Search

The acceleration of urbanization has disrupted natural water cycles, resulting in increased impervious urban surfaces and non-point source pollution from stormwater runoff. Addressing urban stormwater recharge has become crucial. This study introduces a novel silica sand-based permeable filtration material, investigating its surface characteristics, pore structure, permeability, and pollutant interception capabilities. The results demonstrate that hydrophilic binder coating modification of the permeable surface sand aggregate, combined with hydrophilic inorganic additives, having a porous structure with an average pore size of less than 50 μm and a porosity between 15% and 35%, significantly enhances surface hydrophilicity, achieving a permeation rate of up to 6.8 mL/(min·cm²). Moreover, it shows exceptional filtration and anti-clogging properties, achieving over 98% suspended solids interception and strong resistance to fouling. Dynamic biofilm formation experiments using simulated rain and domestic wastewater explore biofilm morphology and function on silica sand filtration well surfaces. Mature biofilms sustain COD removal efficiency exceeding 70%, with levels consistently below 50 mg/L, NH4+ decreasing to 2 mg N/L, and total nitrogen maintained below 10 mg N/L. The system features anoxic, anoxic, and aerobic zones, fostering synergistic organic matter and nitrogen removal by diverse microorganisms, enhancing pollutant mitigation. Silica sand-based permeable filtration material effectively mitigates urban stormwater runoff pollutants—suspended solids, organic matter, and nitrogen—offering an innovative solution for sponge city development and rainwater resource management. [ABSTRACT FROM AUTHOR]

The acceleration of urbanization has disrupted natural water cycles, resulting in increased impervious urban surfaces and non-point source pollution from stormwater runoff. Addressing urban stormwater recharge has become crucial. This study introduces a novel silica sand-based permeable filtration material, investigating its surface characteristics, pore structure, permeability, and pollutant interception capabilities. The results demonstrate that hydrophilic binder coating modification of the permeable surface sand aggregate, combined with hydrophilic inorganic additives, having a porous structure with an average pore size of less than 50 μm and a porosity between 15% and 35%, significantly enhances surface hydrophilicity, achieving a permeation rate of up to 6.8 mL/(min·cm²). Moreover, it shows exceptional filtration and anti-clogging properties, achieving over 98% suspended solids interception and strong resistance to fouling. Dynamic biofilm formation experiments using simulated rain and domestic wastewater explore biofilm morphology and function on silica sand filtration well surfaces. Mature biofilms sustain COD removal efficiency exceeding 70%, with levels consistently below 50 mg/L, NH4+ decreasing to 2 mg N/L, and total nitrogen maintained below 10 mg N/L. The system features anoxic, anoxic, and aerobic zones, fostering synergistic organic matter and nitrogen removal by diverse microorganisms, enhancing pollutant mitigation. Silica sand-based permeable filtration material effectively mitigates urban stormwater runoff pollutants—suspended solids, organic matter, and nitrogen—offering an innovative solution for sponge city development and rainwater resource management.

In this work, the efficiency of a polyelectrolyte complex (PEC) to retain different cellulose micro/nanofibers (CMNFs) during paper formation and to improve the physical properties of recycled unbleached fiber paper was analyzed. CMNFs were obtained from a commercial bleached eucalyptus pulp (BEP) using a PFI refiner followed by a chemical treatment with oxalic acid at two different concentrations. Finally, the pulp was fibrillated using a high-pressure homogenizer at three different intensities. The PEC was formed by addition of the xylan (Xyl) solution on chitosan (CH) solution with a Xyl/CH mass ratio of 80/20. The required dosages of PEC solution to neutralize the charges of different nanocellulose fractions were determined by ζ-potential measurements, and the CMNF retentions on recycled unbleached fibers were evaluated in a Britt Dynamic Drainage Jar. The results showed that the maximum retention was obtained when the neutral PEC-CMNF system was added to pulp. Besides, a significant decrease on °SR was observed when PEC and PEC-CMNF systems were added to the untreated pulp, limiting the negative effects of nanocellulose addition on pulp drainability. The incorporation of PEC-CMNF systems to the handsheets increased the tensile index (up to 28%), Mullen index (up to 40%) and internal bonding (up to 255%). Finally, the compressive strength of the handsheets, namely SCT and CMT, increased up to 30 and 70%, respectively. These simultaneous improvement on drainability and mechanical properties makes the proposed PEC-CMNF system a promising solution for the production of packaging paper. [ABSTRACT FROM AUTHOR]

