making! PAPER
The e-magazine for the Fibrous Forest Products Sector
Produced by: The Paper Industry Technical Association
Volume 2 / Number 1 / 2016
PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
CONTENTS:
FEATURE ARTICLES: 1. Papermaking : Improving strength and retention with white-grade recycled pulps 2. Sludge Management : Using worms to process paper and pulp mill sludge 3. Coating Pigments : Designing TiO 2 nanopowders for paper coating applications 4. Wood Panels : Production of binderless boards 5. Solenis : Total Mill Perspective Helps Mills Stay Competitive 6. ABB : Energy Management: Lowering energy prices by managing supply & demand 7. Salvtech : Company profile 8. Valmet : Improved performance with Industrial Internet 9. Marketing : Green marketing initiatives in India 10. Communication Skills : Proven ways to improve communication skills 11. Presentation Skills : Hints and tips to improve presentation skills 12. Leadership : A leading soldier’s views on leadership 13. Self-Motivation : Eight steps to improve motivation 14. Leadership : Understanding how the mind affects every day behaviour SUPPLIERS NEWS SECTION: Products & Services : Extended information on the latest products and services from: ABB Henkel Sensonics Ltd Archroma Midland Pallet Trucks SKF Denver Gardner Pilz Versaperm
( PITA Corporate Member )
DATA COMPILATION: Installations : Overview of equipment orders and installations since November 2015. Research Articles : Recent peer-reviewed articles from the technical paper press. Technical Abstracts : Recent peer-reviewed articles from the general scientific press. PITA Calendar of World Events : Latest calendar of national and international events. The Paper Industry Technical Association (PITA) is an independent organisation which operates for the general benefit of its members – both individual and corporate – dedicated to promoting and improving the technical and scientific knowledge of those working in the UK pulp and paper industry. Formed in 1960, it serves the Industry, both manufacturers and suppliers, by providing a forum for members to meet and network; it organises visits, conferences and training seminars that cover all aspects of papermaking science. It also publishes the prestigious journal Paper Technology and the PITA Annual Review , both sent free to members, and a range of other technical publications which include conference proceedings and the acclaimed Essential Guide to Aqueous Coating .
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Contents
PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
Improvement in the Retention and Strength of Paper Made from White- grade Wastepaper White ledger is white-grade recycled pulp that replaces the bleached kraft pulp (BKP) that typically forms the top ply of duplex boards. However, sheets made from white ledger are inferior in strength compared with those made from virgin pulp. Therefore, it is necessary to select a proper additive in order to overcome the disadvantages of using white ledger. In this study, the physical properties of white ledger used at a mill that produced duplex boards were analysed. The effect of cationic polyacrylamides (C-PAMs) with different charge densities and molecular weights on first-pass retention and paper strengths was simultaneously measured. White ledger contains fibre fines and filler fines, which reduced the strength of paper made from white ledger compared with paper made with BKP. This indicates that the improvement of first-pass retention and paper strength is important when the amount of white ledger increases in the top ply of a duplex board. The charge density of CPAM, which acts as a retention aid, is more important than its molecular weight in terms of improving the first-pass retention and paper strength of white ledger. The charge density of C-PAM must be high enough to catch anionic fine particles. Ji Young Lee,a Eun Hye Kim,b and Yong Joo Sung c,* Contact information: a: Department of Environmental Materials Science/IALS and b: Department of Forest Products, Gyeongsang National University, Jinju 52828, South Korea; c: Department of Biobased Materials, College of Agriculture and Life Science, Chungnam National University, Daejeon 34134, South Korea; * Corresponding author: yosung17@cnu.ac.kr . Article submitted: January 26, 2016; Peer review completed: March 18, 2016; Revised version received: March 25, 2016; Accepted: March 31, 2016; Published: April 13, 2016. DOI: 10.15376/biores.11.2.4718-4726 www.bioresources.com BioResources 11(2) 4718-4726 The Paper Industry Technical Association (PITA) is an independent organisation which operates for the general benefit of its members – both individual and corporate – dedicated to promoting and improving the technical and scientific knowledge of those working in the UK pulp and paper industry. Formed in 1960, it serves the Industry, both manufacturers and suppliers, by providing a forum for members to meet and network; it organises visits, conferences and training seminars that cover all aspects of papermaking science. It also publishes the prestigious journal Paper Technology and the PITA Annual Review , both sent free to members, and a range of other technical publications which include conference proceedings and the acclaimed Essential Guide to Aqueous Coating .
