Paper Mill Sludge Research Articles

Examination of Three Different Organic Waste Biochars as Soil Amendment for Metal-Contaminated Agricultural Soils

The efficiency of biochars (BCs) derived from paper mill sludge (PM-BC), distillery sludge (DS-BC), and pruned branches from roadside trees (PB-BC) for immobilization of selected heavy metals (Cd and Zn) in agricultural soils was examined in the current study. This examination was conducted in order to elucidate whether the recycling of organic wastes could be used as a management option for metal-contaminated agricultural soils. Biochars were applied to contaminated upland soil exceeding the guideline values for Cd (4 mg kg−1) and Zn (300 mg kg−1) in Korea. Both the incubation study and the pot trial with lettuce cultivation were carried out using soil-BCs mixtures at 0, 1, 2, and 5 % (w/w). From the incubation study, it appears that BCs incorporated into the soil induces an increasing soil pH and a significant decline (Cd 36 ~ 100 %; Zn 54 ~ 100 %) in the phytoavailable metal pool examined by 1 M NH4NO3 extraction. The PM-BC was most effective in the reduction of Cd and Zn phytoavailability, due to a significantly higher pH and surface area than the DS-BC and PB-BC. Similar results were observed in the pot trial, where the uptake of heavy metals by lettuce greatly declined with PM-BC incorporation (Cd 26 ~ 71 %; Zn 28 ~ 45 %). PM-BC enhanced the lettuce growth performance evidenced by the highest yield of lettuce being observed with PM-BC-treated soils at 5 %. This was attributed to retardation of the metal toxic effect induced by a decrease in Cd accumulation, while the increased nutrient elements originated from PM-BC. This present study indicates that paper mill sludge is a great candidate for biochar production that can be utilized as a soil amendment for metal-contaminated agricultural soils.

Thermogravimetric analysis of the co-pyrolysis of a bituminous coal and pulp mill sludge

Thermal valorization of organic wastes by co-processing with coal may be a management option for such wastes. In this work, the separate pyrolysis of coal and primary and secondary pulp mill sludge was assessed by thermogravimetric (TG) analysis. Then, under the same experimental conditions, the pyrolysis TG curves of the coal blends with a 10 mass% of either primary or secondary pulp mill sludge were obtained. The corresponding differential thermogravimetry curves made evident that the devolatilization of coal starts at higher temperature and reaches higher char yields than that of primary or secondary paper mill sludge. Under blending, lower devolatilization temperatures and char yields, close to the weighted calculated ones, are observed. Non-isothermal kinetic analysis showed that the Arrhenius activation energy (E) corresponding to the pyrolysis of coal was lower than that corresponding to either L1 or L2. Moreover, lower E than the weighted calculated ones was determined for the co-pyrolysis of the blends.

Bioconversion of paper mill sludge to bioethanol in the presence of accelerants or hydrogen peroxide pretreatment

In this study we investigated the technical feasibility of convert paper mill sludge into fuel ethanol. This involved the removal of mineral fillers by using either chemical pretreatment or mechanical fractionation to determine their effects on cellulose hydrolysis and fermentation to ethanol. In addition, we studied the effect of cationic polyelectrolyte (as accelerant) addition and hydrogen peroxide pretreatment on enzymatic hydrolysis and fermentation. We present results showing that removing the fillers content (ash and calcium carbonate) from the paper mill sludge increases the enzymatic hydrolysis performance dramatically with higher cellulose conversion at faster rates. The addition of accelerant and hydrogen peroxide pretreatment further improved the hydrolysis yields by 16% and 25% (g glucose / g cellulose), respectively with the de-ashed sludge. The fermentation process of produced sugars achieved up to 95% of the maximum theoretical ethanol yield and higher ethanol productivities within 9h of fermentation.