Although the splash and spray phenomenon produced by heavy trucks on road pavements is not a significant issue in relation to traffic safety, it may cause considerable inconveniences for those driving cars or motorbikes. This paper addresses the issue of pavement engineering with regard to surface characteristics; particularly pavement texture and its influence on water mobilization and projection in conditions of wet weather and heavy traffic. Considering the theoretical concept of pavement macrotexture, the analysis starts with the hypothesis concerning a relationship between Mean Profile Depth (MPD) and water splashed during rain. In order to focus on the impact of texture on splash and spray, a field experiment was carried out to test the hypothesis using 5 test tracks on a range of different pavement textures. The experiment was performed using a Traffic Speed Drain Meter (TSDM), which is a new drainability survey device presented to PIARC for approval. This equipment employs the laser and image technology and allows one to simultaneously obtain MPD and water splash data. The results of drainability and MPD were compared for each test track. Having analysed the pavements with different MPD ranges in the experiment, it has been concluded that MPD and water splashed apparently have an inversely proportional relationship. In addition, the TSDM proved to be a suitable equipment (repeatability) at an affordable cost (high performance of data collection). Finally, it has been concluded that there is a way to reduce splash and spray adjusting the infrastructure rather trying to solve the issue modifying vehicle moving modes. Therefore, if the issue is properly addressed by civil engineers and road managers, road safety in the areas of heavy rain may be improved at an affordable cost. The experiment presented here is considered a starting point opening the path for further research.

Topology optimization methods improve the structural performance of components. However, in food processing, medical, high-precision, and other industries' designs should also fulfil the requirement of being cleanable. An important aspect of cleanability is drainability, which entails that fluids can always run off the structure under just gravity. Therefore, taking drainability into account during the optimization process is essential for many applications. This paper proposes a drainage filter that turns a blueprint design into a drainable design. In a layer-by-layer fashion, the design is adjusted, to ensure fluids can always run down its surface. A smooth minimum and maximum are used in the formulation to allow for consistent sensitivity calculation. To allow for the small runoff angles, typical for practical drainability, a grid refinement is proposed. Moreover, any drainage direction can be considered. The effectiveness of the method is illustrated in 2D and 3D. [ABSTRACT FROM AUTHOR]

Although the splash and spray phenomenon produced by heavy trucks on road pavements is not a significant issue in relation to traffic safety, it may cause considerable inconveniences for those driving cars or motorbikes. This paper addresses the issue of pavement engineering with regard to surface characteristics; particularly pavement texture and its influence on water mobilization and projection in conditions of wet weather and heavy traffic. Considering the theoretical concept of pavement macrotexture, the analysis starts with the hypothesis concerning a relationship between Mean Profile Depth (MPD) and water splashed during rain. In order to focus on the impact of texture on splash and spray, a field experiment was carried out to test the hypothesis using 5 test tracks on a range of different pavement textures. The experiment was performed using a Traffic Speed Drain Meter (TSDM), which is a new drainability survey device presented to PIARC for approval. This equipment employs the laser and image technology and allows one to simultaneously obtain MPD and water splash data. The results of drainability and MPD were compared for each test track. Having analysed the pavements with different MPD ranges in the experiment, it has been concluded that MPD and water splashed apparently have an inversely proportional relationship. In addition, the TSDM proved to be a suitable equipment (repeatability) at an affordable cost (high performance of data collection). Finally, it has been concluded that there is a way to reduce splash and spray adjusting the infrastructure rather trying to solve the issue modifying vehicle moving modes. Therefore, if the issue is properly addressed by civil engineers and road managers, road safety in the areas of heavy rain may be improved at an affordable cost. The experiment presented here is considered a starting point opening the path for further research. [ABSTRACT FROM AUTHOR]