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Article 1 – Improving Retention and Strength
PAPERmaking! g FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
INTRODUCTION Recycled pulp is an important raw material used in paper products. The use of recycled pulp has increased globally in recent years (Ibarra et al. 2012). Recycled pulp from old newspapers (ONP), old corrugated containers (OCC), old magazines (OMG), white ledger, and mixed office wastes (MOW) is widely used in the manufacture of paperboard. The production of paperboard accounts for 50% of the paper products created by the Korean paper industry. Duplex boards or white lined chipboards are used to package food, pharmaceuticals, detergents, textiles, clothing, and more (Kiviranta 1997). Wood powder and other organic fillers have been added to the middle ply of duplex boards to reduce production costs in Korean duplex board mills (Lee et al. 2014a; Park et al. 2015). Reducing the use of virgin pulps is the first step toward lowering production costs and protecting domestic environments in Korea. The replacement of virgin pulp with recycled pulp is beneficial to the Korean paper industry and to the domestic environment. A duplex board is typically made of many plies. The top ply generally consists of bleached kraft pulps (BKP), white ledger, and ONP. Other plies are made of recycled pulp of lower quality (Kiviranta 1997). Though the ratio of BKP is lower than that of other recycled pulp in the top ply of a duplex board, BKP must be replaced with white-grade recycled pulp to reduce production costs. White ledger consists of general office paper that is non-glossy and is either printed or unprinted; this office paper may include typing paper, copy machine paper, or white notebook paper. The production of white ledger has increased steadily as various printing technologies have developed. White ledger, which is of high quality in terms of its white colour, brightness, and strength, contains a higher portion of chemical pulp and a lower content of recycled materials compared with other recycled pulp (Lee et al. 2015). However, the quality of white ledger has decreased because papermakers have increased the use of high-yield pulp (Zhai and Zhou 2014) and inorganic fillers (Jung and Seo 2015) in general office paper to reduce production costs. The high ash content of other recycled pulp has reduced the yield of raw materials and paper strength (Zhao et al. 2008). Therefore, it is necessary to improve the first-pass retention and paper strength of duplex boards that are made from white ledger and that have high ash content. This study explored the ideal conditions of cationic polyacrylamides (CPAMs) to improve the retention and strength of white ledger stock. The properties of white ledger used at an actual mill of duplex boards were analysed and compared with the properties of recycled pulp from the same mill. Next, the first-pass retention of white ledger stock was measured by adding six types of C-PAMs with different charge densities and molecular weights. After determining first-pass retention values, the handsheets were constructed, and their strength was measured. EXPERIMENTAL CONDITIONS Materials Pulp slurries were collected from the Kleannara mill (Cheongju, Korea) where six-ply duplex boards were produced. The pulp was classified as either recycled pulp or virgin pulp, both of which were used for the manufacture of duplex boards. The recycled pulp included white ledger, ONP, and OCC. The virgin pulp consisted of mixed BKP, which combined softwood BKP and hardwood BKP at a ratio of 5:5. Bleached chemo-thermo mechanical pulp (BCTMP) was also included.
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Article 1 – Improving Retention and Strength
PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
Because C-PAMs were used as dewatering agents at the Kleannara mill, CPAMs were selected as the retention aid in the white ledger line. However, a conventional C-PAM does not react well with increases in white ledger in the top ply line. Therefore, six types of C-PAMs were obtained from Songkang Industrial Co., Ltd. (Eumseongkoon, Korea), and their charge densities and molecular weights are shown in Fig. 1.
Fig. 1. C-PAMs as functions of molecular weight and charge density Methods Analysis of the properties of recycled pulp and virgin pulp
The pulp slurries were obtained from the machine chests of stock preparation lines. The initial consistencies of the pulp slurries were measured and diluted to 1.0% using tap water. The pulp properties, including freeness (TAPPI T227 om-09 2009), ash content (TAPPI T244 cm-99 1999), and fines content (TAPPI T261 cm-10 2010) were measured. The average fibre length was also measured using a fibre analyser (Kajaani FiberLabV.3, Metso, Finland). The handsheets were prepared from recycled pulp and virgin pulp. After handsheets with grammages of 100 ± 4g/m 2 were produced, the sheets were wet-pressed at 3.5kgf/cm 2 for 5 min using a laboratory wet press and dried at 120°C using a cylinder dryer. The dried handsheets were conditioned at 23°C and 50% relative humidity (RH) to control the moisture content of the handsheets at 8%. The physical properties of the handsheets were determined, which included bulk (TAPPI T411 om-10 2010), breaking length (TAPPI T494 om-06 2006), burst index (TAPPI T403 om-10 2010), and compressive strength (TAPPI T818 cm-07 2007). Measurement of the first-pass retention of white ledger stock First-pass retention was measured in terms of TAPPI T261 cm-10 (2010). The white ledger stock was diluted to 0.5% using tap water. Next, the C-PAMs were diluted to a concentration of 0.1% with distilled water. Then, 500 mL of the diluted white ledger stock was added into a dynamic drainage tester (Daeil Machinery, Daejeon, Korea) and stirred at a rate of 600 rpm for 30 sec. C-PAMs were added at the same mixing speed. The filtrate was collected from the stock after 90 sec. The filtrate was weighed, filtered, and dried at 105°C to achieve a stable weight. Equation 1 was used to calculate first-pass retention,
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Article 1 – Improving Retention and Strength
PAPERmaking! g FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
where A is the weight of the original sample, W is the weight of the solids (fines) in the filtrate, U is the weight of the filtrate, and T is total amount of fines in the sample. Preparation of handsheets with white ledger stock and the measurement of their physical properties White ledger stock was diluted using tap water to a consistency of 0.5% to prepare the handsheets. Handsheets with grammages of 100 ± 4g/m 2 were produced according to TAPPI T205 sp-06 (2006), after the C-PAMs were added to the pulp and mixed for 30 sec at 600 rpm. The addition levels of C-PAMs were 0.03, 0.05, and 0.07% of oven-dried fibers. The handsheets were wet-pressed at 3.5kgf/cm 2 for 5 min using a laboratory wet- press and were dried at 120°C for 4 min using a cylinder dryer. The dried handsheets were conditioned at 23°C and 50% RH to control the moisture content of the handsheets at 8%. The physical properties, including the bulk (TAPPI T411 om-10 2010), breaking length (TAPPI T494 om-06 2006), burst index (TAPPI T403 om-10 2010), compressive strength (TAPPI T818 cm-07 2007), and ash content (TAPPI T244 cm-99 1999) of the handsheets were measured.
Fig. 2. Flow diagram of the experimental process RESULTS AND DISCUSSION Pulp Properties of Recycled and Virgin Pulp
The pulp properties of recycled and virgin pulp are shown in Figs. 3 and 4. The Canadian standard freeness of white ledger was lower than that of OCC and that of virgin pulp, but the freeness of white ledger was higher than that of ONP. The fines content of white ledger was higher than that of virgin pulp but lower than that of ONP and OCC. The average fibre length of white ledger was the lowest of the six types of pulp, and its ash content was the second lowest among the five types of pulp. White ledger contains more fine particles (such as fibre fines and filler fines) than BKP. This indicates that
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Article 1 – Improving Retention and Strength
PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
papermakers should monitor the yield or retention of fibre fines and filler fines when the amount of white ledger increases in the top ply of a duplex board.