Combustion of primary and secondary pulp mill sludge and their respective blends with coal: A thermogravimetric assessment

Properties of primary and secondary pulp mill sludge are unalike and are also very different from those of coal. Thermogravimetric analysis was used to assess the separate combustion of coal, primary and secondary pulp mill sludge. Then, the co-combustion of coal with primary and with secondary pulp mill sludge was studied under identical experimental conditions. Both Differential Thermogravimetry burning profiles (DTG) and Differential Scanning Calorimetric analysis (DSC) showed remarkable differences between the combustion of coal, primary and secondary paper mill sludge. However, compared with the combustion of coal, the effects of adding a 10 wt.% of either primary or secondary paper mill sludge were not relevant in terms of weight loss or heat release. This was further proved by non-isothermal kinetic analysis, which was used to evaluate the apparent activation energy corresponding to the single combustions and to the co-combustion of blends.

Fenton-like degradation of Methylene Blue using paper mill sludge-derived magnetically separable heterogeneous catalyst: Characterization and mechanism

For the paper industry, the disposal and management of the yielded sludge are a considerable challenge. In our work, the paper mill sludge-derived magnetically separable heterogeneous catalyst (PMS-Fe-380) was prepared easily through a facile synthesis method. The morphology and structure of PMS-Fe-380 were fully characterized by means of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and Brunauer–Emmet–Teller analysis. The catalytic activity of PMS-Fe-380 was evaluated by degradation of Methylene Blue (MB). The reusability and stability of PMS-Fe-380 were evaluated in five repeated runs, which suggested that PMS-Fe-380 manifested excellent stability of catalytic activity. Moreover, leaching tests indicated that the leached iron is negligible (<0.5mg/L). This study provides an alternative environmentally friendly reuse method for paper mill sludge and a novel catalyst PMS-Fe-380 that can be considered as a promising heterogeneous Fenton-like catalyst.

Properties of paper mill sludge–wood fiber–HDPE composites after exposure to xenon-arc weathering

We used paper mill sludge (PMS) to substitute for part of the wood fibers (WF) used to reinforce high density polyethylene (HDPE). The resulting composites were subjected to xenon-arc weathering. The composite filled with limited PMS (under 10 %) had mechanical properties and aging resistance similar to those without PMS. The composites containing more PMS faded and cracked more readily than those without PMS. Based on the carbonyl index, crystallinity, and wood index, PMS appeared to accelerate the degradation of composites during weathering. Adding PMS to WF–HDPE composites reduced the weathering resistance, and this reduction was not significant if the PMS content did not exceed 20 % of the wood fibers. Therefore, PMS could be used as a reinforcement in wood-plastic composites at levels less than 20 % of the wood fiber content.

Thermogravimetric analysis of the co-combustion of paper mill sludge and municipal solid waste

The thermal characteristics and kinetics of paper mill sludge (PMS), municipal solid waste (MSW) and their blends in the combustion process were investigated in this study. The mass percentages of PMS in the blends were 10%, 30%, 50%, 70% and 90%, respectively. The experiments were carried out at different heating rates (10°C/min, 20°C/min and 30°C/min) and the temperature ranged from room temperature to 1000°C in a thermogravimetric simultaneous thermal analyzer. The results suggested that the ignition temperature and burnout temperature of MSW were lower than that of PMS, and the mass loss rate of MSW was larger especially at low temperatures. There were only two mass loss peaks in the differential thermogravimetry (DTG) curve, while three mass loss peaks were observed when the blending ratios of PMS were 30%, 50%, 70%. The value of the comprehensive combustion characteristic index of the blends indicated a good combustibility when the percentage of PMS (PPMS) in the blends was less than 30%. There existed certain interaction between the combustion process of PMS and MSW, especially at high temperature stage. Activation energy (E) value obtained by the Ozawa–Flynn–Wall (OFW) method and the Starink method were very consistent. When the mass percentage of PMS in the blends was 80%, the E average value attained the minimum.

Chemical and plant tests to assess the viability of amendments to reduce metal availability in mine soils and tailings.

