Pulping Process Research Articles

Sustainable Circular Bioeconomy—Feasibility of Recycled Nutrients for Biomass Production within a Pulp and Paper Integration in Indonesia, Southeast Asia

Sustainable biomass production based on efficient carbon and nutrient recycling is crucial in materially efficient, sustainable biobased production. A circular bioeconomy model of the replacement of mineral fertilizers with recycled nutrients from pulp and paper mill sludge is tested here within a hypothetical case from Indonesia, Southeast Asia. First, the financial feasibility of the use of recycled nutrients originating from pulp and paper processes was analyzed in fast-growing pulpwood production. Secondly, the comprehensive social and environmental benefits of the practice were analyzed through qualitative sustainability analysis. The availability of the basic material of all required parameters referring to Indonesia limited the analysis period to be from 1996 to 2013. The establishment costs of a pulpwood plantation were adjusted according to a reference study, while the other data were compiled from various sources. The financial profitability of the circular model was analysed by using two indicators, net present value (NPV) and internal rate on return (IRR). The application of sludge-based recycled nutrients slightly increased the establishment costs in some circumstances but had no direct impact on the financial profitability, as the financial profitability was not sensitive to the establishment costs. The results showed that the financial profitability of biomass production is not sensitive to the plantation establishment and management costs. The profitability depends on the mean annual increment and product price. The qualitative analysis showed a holistic value of the practice that goes beyond the direct benefits. The use of sludge-based recycled nutrients in the production of pulpwood closed the economic loop, which is illustrative of the circular bioeconomy within the integrated pulp and paper sector including the raw material source, forest plantation.

Bacterial Transformation of Aromatic Monomers in Softwood Black Liquor.

The valorization of lignin, a major component of plant-derived biomass, is essential to sustainable biorefining. We identified the major monoaromatic compounds present in black liquor, a lignin-rich stream generated in the kraft pulping process, and investigated their bacterial transformation. Among tested solvents, acetone extracted the greatest amount of monoaromatic compounds from softwood black liquor, with guaiacol, vanillin, and acetovanillone, in an approximately 4:3:2 ratio, constituting ~90% of the total extracted monoaromatic content. 4-Ethanol guaiacol, vanillate, and 4-propanol guaiacol were also present. Bacterial strains that grew on minimal media supplemented with the BL extracts at 1mM total aromatic compounds included Pseudomonas putida KT2442, Sphingobium sp. SYK-6, and Rhodococcus rhodochrous EP4. By contrast, the extracts inhibited the growth of Rhodococcus jostii RHA1 and Rhodococcus opacus PD630, strains extensively studied for lignin valorization. Of the strains that grew on the extracts, only R. rhodochrous GD01 and GD02, isolated for their ability to grow on acetovanillone, depleted the major extracted monoaromatics. Genomic analyses revealed that EP4, GD01, and GD02 share an average nucleotide identity (ANI) of 98% and that GD01 and GD02 harbor a predicted three-component carboxylase not present in EP4. A representative carboxylase gene was upregulated ~100-fold during growth of GD02 on a mixture of the BL monoaromatics, consistent with the involvement of the enzyme in acetovanillone catabolism. More generally, quantitative RT-PCR indicated that GD02 catabolizes the BL compounds in a convergent manner via the β-ketoadipate pathway. Overall, these studies help define the catabolic capabilities of potential biocatalytic strains, describe new isolates able to catabolize the major monoaromatic components of BL, including acetovanillone, and facilitate the design of biocatalysts to valorize under-utilized components of industrial lignin streams.

