Search

Paper waste is a raw material for a lot of products with different added value. The engineering, economic and environmental aspects of paper waste recycling are analysed for production of composite material, cellulose nanofibers and nanocrystals, bricks with paper components, porous carbon, film of biopolymer, enzymatic sugar and bioenergy: bioethanol, hydrogen and biofuel. Through multicriteria analysis, it was possible to determine the most feasible paper waste recycling product in case of four product groups: egg packaging boxes, cardboard, reused paper, cellulose nanomaterials (nanofibers and nanocrystals). The production of cellulose nanofibres and cellulose nanocrystals has an advantage over egg packaging and cardboard production as well as reusable paper.

One-time ultrasonication pre-treatment of Rhodobacter sphaeroides was evaluated for improving biohydrogen production via photofermentation. Batch experiments were performed by varying ultrasonication amplitude (15, 30, and 45%) and duration (5, 10, and 15 min) using combined effluents from palm oil as well as pulp and paper mill as a single substrate. Experimental data showed that ultrasonication at amplitude 30% for 10 min (256.33 J/mL) achieved the highest biohydrogen yield of 9.982 mL H2/mLmedium with 5.125% of light efficiency. A maximum CODtotal removal of 44.7% was also obtained. However, when higher ultrasonication energy inputs (>256.33 J/mL) were transmitted to the cells, biohydrogen production did not improve further. In fact, 20.6% decrease of biohydrogen yield (as compared to the highest biohydrogen yield) was observed using the most intense ultrasonicated inoculum (472.59 J/mL). Field emission scanning electron microscope images revealed the occurrence of cell damages and biomass losses if ultrasonication at 472.59 J/mL was used. The present results suggested that moderate ultrasonication pre-treatment was an effective technique to improve biohydrogen production performances of R. sphaeroides.

International audience; The hemp plant Cannabis sativa Linn, referring to industrial hemp, is a high-yielding annual industrial crop grown providing fibers from hemp stalk and oil from hemp seeds. Although hemp is a niche crop, hemp production is currently undergoing a renaissance. More than 30 countries grow hemp, with China being the largest hemp producing and exporting country. Europe and Canada are also important actors in the global hemp market. Traditionally, hemp as a fiber plant has been used for the production of apparels, fabrics, papers, cordages and building materials. The hurds, as waste by-product of fiber production, were used for bedding of animals, the seeds for human nutrition, e.g., as flour, and the oil for a wide range of purposes, from cooking to cosmetics. Hemp has also been an important crop throughout human history for medicine. Other more recent applications include materials for insulation and furniture, automotive composites for interior applications and motor vehicle parts, bioplastics, jewelry and fashion sectors, animal feed, animal bedding, and energy and fuel production. Foods containing hemp seed and oil are currently marketed worldwide for both animal and human nutrition. They also find applications in beverages and in neutraceutical products. Hemp oil is also used for cosmetics and personal care items, paints, printing inks, detergents and solvents. It is estimated that the global market for hemp consists of more than 25,000 products. Currently, the construction and insulation sector, paper and textile industries, and food and nutrition domains are the main markets while the cosmetics and automotive sector are growing markets. Innovative applications, e.g., in the medical and therapeutic domains, cosmeceuticals, phytoremediation, acoustic domain, wastewater treatment, biofuels, biopesticides and biotechnology, open new challenges. Hemp is also the object of numerous fundamental studies. This review presents and discusses the traditional and new uses of industrial hemp.