The goal of this research was to assess the potential of several industrial wastes to immobilise metals in two polluted soils deriving from an old Pb/Zn mine. Two different approaches were used to assess the performance of different amendments: a chemical one, using extraction by ethylenediaminetetraacetic acid (EDTA), and a biological one, using Lupinus albus as a bio-indicator. Four amendments were used: inorganic sugar production waste (named 'sugar foam', SF), sludge from a drinking water treatment sludge (DWS), organic waste from olive mill waste (OMW) and paper mill sludge (PMS). Amendment to soil ratios ranged from 0.1 to 0.3 (w/w). All the amendments were capable of significantly decreasing (p < 0.05) EDTA-extractable Pb, Zn and Cu concentrations in the two soils used, with decreases in ranges 21-100, 25-100 and 2-100 % for Pb, Zn and Cu, respectively. The amendments tested were also effective in reducing the bioavailability of Pb and Zn for L. albus, which gave rise to a decrease in shoot metal accumulation by the lupine plants compared to that found in the control soil. That decrease reached up to 5.6 and 2.8 times for Pb and Zn, respectively, being statistically significant in most cases. Moreover, application of the OMW, DWS and SF amendments led to higher average values of plant biomass (up to 71%) than those obtained in the control soil. The results obtained showed the technology put forward to be a viable means of remediating mine soils as it led to a decrease in the availability and toxicity of metals and, thus, facilitated the growth of a vegetation layer.

Simultaneous adsorption and dechlorination of pentachlorophenol from effluent by Ni–ZVI magnetic biochar composites synthesized from paper mill sludge

The Ni–zero-valent iron magnetic biochar composites (Ni–ZVI-MBC) were synthesized from paper mill sludge and used as an adsorbent for the removal of pentachlorophenol (PCP) from the synthetic and real paper mill effluent. The synthesized Ni–ZVI-MBC was characterized and analyzed for the stability of Ni and ZVI particles in the biochar matrix. The Ni–ZVI-MBC involves simultaneous adsorption and dechlorination mechanism resulting in higher PCP removal efficiency. The presence of Ni as a catalyst in Ni–ZVI-MBC enhances the dechlorination rate and the adsorption of PCP by preventing the accumulation of PCP in the biochar matrix. The effect of operating parameters (solution pH, Ni loading, initial PCP concentration in the solution and temperature) on adsorption and dechlorination efficiency was studied. The exhausted Ni–ZVI-MBCs were used for the brick formation and the bricks showed good compressive strength and negligible heavy metal and PCP leaching.

Simultaneous biodegradation of organic (chlorophenols) and inorganic compounds from secondary sludge of pulp and paper mill by Eisenia fetida

Present research communicates the role of Eisenia fetida in converting pulp and paper mill sludge into valuable products by removing the high concentration of different chlorophenols and metals present in the sludge. Pulp and paper mill sludge was toxic to Eisenia fetida and therefore, it was mixed with composted material in different ratio of experimental set up such as Set up: 1, (95:5), Set up: 2 (80:20) and Set up: 3 (50:50) on dry weight basis. We found very promising results by the application Eisenia fetida in the sludge. Eisenia fetida removed all the twelve different chlorophenols more than 95 % from the sludge which is declared as carcinogenic compounds by United States Environmental Protection Agency (US-EPA) in 90 days of incubation. Heavy metals concentration was decreased significantly during the incubation period whereas some metal concentration was also increased in the sludge due to mineralization. Carbon (C) and Nitrogen (N) were increased in the composted material, C:N ratio for Set 1 9:4 in Set 2 13:4 and Set 3 18:4 was observed which acts as soil conditioner. Whereas some other metals like (Ca, Mg, Na, K, Fe and Zn) was increased that are essential for the plant growth. There was great reduction in adsorbable organic halogen (AOX) 95 % and extractable organic halogen (EOX) 90 % as compare to control. Eisenia fetida also removed pentachlorophenol (PCP) from the sludge with artificially increased concentration about 100 mg/kg. By observing chlorophenols concentration, metals and carbon–nitrogen ratio, Eisenia fetida is acting as a potential candidate for the reclamation of industrial sludge. The result indicated that vermicomposting with Eisenia fetida is better option to manage the sludge or convert the sludge into nutrient-rich composted material in a short span of time.