Selective substitution of long-acyl groups into alcohols of kraft lignin over transesterification using ionic liquid

Kraft lignin is a valuable aromatic renewable resource that is discharged in large quantities during the kraft pulping process. In this study, kraft lignin derivatives with improved solubility and thermal properties were prepared by a facile chemical modification of the aliphatic hydroxy (R-OH) group in kraft lignin with various ester groups. Kraft lignin was subjected to homogeneous transesterification with vinyl esters as acyl donors using an ionic liquid as a green solvent and catalyst. The selective introduction of acyl groups into the R-OH group was confirmed by nuclear magnetic resonance (NMR) spectroscopy, and it was estimated that approximately 90% of the R-OH group was converted whereas more than 80% of the aromatic hydroxy (Ar-OH) group was retained. The R-OH-selective introduction of long-chain acyl groups of more than six carbons successfully provided superior solubility in common low-boiling solvents, such as chloroform and tetrahydrofuran, and sufficient heat-meltability to be molded into films by hot-pressing. All the kraft lignin derivatives showed high glass transition temperatures of over 100 °C, indicating their potential to be heat-resistant materials. The kraft lignin derivatives, in which only the R-OH group was acylated, retain their inherently rich Ar-OH groups and thus, can be applied as desirable precursors in a wide range of further chemical treatments for functional polymer materials.

Antioxidant Additives Produced from Argan Shell Lignin Depolymerization

The present work summarizes the results of an experimental study focused on producing antioxidant additives for biofuels from argan shell lignin. The generation of this waste has noticeably increased in specific regions of Morocco as a result of the upward trend in the production of argan oil. Lignin extracted from argan shells via a semi-chemical pulping process was depolymerized under hydrothermal conditions in a stirred autoclave reactor at a temperature range of 250–350 °C. Lignin conversion to phenolic compounds was conducted in subcritical water together with different reaction medium (H2, CO2, and HCOOH). The organic fraction in the aqueous liquid product was extracted and blended with biodiesel at a dosage of 1 wt % to evaluate its antioxidant potential. According to the obtained results, the biodiesel oxidation stability time was drastically improved up to 400%. The depolymerization temperature was observed as a critical factor in the antioxidant potential of the additives, showing a maximum value at 300 °C, regardless of the reaction medium. An extensive characterization of the produced additives was performed. The phenolic monomers present in the produced additives were identified using gas chromatography–mass spectrometry, finding a notable presence of catechol, especially in the additives obtained at 300 °C, which led to the best results of biodiesel oxidation stability. Gel permeation chromatography analyses of the additives also showed a well dissolution of relatively big molecules (up to 7000 Da) in biodiesel. More efforts are required to verify the actual antioxidant potential of these types of molecules.

Can carbon capture be a new revenue opportunity for the pulp and paper sector?

Transition towards carbon neutrality will require application of negative carbon emission technologies (NETs). This creates a new opportunity for the industry in the near future. The pulp and paper industry already utilizes vast amounts of biomass and produces large amounts of biogenic carbon dioxide. The industry is well poised for the use of bioenergy with carbon capture and storage (BECCS), which is considered as one of the key NETs. If the captured carbon dioxide can be used to manufacture green fuels to replace fossil ones, then this will generate a huge additional market where pulp and paper mills are on the front line. The objective of this study is to evaluate future trends and policies affecting the pulp and paper industry and to describe how a carbon neutral or carbon negative pulp and paper production process can be viable. Such policies include, as examples, price of carbon dioxide allowances or support for green fuel production and BECCS implementation. It is known that profitability differs depending on mill type, performance, energy efficiency, or carbon dioxide intensity. The results give fresh understanding on the potential for investing in negative emission technologies. Carbon capture or green fuel production can be economical with an emission trade system, depending on electricity price, green fuel price, negative emission credit, and a mill’s emission profile. However, feasibility does not seem to evidently correlate with the performance, technical age, or the measured efficiency of the mill.

Technological evaluation of Pinus maximinoi wood for industrial use in kraft pulp production