The objectives of the four-year quieter concrete pavement research study presented in this report were to measure noise from tire/pavement interaction, pavement smoothness, and drainability characteristics of concrete pavement surface textures currently used on the California state highway network. This study also was undertaken to develop recommendations for safe, durable, and cost-effective concrete pavement surface textures that minimize noise from tire/pavement interaction. The fourth and final year of this research study included testing on 60 test sections grouped by texture type as follows: 27 diamond ground (DG), 12 diamond grooved (Gr), 19 longitudinally tined (LT), 1 burlap drag (BD), and 1 longitudinally broomed (LB). Five of the 60 test sections were continuously reinforced concrete pavement (CRCP) and the rest were jointed plain concrete pavement (JPCP). This report presents the results of measurements of tire/pavement interaction noise and of the pavement smoothness and surface drainability characteristics of concrete pavement textures commonly used for new construction finishes or pavement preservation and rehabilitation strategies. Tire/pavement interaction noise was measured using the on-board sound intensity (OBSI) method; smoothness was measured in terms of the International Roughness Index (IRI) using a wide-spot (RoLineTM) laser; pavement surface drainability was measured using outflow meter measurements as well as in terms of Mean Profile Depth (MPD) and Mean Texture Depth (MTD). The results indicate that the OBSI levels for the concrete pavement sections evaluated in this study ranged from 100 dBA to 112 dBA, which is the same as the range of OBSI levels for concrete pavement textures measured in other similar studies. The average OBSI levels for the three commonly used texture types in California (DG, Gr, and LT) where the textures were not worn out ranged from 104 to 107 dBA, with DG and Gr sections typically being quieter than LT sections of similar age and texture condition. For comparison, the OBSI levels for the experimental grind-and-groove sections averaged 101 dBA. The average IRI values for the DG, Gr, and LT sections across all three texture conditions (new, aged, or worn out) were 68, 81, and 96 inches/mile, respectively. The results for the outflow meter times and the MPD values indicate that diamond-grooved sections had a greater capacity for allowing water to move out from under the tire. This suggests that diamond-grooved concrete pavements would generally be more effective in reducing the risk of hydroplaning than diamond-ground or longitudinally tined concrete pavements.

An industry compatible chemo-refining approach was tested for preparation of micro-nanofibrillated cellulose (MNFC) from bleached softwood pulp using sodium meta-periodate and sodium chlorite as oxidizers followed by refining in Valley beater. SEM and FTIR analyses confirmed micro-nano scale fibrillation and chemical functional group modification in laboratory prepared MNFC, respectively. The water retention value, carboxyl content and viscosity of MNFC were found comparable with imported NFC as reference (R-NFC). To evaluate MNFC as strength enhancer for paper properties, 5% MNFC addition to bleached mixed hardwood pulp showed 6% reduction in bulk with 36%, 24% and 97% increment in breaking length, burst index and double fold of the handsheets, respectively without affecting tear index and optical properties than the control. Surface properties were also improved. Pulp drainability (37°SR) after MNFC addition was found suitable for papermaking. These laboratory results confirmed the potential of MNFC as a suitable strength additive for paper quality improvement. [ABSTRACT FROM AUTHOR]

This research report presents the results of tire/pavement noise, friction, drainability, and profile measurements performed on conventional diamond grind (CDG) and grind and groove (GnG) concrete pavement surface textures as a part of the California Department of Transportation (Caltrans) Quieter Pavement Research (QPR) study to investigate tire/pavement noise on concrete pavements. The On-board Sound Intensity (OBSI) method (AASHTO TP 76) was used to measure tire/pavement noise. Longitudinal profile data were collected at the same time as the OBSI data using an inertial profiler (ASTM E950) and were used to calculate the International Roughness Index (IRI). Friction was measured using the Towed Skid Trailer (ASTM E274) and the California Portable Skid Tester (CT 342), and estimated using the Circular Track Meter (ASTM E2157) and Dynamic Friction Tester (ASTM E1911). Drainability was measured using the Outflow Meter (ASTM E2380). Seven pilot projects scheduled for CDG were selected for this research study. They include one each in San Diego, San Joaquin, and Yolo counties, and four in Sacramento County. At these seven sites, measurements were made before and after construction, and in between construction phases when possible. The GnG surface texture was found to be quieter than the CDG, with lane average OBSI values on the GnG texture ranging from 99.5 dBA to 101.7 dBA, with an average of 100.8 dBA, compared with a range of 100.6 dBA to 104.7 dBA, and an average of 102.8 dBA measured on the CDG surface texture. The average OBSI level for all GnG sections was 100.8 dBA compared with an average of 102.8 for all CDG sections. OBSI values on the CDG texture on the San Diego 5 project decreased by 0.5 dBA over 1.3 years where OBSI was measured several times after initial construction. This reduction was attributed to flattening of the “fins” produced by CDG during construction. The average OBSI for all sections prior to treatment was 104.4 dBA, although not all sections had measurements of both CDG and GnG. The IRI measurements showed that both CDG and GnG texturing treatments improved smoothness substantially compared with the pretreatment values. The average IRI was reduced from 142 in./mi for the preconstruction surface textures to 64 in./mi on average after the CDG treatment and to 49 in./mi on average after the GnG texture treatment. Both the OBSI and IRI are improved by CDG and even more so by the GnG texturing. Both CDG and GnG remove sealant overbanding and reduce or eliminate faulting at joints and cracks. Both processes also remove imperfections in the slabs caused by curling, warping, and most of whatever roughness was introduced during initial construction. All of these changes that result from CDG and GnG are likely to contribute to reductions in both noise and roughness. In this study, however, the individual contributions of removal of faulting and overbanding to noise and roughness reductions were not measured. The few friction measurements on the GnG texture using CT 342 were not sufficient to draw conclusions, indicating that further attention should be given to use of this test on this texture if Caltrans continues to use the test. The skid tests using ASTM E 274 indicated that both the CDG and GnG textures passed specifications used by most state highway departments.