Removal of fluoxetine from water by adsorbent materials produced from paper mill sludge

In this work, three adsorbents were produced by using as precursor primary paper mill sludge and applying KOH, NaOH or ZnCl2 as chemical activating agents (PS800-10KOH, PS800-10NaOH and PS800-10ZnCl2) and subjected to pyrolysis. The produced materials were tested for removal of fluoxetine from water, reported as one of the most persistent pharmaceuticals in the aquatic environment. Also, primary sludge pyrolysed under the same conditions but without activation (PS800-10) and a commercial activated carbon (PBFG4) were studied for comparison. Physical and chemical properties of the materials were determined and adsorption kinetic and equilibrium studies were performed in batch experiments. Equilibrium studies allowed testing the capacity of the produced materials for adsorb fluoxetine-HCl, showing no apparent correlation between the SBET areas and the adsorption capacities of the materials. The maximum adsorption capacity (mgg−1) was of 191.6±4.8 for PS800-10KOH; 136.6±9.6 for PS800-10NaOH; 28.4±0.3 for PS800-10ZnCl2; 120.4±2.5 for PS800-10 and 96.2±1.0 for PBFG4. It was demonstrated that many factors influence the removal of fluoxetine from solution and that the surface area is not the main factor in the process. Also the activation process did not enhance the properties of the produced materials.

Adsorptive removal of pharmaceuticals from water by commercial and waste-based carbons

This work describes the single adsorption of seven pharmaceuticals (carbamazepine, oxazepam, sulfamethoxazole, piroxicam, cetirizine, venlafaxine and paroxetine) from water onto a commercially available activated carbon and a non-activated carbon produced by pyrolysis of primary paper mill sludge. Kinetics and equilibrium adsorption studies were performed using a batch experimental approach. For all pharmaceuticals, both carbons presented fast kinetics (equilibrium times varying from less than 5 min to 120 min), mainly described by a pseudo-second order model. Equilibrium data were appropriately described by the Langmuir and Freundlich isotherm models, the last one giving slightly higher correlation coefficients. The fitted parameters obtained for both models were quite different for the seven pharmaceuticals under study. In order to evaluate the influence of water solubility, log Kow, pKa, polar surface area and number of hydrogen bond acceptors of pharmaceuticals on the adsorption parameters, multiple linear regression analysis was performed. The variability is mainly due to log Kow followed by water solubility, in the case of the waste-based carbon, and due to water solubility in the case of the commercial activated carbon.

Facile synthesis of paper mill sludge-derived heterogeneous catalyst for the Fenton-like degradation of methylene blue

Paper mill sludge-derived heterogeneous catalyst was synthesized through a facile method. X-ray diffraction (XRD) analysis confirmed the existence of α-Fe2O3, and Fourier transformed infrared (FT-IR) spectroscopy proved the formation of chemical bonds (Fe–O–Si). The as-prepared catalyst exhibited effective methylene blue (MB) degradation and exhibited an excellent stability of catalytic activity. This study provides an alternative environmentally friendly reuse method for paper mill sludge and a low cost and effective heterogeneous catalyst.

Application of pyrolysed agricultural biowastes as adsorbents for fish anaesthetic (MS-222) removal from water

This work aims to test the adsorption process for the removal of the fish anaesthetic MS-222 from water using biochars obtained from agricultural biowastes (Eucalyptus bark, peanut shells, walnut shells, peach stones, grape seeds and olive waste) as adsorbents. An industrial residue (primary paper mill sludge) and a commercial activated carbon were tested for comparison purposes. The starting materials and the resulting biochars were characterized by elemental and proximate analyses, total organic carbon, FTIR, 13C and 1H solid state NMR, and SEM. Also, specific surface area and porosity of biochars were determined. Then, batch kinetic and equilibrium experiments were performed on the adsorption of MS-222 onto the different produced biochars. The fastest kinetic was obtained using primary sludge pyrolysed (30min to equilibrium attainment) and the highest biochars adsorption capacity was obtained using peanut shells (34mgg−1 of maximum adsorption capacity, predicted by the Langmuir–Freundlich model). Commercial activated carbon reaches 349mgg−1 of maximum adsorption capacity, as predicted by Langmuir model.

