Functionalized nanocelluloses in wastewater treatment applications

Abstract The chemicals currently used for wastewater treatment are mainly based on synthetic inorganic or organic compounds. Oil-derived polyelectrolytes are used for the removal of colloidal solids from wastewater by flocculation and coagulation, for example, while activated carbon adsorbents are typically used to remove soluble impurities such as heavy metals and recalcitrance organic matter. Many of these chemicals have associated negative health impacts, and use of activated carbon has proved to be expensive. Moreover, the present synthetic chemicals are not readily biodegradable or renewable. Thus there is a high demand for “green” water chemicals which could offer a sustainable solution for achieving high-performance, cheap water purification. Water chemicals of a new type based on nano-scale particles (nanofibrils) derived from cellulose, i.e. nanocelluloses, are examined as possible bio-based chemicals for wastewater treatment. Two anionic nanocelluloses (dicarboxylic acid, DCC, and sulphonated ADAC) were tested as flocculants in the coagulation-flocculation treatment of municipal wastewater, while the flocculation performance of cationic nanocellulose (CDAC) was studied with model kaolin clay suspensions, and nanocelluloses produced from sulphonated wheat straw pulp fines (WADAC) were tested for the adsorption of lead (Pb(II)). The anionic nanocelluloses (DCC and ADAC) showed good performance in treating municipal wastewater in a combined coagulation-flocculation process with a ferric coagulant. In the case of both anionic nanocelluloses the combined treatment resulted in a lower residual turbidity and COD in a settled suspension with highly reduced total chemical consumption relative to coagulation with ferric sulphite alone. Likewise, the CDACs resulted in powerful aggregation of kaolin colloids and maintained effective flocculation performance over wide pH and temperature ranges. The capacity of the nanofibrillated and sulphonated fines cellulosics (WADAC) for the adsorption of Pb(II) was 1.2 mmol/g at pH 5, which is comparable to the capacities of commercial adsorbents.Tiivistelmä Jätevesien kemiallinen käsittely pohjautuu pääsääntöisesti synteettisten epäorgaanisten ja orgaanisten kemikaalien käyttöön. Öljypohjaisia polyelektrolyytteja käytetään kolloidisten partikkeleiden poistamiseen jätevesistä koaguloimalla ja flokkuloimalla, kun taas liuenneita epäpuhtauksia, kuten raskasmetalleja, poistetaan useimmiten adsorboimalla ne aktiivihiileen. Synteettiset vesikemikaalit valmistetaan uusiutumattomista luonnonvaroista ja niiden hajoaminen luonnossa voi olla hidasta, minkä lisäksi monet näistä käytetyistä synteettisistä vesikemikaaleista ovat terveydelle haitallisia. Aktiivihiilen käyttö puolestaan on kallista, johtuen sen korkeista valmistus- ja käyttökustannuksista. Uusille ”vihreille vesikemikaaleille, jotka tarjoavat ympäristöystävällisempiä, halpoja sekä tehokkaita ratkaisuja vedenpudistukseen, onkin suuri kysyntä. Tässä työssä selluloosasta valmistettuja nanokokoisia partikkeleita, eli nanoselluloosia, on tutkittu yhtenä varteenotettavana biovaihtoehtona uusiksi kemikaaleiksi jätevesien puhdistukseen. Kahden anionisen nanoselluloosan (dikarboksyyli, DCC, ja sulfonoitu, ADAC) flokkauskykyä testattiin koagulointi-flokkulointi reaktioissa kunnallisen jäteveden puhdistuksessa. Kationisen nanosellun (CDAC) flokkauskykyä tutkittiin puolestaan kaoliinisaven malliliuoksilla ja vehnän korsisellun hienoaineista nanofibrilloimalla sekä sulfonoimalla valmistetuilla (WADAC) nanoselluloosamateriaaleilla testattiin lyijyn (Pb(II)) adsorptiota vesiliuoksista. Anioniset nanoselluloosat (DCC ja ADAC) toimivat tehokkaasti kunnallisen jäteveden flokkauksessa ferri-sulfaatin kanssa yhdistetyissä koagulointiflokkulointi reaktioissa. Yhdistetyissä reaktioissa molemmat anioniset nanoselluloosat vähensivät sameutta sekä COD pitoisuutta laskeutetuissa jätevesinäytteissä huomattavasti pienemmillä kemikaalikulutuksilla paremmin kuin pelkästään ferri-sulfaatilla koaguloitaessa. Myös CDAC:t toimivat tehokkaasti flokkauksessa keräten tehokkaasti kaoliinin kolloidipartikkeleita yhteen laajalla pH- ja lämpötila-alueella. Nanofibrilloidun ja sulfonoidun vehnäsellun hienoaineen (WADAC) adsorptiokapasiteetti lyijylle Pb(II) oli 1.2 mmol/g pH:ssa 5, mikä on verrannollinen kaupallisten adsorptiomateriaalien kapasiteettiin