The paper and pulp industry (PPI) produces high quantities of solid and liquid discharge and is regarded as the most polluting industry in the world causing adverse effects to environments and human beings. Hence changes in the way PPI sludge and waste materials are treated is urgently required. Nearly, 10 million tons of waste is generated per year, however PPI waste is enriched with many organic chemicalscontaining a high percentage of lignin, cellulose, and hemicellulose which can be used as valuable raw materials for the production of bioenergy and value-added chemicals. Pretreatment of complex lignocellulosic materials of PPI waste is difficult because of the cellulose crystallinity and lignin barrier. At present most of this waste is recycled in a conventional treatment approach through biological and chemical processes, incurring high cost and low returns. Henceefficient pretreatment techniques are required by which complete conversion of PPI waste is possible. Therefore, the present chapter provides the scope of integration of pretreatment methods through which bioenergy recovery is possible during the PPI waste treatment. Detailed information is presented on the various pre-treatment techniques (chemical, mechanical, enzymatic and biological) in order to increase the efficiency of PPI waste treatment and energy recovery from PPI waste. Along with acid and alkali based efficient chemical treatment process, physical methods (i.e. shearing, high-pressure homogenization, etc.), biochemical techniques (whole cell-based and enzyme-based) and finally biological techniques (e.g. aerobic and anaerobic treatment) are discussed. During each of the treatment processes, scope of energy recovery and bottlenecks of the processes were elaborated. The review thus provides systemic insight into developing efficient pretreatment processes which could increase carbon recovery and treatment efficiency of PPI waste.

Dried leaves are a potential source of energy although these are not commonly used beside to satisfy daily energy demands in rural areas. This paper aims at preparing a leafy biomass feedstock in the form of briquettes which can be directly used for combustion or to extract the combustible gas using a gasifier. Teak (Tectona grandis) and rubber (Hevea brasiliensis) leaves are considered for the present study. A binder-assisted briquetting technique with tapioca starch as binder is adopted. Properties of these leafy biomass briquettes such as moisture content, calorific value, compressive strength, and shatter index are determined. From the study, briquettes with biomass-to-binder ratio of 3:5 are found to be stable. Higher mass percentage of binder is considered for preparation of briquettes due to the fact that leafy biomasses do not adhere well on densification with lower binder content. Ultimate analysis test is conducted to analyze the gasification potential of the briquettes. Results show that the leafy biomass prepared from teak and rubber leaves has calorific values of 17.5 and 17.8 MJ/kg, respectively, which are comparable with those of existing biomass feedstock made of sawdust, rice husk, and rice straw.

The hemicelluloses fraction of black liquor is an underutilized resource in many chemical pulp mills. It is possible to extract and separate the lignin and hemicelluloses from the black liquor and use the hemicelluloses for biochemical conversion into biofuels and chemicals. Precipitation of the lignin from the black liquor would consequently decrease the thermal load on the recovery boiler, which is often referred to as a bottleneck for increased pulp production. The objective of this work is to techno-economically evaluate the production of sodium-free lignin as a solid fuel and butanol to be used as fossil gasoline replacement by fractionating black liquor. The hydrolysis and fermentation processes are modeled in Aspen Plus to analyze energy and material balances as well as to evaluate the plant economics. A mathematical model of an existing pulp and paper mill is used to analyze the effects on the energy performance of the mill subprocesses.

Enzymatic hydrolysis of waste paper is becoming a perspective way to obtain raw material for production of liquid biofuels. Reducing sugars solutions that arise from the process of saccharification are a precursors for following or simultaneous fermentation to ethanol. Different types of waste paper were evaluated, in terms of composition and usability, in order to select the appropriate type of the waste paper for the enzymatic hydrolysis process. Novozymes® enzymes NS50013 and NS50010 were used in a laboratory scale trials. Technological conditions, which seem to be the most suitable for hydrolysis after testing on cellulose pulp and filter paper, were applied to hydrolysis of widely available waste papers - offset paper, cardboard, recycled paper in two qualities, matte MYsol offset paper and for comparison again on model materials. The highest yields were achieved for the cardboard, which was further tested using various pretreatment combinations in purpose of increasing the hydrolysis yields.

Economic feasibility of steam explosion pretreatment for improvement of biogas production from wheat straw and paper tube residuals was investigated. The process was simulated by Aspen plus ®, and the economical feasibility of five different plant capacities was studied by Aspen Process Economic Analyzer. Total project investment of a plant using paper tube residuals or wheat straw was 63.9 or 61.8 million Euros, respectively. The manufacturing cost of raw biogas for these two feedstocks was calculated to 0.36 or 0.48 €/m(3) of methane, respectively. Applying steam explosion pretreatment resulted in 13% higher total capital investment while significantly improved the economy of the biogas plant and decreased the manufacturing cost of methane by 36%. The sensitivity analysis showed that 5% improvement in the methane yield and 20% decrease in the raw material price resulted in 5.5% and 8% decrease in the manufacturing cost of methane, respectively.