Production of lactic acid from the mixture of softwood pre-hydrolysate and paper mill sludge by simultaneous saccharification and fermentation.

Paper mill sludge is a solid waste material composed of pulp residues and ash generated from pulping and paper making process. The carbohydrate portion of the sludges from Kraft/Recycle paper mill has chemical and physical characteristics similar to those of commercial wood pulp. Because of its high carbohydrate content and well-dispersed structure, the sludge can be biologically converted to value-added products without pretreatment. In bioconversion of solid feedstock such as paper mill sludge, a certain amount of water must be present to attain fluidity. In this study, hemicellulose pre-hydrolysate, in place of water, was added to the sludge to increase the concentration of the final product. Pre-hydrolysate was obtained by hot-water treatment of pine wood in which the total sugar concentration reached 4 wt.%. The mixture was processed by simultaneous saccharification and fermentation (SSF) using enzymes (cellulase and pectinase) and Lactobacillus rhamnosus (ATCC-10863). Pectinase was added to hydrolyze mannose oligomers in the pre-hydrolysate to monomers. During the SSF of the mixture, calcium carbonate in the paper sludge acted as a buffer, yielding calcium lactate as the final product. External pH control was unnecessary due to the buffer action of calcium carbonate that maintained the pH near optimum for the SSF. The lactic acid yield in the range of 80-90 % of the theoretical maximum was obtained. Use of the mixed feed of pre-hydrolysate and pulp mill sludges in the SSF raised the product concentration to 60 g of lactate/L.

Lignin in Paper Mill Sludge is degraded by White-Rot Fungi in Submerged Fermentation

This study investigated biological treatment of paper mill sludge and lignin degradation by fungi. Four different Basidiomycetes white-rot fungi (WRF) were used: Coriolus versicolor, Tyromyces albidus, Trametes gallica and Pleurotus ostreatus. The fungi were cultured in submerged fermentation cultures with paper mill sludge. The pH values of the cultures and ligninolytic enzymes production profiles of the four fungi were monitored and reported here. The highest laccase activity of 202 U/L was obtained in T. albidus at day 25 while the maximum manganese-dependent peroxidase (MnP) activity of 50 U/L was obtained in C. versicolor from day 15 to 25. The P. ostreatus showed highest total cellulase activity with the peak of 0.26 μmol at day 15 while the other three WRF showed negligible total cellulase activity. The lignin contents were significantly decreased in the four WRF-treated sludge samples and were confirmed by acetyl bromide and FTIR analyses. The results suggested that lignin was preferentially used and significantly degraded or converted in all the four WRF-treated sludge samples.

Stabilizing Sand Roads with Wood Products and Byproducts

Significant regions of the United States are covered with unstable sands that present traction and maintenance problems on unsurfaced, low-volume roads. Gravel for road surfacing is often unavailable or expensive because of the lack of local gravel deposits. The majority of these sandy areas occur in forested lands with thriving timber and paper industries. The objectives of this study were to review the various wood products and byproducts that are available and carry out a qualitative evaluation of their potential for stabilizing low-volume roads in unstable sands. Wood-related materials may provide cost-effective and environmentally beneficial alternatives for road stabilization materials in areas where gravel is not available or economical for use. The results of a literature search and market survey of wood products, byproducts, and paper mill byproducts are presented along with grain-size distribution test results for unstable sands and some materials. The performance of U.S. Forest Service roads previously stabilized with wood chips, chunkwood, and paper mill sludge was evaluated by site observation. Most of the materials were found to be at least marginally effective in some environments. Paper mill boiler ash shows particular promise as a recycled material for road stabilization and is recommended for further study.