Fig. 3. Freeness (left) and average fibre length (right) of recycled and virgin pulp (W/L = white ledger)
Fig. 4. Ash content (left) and fines content (right) of recycled and virgin pulp (W/L = white ledger) Figures 5 and 6 show the physical properties of the handsheets, which consist of recycled and virgin pulps. The bulk of the white ledger handsheets was similar to that of the OCC and ONP handsheets, and lower than that of the BCTMP and BKP handsheets (Seo et al. 2014). The strength of the white ledger handsheets was greater than the strength of ONP and OCC. However, the strength of the white ledger handsheets was lower than the strength of the BCTMP and BKP handsheets. The low strength of the white ledger handsheets in comparison with those made exclusively with virgin pulp is directly related to its low average fibre length (Retulainen et al. 1997) and high ash content (Kroguerus 1997; Lee et al. 2014b). In addition, the changes in the fibre properties reduced the paper strength during the recycling process (Hubbe et al. 2007; Gulsoy et al. 2013). The white ledger slurry produced handsheets that were lower in strength compared with BKP handsheets. The slurry contained fillers, pigments, and short fibres. Therefore, it is necessary to improve the first-pass retention and paper strength of white ledger handsheets. However, improving first-pass retention tends to result in increased ash content in sheets made from white ledger. Therefore, it is very important to select a proper retention aid that improves both first-pass retention and paper strength.
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Article 1 – Improving Retention and Strength
PAPERmaking! g FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
Fig. 5. Bulk (left) and breaking length (right) of handsheets made from recycled and virgin pulp (W/L = white ledger)
Fig. 6. Burst strength (left) and compressive strength (right) of handsheets made from recycled and virgin pulp (W/L = white ledger) Evaluation of First-Pass Retention and the Physical Properties of Handsheets Made from White Ledger Figure 7 shows the first-pass retention of white ledger stock using different dosages and types of C-PAMs. C-PAMs have different molecular weights and charge densities; therefore, the first-pass retention values were products of the varying dosages and types of C-PAMs. The majority of the C-PAMs led to increases in the first-pass retention of the white ledger stock. C-PAM C showed the highest first-pass retention, while B and F displayed the second highest first-pass retention values among the C-PAMs. A, D, and E did not produce noticeable increases in first-pass retention compared with the other C- PAMs. C-PAMs C and F had molecular weights that were similar to the molecular weight of C-PAM A, but their charge densities were higher than that of C-PAM A. Moreover, C- PAM B had the highest charge density among the C-PAMs. Because white ledger contains many fillers and pigments, a C-PAM must have a high charge density to gather anionic fillers and pigments (Gess 1998; Im et al. 2015). Charge density is an important property of C-PAMs for the improvement of the first-pass retention of white ledger. As mentioned previously, the retention aid should improve the paper strength. In the current study, the strength of white ledger was lower than the strength of BKP. In this study, three C-PAMs (B, C, and F) that had the highest first-pass retention were selected for further study. Handsheets from white ledger stock with C-PAMs B, C, and F were evaluated for the ability of these C-PAMs to improve paper strength. Paper strength is affected by ash content (Xu et al. 2005; Jung et al. 2015). Therefore, the effect of C-PAMs on paper strength was analysed as a function of ash content. Figures 8 through 10 show the breaking length, burst strength, and compressive strength of the handsheets. B and F were similar in strength because of their ash content. C had the lowest paper strength,
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Article 1 – Improving Retention and Strength
PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
though its ash content was similar to the ash content of B and F. Compared with C-PAMs B and F, C-PAM C contained a low charge density, suggesting that charge density was an important factor in first-pass retention and strength. The molecular weight of the C-PAMs was also important. The molecular weight of C-PAM B was lower than that of C-PAM F. Of the six C-PAMs, the molecular weight of C-PAM B was the median value. This result indicated that the C-PAM with the highest charge density should also have a molecular weight that is higher than average in order to improve both first-pass retention and paper strength. The charge density of a C-PAM, which acts as a retention aid, is more important than its molecular weight for improving the first-pass retention and strength of white ledger sheets. The charge density must be sufficiently high to allow the CPAM to gather anionic fine particles.
Fig. 7. First-pass retention values of white ledger with different dosages and types of C- PAMs
Fig. 8. Breaking length as a function of ash content in handsheets made from white ledger and C-PAMs
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PAPERmaking! g FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
Fig. 9. Burst strength as a function of ash content in handsheets made from white ledger and C-PAMs
Fig. 10. Compressive strength as a function of ash content in handsheets made from white ledger and C-PAMs CONCLUSIONS 1. White ledger contained fibre fines and filler fines, which resulted in inferior paper strength compared with the strength of paper made with BKP. Thus, first-pass retention is very important when the amount of white ledger increases in the top ply of a duplex board. Sheet strength must be monitored because an increase in first-pass retention is directly related to an increase in ash content. In addition, a proper additive must be selected. 2. The charge density of a C-PAM, which acts as a retention aid, is more important than its molecular weight in terms of simultaneously improving the first-pass retention and strength of white ledger paper. The charge density must be sufficiently high to allow the C-PAM to catch anionic fine particles. ACKNOWLEDGEMENTS This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. NRF-2015R1A2A2A01006463).