Production of test liner and fluting from old corrugated containers, is one of the most common paper recycling processes in Iran. This type of papers, have high basis weight and also contain significant fine fibrous and non-fibrous materials; hence, the drainage and in addition, the retention of fine materials, are the obstacles these paper mills may encounter. In these cases, usually application of drainage/retention aids, such as nanoparticle systems can be of much help. In this due, colloidal silica and bentonite are the two of the most commonly used nano-particles with polyelectrolytes in papermaking wet-end. Therefore, in this research, the effect of bentonite and silica sol nano-particles on the performance of cationic starch was compared in terms of drainability, retention and strength properties of paperboard from recycled old corrugated containers. The analysis of the particle size for these two nanoparticles showed that although the thickness of bentonite platelets (maximum 22 nm) was less than nanosilica dimensions (less than 50 nm), the effect of bentonite-cationic starch was not significant in terms of retention, against the nanosilica. Regarding the drainability, following dosing of both silica and bentonite, the parameter much improved (up to 186% in the case of nanosilica). On the other hand, application of cationic starch containing systems in paper handsheets resulted in improvement in tensile and tear indices, however, these properties decreased following addition of nano-particles. Also, internal bonding (Scott- type) incredibly increased (up to 354%) by application of cationic starch and nanosilica. At last, generally in the case of OCC furnish, the nanosilica-cationic starch system had a better performance in terms of drainability, retention of fine materials and fiber fines and also strength properties, rather than cationic starch-bentonite.

The importance of recycling and utilization of recycled fiber has recently been recognized because of concerns about environmental issues and economic aspects. In spite of several advantages offered by paper recycling such as wood savings through substitution of virgin pulp and reduction in chemical usage, recycled pulp also contains plenty of fines having high relative surface area and high amount of amorphous cellulose. These fines adsorb water to a large extent and dewatering rate is lower compared to virgin pulp. Selective hydrolysis of these excess ultra-fines through eco-friendly cellulase enzymes can be utilized for enhancing the drainage rate leading to increased paper production. The present study deals with the isolation, production, biochemical characterization of alkali stable endoglucanase enzyme from Pycnoporus sanguineus NFCCI-3628 and its potential application for the improvement of pulp drainage. The enzyme produced by the fungus was stable even in neutral to alkaline pH range 7-8. In the experiments carried out, significant improvement of ~9-14% in drain ability of pulp treated with endoglucanase enzyme was achieved along with better paper properties such as tensile index & smoothness.