Material flows and their contributions to fuel properties are balanced for the mechanical section of a mechanical-biological treatment (MBT) plant producing solid recovered fuel (SRF) for the UK market. Insights for this and similar plants were secured through a program of sampling, manual sorting, statistics, analytical property determination, and material flow analysis (MFA) with error propagation and data reconciliation. Approximately three-quarters of the net calorific value (Q(net,p,ar)) present in the combustible fraction of the biodried flow is incorporated into the SRF (73.2 ± 8.6%), with the important contributors being plastic film (30.7 MJ kg(ar)(-1)), other packaging plastic (26.1 MJ kg(ar)(-1)), and paper/card (13.0 MJ kg(ar)(-1)). Nearly 80% w/w of the chlorine load in the biodried flow is incorporated into SRF (78.9 ± 26.2%), determined by the operation of the trommel and air classifier. Through the use of a novel mass balancing procedure, SRF quality is understood, thus improving on the understanding of quality assurance in SRF. Quantification of flows, transfer coefficients, and fuel properties allows recommendations to be made for process optimization and the production of a reliable and therefore marketable SRF product.

A microbial consortium MC1 was used to pretreat filter paper, office paper, newspaper, and cardboard to enhance methane production. The results of pretreatment indicated that sCOD of hydrolysates of the four substrates increased significantly in the early stage, and peaked on day 7. During pretreatment, ethanol, acetic acid, propionic acid, butyric acid, and glycerol were the predominant volatile organic products in hydrolysates. MC1 had strong degradation ability on the four substrates, and the weight loss of filter paper, office paper, newspaper, and cardboard reached 78.3%, 80.5%, 39.7%, and 49.7%, respectively. The results of anaerobic digestion showed that methane production yields and rates of the four substrates significantly increased after pretreatment. This study is the first attempt to explore the microbial pretreatment method for anaerobic digestion of waste paper and cardboard. Microbial consortium pretreatment could be an effective method for enhancing methane production of waste paper and cardboard into bioenergy.

The objective of this research was to develop an integrated process to produce biogas and high-quality particleboard using saline creeping wild ryegrass (CWR), Leymus triticoides through anaerobic digestion (AD). Besides producing biogas, AD also serves as a pretreatment method to remove the wax layer of CWR for improving binding capability and then the residue is used to produce high-quality particleboard. CWR was digested for three time periods, 15, 22, and 33 days with the volatile solid (VS) loading of 10 g-VS/L-sludge and the food to microorganism (F/M) ratio of 1.41. The highest biogas yield after digestion for 33 days was 251 mL/g-VS, which is corresponded to energy of 8419 BTU/kg-dry CWR. The highest methane content of biogas was 63%. Compared with particleboards manufactured from urea formaldehyde (UF) and untreated CWR, the mechanical and long-term (24 h) water resistance properties of particleboards made from UF and 33-day AD CWR residue were statistically significantly improved, except for modulus of elasticity (MOE). For example, the modulus of rupture (MOR) was increased by 39%. The results indicated that the integrated process could be a cost-effective and environmentally friendly method for producing bioenergy and particleboard with agricultural residues.

This work evaluates the environmental performance of using pulp and paper sludge as feedstock for the production of second generation ethanol. An ethanol plant for converting 5400 tons of dry sludge/year was modelled and evaluated using a cradle-to-gate life cycle assessment approach. The sludge is a burden for pulp and paper mills that is mainly disposed in landfilling. The studied system allows for the valorisation of the waste, which due to its high polysaccharide content is a valuable feedstock for bioethanol production. Eleven impact categories were analysed and the results showed that enzymatic hydrolysis and neutralisation of the CaCO3 are the environmental hotspots of the system contributing up to 85% to the overall impacts. Two optimisation scenarios were evaluated: (1) using a reduced HCl amount in the neutralisation stage and (2) co-fermentation of xylose and glucose, for maximal ethanol yield. Both scenarios displayed significant environmental impact improvements.