Interaction between coal and lignin briquettes in co-carbonization

Abstract The utilization of bio-based side streams in metallurgical coke making promotes two major factors in the mitigation of climate impact in the steel industry. Circular economy as the waste material from biorefinery industry is utilized as a raw material in the steel industry, and mitigation of the production of fossil-based CO2 emissions. In this work, lignin from the hydrolysis process was used in a briquetted form as part of the raw material blend in metallurgical coke making. For the experiments and analyses, lignin briquettes were pyrolyzed at 450, 600 and 1200 °C, while one sample was left non-pyrolyzed. In the co-carbonization of briquetted lignin, lignin chars and bituminous coal, the focus was to evaluate the interaction between char and coal in the carbonization. This was studied by thermogravimetric analysis (TGA), optical dilatometry, and light optical microscopy. The results suggested that the interaction between the coal and lignin reduced when the pyrolysis temperature of the briquettes, prior to co-carbonization, was elevated. This was due to the decrease of overlapping of the pyrolysis rates of chars and coking coal. Combined with the dilation and shrinking behaviour of the chars, presented in this paper, separate char and coke structures were formed in the final coke in co-carbonization

Kulttuurintutkimus osana yhteiskuntaa

Kulttuurintutkijat tarkastelevat ihmisten arkea, heidän toimintaansa taustoittavia arvoja ja asenteita sekä niiden sosiaalisesti ja kulttuurisesti rakentuvia merkityksiä (esim. Kovala 2007, 177; myös Stark tässä teoksessa). Kulttuurintutkimusta tehdään Suomessa monilla eri humanistisilla ja yhteiskuntatieteellisillä aloilla, kuten kulttuuriantropologiassa, etnologiassa, perinteen- ja mediatutkimuksessa, kielitieteessä ja kirjallisuustieteessä1 . Sen kautta on mahdollista tunnistaa erilaisia elämäntapoja, ala- tai toimintakulttuureita, arvojärjestelmiä ja hierarkioita sekä ymmärtää, miten nämä vaikuttavat yhteisöjen ja yksilöiden toimintaan. Lisäksi ilmiöiden ajallisen monikerroksisuuden ymmärtäminen on kiinteä osa kulttuurintutkimuksen näkökulmaa. (Eriksen 2004; Pink 2009.) Kulttuurinen ulottuvuus jää kuitenkin helposti huomaamatta esimerkiksi yhteiskunnallisessa kehittämisessä ja suunnittelussa sen itsestään selvän ja vaikeasti havaittavan luonteen vuoksi.peerReviewe

Enhancing packaging board properties using micro- and nanofibers prepared from recycled board

Abstract In this study, cellulose microfibers and cellulose nanofibers (CNF) prepared from recycled boxboard pulp using a mechanical fine friction grinder were used as reinforcements in a board sheet. Micro- and nanofibers manufactured by mechanical grinding have typically broad particle size distribution, and they can contain both micro- and nano-sized fibrils. Deep eutectic solvent of choline chloride and urea was used as a non-hydrolytic pretreatment medium for the CNF, and reference CNF were used without any chemical pretreatment. The CNF were ground using three grinding levels (grinding time) and their dosage in the board varied from 2 to 6 wt%. The results indicate that the board properties could be tailored to obtain a balance between the processability and quality of the products by adjusting the amount of CNF that was added (2–6 wt%). A preliminary cost assessment indicated that the most economical way to enhance the board strength properties was to add around 4% of CNF with a moderate grinding level (i.e., grinding energy of 3–4 kWh/kg). Overall, the strength properties of the manufactured board sheets improved by several dozen percentages when CNF was used as the reinforcement

Cationic nanocelluloses in dewatering of municipal activated sludge

Abstract This study used cationic nanocelluloses (CNFC I and II) produced by nanofibrillizing periodate oxidized and aminoguanidine hydrochloride reacted wood cellulose as flocculation agents for municipal activated sludge. For both CNFC I and II, the diameters ranged from about 2–8 nm. Lengths ranged from hundreds of nanometers for CNFC I and about 50–100 nm for CNFC II. The charge densities for CNFC I and II were 1.07 and 1.70 meq g−1, respectively. The study examined the flocculation performance of the two CNFCs in the conditioning treatment of municipal activated sludge and compared the results with the performance of both a commercial coagulant and polyelectrolyte (polyacrylamide). Results showed that both CNFC I and II were able to flocculate activated sludge efficiently at effective doses similar to those of the commercial cationic polymer and at doses lower than the reference coagulant. Their efficiency in reducing turbidity was nearly as good as that of the synthetic reference polymer, and their COD was even better than that of the synthetic reference polymer. The performance of CNFC II was slightly better than that of CNFC I. In centrifugation analyses, the use of both CNFCs resulted in dense sludge cakes with moderate swelling and good colloidal-removal efficiency

Nanofibrillation of deep eutectic solvent-treated paper and board cellulose pulps