As is well known, solar pavements are gaining more and more relevance in civil engineering due to their potential in terms of energy harvesting. This notwithstanding, several issues still hinder these typologies from getting an outstanding role, among which their uncertain durability, their surface performance (friction, drainability, texture). In the light of the above, the study described in this paper focuses on permeable and solar roadways. An innovative pavement type was designed by means of the synergistic consideration of hydraulicand transport-related issues and performance. Once formulated and designed, the pavement underwent the preliminary feasibility study in terms of hydraulic and friction-based characteristics in order to assess its ability to perform satisfactory in dry and wet conditions. Results of the study demonstrate that the idea of coupling energy harvesting and premium properties (such as permeability) can be further developed and future research will be devoted to produce a prototype. The contributions of this study is to improve from a draining point of view the typical solar pavement structures. Results can benefit both practitioners and researchers. [ABSTRACT FROM AUTHOR]

In the present study, biomass based fly ash was used to remove lignocellulose from the spent liquor (SL) of a thermomechanical pulping process. The effect of independent parameters, e.g. time, temperature and dosage, on the performance of fly ash in treating SL was studied using an optimal design of response surface methodology. Under the optimal conditions (time 160 min, temperature 40 °C and fly ash dosage of 150 g/L), the removals of turbidity, COD and lignin were 75.1%, 61.3% and 63.5%, respectively. Furthermore, the sedimentation and drainability of fly ash/SL systems were investigated to separate fly ash from SL after the treatment. The sedimentation analysis showed that fly ash would not be settled from the system fast, but sedimentation was improved at a higher temperature of 60 °C than 30 °C. Interestingly, the drainability analysis showed that fly ash could be separated from the SL by filtration. Increasing the fly ash dosage from 120 g/L to 180 g/L reduced the average filtrate rate from 95 mL/min to 25 mL/min, and it was improved from 35 mL/min to 75 mL/min with the temperature increasing from 25 °C to 75 °C. Agitation intensity did not affect the filtration performance, but it increased the solid content of the filtrate from 0.30 wt.% to 0.35 wt.%. [ABSTRACT FROM AUTHOR]

The dynamic drainage, zeta potential, cationic demand, fiber morphology, ash content, and silica content of rice straw soda-anthraquinone (soda/AQ) pulps were measured to study the effects of a mechanical treatment on the drainage performance. The physical properties of handsheets prepared from each beaten sample were also analyzed. It was indicated that pulp fibers played an important role in increasing the beating degree in comparison with non-fibrous cells during refining. The dynamic drainage curve could be divided into three different stages in terms of the drainage rate, and the difference between the pulps screened-out non-fibrous cells (Pnof), and unremoved non-fibrous cells (Pf) decreased with refining. Due to the absence of a large quantity of nonfibrous cells, as the beating proceeded, the straw pulp presented an everincreasing tendency in terms of kink index and curl index. Also, cationic demands of pulps increased linearly and the zeta potential of the fibers decreased gradually with beating. Rice straw was found to be favorable for papermaking, helping to compensate for an acute shortage of wood in China. [ABSTRACT FROM AUTHOR]

The pulp and paper industry has started applying new, ecologically sound technology (biotechnology) in its manufacturing processes. Many interesting enzymatic applications have been proposed. Implemented technologies tend to change the existing industrial process as little as possible. Enzymes have great potentials in solving many problems associated with the use of recycled fiber, especially related to deinking, drainability, hornification, refining, and stickies. Based on the promising results of mill-scale trials, several mills in the world have started using enzymes for deinking. The potentials of cellulase enzymes have also been demonstrated for reducing the energy requirement in pulp refining, improving the machine runnability and stickies control when using recycled fiber. They have the important benefits in that they can be considered a “green” product. They are natural occurring compounds with little adverse impact on the environment. This paper deals with the importance of recycling of paper, problems associated with the recycling, and potentials of enzymes in solving these problems. A few case studies have also been included.

Pervious concrete provides a sound solution for managing storm waters in built environments where the water runoff as well as the natural recharge of the groundwater are important issues. The use of pervious concrete is also commonly related to other environmental benefits such as the Urban Heat Island reduction, traffic noise absorption, and pollutant filtering. Despite the broad capabilities, comprehensive standards are still limited and many issues have not yet been completely fixed. For example, compaction is often underestimated and one of the common compaction effort is provided by hand-rolling; however, different compaction energies, techniques, or timing can significantly affect mechanical and functional properties of the material. Performance can be furthermore improved by adding a small amount of fine sand, as suggested by many; sand can lead towards better raveling and skid resistance, also improving the maximum flexural strength. On the other hand, too much sand and improper compaction energy may lead to an excessively low void content and reduced drainability features. Compaction and sand addition should be therefore analyzed more in details. The present research aimed at (1) evaluating the effect of differential levels of compaction energy and (2) analyzing the influence of fine sand addition into several pervious concrete mixtures. Results suggested that adding small amounts of fine sand (around 5% of the total aggregate weight) to pervious concrete mixtures provided better mechanical and surface properties, and a consequent reduction of drainability. However, the correct balance of mechanical and hydrological properties can be achieved due to both accurate mix-design and proper compaction plan. [ABSTRACT FROM AUTHOR]