This study characterized Pinus maximinoi wood and evaluated its performance for pulp production. Samples of Pinus taeda wood were used as reference material. For both species, wood chips from 14-year-old trees were used for the technological characterization, pulping, bleaching process analysis, and pulp properties. A modified kraft pulping process was carried out targeting kappa number 28±5% on brownstock pulp. The bleaching sequence was applied for bleached pulp with final brightness of 87±1 % ISO. Refinability and resistance properties were measured in the bleached pulps. Compared to P. taeda wood, P. maximinoi showed slightly higher basic density (0.399 g/cm³) and higher holocellulose (64.5%), lignin (31.1%), and extractives content (4.5%), along with lower ash content (0.16%). P. maximinoi tracheids showed greater wall thickness (6.4 µm) when compared to P. taeda tracheids. For the same kappa number, P. maximinoi and P. taeda resulted in similar screened yield, with an advantage observed for P. maximinoi, which resulted in lower specific wood consumption (5.281 m³/o.d. metric ton), and lower black liquor solids (1.613 metric tons/o.d. metric ton). After oxygen delignification, P. maximinoi pulp showed higher efficiency on kappa reduction (67.2%) and similar bleaching chemical demand as P. taeda pulp. Compared to P. taeda pulps, the refined P. maximinoi pulps had similar results and the bulk property was 10% higher. Results showed that P. maximinoi is an interesting alternative raw material for softwood pulp production in Brazil.

Formic acid pulping process of rice straw for manufacturing of cellulosic fibers with silica

Emerging technology has the potential to develop entirely new approaches for producing cellulose fiber-based materials along with fuels and chemical raw materials like lignin and furfural. Rice straw is a rich source of cellulosic fibers and inorganic micronic-sized particles termed as ash. They can prove helpful in development of new or enhanced agricultural residue-based materials and products that offer cost effective substitutes for nonrenewable materials used in different domestic and industrial applications. Lignocellulose is an abundant material that is submicronic at the basic level. Rice straw is a fibrous lignocellulosic material obtained as agricultural residue, but it differs from most crop residues in its high content of silicon dioxide (SiO2). Ash content on a dry weight basis ranges from 13% to 20%, varying according to the state of conservation of the straw after harvest. The ash in rice straw has nearly 75% SiO2. The particle size analysis shows variation from few microns to hundreds of microns for inorganic residues left after burning at high temperatures above 550°C. Proximate analysis of rice straw shows that it contains 54% to 56% holocellulose and 15% to 18% lignin, both of which are natural biopolymers. The compound analysis shows the different compounds present in rice straw ash. Rice straw is available in hundreds of million tons in India and other Asian countries, so suitable technologies are required to convert rice straw from a biomass waste to useful bioproducts like pulp, paper, and paperboard. This research paper is intended to obtain pulp with fibers having inherent silica present in it to give high opacity paper and better bonding between fibers.

Siloxane-Starch-Based Hydrophobic Coating for Multiple Recyclable Cellulosic Materials.

The results of the application of a new hydrophobization agent based on a triethoxymethylsilane and standard starch aqueous mixture for mass-produced cellulosic materials—printing paper, paperboard, and sack paper—have been evaluated to examine whether such a mixture can be used in industrial practice. The application of this agent on laboratory sheets prepared in a repetitive recycling process was performed to investigate its influence on the formation and properties of the products, as well as the contamination of circulating water. Measurements of the water contact angle, Cobb tests, and water penetration dynamics (PDA) were performed to test the barrier properties of the resulting materials. The effects of the applied coatings and recycling process on the paper’s tensile strength, tear index, roughness, air permeance, and ISO brightness were studied. Studies have proven that this formulation imparts relatively high surface hydrophobicity to all materials tested (contact angles above 100°) and a significant improvement in barrier properties while maintaining good mechanical and optical performance. The agent also does not interfere with the pulping and re-forming processes during recycling and increases circulation water contamination to an acceptable degree. Attenuated total reflectance Fourier-transform infrared (FT-IR) spectra of the paper samples revealed the presence of a polysiloxane network on the surface.