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PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
REFERENCES CITED x Gess, M. D. (1998). “Retention in neutral and alkaline papermaking,” in: Retention of Fines and Fillers during Papermaking (1st Ed.), TAPPI Press, Atlanta, GA, USA. x Gulsoy, S. K., Kustas, S., and Erenturk, S. (2013). “The effect of old corrugated container (OCC) pulp addition on the properties of paper made with virgin softwood kraft pulps,” BioResources 8(4), 5842 -5849. DOI:10.15376/biores.8.4.5842-5849 x Hubbe, M. A., Venditti, R. A., and Rojas, O. T. (2007). “ What happens to cellulosic fibers during papermaking and recycling? A review,” BioResources 2(4), 739 -788. DOI: 10.15376/biores.2.4.739-788 x Ibarra, D., Monte, M. C., Blanco, A., Martínez, A. T., and Martínez, M. J. (2012). “Enzymatic deinking of secondary fibers: Cellulases/hemicellulases versus laccase- mediator system,” Journal of Industrial Microbiology and Biotechnology 39(1), 1-9. DOI: 10.1007/s10295-011-0991-y x Im, W. H., Seo, D. I., Oh, K. D., Jeong, Y. B., Youn, H. J., and Lee, H. L. (2015). “Effects of preflocculated filler flocs and nano -sized coating binder on fold cracking of coated paper,” Journal of Korea TAPPI 47(5), 91 -97. DOI: 10.7584/ktappi.2014.47.5.091 x Jung, J. K., and Seo, Y. B. (2015). “Development of hybrid calcium carbonate for high loading paper: Manufacture and application of hybrid calcium carbonate,” Journal of Korea TAPPI 47(4), 30-37. DOI: 10.7584/ktappi.2015.47.4.030 x Kiviranta, A. (1997). “Paperboard grades in paper and board grades” in: Papermaking Science and Technology (1st ed.), TAPPI Press, Atlanta, GA, USA. x Kroguerus, B. (1997). “Fillers and pigments in papermaking chemistry,” in: Papermaking Science and Technology (1st Ed.), TAPPI Press, Atlanta, GA, USA. x Lee, T. J., Choi, D. C., Kim, M. S., and Ryu, J. Y. (2015). “Studies on deinking properties of recovered paper for manufacturing eco-friendly thermal recording paper,” Journal of Korea TAPPI 47(6), 98 -105. DOI:10.7584/ktappi.2015.47.6.098 x Lee, J. Y., Kim, C. H., Seo, D. J., Lim, G. B., Kim, S. Y., Park, J. H., and Kim, E. H. (2014a). “Fundamental study on developing wood powder as an additive of paperboard,” TAPPI Journal 13(11), 17 -22. x Lee, J. Y., Lim, G. B., Kim, S. Y., Park, J. H., Kim, E. H., Sung, Y. J., Heo, Y. J., Kim, Y. H., and Lee, S. R. (2014b). “Applicat ion evaluation of physical and strength properties of paperboard by kraft pulp mixing made from agricultural byproducts,” Journal of Korea TAPPI 46(5), 43-50. DOI:10.7584/ktappi.2014.46.5.043 x Park, J. H., Lee, J. Y., Kim, C. H., and Kim, E. H. (2015). “Eff ects of lignocellulosic bulking agents made from agricultural byproducts on physical properties and drying energy consumption of duplex board,” BioResources 10(4), 7889 -7897. DOI: 10.15376/biores.10.4.7889-7897 x Retulainen, E., Niskanen, K., and Nilsen, N. (1997). “Fibers and Bonds in Paper Physics,” in: Papermaking Science and Technology (1st ed.), TAPPI Press, Atlanta, GA, USA. x Seo, Y. B., Lee, M. W., Lee, Y. H., and Jung, J. K. (2014). “Application of in -situ CaCO3 formation method for better utilization of recycled fibers: Enhancing attachment of CaCO3 to fibers by polymer pre- treatment,” Journal of Korea TAPPI 46(5), 19-26. DOI: 10.7584/ktappi.2014.46.5.019 x TAPPI T244 cm- 99. (1999). “Acid -insoluble ash in wood, pulp, paper, and paperboard,” TAPPI Press, Atlanta, GA. x TAPPI T205 sp- 06. (2006). “Forming handsheets for physical tests of pulp,” TAPPI Press, Atlanta, GA.
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x TAPPI T494 om- 06. (2006). “Tensile properties of paper and paperboard (using constant rate of elongation apparatus),” TAPPI Press, Atlanta, GA . x TAPPI T818 cm- 07. (2007). “Ring crush of paperboard (flexible beam method),” TAPPI Press, Atlanta, GA. x TAPPI T227 om- 09. (2009). “Freeness of pulp (Canadian standard method),” TAPPI Press, Atlanta, GA. x TAPPI T261 cm- 10. (2010). “Fines fraction by weight of paper stock by wet screening,” TAPPI Press, Atlanta, GA. x TAPPI T403 om- 10. (2010). “Burst strength of paper,” TAPPI Press, Atlanta, GA. x TAPPI T411 om- 10. (2010). “Thickness (caliper) of paper, paperboard, and combined board,” TAPPI Press, Atlanta, GA. x X u, Y., Chen, X., and Pelton, R. (2005). “How polymers strengthen filled papers,” TAPPI Journal 4(11), 8-12. x Zhai, R., and Zhou, X. (2014). “Enhanced effect of NaOH/thiourea/urea aqueous solution on paper strength of high yield pulp,” BioResources 9(2), 215 4-7166. DOI: 10.15376/biores.9.2.2154-2166 x Zhao, Y., Kim, D. H., White, D., Deng, Y., Patterson, T., Jones, P., Turner, E., and Ragauskas, J. A. (2008). “Developing a new paradigm for linerboard fillers,” TAPPI Journal 7(3), 3-7.