Maintenance and reconstruction of road pavements involve the production of huge amount of discarded material, such as reclaimed asphalt (RA), every year. As a consequence, issues related to RA stockpiles and disposals are dramatically increasing. At the same time, the growing importance of environmental and economic matters has led researchers and engineers to promote reusing milled materials rather than using valuable and nonrenewable natural resources (bitumen and aggregates). Road pavement maintenance and construction usually involve the use of porous asphalt (PA) mixtures, in particular in the case of motorways and highways. In fact, PA mixtures are widely employed as pavement surface layer thanks to their ability in reducing traffic noise and enhancing safety in wet conditions. In this sense, the reuse of RA into PA should be strongly encouraged. Unfortunately, technical specifications adopted in many countries do not allow any recycled materials in porous asphalt surface layers yet. Thus, reliable techniques allowing the use of RA in new PA mixtures are needed. In this research study, the use of coarse RA from old PA as aggregate in new PA mixtures was evaluated. Because a previous laboratory study demonstrated that the use of 15% of RA aggregates in PA mixtures seems possible (or even recommendable) as long as an accurate mix design with adequate binder contents is performed, new laboratory and field evaluations on recycled PA mixtures with15% of RA aggregates were carried out. On one hand, cyclic coaxial shear tests (CASTs) were performed under both dry and water-submerged conditions in order to evaluate the simultaneous effect of traffic and water exposure. On the other hand, a comprehensive laboratory experimental program for assessing acceptability, durability, fracture resistance, and water sensitivity was carried out on materials taken from the field during the construction of a full-scale trial section. Moreover, drainage properties of surface layers were measured along such a trial section. Overall test results demonstrated that including 15% of selected coarse recycled aggregates into porous asphalt mixtures does not compromise performances and durability of both asphalt-plant and laboratory produced mixtures. It was demonstrated that recycled mixture with 5.25% of total binder content and prepared by accurate mix design can perform as well as (or even better than) standard PA mixture in terms of workability, acceptability, abrasion resistance, repeated loading resistance, fracture propagation resistance, moisture sensitivity, and water drainability. [ABSTRACT FROM AUTHOR]

Currently, bleached eucalypt pulps are largely used for printing and writing (P&W) and sanitary (tissue) paper grades. Among the many pulp quality requirements for P&W and tissue paper production the xylan content is one of the most significant. For P&W papers, increasing xylans improve pulp refinability and strength properties but negatively affect bulk and drainability. For tissue paper, xylans are purportedly advantageous during paper drying in the Yankee cylinder but negatively affect paper bulk and may increase dusting during paper manufacture. On the other hand, bleachability is a very important parameter for both P&W and tissue grade pulps since bleaching cost is the second most significant in eucalypt bleached kraft pulp production. The aim of this study was evaluating the influence of eucalyptus pulp xylan content on its bleachability, refinability and drainability. A sample of industrial unbleached eucalyptus kraft pulp containing 15.6 % xylans was treated with various alkali charges at room temperature in order to obtain materials with different xylan contents. The pulps were bleached to 90 % ISO brightness with the O-D-(EP)-D sequence and evaluated for their refinability and drainability. By increasing the alkali concentration in the range of 10-70 g/L pulps of 14.5-5.9 % xylans were produced with no significant impact on cellulose crystallinity. The decrease of xylan content significantly decreased pulp bleaching chemical demand, water retention value and refinability and increased pulp drainability. [ABSTRACT FROM AUTHOR]

A combined laboratory and field study was undertaken to evaluate the effect of gradation on resilient modulus (MR) and falling weight deflectometre (FWD) modulus (MFWD) as measures of stability and coefficient of permeability (k) as an indicator of drainability of aggregate bases. Aggregates from three different sources in Oklahoma and three gradations consisting ofM-AASHTO #57,ODOT Type AandOKAA TypeMwere used.MRandktests on compacted aggregate specimens were conducted in the laboratory. Also, a 152.4-m long test section was constructed with the aforementioned gradations and FWD andin-situfalling head permeability tests were conducted periodically. Results showed that denser gradations resulted in higherMRandMFWDand lowerkvalues, both in the laboratory and in the field.MFWDand fieldkvalues were found to increase and decrease, respectively, with time, possibly due to traffic-induced compaction. Regression models were developed to estimateMRandkin terms of gradation and source properties of aggregates. [ABSTRACT FROM PUBLISHER]