Paper sludge (PS) from the paper and pulp industry consists primarily of cellulose and ash and has significant potential for ethanol production. Thirty-seven PS samples from 11 South African paper and pulp mills exhibited large variation in chemical composition and resulting ethanol production. Simultaneous saccharification and fermentation (SSF) of PS in fed-batch culture was investigated at high solid loadings and low enzyme dosages. Water holding capacity and viscosity of the PS influenced ethanol production at elevated solid loadings of PS. High viscosity of PS from virgin pulp mills restricted the solid loading to 18% (w/w) at an enzyme dosage of 20 FPU/gram dry PS (gdPS), whereas an optimal solid loading of 27% (w/w) was achieved with corrugated recycle mill PS at 11 FPU/gdPS. Ethanol concentration and yield of virgin pulp and corrugated recycle PS were 34.2g/L at 66.9% and 45.5 g/L at 78.2%, respectively.

Fines concentration harms paper machine runability and output quality in recovered paper processing, hence, their extraction would be fundamentally beneficial. In this study, separated fines from an industrial recycled fiber pulp (RFP) were characterized and evaluated for their potential biogas yields with a focus on understanding the role of varying lignin and ash contents. Further, these results were compared with biogas yields from conventional chemical and mechanical pulps. Overall, methane yields of fines from mechanical pulps (21-28mL/gVS) and RFP (127mL/gVS) are relatively low compared to the high methane yields of 375mL/gVS from the chemical pulp fines. However, it was shown that the high ash content in RFP fines (up to 50%) did not negatively influence overall yield, rather, it was the presence of slowly biodegrading lignin-rich fiber fines.

This paper evaluates the implementation of three waste-to-energy projects at the University of Cincinnati: waste cooking oil-to-biodiesel, waste paper-to-fuel pellets and food waste-to-biogas, respectively. The implementation of these waste-to-energy (WTE) projects would lead to the improvement of campus sustainability by minimizing waste management efforts and reducing GHG emissions via the displacement of fossil fuel usage. Technical and economic aspects of their implementation were assessed and the corresponding GHG reduction was estimated. Results showed that on-site implementation of these projects would: (1) divert 3682 L (974 gallons) of waste cooking oil to 3712 L (982 gallons) of biodiesel; (2) produce 138 tonnes of fuel pellets from 133 tonnes of waste paper (with the addition of 20.75 tonnes of plastics) to replace121 tonnes of coal; and (3) produce biogas that would be enough to replace 12,767 m 3 natural gas every year from 146 tonnes of food waste. The economic analysis determined that the payback periods for the three projects would be 16 months for the biodiesel, 155 months for the fuel pellet, and 74 months for the biogas projects. The reduction of GHG emission from the implementation of the three WTE projects was determined to be 9.37 (biodiesel), 260.49 (fuel pellets), and 11.36 (biogas) tonnes of CO 2 -eq per year, respectively.

Waste paper belongs to a group of quantitatively the most produced waste types. Enzymatic hydrolysis is becoming a suitable way to treat this type of waste and at the same time, to produce a valuable liquid biofuel, because reducing sugars solutions that are formed during the process of saccharification can be a precursor for following or simultaneous fermentation. If it will be possible to make the enzymatic hydrolysis of the waste paper economically viable, it could serve as one of the new ways to lower the dependence of the transport sector on oil in the future. Only several studies comparing the enzymatic hydrolysis of different waste papers were performed in the past; they are summarized in this manuscript. In our experimental trials, suitable technological conditions for waste paper enzymatic hydrolysis using enzymes from Novozymes® biomass kit: enzymes NS50013 and NS50010 were investigated. The following enzymatic hydrolysis parameters in laboratory scale trials were verified on high cellulose content substrates-filter paper and cellulose pulp: type of buffer, pH, temperature, concentration of the substrate, loading of the enzyme and rate of stirring.