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Article 1 – Improving Retention and Strength
PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
Simultaneous biodegradation of organic (chlorophenols) and inorganic compounds from secondary sludge of pulp and paper mill by Eisenia fetida Background: 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. Conclusions: 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. Santosh Kumar Karn • Swapan Kumar Chakrabarti S. K. Karn, Key Laboratory of Marine Environmental Corrosion and Biofouling, Institute of Oceanology, Chinese Academy of Sciences, No. 7 Nanhai Road, Qingdao 266071, Shandong, China e-mail: santoshkarn@gmail.com S. K. Chakrabarti, Environment Management Division, Thapar Centre for Industrial Research and Development, Yamunanagar 135001, India 123 Received: 4 May 2014 / Accepted: 3 February 2015 / Published online: 15 February 2015 Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited. The Author(s) 2015. This article is published with open access at Springerlink.com Int J Recycl Org Waste Agricult (2015) 4:53 – 62 DOI 10.1007/s40093-015-0085-3 The Paper Industry Technical Association (PITA) is an independent organisation which operates for the general benefit of its members – both individual and corporate – dedicated to promoting and improving the technical and scientific knowledge of those working in the UK pulp and paper industry. Formed in 1960, it serves the Industry, both manufacturers and suppliers, by providing a forum for members to meet and network; it organises visits, conferences and training seminars that cover all aspects of papermaking science. It also publishes the prestigious journal Paper Technology and the PITA Annual Review , both sent free to members, and a range of other technical publications which include conference proceedings and the acclaimed Essential Guide to Aqueous Coating .
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Article 2 – Treating Paper Mill Sludge
PAPERmaking! g FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
Introduction The rapid increase in population and the increasing demand for industrial establishments overexploitation of available resources to meet human requirements have created problems such as pollution of the land, air and water environments. Pulp and paper mills generate significant amount of biodegradable sludge (34 and 105kg/t product in large and small paper mills, respectively) during the papermaking and pulp making stages (Pokhrel and Viraraghavan 2004). The disposal of industrial sludge from effluent treatment plant is a global concern to the industries, not a unique problem for the pulp and paper industry. Among the four major modes of sludge disposal; sea discharge, landfill, incineration and land application, nowadays most of industry disposing the sludge by only land application. According to the recent estimate carried out by the US-EPA (1991) half of the 6,500 municipal landfill sites have been closed by the end of the last century and another 54% of the remaining landfills will be closed within next 5 years. The final disposal route for excess sludge generated by wastewater treatment is becoming a serious issue mainly due to the growth of population and sludge accumulation in large cities and growth in the amount and complexity of the related industrial activities. For this reason, it is necessary to reduce the amount of sludge generation by improving the efficiency of the treatment methodologies and implementing new technologies able to use sludge as raw material for compost, generate biomolecules and energy. To cope with this problem United States undertook a long-term research and demonstration program involving all the segments of society from regulators to farmers for the utilisation of biosolids for gainful purposes and to find a long-term solution. Organochlorines are found in the sludge produced at pulp and paper mills. Accounting for as much as four percent of the total weight of the material contaminated sludge is spread on the land, buried in landfills or incinerated releasing chlorinated by-products into the air including polychlorinated phenols and dioxins (Mantykoski et al. 1989). In forests where pulp mill sludge has been dumped chlorinated phenols/dioxins have accumulated in the tissues of field animals and caused biochemical effects in birds (ERT 1987). Vermicomposting are well-known processes for solid organic waste reclamation: the final product vermicompost can be used as sources of organic matter for soil amendment, as sources of nutrients for soil fertilisation or as growing media constituents for soilless cultivation (Gonzalez et al. 2010). Vermicomposting is a bio-oxidative process which engages earthworms and microorganisms. The microorganisms both in the earthworm guts and in the feedstock are responsible for the biochemical degradation of the organic matter while the earthworms are responsible for the fragmentation of the substrate which increases the surface area exposed to the microorganisms. Hence the earthworms directly modify the physical properties of the material and indirectly modify its chemical properties. It is well-established that a large number of organic wastes can be ingested by earthworms and egested as peat-like material termed as vermicompost. It is much more fragmented, porous and microbially active than parent material (Edwards 1988; Edwards and Bohlen 1996) due to humification and increased decomposition. Recent study conducted by Huang et al. (2014) found that changes physiochemical properties and microbial profiles during vermicomposting to make the reliable material and Hanc and Chadimova (2014) found nutrient recovery after vermicomposting. Due to the certain limitations of the other processes, vermicomposting receiving more attention for stabilisation of various wastes including for decreased duration of treatment process, increased pathogen reduction and better product quality (Hait and Tare 2011). Butt (1993) showed that solid paper mill sludge was a suitable feed for Lumbricus terrestis under laboratory conditions. Elvira et al. (1998) have also reported vermicomposting of paper mill sludge using Eisenia andrei under laboratory as well as field conditions. Gajalakshmi et al. (2002) studied the
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Article 2 – Treating Paper Mill Sludge
PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
vermicomposting of paper waste using anecic earthworm Lampito mauriti . Today this is needful to treat the industrial sludge for the removal of organic and inorganic contaminants and manage it properly for the useful application; therefore, present study deals with the treatment of chlorophenols and inorganic constituents from the sludge of pulp and paper mill using Eisenia fetida further it can be applied as a compost material. Materials and methods Collection of sludge sample Dewatered secondary sludge samples of pulp and paper mill were collected from the effluent treatment plant of BILT, Unit-Shree Gopal, Yamunanagar, Haryana, India. This mill adopts kraft process for pulping of raw materials mainly eucalyptus, poplar and bamboo. The effluent and sludge generated by the process is treated in activated sludge process for the biological removal of organics. Vermicomposting set up Dewatered secondary sludge was collected in large-sized plastic containers and then brought to the laboratory for further processing. Sludge was mixed with composted material in different proportions Set up: 1 (95:5) Set up: 2 (80:20) and Set up: 3 (50:50) to maintain the moisture content and reduce the toxicity level of the secondary sludge for the adaptation of worms. Vermicomposting experiments were performed in plastic trays. No external addition of Nitrogen (N) and Phosphorus (P) was added during vermicomposting. pH, temperature and moisture were maintained in the range of 7.5 – 8.5; 27 – 30°C and 60 – 75%, respectively