The influence of the enzyme addition point on fiber properties was analyzed by treating two industrial recycled pulp samples -- with and without industrial refining -- with a mixture of cellulases and hemicellulases. The effects of the enzyme treatment variables -- enzyme dosage, time, and consistency -- on the fiber properties were studied. The aim of this work was to improve the drainability and the recovery of the strength properties of recycled fibers. The properties of the pulps treated enzymatically and refined in a PFI mill were also evaluated. According to the statistical analysis, opposite effects on drainability were obtained by varying pulp consistency, enzyme dosage, and enzyme application point (i.e., before or after the industrial mechanical treatment). Drainability and strength properties increased when the enzymatic treatment was applied to the pulp without industrial refining, whereas no improvement was observed for pulp with industrial refining. [ABSTRACT FROM AUTHOR]

The pulp and paper industry has started applying new, ecologically sound technology (biotechnology) in its manufacturing processes. Many interesting enzymatic applications have been proposed. Implemented technologies tend to change the existing industrial process as little as possible. Enzymes have great potentials in solving many problems associated with the use of recycled fiber, especially related to deinking, drainability, hornification, refining, and stickies. Based on the promising results of mill-scale trials, several mills in the world have started using enzymes for deinking. The potentials of cellulase enzymes have also been demonstrated for reducing the energy requirement in pulp refining, improving the machine runnability and stickies control when using recycled fiber. They have the important benefits in that they can be considered a "green" product. They are natural occurring compounds with little adverse impact on the environment. This paper deals with the importance of recycling of paper, problems associated with the recycling, and potentials of enzymes in solving these problems. A few case studies have also been included. [ABSTRACT FROM AUTHOR]

Abstract: The experiments have been carried out in the laboratory to investigate the interactions among negatively charged fibres, fines and positively charged polymer particles on two different papermaking slurries of old corrugated containers (OCC) pulp and mixed office waste (MOW) paper pulp. The effects of different wet-end chemicals such as polyacrylamide, polyamide amine and polyethylene amine on fibre surface chemistry have been followed by electrokinetic measurements (zeta potential) of papermaking stock to control the retention and drainage and see how well they perform in the wet-end of the paper machine. The flocculation behaviour has been investigated by different procedures: dewatering test and measuring the first pass retention. Treatment of pulps with chemical additives resulted in substantial improvement of drainage with increase in first pass retention. For OCC pulp, the best results were obtained with 0.5% polyacrylamide improving the drainage by 82% with corresponding first pass retention of 87.5% against 81.8% for the control pulp. However, for MOW pulp, the best results were obtained with 0.3% polyethylene amine improving the drainage by 63% with corresponding first pass retention of 86.0% against 74.2% for the control pulp. The studies on zeta potential of secondary fibres revealed the dependence of first pass retention and drainage on zeta potential of pulps. As the zeta potential approaches zero, the conditions approach optimum for first pass retention and drainage. This way, zeta potential control can lead to environmental protection and competitiveness by using secondary fibres more extensively. [Copyright &y& Elsevier]

Abstract: This paper provides an analysis of different measurements and derived parameters that may be used to characterize drainability and filterability dynamics. To better simulate the phenomena of gravity drainage and expression dewatering, specific devices and procedures were used in bench-scale conditioning and dewatering experiments. The setup included a plow simulator kit for drainage simulation and a mechanical dewatering unit, namely, the Crown Press™, which simulates full-scale belt filter press dewatering. The effects of enzyme product additions prior to polymer conditioning of biosolids samples were investigated. The results showed that enzyme additions enhanced the drainability of the biosolids samples and this positively affected filterability of the samples in the press unit. According to these results, enzyme product addition for biosolids samples with polymer conditioning seems a promising new method of enhancing the performance of mechanical dewatering units in the future. [Copyright &y& Elsevier]