Some Parties (Countries) to the UNFCCC decided to include the carbon uptake by harvested wood products (HWP) in a new general accounting framework after 2012 (post Kyoto). The analysis aims to make a comparison between the cascaded use of HWP and the use of wood for energy. We combine the new HWP framework with an assumed increased 50 million m3harvest level in Canada and evaluate the impact of the GHG emissions over a 100-year period. Our reference case assumes all harvested wood is an immediate CO2emission (IPCC default) and no substitution effects, i.e. annual GHG emissions of 41 million tonnes CO2eq. In our wood utilization scenario's, harvested trees are allocated (in varying shares) to three end-products: construction wood, paper products and pellets for power production. In comparison with our base case, a combination of fossil fuel substitution, material substitution and temporary carbon uptake by HWP leads to significant decreases in GHG emissions. All scenario's show annual GHG emission between 18 and 21 million tonnes CO2eqexcept for triple use without recycling (at least 24 million tonnes CO2eq). We conclude that GHG emissions of our scenarios are substantially lower than IPCC default. However, it is difficult to incorporate one single method to account for GHG uptake and emissions by HWP, due to end use efficiency and recycling options. Further GHG allocation over individual countries is not straightforward and needs further research. © 2013 Elsevier Ltd.

The consumption and food transfer efficiency of two commercially used termite bait materials, southern yellow pine wood and cardboard, and one potential bait material, maize (Zea mays L.) cob, were evaluated for use against the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), in the laboratory. In the no-choice test, the consumption of wood and cob was similar and significantly more than cardboard. Tunneling under the food sources was similar. In the two-choice test, the consumption was cobwood, woodcardboard, cob = cardboard, and tunneling under these choices was cob = wood, wood = cardboard, cobcardboard. In the three-choice test, no significant difference was detected in consumption, but tunnels made under the cob were significantly more than wood and cardboard. Nile blue A was used to study food transfer of bait material among termite cohorts. Dyed cardboard, cob, or wood (0.1% Nile blue A) was provided to termites as food. Termites feeding on wood turned blue in significantly greater number at 6 h compared with cardboard and cob, but there was no significant difference after 12 h. Blue termites feeding on different bait materials were then collected and combined with undyed termites. When undyed (white) termites were placed with blue termites and food (wood block), termites turned blue in the same percentage regardless of original bait material fed on. However, when no food was provided (starvation group), the rate of white termites turning blue was dramatic; in dyed wood treatment, significantly more termites turned blue than that of cardboard, although neither were significantly different from cob. Our study is the first to show that, cob, an otherwise waste product of the food and biofuel industry, is as efficient as wood and cardboard as a termite bait matrix.

International audience; The literature on the presence of heavy metals in contaminated wastes is reviewed. Various categories of materials produced from domestic and industrial activities are included, but municipal solid waste, which is a more complex material, is excluded. This review considers among the most abundant the following materials - wood waste including demolition wood, phytoremediation scavengers and chromated copper arsenate (CCA) timber, sludges including de-inking sludge and sewage sludge, chicken litter and spent pot liner. The partitioning of the metals in the ashes after combustion or gasification follows conventional behaviour, with most metals retained, and higher concentrations in the finer sizes due to vaporisation and recondensation. The alkali metals have been shown to catalyse the biomass conversion, particularly lithium and potassium, although other metals are active to a lesser extent. The most prevalent in biomass is potassium, which is not only inherently active, but volatilises to become finely distributed throughout the char mass. Because the metals are predominantly found in the ash, the effectiveness of their removal depends on the efficiency of the collection of particulates. The potential for disposal into soil depends on the initial concentration in the feed material.