MEA-conversion of agro-wastes to paper-pulp: Optimization of pulping conditions

This paper investigates the potentials of a novel environmental friendly pulping (Monoethanoleamine-MEA) process in comparison with conventional Soda and Kraft pulping processes in furnishing high yield pulp from agro-biomass for the formation Papers and other paper products. The pulping investigation had three (3) factors at three (3) different levels each: Factor 1, MEA concentration (50, 75 and 100%); Factor 2, cooking time (60, 90 and 120minutes); Factor 3, liquor-biomass ratio (4, 6 and 8) at a fixed temperature of 123±5oC. Consequently, the experimental design had 27 treatments (3×3×3) and 2 replicates. By using a central composite factorial design, equations relating the dependent variable (pulp yield) to the different independent variables (cooking temperature, cooking time and liquor concentration) were derived; reproducing the experimental result for the dependent variable with errors less than 15%. Models were evaluated to analyze the effect of experimental pulping conditions on pulp properties and evaluate the effect of these properties on furnished paper samples. Pulp Screened Yields was in the range of 42.45 to 49.18% calculated on oven dry (O.D) basis. The resultant pulps obtained from the cooking operation had very good appearance, exhibiting fairly bright color, with slow tendency to felt, thereby making drainage and consequent paper making time short. It is recommended that the cellulosic pulp obtained from MEA pulping of EFB is appropriate as virgin fiber for strengthening secondary fibers in recycled papers and also for developing certain types of writing, printing and packaging paper materials. Conclusive investigation on EFB fiber in this research study asserts that it has a promising future (when used in blend with certain long fiber plant i.e. kenaf) in substituting wood in the pulp, paper and fiber- board industry. Conclusive investigation also asserts from over-all parameter achieved that monoethanolamine-MEA when used as the main de-lignifying agent furnished pulp and subsequent paper with good strength properties that can adequately match those from conventional (i.e. kraft and soda) processes and because it works without the use of sulphur compounds, it attributes a particular benefit of simple MEA recovery by distillation, allowing black liquor combustion to be dispensed and the dissolved lignin recovered without negative impact on the environment.

Newly generated and increased bound phenolic in lychee pulp during heat-pump drying detected by UPLC-ESI-triple-TOF-MS/MS.

During the thermal processing of fruit, it has been observed for phenolic compounds to either degrade, polymerize, or transfer into macromolecules. In this study, the bound and free phenolic compound composition, content, and phenolic-related enzyme activity of lychee pulp were investigated to determine whether the free phenolic had converted to bound phenolic during heat-pump drying (HPD). It was found that after HPD, when compared with the fresh lychee pulp (control), the content of bound phenolics of dried lychee pulp had increased by 62.69%, whereas the content of free phenolics of dried lychee pulp decreased by 22.26%. It was also found that the antioxidant activity of bound phenolics had also increased after drying. With the use of high-performance liquid chromatography-tandem mass spectrometry, it was identified that (+)-gallocatechin, protocatechuic aldehyde, isorhamnetin-3-O-rutoside, 3,4-dihydroxybenzeneacetic acid, and 4-hydroxybenzoic acid were newly generated during HPD, when compared with the control sample. After drying, the contents of gallic acid, catechin, 4-hydroxybenzoic acid, vanillin, syringic acid, and quercetin in bound phenolics had also increased, and polyphenol oxidase and peroxidase still showed enzyme activity, which could be related to the conversion of free phenolics to bound phenolics. Overall, during the thermal processing of lychee pulp, the free phenolics weres found to be converted into bound phenolics, new substances were generated, and antioxidant activity was increased. Hence, it was concluded that HPD improved the bound phenolics content of lychee pulp, thus providing theoretical support for the lychee processing industry. © 2021 Society of Chemical Industry.

H2O2 bleaching of brown pulp with adsorbed xylan and its modifying effects on the mechanical properties of paper

Xylan is the primary hemicellulose in most hardwood species, especially in birch. Research has highlighted the exploitation of xylans as a strength-enhancing additive to paper due to the current trend for the effective utilization of biomass. In this paper, a new pulping process was proposed, which involved the extraction of xylan prior to pulping, followed by the re-adsorption of the pulp after the final stage in the digester, followed by a suitable bleaching process. The aim of this work was to bleach hardwood kraft pulp (brown pulp) with adsorbed birch xylan via hydrogen peroxide and study the effect of the bleaching parameters on the paper properties. The results showed that the optical properties of paper decreased; however, the mechanical properties increased after the brown pulp adsorbed birch xylan. During the bleaching process, better mechanical properties were obtained with shorter bleaching times and lower bleaching temperatures, initial pHs, and MgSO4 dosages. However, the optical properties were improved as the bleaching time, temperature, initial pH, and MgSO4 dosage were increased. The adsorption of birch xylan could effectively modify the mechanical properties of paper made from brown pulp under various phases.