throughout the period of study (for 90 days). The trays were covered with a jute mat and were kept in the shed. The composted material with earthworm 1 kg was spread and mixed at the top layer. Normally (1kg worms present in 10kg dry material). Earthworm species Eisenia fetida were obtained from a stock culture of Krishi Vigyan Kendra (KVK) Tepla Ambala, Haryana an ICAR unit of Govt. of India, with decomposed cow dung spiked with plant litters. Wheat straws (WS) were used to prepare as bedding materials for the experiments. Further in another set chlorophenols degradation ability E. fetida was observed in sludge (proportion like set up: 2) with artificially spiked concentration of PCP in the sludge at the rate of 100mg/kg and mixed thoroughly in plastic trays mentioned above and inoculated E. fetida and incubated under the same condition for 3 months. The tray were covered with jute mate to maintain the pH; temperature, moisture as mentioned as before. Sludge characterization The sludge sample were analysed for physiochemical characteristic such as moisture, pH, carbon, hydrogen, nitrogen, sulphur, zeta potential, absorbable organic halogen (AOX) and extractable organic halogen (EOX). Two grams of sludge sample was taken and dried into oven at 105°C for 24h. The sample was then ground in mortar pestle to obtain particles having size of about 0.1mm. The dried sludge sample (10-100mg) was taken for CHNS analysis using Elemental analyzer (Thermo Scientific, USA). Zeta potential was analysed by maintaining pH of the sample to neutral and placing the sample in zeta potential analyzer, Muteck SZP06 (BTG Mutek GmbH, Germany). The AOX and EOX concentrations were determined using Euroglas Netherlands instrument ECS-2000 according to the manufacturer’s recommended procedure. Determination of chlorophenol Chlorophenols extraction and analysis was done by (NCASI (1986) method CP-85.01) method with a little modification. Secondary sludge samples were taken in ice bath and
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Article 2 – Treating Paper Mill Sludge
PAPERmaking! g FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
sonicated using a Sonicator (SG-25) Roop Telesonic Ultrasonics Ltd. India with variable power intensity between 3 and 7.4W/cm2 and a frequency of 24kHz. The sample was immersed in ice and sonicated for total of 10 min with 1.5 min burst followed by 5 min rest in ice. Next added 1.3ml K2CO3 (pH 11.5) again sonicated for 2 min and added 1.5ml of acetic anhydride and sonicated for 2 min again added 0.5ml acetic anhydride further added 5ml of hexane and again sonicated and centrifuged and further extracted with hexane. After centrifugation at 10,000 rpm for 15 min, the supernatant was used to analyse the chlorophenols. The GC analysis were performed in electron capture detection mode with a gas chromatograph Nucon GC-5765 (Centurion Scientific, India) capillary column DB-5 (30 metre length 0.025mm i.d. 0.25 lm film thickness) was used at a temperature program of 50°C (2 min) then raised to 10°C/min to 280°C where it was held for 10 min. Helium was used as the carrier gas at a constant flow of 1.2ml/min. The samples were analysed in splitless mode at an injection temperature of 250°C and detector temperature 280°C. The Metals was determined as per (APHA 1995) first sludge sample was digested with nitric and perchloric acid (3:1) and filtered through Whatman no.42 paper. The filtrate was used for characterisation of phosphorus content and the trace elements were analysed on furnace atomic absorption spectroscopy (AAS) and rest were analysed on flame AAS. The hydride forming elements were analysed using hydride generator. Statistical analysis Data were statistically analysed by analysis of variance (ANOVA) and the mean differences were compared by Tukey – Kramer Multiple Comparison Test at p<0.05. All experiments were performed in three replicates and analyses were performed using GraphPad Prism (v 4.03) software. (CA, USA). Results and discussion Characterisations of sludge In recent time, interest for vermicomposting (using earthworms to breakdown organic materials) has increased (Hand 1988; Edwards 1988; Edwards and Bohlen 1996) due to its potential. In its basic form, this is a low-cost technology system that primarily uses earthworms in the processing or treatment of organic wastes (Hand 1988). Certain species of earthworm can consume organic material residuals very rapidly and fragment them into much finer particles and reducing the pollutants by passing them through a grinding gizzard. The earthworms derive their nourishment from microorganisms that grow upon these materials. At the same time, they promote further microbial activity since the faecal material or casts that they produce is much more fragmented and microbially active than what they consume (Edwards 1988; Edwards and Bohlen 1996). During this process, the important plant nutrients in the material (particularly the N, K, P and Ca) are released and converted through microbial action into forms that are much more soluble and available to plants than those in the parent compounds. Therefore, first, collected secondary sludge samples were characterised for various physical and chemical characteristics such as pH, organic matter, CHNS, AOX, and EOX described in (Table 1). All the twelve different chlorophenols were also analysed and described in (Table 2) and metals are described in (Table 3). Sludge sample were rich in organic C, H, N and S content. Vermicomposted material significantly modified the physical and chemical properties of all sets mixtures. injected volume was 0.1μl. Determination of metals
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Article 2 – Treating Paper Mill Sludge
PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
The vermicompost was much darker in colour than before and has been processed more homogeneous mixture after 90 days of earthworm activity, the pH observed normal about 7.2 in the final vermicompost. Organic percentages were increased after composting for Set 1 it increased 36 % for Set 2; 35 % whereas for Set 3, it increased up to 50 %. The C:N ratio, one of the most widely used indicating for maturity of organic waste. In our experiments C:N ratio was between 9.4 and 18.4 after 90 days of worms activity. In Set 1, we observed 9:4; in Set 2, 13:4 and Set 3, 18:4. In initial stage, C:N ratio was 8:4 for Set 1, 9:3 for Set 2 and was 14:3 for Set 3. According to Senesi (1989) a decline of C:N ratio to less than 20 indicates an advanced degree of organic matter stabilisation and reflects a satisfactory degree of maturity of organic waste. Total K and N were also increased by the end of vermicomposting due to mineralisation of organic matter. Previously Benitez et al. (2000) has also reported that decomposition of organic materials by earthworm accelerates the N mineralisation process and subsequently changes the N profile of the substrate. Kaushik and Garg (2004) have reported a 2.0 – 3.2 fold increase in TKN during vermicomposting of textile mill sludge mixed with cow dung and wheat straw. Therefore, vermicomposting is a considerable technology for the waste or specially sludge to increase the soil nutrient condition. Different organochlorine contaminants like AOX and EOX in the sludge were analysed (described in Table 4). AOX values ranged from 451 to 5,140mg/kg dry solids. However, 93 – 95% decreases in the AOX and 90 – 92% decrease in EOX level, after composting which makes it less toxic more stable and reliable material for use. Earthworms accumulate many lipophilic organic pollutants from the surrounding soil environment not only through passive absorption through the body wall of the dissolved fraction in the interstitial water but also by intestinal uptake during the passage of soil through the gut. The accumulation increases as the concentration of the pollutant in the soil environment (Belfroid et al. 1995a, b).
