Biodegradation studies of recycled vegetable oils, surface-active agents, and condensing wastewaters

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

Peracetic acid for conditioning of municipal wastewater sludge:hygienization, odor control, and fertilizing properties

Abstract Peracetic acid (PAA) is an environmentally friendly disinfectant and oxidizer used in several water and wastewater treatment applications. In the present study, PAA was utilized for the conditioning of municipal wastewater sludge before thickening and dewatering. It was shown that PAA can effectively prevent odor formation (i.e., H₂S and NH₃) and provide hygienization (using E. coli and Salmonella as indicators). Phytotoxicity can be prevented by controlling the amount PAA-conditioned sludge that is mixed in the soil to be fertilized. The required PAA dose for hygienization was relatively high (480 mg 100% PAA perL sludge) but the results indicated that other sludge stabilization processes are not necessarily required. Therefore, the proposed process involving PAA could be feasible in cases where limited land area is available for sludge processing or quick conditioning of sludge is required

Removal of metals by sulphide precipitation using Na₂S and HS⁻-solution

Abstract Precipitation of metals as metal sulphides is a practical way to recover metals from mine water. Sulphide precipitation is useful since many metals are very sparingly soluble as sulphides. Precipitation is also pH dependent. This article investigates the precipitation of metals individually as sulphides and assesses which metals are precipitated as metal hydroxides by adjustment of the pH. The precipitation of different metals as sulphides was studied to determine the conditions under which the HS⁻ solution from the sulphate reduction reaction could be used for precipitation. H₂S gas and ionic HS⁻ produced during anaerobic treatment could be recycled from the process to precipitate metals in acidic mine drainage (AMD) prior to anaerobic treatment (Biological sulphate reduction), thereby recovering several metals. Precipitation of metals with HS⁻ was fast and produced fine precipitates. The pH of acid mine water is about 2–4, and it can be adjusted to pH 5.5 before sulphide precipitation, while the precipitation, on the other hand, requires a sulphide solution with pH at 8 and the sulphide in HS⁻ form. This prevents H₂S formation and mitigates the risk posed from the evaporation of toxic hydrogen sulphur gas. This is a lower increase than is required for hydroxide precipitation, in which pH is typically raised to approximately nine. After precipitation, metal concentrations ranged from 1 to 30 μg/L

The utilization of industrial by-products as soil conditioners and fertilizers in non-food potato production

Abstract Peatlands require soil improvement to be suitable for cultivation. Creating eco-friendly and cost-effective carbon sinks in peatlands originated from peat production has several benefits. For this purpose various valuable biomass can be used by utilizing industrial by-products also as soil conditioners and fertilizers. For example, the addition of such materials has potential to transform peat bogs, which otherwise would slowly release methane, into productive cultivated areas. The rehabilitation of peat bogs from unused land into various agricultural and forestry areas is also a viable business activity. The examined industrial by-products could have many agricultural applications in non-food potato production, wherein monoculture causes problems such as condensed soil, lost humus or soil organic matter, and reduced nutrient retention capacity, leading to increased leaching of nutrients and negative impacts on the environment. Five industrial by-products were examined in this study as soil conditioners and fertilizers: fiber sludge, biocarbon, hygienic biodige state, paper mill sludge, and gypsum waste. Based on the results of a nutrient content analysis, hygienic biodigestate and fiber sludge were the most effective fertilizers

Reliability of biodegradation measurements for inhibitive industrial wastewaters

Abstract Industrial wastewaters may contain toxic or highly inhibitive compounds, which makes the measurement of biological oxygen demand (BOD) challenging. Due to the high concentration of organic compounds within them, industrial wastewater samples must be diluted to perform BOD measurements. This study focused on determining the reliability of wastewater BOD measurement using two different types of industrial wastewater, namely pharmaceutical wastewater containing a total organic carbon (TOC) value of 34,000 mg(C)/L and industrial paper manufacturing wastewater containing a corresponding TOC value of 30 mg(C)/L. Both manometric respirometry and the closed-bottle method were used in the study, and the results were compared. It was found that the dilution wastewaters containing inhibitive compounds affected BOD values, which increased due to the decreased inhibiting effect of wastewater pollutants. Therefore, the correct BOD for effluents should be measured from undiluted samples, while the diluted value is appropriate for determining the maximum value for biodegradable organic material in the effluent. The accuracy of the results from the blank samples was also examined, and it was found that the readings of these were different to those from the samples. Therefore, the blank value that must be subtracted may differ depending on the sample