Multi-criteria analysis for site selection for the reuse of reclaimed water and biosolids

Low pH soils with insufficient organic matter can benefit from the application of reclaimed water (RW) and biosolids. The presence of nutrients also aids plant growth. This paper presents the results of two integrated research studies, both carried out in the Beira Interior Region (Covilha, Portugal); one used RW for irrigation, the other applied paper mill sludge to agricultural land. In both cases, multiple criteria based on GIS tools were used for site selection. In the first study, the characteristics of RW analyzed over 2 years were found suitable for crop irrigation. The RW had moderate organic content, low electrical conductivity (CE), high nutrient content (N, P), and low concentrations of nitrate, metals and phytotoxic elements (Al, B, Cl and Na). The multi-criteria analysis was carried out taking into account environmental, technical and economic criteria and a suitable area of 30.5 ha was found for RW irrigation. In the second work, the paper mill sludge was considered suitable for application to agricultural land. Its concentrations of N, P and heavy metals did not a present risk for soil contamination and were suitable for soil improvement and crop production. A multi-criteria analysis based on similar criteria was conducted and a suitable area of 253 ha was found for sludge application.

Linking Organic Carbon, Water Content, and Nitrous Oxide Emission in a Reclaimed Coal Mine Soil

AbstractMine‐land reclamation for biomass production is often achieved by means of large applications of N and organic C with amendments that could create soil conditions favorable for N2O production and emissions. To investigate this possibility, we conducted a laboratory experiment using mine soil collected from an active surface coal mine site near Philipsburg, Pennsylvania. During a 37‐d incubation period, we measured N2O and CO2 fluxes from non‐amended soil and from soil amended with ammonium nitrate (L + F), composted poultry manure (Comp), poultry manure alone (Man) and mixed with 3 rates of paper mill sludge (PMS) to obtain carbon to nitrogen ratios of 14, 20 and 27 (Man + PMS14, 20 and 27), each at 60% and 80% water filled pore space (WFPS). Results showed that manure alone leads to a greater emission of N2O under laboratory conditions than with L + F. However, composting manure effectively reduced the emissions compared to that of L + F despite a large addition of organic C and N. Composted manure‐treated soil emitted less than all other manure‐based treatments at both 60% and 80% WFPS. The emissions were greater from soil amended with the Man + PMS treatments compared to non‐amended and L + F‐amended soil, and it increased during periods of intense microbial activity created by the application of manure and PMS. Higher water content increased emissions particularly during periods of intense microbial activity coupled with inorganic N availability. Cumulative N2O emissions from manure‐treated soils represented less than 0·1% loss of total applied N. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Resistance of paper mill sludge/wood fiber/high‐density polyethylene composites to water immersion and thermotreatment

ABSTRACTThe disposal of paper mill sludge (PMS) is a difficult environmental problem. Thus, PMS has been used as a substitute for wood fiber (WF) to reinforce high‐density polyethylene (HDPE). In this study, we compared PMS–WF–HDPE composites with composites without PMS after water immersion and thermal treatment. Water immersion and thermal treatment were conducted at 25 and 70°C, respectively. The results show that the composites with PMS absorbed less water but lost more of their original flexural properties after immersion; thereby, their strength was compromised. These reduced mechanical properties could be partially restored after redrying. After the thermotreatment, the composites with added PMS lost their weight and flexural properties, whereas the composites without PMS gained flexural strength. The results show that the thermotreatment improved the impact strength of the composites when no more than one‐third of WF was replaced with PMS. Fourier transform infrared spectroscopy and energy‐dispersive X‐ray energy‐dispersive spectroscopy showed that the wood index of the PMS composite decreased more than the index of the non‐PMS composite, whereas the carbonyl index increased more. However, the PMS composite showed a lower increase in the total oxygen/carbon weight ratio. This study suggested that limited amounts of WF could be substituted with PMS to reinforce HDPE. However, WF–PMS–HDPE composites should not be used in hot, humid environments for long periods. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41655.