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Drainage and deforestation of tropical peat swamp forests (PSF) in Southeast Asia cause carbon emissions and biodiversity loss of global concern. Restoration efforts to mitigate these impacts usually involve peatland rewetting by blocking canals. However, there have been no studies to date of the optimal rewetting approach that will reduce carbon emission whilst also promoting PSF regeneration. Here we present results of a large-scale restoration trial in Sumatra (Indonesia), monitored for 7.5 years. Water levels in a former plantation were raised over an area of 4800 ha by constructing 257 compacted peat dams in canals. We find peat surface subsidence rates in the rewetted restoration area and adjoining PSF to be halved where water tables were raised from ~ - 0.6 m to ~ - 0.3 m, demonstrating the success of rewetting in reducing carbon emission. A total of 57 native PSF tree species were found to spontaneously grow in the most rewetted conditions and in high densities, indicating that forest regrowth is underway. Based on our findings we propose that an effective PSF restoration strategy should follow stepwise rewetting to achieve substantial carbon emission reduction alongside unassisted regrowth of PSF, thereby enabling the peat, forest and canal vegetation to establish a new nature-based ecosystem balance., (© 2024. The Author(s).)

Main Conclusion: The propagation of Rafflesia spp. is considered to be important for future development of ornamental and other applications. Thus far, the only successful propagation technique has been grafting. This mini-review succinctly emphasizes what is known about Rafflesia species. Members of the genus Rafflesia (Rafflesiaceae), which are holoparasitic plants known to grow on a host vine, Tetrastigma sp., are widely spread from the Malayan Peninsula to various islands throughout Indonesia. The plant's geographical distribution as well as many other aspects pertaining to the basic biology of this genus have still not been studied. The young flower buds and flowers of wild Rafflesia hasseltii Suringar, Rafflesia keithii Meijer and Rafflesia cantleyi Solms-Laubach are used in local (Malaysia and Indonesia) traditional ethnomedicine as wound-healing agents, but currently no formal published research exists to validate this property. To maintain a balance between its ethnomedicinal and ornamental use, and conservation, Rafflesia spp. must be artificially cultivated to prevent overexploitation. A successful method of vegetative propagation is by host grafting using Rafflesia-impregnated Tetrastigma onto the stem of a normal Tetrastigma plant. Due to difficulties with culture contamination in vitro, callus induction was only accomplished in 2010 for the first time when picloram and 2,4-D were added to a basal Murashige and Skoog medium, and the tissue culture of holoparasitic plants continues to be extremely difficult. Seeds harvested from fertile fruit may serve as a possible method to propagate Rafflesia spp. This paper provides a brief synthesis on what is known about research related to Rafflesia spp. The objective is to further stimulate researchers to examine, through rigorous scientific discovery, the mechanisms underlying the ethnomedicinal properties, the flowering mechanisms, and suitable in vitro regeneration protocols that would allow for the fortification of germplasm conservation.

This work assesses the effects of white rice husk ash (WRHA) as pozzolanic material, virgin kraft pulp (VKP), old corrugated container (OCC) and fibers derived from fiberboard (FFB) as reinforcing agents on some properties of blended cement composites. In the sample preparation, composites were manufactured using fiber-to-cement ratio of 25:75 by weight and 5% CaCl(2) as accelerator. Type II Portland cement was replaced by WRHA at 0%, 25% and 50% by weight of binder. A water-to-binder ratio of 0.55 was used for all blended cement paste mixes. For parametric study, compressive strength, water absorption and density of the composite samples were evaluated. Results showed that WRHA can be applied as a pozzolanic material to cement and also improved resistance to water absorption. However, increasing the replacement level of WRHA tends to reduce the compressive strength due to the low binding ability. The optimum replacement level of WRHA in mortar was 25% by weight of binder; this replacement percentage resulted in better compressive strengths and water absorption. OCC fiber is shown to be superior to VKF and FFB fibers in increasing the compressive strength, due to its superior strength properties. As expected, the increase of the WRHA content induced the reduction of bulk density of the cement composites. Statistical analysis showed that the interaction of above-mentioned variable parameters was significant on the mechanical and physical properties at 1% confidence level., (Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.)