Membrane Filtration Opportunities for the Treatment of Black Liquor in the Paper and Pulp Industry

Black liquor is a highly alkaline liquid by-product of the kraft pulping process, rich in organic molecules (hemicelluloses, lignin, and organic acids) and inorganic pulping chemicals such as sodium salts and sulphur-containing compounds. The release of this wastewater without further treatment could have serious environmental and financial implications. Therefore, a costly treatment process is used nowadays. Nanofiltration has been studied in the last few years as a promising alternative to recycle the cooking chemicals required for the separation of lignin and cellulose, but the development of pH-stable membranes with the potential to operate at industrial scales is fundamental in order to make this possible. In this study, the filtration performance of two in-house made membranes is evaluated and compared with a commercial NF membrane to determine the viability of their use for the treatment of black liquor. For this purpose, filtration experiments with simulated black liquor were performed. We identified that Membrane A has the higher potential for this application due to its competitive permeate flux (ca. 24 L m−2 h−1 at a trans-membrane pressure of 21.5 bar), and high rejection of organic components and salts from the cooking liquor (on average, 92.50% for the TOC, 84.10% for the CO32−, 88.70% for the sulphates, 73.21% for the Na+, and 99.99% for the Mg2+).

Minimization of Environmental Impact of Kraft Pulp Mill Effluents: Current Practices and Future Perspectives towards Sustainability

Kraft mill effluents are characterized by their content of suspended solids, organic matter and color due to the presence of lignin, lignin derivatives and tannins. Additionally, Kraft mill effluents contain adsorbable organic halogens and wood extractive compounds (resin acids, fatty acids, phytosterol) and show high conductivity due to the chemical compounds used in the digestion process of pulp. Currently, Kraft mills are operating under the concept of a linear economy and, therefore, their effluents are generating serious toxicity effects, detected in daphnia, fish and biosensors. These effluents are treated by activated sludge and moving bed biofilm systems that are unable to remove recalcitrant organic matter, color and biological activity (toxicity) from effluents. Moreover, under climate change, these environmental effects are being exacerbated and some mills have had to stop their operation when the flows of aquatic ecosystems are lower. The aim of this review is to discuss the treatment of Kraft pulp mill effluents and their impact regarding the current practices and future perspectives towards sustainability under climate change. Kraft pulp mill sustainability involves the closure of water circuits in order to recirculate water and reduce the environmental impact, as well as the implementation of advanced technology for these purposes.

Direct fractionation of wood chips by deep eutectic solvent facilitated pulping technology and application for enzyme hydrolysis

In the practical application of deep eutectic solvents (DESs) for fractionation of lignocelluloses, the rigorous requirements for the size of starting materials and the long duration of the treatment (even required 12 h) have impeded industrial applications of DES. Herein, the energy-efficient pulping technology was proposed for direct fractionation of wood chips by applying DES (choline chloride: lactic acid) as a cooking solvent. The combination of the pulping technology and DES treatment process enables direct fractionation of wood chips (by bypassing the excessive powderization step) and substantially reduces the pretreatment time owing to the synergistic effect of elevated temperature and pressure. The DES pulping technology can selectively dissolve lignin by cleavage of the lignin-carbohydrate complex (LCC) and β-O-4 linkages, the wood chips can be converted into DES-Pulp at a cooking temperature of 130 °C and preservation time of 1 h, which is an efficient pretreatment method for the enzymatic hydrolysis of wood chips. The enzymatic saccharification ratios of the DES-Pulps are between 35.4% and 88.2% at different DES cooking temperatures. The DES pulping process at a cooking temperature of 140 °C and cooking preservation time of 1 h exhibited the highest cellulose saccharification ratio of 88.2%. For DES-Pulp prepared from low cooking temperature, mechanical treatment can improve their saccharification efficiency, for example, the enzymatic hydrolysis efficiency of the DES-Pulp combined with PFI refining (10 min) was improved from 71.4% to 85.4% at a cooking temperature of 130 °C.

