biodegradable and/or toxic. In this thesis, the biodegradability of recycled vegetable oils, surface-active agents, and condensing waters from the process of wood drying were studied using the manometric respirometric BOD OxiTop method. The biodegradation of organic compounds was measured under the standard conditions (OECD 301F), and also in other matrices, such as different waters and soils. These are very different environments with respect to the biodegradation reaction in nature. The main differences in waters and soils are their organic and inorganic nutrient contents, bacteria strains, and temperatures. The BOD OxiTop method is based on automatic pressure detection in a closed reactor vessel. Oxygen is consumed and carbon dioxide is formed in the aerobic reaction. The pressure decrease is detected after the carbon dioxide is adsorbed into a NaOH pellet or solution. The pressure change is dependent on oxygen consumption. The degree of biodegradation is calculated from the BOD value of the sample. The studied recycled vegetable oils were found to be 60–83% biodegradable, and the added surface-active agent did not affect their biodegradation. Biodegradation of tall oil soaps was also examined in sand, topsoil, groundwater, and surface water, as well as under OECD 301F standard conditions. Tall oil soaps were proven to be 50–85% biodegradable. Concrete solvent agent (CSA) was also proven to be 78–83% biodegradable under standard conditions. Another detergent, cetyltrimethylammonium bromide (CTAB), was found to be toxic, whereas Triton X-100 biodegraded by only 6% in solution. Biodegradation of the soil matrix was found to be enhanced with added surface-active agents. This can be explained by better wetting of small pores with surface-active agents, as compared to the behavior of pure water. The biodegradation of the matrix occurred even with toxic surface-active agents. Organic pollutants of wastewaters from the process of wood drying were 25–61% biodegradable during a 28-day period, and were proven to be quite pure when considering the carbon content of the samples. Based on these results, the disposal into drainage of condensing waters from wood drying may be regarded as safe, which from an economical viewpoint is a very important conclusion. / Tiivistelmä Biohajoavuus on luonnollinen aerobinen tai anaerobinen hajoamisprosessi, jossa bakteerit käyttävät orgaanista materiaalia energian lähteenä. Aerobisessa reaktiossa bakteerit tarvitsevat happea elektronien vastaanottajaksi, kun taas anaerobinen reaktio tapahtuu hapettomissa olosuhteissa. Yhdisteet hajoavat joko täysin tai osittain sekä tuottavat yksinkertaisia epäorgaanisia yhdisteitä, kuten CO2, CH4, NH3, NO3− tai H2O. Reaktiossa voi myös muodostua sivutuotteita, jotka voivat olla biohajoamattomia ja/tai toksisia. Tässä työssä on tutkittu kierrätettyjen kasviöljyjen, pinta-aktiivisten aineiden sekä jätevesien sisältämien orgaanisen aineksien biohajoavuuksia käyttäen manometristä respirometristä BOD OxiTop-menetelmää. Biohajoavuutta mitattiin standardiolosuhteiden (OECD 301F) lisäksi muissakin olosuhteissa, kuten erilaisissa maissa ja vesissä. Nämä ovat kaikki hyvin erilaisia ympäristöjä luonnossa tapahtuville biohajoavuusreaktioille. Pääasialliset erot ovat sekä orgaanisten että epäorgaanisten ravinteiden määrässä, bakteerikannoissa ja lämpötilassa. BOD OxiTop-menetelmä perustuu automaattiseen paineen muutoksen havainnointiin suljetussa astiassa. Aerobisessa reaktiossa kuluu happea ja muodostuu hiilidioksidia, joka imeytetään NaOH-pelletteihin tai -liuokseen ja tästä muodostuu alipaine. Paineen muutokset muunnetaan hapenkulutuksen arvoiksi, joista lasketaan biohajoavuusaste. Tutkittujen kierrätettyjen kasviöljyjen biohajoavuusasteet vaihtelivat välillä 60–83 %, eikä lisätty pinta-aktiivinen aine vaikuttanut kyseisten ekoöljyjen biohajoavuuteen. Mäntysaippuoiden biohajoavuus tutkittiin standardiolosuhteiden lisäksi hiekassa, mullassa, pohjavedessä sekä pintavedessä. Niiden biohajoavuusasteet vaihtelivat välillä 50–85 %. Betoninpesuaineen biohajoavuusaste standardiolosuhteissa oli 78–83 %. Kahdesta tutkituista pinta-aktiivisista aineista setrimoniumbromidi (CTAB) oli myrkyllinen liuosolosuhteissa eikä täten biohajonnut ja Triton X-100 biohajosi vain 6 %. Pinta-aktiivisen aineen lisääminen maahan aiheutti matriisina käytetyn maan biohajoamisen. Tämä voitiin selittää siten, että pintajännityksen laskemisen jälkeen neste voi paremmin tunkeutua maan pieniin huokosiin ja näin tuoda hajoamatonta orgaanista ainesta ja uusia bakteereita biohajoavuuskäyttöön. Tämä ilmiö havaittiin myös myrkyllisen pinta-aktiivisen aineen lisäyksen jälkeen. Jätevesien sisältämät orgaaniset ainekset hajosivat 25–61 % 28 päivän aikana ja niiden havaittiin olevan hiilen määrän huomioon ottaen hyvin puhtaita. Tässä tutkimuksessa saatujen tulosten perusteella tutkitut puunkuivauksen kondenssivedet voidaan laskea viemäriin, mikä on erittäin tärkeä tulos ekologiselta ja taloudelliselta kannalta katsottuna.