Cellulosic wastes, from sources such as low-quality cardboard and paper, are regarded as potential feedstocks for bioethanol production. One pathway from these cellulosic materials to ethanol is saccharification (hydrolysis) followed by fermentation. Saccharification is commonly performed using enzymes that are able to cleave the cellulosic structure to smaller units, preferably to glucose monomers. During the hydrolysis, mixing conditions have a considerable impact on the performance of the enzymes. Thus mixing conditions in the hydrolysis tank can also influence the downstream operations and, consequently, the overall economy of the bioethanol process. In this experimental study, four types of impeller, at different hydrolysis conditions were used. The effect of mixing on the glucose yield and on the filtration characteristics of the hydrolysate was evaluated. It was shown that not only the sugar yield depended on the mixing conditions: the effect on the solid–liquid separation step was even more significant. Post-print / Final draft

This article presents the advanced technology that has been developed by BioEnergy International of Gainesville, Florida, utilizing novel recombinant strains of bacteria developed by Lonnie Ingram of the University of Florida. The first commercial applications of these unique fermenting organisms convert 5-carbon sugars, as well as 6-carbon sugars, and oligomers of cellulose (e.g., cellobiose and cellotriose) directly to ethanol. The proposed systems that will be utilized for conversion of agricultural wastes, mixed waste papers, and pulp and paper mill waste in forthcoming commercial installations are now under design. This involves the extensive experience of Raphael Katzen Associates International, Inc. in acid hydrolysis, enzyme production, enzymatic hydrolysis, large-scale fermentation engineering, and distillation/dehydration. Specific examples of this advanced technology will be presented in different applications, namely: 1. Conversion of the hemicellulose content of sugar cane bagasse to 5-carbon sugars by mild-acid prehydrolysis, followed by fermentation of the 5-carbon sugar extract with recombinant Escherichia coli in a commercial installation soon to be under construction in Brazil. This unique process utilizes the surplus hemicellulose fraction of bagasse not required for steam and power generation to produce ethanol, additional to that from the original can juice, which has been converted by conventional sucrose fermentation to ethanol. The process also recovers and converts to ethanol the majority of sucrose normally lost with the bagasse fibers. Resultant beer is enriched in an innovative process to eliminate the need for incremental rectification capacity. 2. Application of this technology to mixed waste paper in Florida, with a moderate loading of newsprint (85% mechanical wood fiber), will involve a mild-acid prehydrolysis, the partial extraction of the 5-carbon sugars produced from hemicellulose as a feedstock for propagation of the recombinant Klebsiella oxytoca bacterium. Included is a facility providing for in-house production of cellulase enzyme, as an active whole broth for direct use in simultaneous saccharification and fermentation (SSF) of the remaining cellulose and residual 5-carbon sugars to ethanol. This is followed by distillation and dehydration in the advanced commercially available low-energy recovery system. 3. Another potential application of this unique technology involves utilization of a variety of wastes from several pulp and paper mills in close proximity, permitting collection of these wastes at low cost and reducing the considerable cost encountered in disposing of such low-energy wet waste.(ABSTRACT TRUNCATED AT 400 WORDS)

Jatropha curcas is a major biodiesel crop. Large amount of deoiled cake is generated as by-product during biodiesel production from its seeds. Deoiled J. curcas seed cake was assessed as substrate for the production of xylanase from thermophilic fungus Scytalidium thermophilum by solid-state fermentation. The seed cake was efficiently utilized by S. thermophilum for its growth during which it produced good amount of heat stable extracellular xylanase. The solid-state fermentation conditions were optimized for maximum xylanase production. Under the optimized conditions viz. deoiled seed cake supplemented with 1% oat-spelt xylan, adjusted to pH 9.0, moisture content 1:3 w/v, inoculated with 1 x 10(6) spores per 5 g cake and incubated at 45 degrees C. 1455 U xylanase/g deoiled seed cake was obtained. The xylanase was useful in biobleaching of paper pulp. Solid-state fermentation of deoiled cake appears a potentially viable approach for its effective utilization. (C) 2010 Elsevier Ltd. All rights reserved.

There is great interest in developing black liquor gasification technology over recent years for efficient recovery of bio-based residues in chemical pulp mills. Two potential technologies of producing dimethyl ether (DME) and methane (CH(4)) as alternative fuels from black liquor gasification integrated with the pulp mill have been studied and compared in this paper. System performance is evaluated based on: (i) comparison with the reference pulp mill, (ii) fuel to product efficiency (FTPE) and (iii) biofuel production potential (BPP). The comparison with the reference mill shows that black liquor to biofuel route will add a highly significant new revenue stream to the pulp industry. The results indicate a large potential of DME and CH(4) production globally in terms of black liquor availability. BPP and FTPE of CH(4) production is higher than DME due to more optimized integration with the pulping process and elimination of evaporation unit in the pulp mill.