Several effluents from laccase-mediator treatments of kraft pulp were recovered and subsequently reused with fresh pulp in order to simulate recirculation of effluents during biobleaching. The effluents were used as a new bleaching stage without any modification except enzyme addition. Pulp treated with effluents were afterwards chemically bleached by using the simple sequence LQPo, where L represents the treatment with effluent and laccase addition, Q is a chelating stage and Po is an alkaline peroxide stage. This system showed a promising potential on delignification, with kappa number ranging from 5.5 to 6.6 after LQPo sequence, depending on the type of effluent employed in L stage. Improvements on pulp brightness were also reported compared with control experiment., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Biofuels from lignocellulosic materials like wood are renewable and sustainable alternatives to petroleum and other fossil fuels. Wood can be grown and harvested without adding to the carbon load of the atmosphere and thus can be part of the solution to the problem posed by global climate changes. Recently much interest has developed on the concept of the forest product biorefinery, where wood is hydrolyzed prior to conventional pulping and papermaking processes and the hydrolyzate consisting of hemicellulose sugars are to be used as a feedstock for biofuels or bioplastics. The purification of the hydrolyzate stream and the separation of fermentable sugars from it thus constitutes an important step in biorefinery processes. The separation of particulate material from wood hydrolyzates is considered in this paper. Sugar maple hardwood was extracted with hot water at 160 degrees C. The extracts contain hemicelluloses (primarily xylooligomers, xylose and xylan), acetic acid and smaller amounts of lignin. The colloidal stability of the extracts plays a critical role in the separation and purification of the wood extracts. Here, we report the size and charge of the particles in the extract measured using standard instruments based on light scattering and microelectrophoresis. Particles were found to be in the size range from approximately 220nm to 270nm. Zeta potential measurements showed them to be negatively charged. By treating the extracts with a cationic flocculating agent poly-DADMAC, it was possible to preferentially precipitate out the colloidal fraction containing lignin and lignin derived compounds. Upon the addition of poly-DADMAC the turbidity of the suspension reduced from 920 NTU to 4 NTU in a 24 h period and particulates sedimented from the extract. The lignin concentration was reduced in the supernatant, while the sugar content remained unchanged. The addition of an indifferent electrolyte hindered the effectiveness of the polyelectrolyte. The optimum pH for the effectiveness of the polymer was found to be around 4.5. In order to accelerate the sedimentation of the particles, Kaolin was added to attach to the flocs after adding the polyelectrolyte. Kaolin helped accelerate the separation of the particulates by almost an order of magnitude. This work shows that flocculation with a cationic polyelectrolyte followed by separation by sedimentation, centrifugation or microfiltration can be an effective technique to purify biorefinery wood extracts.

The conversion of biomass to chemicals and energy is imperative to sustaining our way of life as known to us today. Fossil chemical and energy sources are traditionally regarded as wastes from a distant past. Petroleum, natural gas, and coal are not being regenerated in a sustainable manner. However, biomass sources such as algae, grasses, bushes and forests are continuously being replenished. Woody biomass represents the most abundant and available biomass source. Woody biomass is a reliably sustainable source of chemicals and energy that could be replenished at a rate consistent with our needs. The biorefinery is a concept describing the collection of processes used to convert biomass to chemicals and energy. Woody biomass presents more challenges than cereal grains for conversion to platform chemicals due to its stereochemical structures. Woody biomass can be thought of as comprised of at least four components: extractives, hemicellulose, lignin and cellulose. Each of these four components has a different degree of resistance to chemical, thermal and biological degradation. The biorefinery concept proposed at ESF (State University of New York - College of Environmental Science and Forestry) aims at incremental sequential deconstruction, fractionation/conversion of woody biomass to achieve efficient separation of major components. The emphasis of this work is on the kinetics of hot-water extraction, filling the gap in the fundamental understanding, linking engineering developments, and completing the first step in the biorefinery processes. This first step removes extractives and hemicellulose fractions from woody biomass. While extractives and hemicellulose are largely removed in the extraction liquor, cellulose and lignin largely remain in the residual woody structure. Xylo-oligomers and acetic acid in the extract are the major components having the greatest potential value for development. Extraction/hydrolysis involves at least 16 general reactions that could be divided into four categories: adsorption of proton onto woody biomass, hydrolysis reactions on the woody biomass surface, dissolution of soluble substances into the extraction liquor, and hydrolysis and dehydration decomposition in the extraction liquor. The extraction/hydrolysis rates are significantly simplified when the reactivity of all the intermonomer bonds are regarded as identical within each macromolecule, and the overall reactivity are identical for all the extractable macromolecules on the surface. A pseudo-first order extraction rate expression has been derived based on concentrations in monomer units. The reaction rate constant is however lower at the beginning of the extraction than that towards the end of the extraction. Furthermore, the H-factor and/or severity factor can be applied to lump the effects of temperature and residence time on the extraction process, at least for short times. This provides a means to control and optimize the performance of the extraction process effectively., (Copyright 2010 Elsevier Inc. All rights reserved.)