Abstract: This paper reports on the ability of an enzymatic pre-treatment to significantly improve the conditioning of wastewater sludges (biosolids) significantly using by a polymeric flocculant. Experiments used anaerobically digested biosolids samples from two different municipal wastewater treatment facilities, and a formulation containing several different hydrolytic enzymes. Samples were incubated at 35°C for 16h then conditioned with the cationic polymer solution. A laboratory scale mechanical dewatering unit, which simulates full-scale belt filter presses, was used in dewatering of the biosolids. Dewaterability was evaluated using capillary suction time (CST), solid content of final cake product, filtrate turbidity, and suspended solids analysis. The enzyme additions enhanced dewaterability of the polymer conditioned samples in terms of CST and solids content of final product, demonstrating the possibility of significant volume reductions using enzymatic treatment at full-scale. The biosolids structures with the additions of enzyme, polymer, and both additives were determined using field emission scanning electron microscopy. [Copyright &y& Elsevier]

The surface properties of several purified cellulose (Sigmacell 101, Sigmacell 20, Avicel pH 101, and Whatman CF 11) were characterised, before and after cellulase adsorption. The following techniques were used: thin-layer wicking (except for the cellulose Whatman), thermogravimetry, and differential scanning calorimetry (for all of the above celluloses). The results obtained from the calorimetric assays were consistent with those obtained from thin-layer wicking – Sigmacell 101, a more amorphous cellulose, was the least hydrophobic of the analysed celluloses, and had the highest specific heat of dehydration. The other celluloses showed less affinity for water molecules, as assessed by the two independent techniques. The adsorption of protein did not affect the amount of water adsorbed by Sigmacell 101. However, this water was more strongly adsorbed, since it had a higher specific heat of dehydration. The more crystalline celluloses adsorbed a greater amount of water, which was also more strongly bound after the treatment with cellulases. This effect was more significant for Whatman CF-11. Also, the more crystalline celluloses became slightly hydrophilic, following protein adsorption, as assessed by thin-layer wicking. However, this technique is not reliable when used with cellulase treated celluloses. [ABSTRACT FROM AUTHOR]

• MNFC preparation by chemo-refining route - potential to implement in paper industry. • Pretreatment with sodium meta-periodate and sodium chlorite followed by refining. • Nano and micro range fibres with improved WRV and carboxylic content. • Improved paper properties after MNFC addition without lowering pulp drainability. Micro-nanofibrillated cellulose was prepared using bleached mixed hardwood pulp by a low energy consuming chemo-refining approach having potential to be implemented easily in paper industry. Bleached mixed hardwood pulp was pretreated with sodium meta-periodate and sodium chlorite and micro-nanofibrillated by using refining in Valley beater. Scanning electron microscopy images of prepared micro-nanofibrillated cellulose showed 87 % fibre distribution in nano range, 4.47 ± 0.5 g/g water retention value and 2.13 ± 0.1 meq/100 g carboxyl content. Carboxylation effect of given chemical pretreatment was further confirmed by FTIR analysis. Paper handsheets, having bleached mixed hardwood pulp and prepared micro-nano-fibrillated cellulose, resulted in about 5% lower bulk with 27 %, 32 % and 87 % higher breaking length, burst factor and double fold, respectively than control (without nano-fibrillated cellulose). Prepared micro-nanofibrillated cellulose addition didn't show negative effect on pulp drainability (33 °SR). This work showed that micro-nanofibrillated cellulose might also be prepared using conventional routes of paper industry to improve paper properties. [ABSTRACT FROM AUTHOR]

The performance of road and airport wearing courses does not depend only on their bearing capacity. Many of the properties and characteristics of a pavement, such as its friction, drainability, and acoustic absorption, influence its real and perceived economic value. Thus, research is needed to develop reliable contracts and acceptance criteria for wearing courses, taking into account a variety of characteristics. The goal of the study described in this paper was to formalize and validate a model for determining pay adjustments on the basis of traditional and 'premium' qualities. A new quality measure and a new and comprehensive algorithm, based on performance-related specifications and life-cycle cost analysis, were formulated and applied to a case study. The algorithm can also be applied to porous asphalt concretes or similar open-graded friction courses. Analyses and validation demonstrate that the proposed algorithm can efficiently solve typical problems that arise in contract administration for which decisions based on objective criteria are needed. [ABSTRACT FROM AUTHOR]