Biomass-based composite catalysts for catalytic wet peroxide oxidation of bisphenol A:preparation and characterization studies

Abstract The wet granulation process was used to prepare new, efficient, and cost-effective granular biomass-based composite catalysts for catalytic wet peroxide oxidation (CWPO) of bisphenol A (BPA). The most stable composite granules was prepared by mixing biomass-based carbon residue (CR) with metakaolin (MK) combined with calcium oxide (CaO) or cement and a solvent (NaOH or KOH). For all the prepared composite granules, the optimized binding agents to carbon ratio was 0.3, the solvent to carbon ratio 1.2, and the agitation rate 1200 rpm. The specific surface area of the prepared catalysts was 152–205 m2/g. The composite granular catalyst (CR + MK + CaO + NaOH) had the most durable and stable structure (compressive strength of 27 N) and the most basic surface (15 mmol/g) measured with temperature programmed desorption. This catalyst was the most active in CWPO of BPA and total organic carbon removal of 50% and 48%, respectively

Use of calcined dolomite as chemical precipitant in the simultaneous removal of ammonium and phosphate from synthetic wastewater and from agricultural sludge

Abstract Phosphorus as phosphate and nitrogen as ammonium or nitrate are the main nutrients in wastewaters and agricultural sludges. They runoff easily to waterways and cause eutrophication in water bodies. However, ammonium and phosphate could be precipitated simultaneously and used as recycled nutrients. In this research, dolomite calcined at 650 °C, 750 °C, or 950 °C and commercial MgO were used as precipitants in simultaneous phosphate and ammonium removal from synthetic (NH₄)₂HPO₄ solution and agricultural sludge. Calcination at 750 °C was the preferred option as dolomite was decomposed to MgO and CaCO₃ for optimal struvite precipitation. Molar ratios of 1.1–1.6:1–2:2 (Mg:P:N) were employed in the experiments. Very robust ammonium removal was obtained with MgO (57%), dolomite 650 °C and dolomite 750 °C (75%). MgO removed almost all phosphate, while dolomite 650 °C removed 65%, and dolomite 750 °C removed 60% (70% from agricultural sludge). Some part of the phosphate was adsorbed, most likely by CaCO₃, during dolomite precipitation. Struvite was the only identified reaction product in all samples after 24 h of precipitation. Calcined dolomite had great potential in ammonium and phosphate precipitation from both synthetic waters and agricultural sludges and the precipitates could be used as recycled fertilizers

Azepanium based protic ionic liquids:synthesis, thermophysical properties and COSMO-RS study

Abstract Protic ionic liquids (ILs) with seven-membered azepanium cation were synthesized and characterized. The molecular structure of the synthesized ILs was confirmed using 1H NMR and 13C NMR spectroscopy. In one hand, sulfonic acid (SO3H) group was tethered to the azepanium moiety combined with HSPO4 or H2PO4−anion and on the other hand azepanium based alkyl sulfate ILs were synthesized by reacting azepane with corresponding dialkyl sulfates. Thermo-physical properties (density, viscosity, glass transition temperature, thermal decomposition temperature) of the synthesized ILs were measured. All the studied ILs showed good thermal stability. From the viscosity and density data of alkyl sulfate ILs, the volumetric properties such as molar volume, lattice energy and standard molar entropy were calculated. COSMO-RS was used to predict hydrogen bonding energy, interaction energy, Van der Waals energy and H-bond accepting and H-bond donating nature of these pure ILs. Activity coefficient values have also predicted for these ILs with cellulose