This study evaluates the usage of waste newspaper as a supplement raw material for laboratory-made single-layer particle-boards. The boards were made of various ratios (75/25, 50/50, 25/75 and 0/100) of waste paper flakes to wood particles mixtures (wt/wt). The effects of press temperature and maleic anhydride on the properties of the boards were determined. Evaluated properties were modulus of rupture, modulus of elasticity, internal bonding strength, and thickness swelling. Panels made from waste newspaper satisfied the modulus of rupture, modulus of elasticity and internal bonding strength requirements of European Norms standards. Performing a statistical analysis of the results, press temperature and maleic anhydride content were found to be positively effective on the mechanical properties at a 95% confidence level. The results from this study indicated that technically waste paper could be a potential substitute material for particleboard manufacture.

Thanks to multiple recirculation of process water, the German paper industry has succeeded in decreasing the specific fresh water demand from an average of 50 m3/t thirty years ago to 13 m3/t today. Although the increasing closure of white water loops creates many problems, it is bound to be part of the German paper industry's ongoing development. For a few years, in the production of packaging paper, two paper mills have been running with a totally closed water system including different process water treatment plants as 'kidneys'. This paper presents a comprehensive survey of the pros and cons of closed process water systems followed by significant examples of effluent-free production of corrugating medium and test liner. Additionally, operation experiences and economic aspects are discussed.

The flame retardancy of medium density fiberboard (MDF) made from mixture of rubberwood fibers and recycled old corrugated containers was studied. Aluminum trihydroxide (ATH) was used as a fire retardant additive and mixed with the fibers to manufacture experimental MDF panels using wet process. Phenol formaldehyde (PF) resin in liquid, 2% based on oven dry weight of fibers, was used along with 0%, 10%, 15% and 20% of ATH. The flame retardant test was done using the limiting oxygen index (LOI) test. The other properties investigated include internal bond strength, thickness swelling and water absorption. The results showed that ATH loading increased as the LOI of MDF increased. This demonstrated that ATH could improved the fire retardant property of MDF at sufficient loading. An increase in concentration of ATH showed an increase in the IB values of MDF made without resin. MDF panels made without resin showed a progressive increase in internal bond as the composition of recycled old corrugated containers fiber increased. Addition of resin improved internal bond strength and reduced thickness swelling, and water absorption. Thickness swelling of panel increased as the composition of recycled old corrugated containers fiber increased. Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) showed that there is indication of ATH and resin filling the void space in between fibers.

The operation of an activated sludge process at a paper mill (AIPM) in Hedera, Israel, was often characterized by disturbances. As part of a research and development project, a study on new biological treatment was initiated. The study included the operation of three pilot units: a. anaerobic treatment by upflow anaerobic sludge blanket (UASB); b. aerobic treatment by two pilot units including activated sludge and membrane bioreactor (MBR), which have been operated in parallel for comparison reasons. The pilot plant working on anaerobic treatment performed COD reduction from 2,365 to 755 mg/L, expressed as average values. Based on the pilot study, a full scale anaerobic treatment system has been erected. During a period of 100 days, after achieving steady state, the MBR system provided steady operation performance, while the activated sludge produced effluent characterized by oscillatory qualities. The following results, based on average values, indicate much lower suspended solids concentrations in the MBR effluent, 2.5 mg/L, as compared to 25 mg/L in the activated sludge. The ability to develop and maintain a concentration of over 11,000 mg/L of mixed liquor volatile suspended solids in the MBR enabled an intensive bioprocess at relatively high cell residence time. This study demonstrates that the anaerobic process, followed by aerobic MBR can provide effluent of high quality which can be considered for economic reuse in the paper mill industry.

The reaction kinetics of ozone bleaching of wheat straw pulp has been studied for the first time. The results were compared with eucalyptus pulp in order to know that both raw materials have a similar behaviour. Ozone treatments were carried out in a special reactor at low consistency (0.5% o.d.p.). The main variables were consumption of ozone by the pulp and application of a xylanase treatment (X) prior to the oxygen stage (O). The responses measured were kappa number, viscosity and brightness, to give the kinetic expressions for delignification, cellulose degradation and elimination of chromophore groups, along with calculation of selectivity. Cellulose degradation and elimination of lignin and chromophore groups show first-order kinetics in all cases. The kinetics of the enzyme pre-treatment effect shows similar behaviour in both raw materials, although the constants of delignification and elimination of chromophore are higher in straw pulp.