Abstract In this work, several cellulose board grades, including waste board, fluting, and waste milk container board, were pretreated with green choline chloride-urea deep eutectic solvent (DES) and nanofibrillated using a Masuko grinder. DES-treated bleached chemical birch pulp, NaOH-swollen waste board, and bleached chemical birch pulp were used as reference materials. The properties of the nanofibrils after disc grinding were compared with those obtained through microfluidization. Overall, the choline chloride-urea DES pretreatment significantly enhanced the nanofibrillation of the board pulps in both nanofibrillation methods—as compared with NaOH-treated pulps—and resulted in fine and long individual nanofibrils and some larger nanofibril bunches, as determined by field emission scanning electron microscopy and transmission electron microscopy. The nanofibril suspensions obtained from the DES pretreatment had a viscous, gel-like appearance with shear thinning behavior. The nanofibrils maintained their initial crystalline structure with a crystallinity index of 61%–47%. Improved board handsheet properties also showed that DES-treated and Masuko-ground waste board and paper nanocellulose can potentially enhance the strength of the board. Consequently, the DES chemical pretreatment appears to be a promising route to obtain cellulose nanofibrils from waste board and paper

Evolution of biocarbon strength and structure during gasification in CO₂ containing gas atmosphere

Abstract This work focuses on the properties of hydrolysis lignin biocarbons with a perspective on utilizing the biocarbons in pyrometallurgical processes. Even if the blast furnace and basic oxygen furnace (BF-BOF) process route was replaced by emerging technologies with lower CO₂ emissions in the future, the need for carbonaceous materials in the iron and steel making industry will still exist. Most of these applications do not require as high standards for the properties of carbonaceous materials as BF but the requirements are still similar to those for BF. The most important properties of carbonaceous materials are the mechanical strength and suitable reactivity. In the case of biocarbon, the apparent density is also considered important. The reactivity and strength properties are investigated with isothermal reactivity tests and compression strength tests for the non-gasified and pre-gasified biocarbon and reference coke samples. The mass loss rate of coke gasification (-0.069%/min) was considerably lower than that of least reactive biocarbon L1200 (-0.18%/min). Regarding the compression strength of the samples, the strength of coke dropped by 56.44% for the samples of pre-gasification level of 50% compared to non-gasified samples while the drop was only 40.68% for the L1200 biocarbon samples. The level of gasification was found to have direct correlation with pore area percentage with R² value 0.92 in case of L1200 and 0.98 in case of coke. Further, the pore area percentage correlated with the compression strength with R²of 0.93 in case of L1200 and 0.98 in case of coke

The effect of seasonal variations on floc morphology in the activated sludge process

Abstract The effect of seasonal variations on floc formation in the activated sludge process (ASP) was studied in a municipal wastewater treatment plant in Finland nearly 16 months. Floc formation was measured with an online optical monitoring device, and results were correlated with the temperature of the upcoming wastewater and the treatment efficiency of the ASP. Results showed that floc formation has a clear, seasonal pattern, with flocs in summer being larger and rounder and having fewer filaments and small particles. In addition, treatment efficiency increased in summer. The study correlated the results of image analysis with the composition (chemical oxygen demand and suspended solids content) and temperature of the wastewater before and after the ASP. Results showed that the composition of upcoming wastewater has no clear correlation with floc morphological parameters. However, the wastewater temperature clearly correlated with floc formation. Results indicated that cold winter conditions enhanced the growth of filamentous bacteria in wastewater, decreasing treatment efficiency. Furthermore, these results confirmed that floc formation has seasonal variations

A thermogravimetric analysis of lignin char combustion

Abstract Understanding the combustion behavior is the basic requirement for a new resource to be used as an alternative fuel for the industrial design of the future plants. In this article, thermogravimetric analysis (TGA) of lignin char combustion in different heating rates (5, 10 and 15 °C/min) was investigated. Extracted combustion indices showed increased weight loss rate, peak temperature and burnout temperature but no change in ignition temperature for all samples when the heating rate increased. Lignin chars containing higher volatile material illustrated higher combustibility through the low ignition and burnout temperatures. Kinetic parameters of lignin combustion were also obtained by the Coat-Redfern method in the first-order kinetic model. High combustibility of high volatile sample (L300: vol%=41) was also confirmed by its low activation energy which was 46.68 compared to 150.34 for L500 (vol%=18) and 174.37 kJ/mol for L650 (vol%=5.1). The pre-exponential factor was also measured to be 2.61E-01, 8.15E+06 and 1.21E+08 min-1for L300, L500 and L650 respectively

From oil digger to energy transition enabler:the critical role of exploration geosciences education in Europe

Abstract Recent disruptions of raw material value chains during the COVID-19 pandemic have highlighted Europe’s depency on imports of metals and minerals. Meanwhile, the European Commission is establishing ambitious policy initiatives, aiming at making Europe climate neutral in 2050. In this contribution, we emphasise the critical role of geosciences education in this energy transition, in forming the next generation of mining professionals. In the Nordic countries, active industry–university collaboration in one of the most active mining hubs in Europe has allowed frequent student–industry interaction, access to real-life learning environments, and development of specialised educational modules. These have been made accessible to exchange students from other European countries via exchange programmes and innovative digipedagogical learning tools