Bioethanol Production and Alkali Pulp Processes as Sources of Anionic Lignin Surfactants.

Lignin is an abundant biopolymer with potential value-added applications that depend on biomass source and fractioning method. This work explores the use as emulsifiers of three native lignin-rich product coming from industrial bioethanol production and alkali or Kraft pulping. In addition to their distinctive characteristics, the different molecular organization induced by emulsification pH is expected to interact in various ways at the water-oil interface of the emulsion droplets. Initially, model oil-in-water (O/W) emulsions of a silicone oil will be studied as a function of lignin source, disperse phase concentration and emulsification pH. Once stablished the effect of such variables, emulsion formulations of three potential bitumen rejuvenators (waste vegetable cooking oil, recycled lubricating oil and a 160/220 penetration range soft bitumen). Droplet size distribution, Z-potential and viscous tests conducted on model emulsions have shown that emulsification pH strongly affects stabilization ability of the lignins tested. Regarding bitumen rejuvenators, lignin emulsification capability will be affected by surfactant source, pH and, additionally, by the dispersed phase characteristics. Lower Z-potential values shown by KL at pH 9 and 11 seem to facilitate emulsification of the less polar disperse phases formed by RLUB and bitumen. In any case, lower particle size and higher yield stress values were found for both bioethanol-derived lignins emulsifying RVO and RLUB at pH 13, which are expected to exhibit a longer stability.

Effect of enzymatic treatments and microfiltration on the physicochemical quality parameters of feijoa (Acca sellowiana) juice

AbstractFeijoa fruit (Acca Sellowiana) has a short postharvest period, thus, processing is usually an alternative. The objective of this work was to evaluate the efficiency of three different commercial enzyme preparations in the extraction of feijoa juice in the yield and quality parameters. The juices with Pectinex®, Lallzyme® and Rohapect® were evaluated under three different concentrations (1, 5 and 10 U mL−1) before and after the pulping process. The samples were valued for total soluble solids, pH, reducing sugars, titratable acidity and colour. The juice that showed the most promise was evaluated for the microfiltration stage and rheological behaviour and particle size distribution were measured. The three treatments with Pectinex had an increase in juice yield in 43, 55 and 60%, while the samples with enzymes Lallzyme and Rohapect had no increase in yield compared to the control. All the tested enzymes had a positive impact on the colour of the juice, improving the colour parameters. The microfiltered juice had a behaviour index value of 1,091, indicating Newtonian behaviour. The fresh juice showed values below one (0.2178), indicating a non‐Newtonian and typically pseudoplastic behaviour. Among three enzymes used, Pectinex® showed the better results for physical–chemical parameters for extraction of feijoa juice.

Wastewater Treatment of Wet Coffee Processing in an Anaerobic Sequencing Batch Reactor Pretreated with Electro Coagulation

The interest for improving the quality of coffee production has led to the increased use of wet processing so as to highlight the quality and aroma of the beverage. The coffee pulping process has been causing environmental problems at the local level not only due to the consumption of water, but more due to the discharge of effluents with large volumes of organic waste. The wet processing generates enormous quantity of wastewater which causes irrepairable damage to the receiving water bodies. Indispensable. However, physico chemical treatment method coupled with biological treatment as proved effective treatment mode for safe and proper disposal of the wastewater generated. In this sense, the objective of the present study is to evaluate the efficacy of electrocoagulation batch reactor as pretreatment for anaerobic sequencing batch reactor to treat coffee processing wastewater.