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Article 2 – Treating Paper Mill Sludge
PAPERmaking! g FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
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Article 2 – Treating Paper Mill Sludge
PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
The secondary sludge sample was also characterized for 12 chlorophenolic compounds identified by USEPA as carcinogenic compound described in later section.
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Article 2 – Treating Paper Mill Sludge
PAPERmaking! g FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
Chlorophenol concentration Chlorophenols are important biocides and as by-product of bleaching in the pulp and paper industry. Their widespread use has resulted in broad distribution of these compounds in the environment. Environmental contamination with chlorophenols is widespread due to the importance of these chemicals as industrial intermediate, pesticides and solvents. Eisenia fetida can be a significant fate for the chlorophenol removal because physical and chemical methods are not feasible due to high cost and generate secondary pollutants and a single microorganism is unable to mineralise a wide range of different chlorophenols. Field and Sierra-Alvarez (2008) wrote a comprehensive review on the aerobic and anaerobic biotransformation of chlorophenols by microorganism. From the present result, we found that all the 12 different chlorophenols decreased significantly as compared to control having very high concentration (Table 4). Chlorophenols were decreased gradually with time; at 90 days from all the three sets, we did not observe any chlorophenols from the sample whereas in control chlorophenols, concentration was remaining the same (Table 4). From the 2nd experiment having spiked concentration of PCP about (100mg/kg) after 90 days, we found that there is also significant decrease in the concentration of PCP and left about 0.02mg/kg, which shows that vermicomposting having high potential for the removal of chlorophenol from the pulp and paper mill sludge. It is well-established that a large number of organic wastes can be ingested by earthworm and egested as peat-like material termed as vermicompost. Edwards (1988); Kaushik and Garg (2003, 2004) have reported the vermicomposting of textile mill sludge using Eisenia fetida . Butt (1993) showed that solid paper mill sludge was a suitable feed for Lumbricus terrestis under laboratory conditions. Elvira et al. (1998) have reported vermicomposting of paper mill sludge using Eisenia Andrei under laboratory as well as field conditions and found suitable for mineralisation and compost formation. Some report also indicates that other annelids, such as aquatic Polychaetes, can metabolise benzopyrene, because they possess cytrochrome P450 enzymes capable of degrading this compound (Driscoll and McElroy 1997). The same enzymatic activity was found in terrestrial earthworms such as Eisenia fetida (Achazi et al. 1998). This may be a reason for Eisenia fetida to remove organic compounds and metabolise successfully. Autochthonous microorganisms degrade hydrocarbons (Johnsen et al. 2005), but if earthworms are added to soil, they will improve aeration, and stimulate microbial activity, thus increasing biodegradation. Eijsackers et al. (2001) reported that there was a steady decrease in the concentrations of Phenenthrene in soil when they added worms and only very low concentrations of Phenanthrene were detected after 40 days.