Switchgrass is a promising feedstock for value-added applications due to its high productivity, potentially low requirements for agricultural inputs and positive environmental impacts. The objective of this paper is to review published research on the conversion of switchgrass into bioethanol and other value-added products. Environmental benefits associated with switchgrass include the potential for carbon sequestration, nutrient recovery from runoff, soil remediation and provision of habitats for grassland birds. Pretreatment of switchgrass is required to improve the yields of fermentable sugars. Based on the type of pretreatment, glucose yields range from 70% to 90% and xylose yields range from 70% to 100% after hydrolysis. Following pretreatment and hydrolysis, ethanol yields range from 72% to 92% of the theoretical maximum. Other value-added uses of switchgrass include gasification, bio-oil production, newsprint production and fiber reinforcement in thermoplastic composites. Future prospects for research include increased biomass yields, optimization of feedstock composition for bioenergy applications, and efficient pentose fermentation to improve ethanol yields.

Wastepaper constitutes approximately half of municipal solid waste, making it a potential source of bioenergy. Newspaper was pretreated with an ammonia-hydrogen peroxide (H2O2) mixture in a shaking bath from room temperature to 80 degrees C, and then its enzymatic digestibility was measured. A significant amount of ink was removed from the newspaper slurry by the reciprocating movement of the shaking bath. In addition, the ammonia-H2O2 significantly swelled the substrate, thereby greatly increasing its susceptibility to enzymatic digestion. After pretreating the newspaper with conditions of 40 degrees C, 3 h, 130 strokes/min, and 4 wt% ammonia-2 wt% H2O2, the enzymatic digestibility was almost 90% of theoretical, or about 25% higher than that of untreated substrate. Digestibility was also investigated as a function of ammonia concentration, H2O2 concentration, shaking speed, pretreatment temperature, and time.

Environmental issues such as the depletion of non-renewable energy resources and pollution are topical. The extent of solid waste production is of global concern and development of its bioenergy potential can combine issues such as pollution control and bioproduct development, simultaneously. Various wastepaper materials, a major component of solid waste, were treated with the cellulase enzyme from Trichoderma viride, thus bioconverting their cellulose component into fermentable sugars. All wastepaper materials exhibited different susceptibilities towards the cellulase as well as the production of non-similar sugar releasing patterns when increasing amounts of paper were treated with a fixed enzyme concentration. The hydrolysis of wastepaper with changing enzyme concentrations and incubation periods also resulted in dissimilar sugar-producing tendencies. A general decline in hydrolytic efficiency was observed when increasing sugar concentrations were produced during biodegradation of all wastepaper materials.

Anaerobic biodegradation of fermented spent sulphite liquor, SSL, which is produced during the manufacture of sulphite pulp, was investigated. SSL contains a high concentration of lignin products in addition to hemicellulose and has a very high COD load (173 g COD 1(-1)). Batch experiments with diluted SSL and pretreated SSL indicated a potential of 12-22 1 methane per hire SSL, which corresponds to 0.13-0.22 1 methane (g VS)(-1) and COD removal of up to 37%. COD removal in a mesophilic upflow anaerobic sludge blanket, UASB, reactor ranged from 10% to 31% at an organic loading rate, OLR, of 10-51 g (1 d)(-1) and hydraulic retention time from 3.7 to 1.5 days. The biogas productivity was 3 1 (1(reactor) d)(-1), with a yield of 0.05 1 gas (g VS)(-1). These results suggest that anaerobic digestion in UASB reactors may provide a new alternative for the treatment of SSL to other treatment strategies Such as incineration. Although the total COD reduction achieved is limited, bioenergy is produced and readily biodegradable matter is removed causing less load on post-treatment installations. (Less)