Ultrasound-assisted extraction of bioactive compounds from ciriguela (Spondias purpurea L.) peel: Optimization and comparison with conventional extraction and microwave

The ciriguela (Spondias purpurea L.) residue resulting from its pulp and juice processing stands out due to the high content of bioactive compounds. This study aimed to optimize the ultrasound-assisted extraction (UAE) process of phenolic compounds from ciriguela peel. The response surface method was used to investigate the effects of process-independent variables (ultrasonic amplitude, UA): 20%, 60% and 100%, and ultrasonic exposure time (T): 5, 10 and 15 min on the dependent variables (content of total phenolic compounds (TPC), DPPH − 1,1-diphenyl-2-picrylhydrazyl free radical scavenging (IC50) and ferric reducing-antioxidant power (FRAP) of ciriguela peel extract. The UA and time influenced TPC, IC50 and antioxidant activity by FRAP. However, the antioxidant activity of DPPH had no significant influence on the variables used. Ideal conditions were set at UA = 100% (200 W) and T = 15 min. The extract of phenolic compounds from the ciriguela peel obtained by optimized ultrasound was compared with other extraction techniques (conventional and microwave-assisted). UAE showed better results concerning the extraction yield of phenolic compounds and high antioxidant activity (35.15 mg GAE/g, IC 50 = 0.19 mg/mL), compared to conventional extraction (30.10 mg GA/g and IC 50 = 1.68 mg/mL) and microwave-assisted (23.31 mg GA/g and IC 50 = 4.29 mg/mL). These results demonstrate the efficacy and better usefulness of the ciriguela residue in obtaining the extracts of bioactive compounds using the ultrasound-assisted extraction technique.

Organic and nutrient removal from pulp and paper industry wastewater by extended aeration activated sludge system

Pulp and paper industries are critical to a country’s economic growth. The type of raw material used and the pulping process determine the quality and quantity of wastewater generated. However, the generated wastewater with a dark colour comprises a high concentration of suspended solids, organic content, chemical oxygen demand (COD), volatile organic compounds, and a variety of other impurities. Therefore, in this study, a bench scale activated sludge treatment system was set up using a reactor consisting of an aeration tank with 5000 mg/L initial biomass and a clarifier chamber for the biomass to settle. The reactor was run few weeks with real domestic wastewater as the influent for 3 weeks to acclimatize the sludge inside the reactor. The reactor was then fed with the influent mixture of 20% industrial pulp wastewater and 80% domestic wastewater. Organic and nutrient parameter concentrations are tested from the influent and effluent sample throughout the study duration and recorded for data analysis. The removal of COD and TSS are at 83% and 90% respectively while the averaged BOD value of the treated wastewater is at 74.6%. The conclusion of this project is that the bench scale EAAS is able to treat BOD and TSS according to standard. However, a modification may be required to increase the efficiency of removing COD to meet the requirement standards. This modification could be either by using a biocarrier or an activated carbon to further enhance the treatment efficiency even at higher wastewater concentration.

Identification and Classification of Technical Lignins by means of Principle Component Analysis and k‐Nearest Neighbor Algorithm

AbstractThe characterization of technical lignins is a key step for the efficient use and processing of this material into valuable chemicals and for quality control. In this study 31 lignin samples were prepared from different biomass sources (hardwood, softwood, straw, grass) and different pulping processes (sulfite, Kraft, organosolv). Each lignin was analyzed by attenuated total reflectance Fourier transform infrared (ATR‐FT‐IR) spectroscopy. Statistical analysis of the ATR‐FT‐IR spectra by means of principal component analysis (PCA) showed significant differences between the lignins. Hence, the samples can be separated by PCA according to the original biomass. The differences observed in the ATR‐FT‐IR spectra result primarily from the relative ratios of the p‐hydroxyphenyl, guaiacyl and syringyl units. Only limited influence of the pulping process is reflected by the spectral data. The spectra do not differ between samples processed by Kraft or organosolv processes. Lignosulfonates are clearly distinguishable by ATR‐FT‐IR from the other samples. For the classification a model was created using the k‐nearest neighbor (k‐NN) algorithm. Different data pretreatment steps were compared for k=1 … 20. For validation purposes, a 5‐fold cross‐validation was chosen and the different quality criteria Accuracy (Acc), Error Rate (Err), Sensitivity (TPR) and specificity (TNR) were introduced. The optimized model for k=4 gives values for Acc=98.9 %, Err=1.1 %, TPR=99.2 % and TNR=99.6 %.