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Article 2 – Treating Paper Mill Sludge
PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
Metal concentration Metals concentration in present sludge having higher concentration is described in (Table 5) because of various source such as metal in the raw material and process involved in pulping and paper-making stage. So, the vermicompost made from pulp and paper mill sludge may have higher metal concentrations. Many metal in the sludge mentioned in table is essential and plays significant role for the plant growth and nutrition, but sometime in higher concentration may have detrimental effect on the plant growth. Therefore, before application of the composted material, determining the heavy metals concentration is needed. From the present study, we found that after vermicomposting metals concentration was increased in the composted material as compared to before, in as such
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Article 2 – Treating Paper Mill Sludge
PAPERmaking! g FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
sludge. Essential elements such as Na, K, Mg, Ca which is necessary for the plant growth, metabolism were increased after composting these metals also need for external supply for the plant growth. Previously, Suthar and Singh (2008) have reported that an earthworm processed waste material contains a higher concentration of K due to enhanced microbial activity during the vermicomposting therefore, enhances the rate of mineralisation. Garg and Kaushik (2005) have also reported an increase in Ca content during the vermicomposting of industrial waste. Result showed that heavy metals such as Fe, Cu, Zn, Cr, Ni concentration in the final vermicompost in all three sets were slightly increased as compared to the initial concentration described in (Table 5). High concentration of Cu and Cr may be harmful for the plant but Zn having beneficial effect to plants. Pb and Cd concentration in final vermicomposted material shown decreased which is more toxic to the plants. Wang et al. (2013) also evaluated the role of earthworm in the sewage sludge and observed the reduction of Pb and Cd concentration after vermicomposting. Al concentration was also increased in the composted material. Singh and Kalamdhad (2012) reported that, the contents of total metals (Fe, Cu, Zn Cr, Ni) concentration increased during the water hyacinth ( Eichhornia crassipes ) composting process. Likewise, similar results were obtained by Singh and Kalamdhad (2013) concerning the increase of these heavy metals during the vermicomposting of water hyacinth employing E. fetida . Hait and Tare (2012) reported in their experiments that vermicomposting caused a significant increase in total heavy metals (Cu, Co, Fe, Mn, Zn, Cr) contents and a significant decrease in water-soluble heavy metals contents as compared to the compost material. Heavy metal like Hg, Se, As was not found in the present sludge. Metal such as Co, Mn was also increased which plays a major role as micronutrients and this result is supported by the finding of Hait and Tare (2012). Elvira et al. (1998) also reported an increase in heavy metals concentrations in vermicompost of paper mill sludge. Deolalikar et al. (2005) suggested that weight and volume reduction due to breakdown of organic matter during vermicomposting may be the reason for increase in heavy metal concentrations in vermicompost. In present results, we also observed weight loss which was about 13, 17 and 20 % gradually for Set 1, Set 2 and Set 3. Conclusions We would like to recommend that earthworms ( Eisenia fetida ) have a great potential to remove chlorophenol from the sludge, even mineralise many metals that are resistant to degradation. Earthworm is extremely resistant to toxic chlorophenols and able to tolerate the high concentrations, normally not present in the soil. Applying Eisenia fetida to a contaminated sludge/site might be an environmentally friendly way to remove the chlorophenols. Author contribution All the lab work was performed by SKK and suggestion was provided by SKC. Manuscript was prepared by SKK and checked by SKC. Both the authors have read and approved the final manuscript. Acknowledgments The authors are thankful to KVK Tepla, for providing Eisenia fetida sp. and TCIRD Yamunanagar, for providing the industrial sludge and Biotechnology Engineering Department, Ambala College of Engineering and Applied Research for providing the facilities for the work. Conflict of interest The authors declare that they have no competing interest.
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Article 2 – Treating Paper Mill Sludge
PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
References x Achazi RK, Flenner C, Livingstone DR, Peters LD, Schaub K, Schiwe E (1998) Cytochrome P450 and dependent activity in unexposed and PAH-exposed terrestrial annelids. Comp Biochem Physiol C 121:339 – 350 x APHA (1995) Standard methods for the examination of water and wastewater, 19th edn. American Public Health Association, American Water Works Association, Water Environment Federation, Washington, DC x Belfroid A, Meiling J, Drenth HJ, Hermens J, Seinen W, Gestel KV (1995a) Dietary uptake of super lipophilic compounds by earthworms ( Eisenia andrei ). Ecotoxicol Environ Saf 31:185 – 191 x Belfroid A, Meiling J, Drenth HJ, Hermens J, Seinen W, Gestel KV (1995b) Dietary uptake of super lipophilic compounds by earthworms ( Eisenia andrei ). Ecotoxicol Environ Saf 31:185 – 191 x Benitez E, Nogales R, Masciandro G, Ceccanti B (2000) Isolation by isoelectric focusing of humic urease complexes from earthworm ( Eisenia fetida ) processed sewage sludges. Biol Fert Soils 31:489 – 493 x Butt KR (1993) Utilization of solid paper mill sludge and spent brewery yeast as a feed for soil-dwelling earthworms. Biores Technol 44:105 – 107 x Deolalikar AV, Mitra A, Bhattacharyee S, Chakraborty S (2005) Effect of vermicomposting process on metal content of paper mill solid waste. J Env Sci Eng 47:81 – 84 x Driscoll SBK, McElroy AE (1997) Elimination of sediment-associated benzopyrene and its metabolites by polychaete worms exposed to 3-methylcholanthrene. Aqu Toxicol 39:77 – 91 x Edwards CA (1988) Breakdown of animal, vegetable and industrial organic wastes by earthworms. In: Edwards CA, Neuhauser EF (eds) Earthworms in waste and environmental management. SPB Academic Publishing, The Hague, pp 21 – 31 x Edwards CA, Bohlen PJ (1996) Biology and ecology of earthworms. Chapman & Hall, London Eijsackers H, Van Gestel CAM, DeJonge S, Muijs B, Slijkerman D (2001) Polycyclic aromatic hydrocarbons-polluted dredged peat sediments and earthworms: a mutual interference. Ecotoxicology 10:35 – 50 x Elvira C, Sampedro L, Benitez E, Nogales R (1998) Vermicomposting of sludge from paper mill and dairy industries with Eisenia andrei: a pilot scale study. Biores Technol 64:205 – 211 x ERT (1987) A resource engineering company land treatment effects on wildlife populations in red pine plantations. Nekoosa Papers, Inc, Wisconsin, US x Field AJ, Sierra-Alvarez R (2008) Microbial degradation of chlorinated phenols. Rev Env Sci Biotech 7:211 – 241 x Gajalakshmi S, Ramasamy EV, Abbasi SA (2002) Vermicomposting of paper waste with the anecic earthworm Lampito mauriti Kingburg. Int J Chem Technol 9:306 – 311 x Garg VK, Kaushik P (2005) Vermistablisation of solid textile mill sludge spiked with poultry droppings by an epigeic earthworm Eisenia fetida. Biores Technol 96:1063 – 1071 x Gonza´lez M, Go´mez E, Comese R, Quesada M, Conti M (2010) Influence of organic amendments on soil quality potential indicators in an urban horticultural system. Biores Technol 101:8897 – 8901 x Hait S, Tare V (2011) Optimizing vermistabilization of waste activated sludge using vermicompost as bulking material. Waste Manage 31:502 – 511
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