Chemosphere 109 (2014) 77–83

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Technical Note

Efficacy of bioconversion of paper mill bamboo sludge and lime waste by composting and vermiconversion technologies B. Sahariah a, I. Sinha a, P. Sharma a, L. Goswami a, P. Bhattacharyya b, N. Gogoi a, S.S. Bhattacharya a,⇑ a b

Department of Environmental Science, Tezpur University, Assam 784028, India Indian Statistical Institute, North East Centre, Tezpur, Assam 784028, India

h i g h l i g h t s  Bioconversion of paper mill bamboo and lime waste is a novel effort.  Solubility of heavy metals in paper mill wastes reduced due to vermiconversion.  Vermicomposted paper mill wastes improve soil health.  Vermicomposted paper mill wastes enhances crop yield.

a r t i c l e

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Article history: Received 18 December 2013 Received in revised form 25 February 2014 Accepted 28 February 2014

Handling Editor: O. Hao Keywords: Paper mill bamboo sludge Lime waste Vermiconversion Eisenia fetida

a b s t r a c t Paper Mill Bamboo Sludge (PMBS) and Paper Mill Lime Waste (PMLW) are extensively produced as solid wastes in paper mills. Untreated PMBS and PMLW contain substantial amount of heavy metals (Zn, Pb, Ni, Cd, Cr) in soluble forms. Efficiency of vermiconversion and aerobic composting with these wastes is reported here. Adopted bioconversion systems enhanced the availability of some essential nutrients (N, P, K and Zn) in various combinations of cow dung (CD) with PMBS and PMLW. Colonization of nitrogen fixing bacteria and phosphate solubilizing bacteria considerably intensified under the vermiconversion system. Moreover, significant metal detoxification occurred due to vermiconversion. Various combinations of bioconverted PMBS and PMLW were applied to tissue cultured bamboo (Bambusa tulda) and chilli (Capsicum annum). Accelerated nutrient uptake coupled with improved soil quality resulted in significant production of chilli. Furthermore, vermiconverted PMBS + CD (1:1) and PMLW + CD (1:3) confirmed as potential enriching substrate for tissue cultured bamboo. Ó 2014 Elsevier Ltd. All rights reserved.

1. Introduction Paper Mill Bamboo Sludge (PMBS) and Paper Mill Lime Waste (PMLW) are generated as by-products of paper production in mills. The disposal of these materials presents acute environmental complications. Paper mills generally consume around 30 000– 35 000 t of bamboo annually (Yen et al., 1996). Hence, bamboo dusts and bamboo chips along with other synthetic additives are the principal constituents of PMBS. The composition of this waste mainly depends on the type of paper produced and the origin of cellulose fibers. However, high occurrence of toxic heavy metals is the major threat for ecological considerations. Lime sludge (i.e. PMLW) is the solid waste produced as subsidiary products of the process that turns wood chips into pulp for paper. The major ⇑ Corresponding author. Tel.: +91 3712 267007/8/9x5610. E-mail addresses: (S.S. Bhattacharya).

[email protected],

http://dx.doi.org/10.1016/j.chemosphere.2014.02.063 0045-6535/Ó 2014 Elsevier Ltd. All rights reserved.

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component is calcium carbonate. Approximately, 0.47 m3 of lime mud/sludge is generated to produce 1 t of pulp (Wirojanagud et al., 2004). Extreme alkalinity due to high occurrence of Ca and Na is the major constraint for utilizing the waste through bioconversion. Aerobic composting and vermiconversion are two of the best known processes for stabilization of solid organic wastes. In recent years, we achieved significant success in useful vermiconversion of coal ashes of various large and medium scale industries such as thermal power plants, tea factories and paper mills (Bhattacharya et al., 2012; Goswami et al., 2013). Moreover, capability of Eisenia fetida, an epigeic earthworm in heavy metal detoxification was identified in our previous experiments. The present investigation deals with the possibilities of utilizing untreated sludge materials viz. PMBS and PMLW employing vermiconversion and composting technologies. We assessed the efficiency of different combinations of these wastes and organic matter through vermicomposting and composting. Moreover, we

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Table 1 Basic properties of PMLW and PMBS (n = 6). Parameters

PMLW

PMBS

pH Water holding capacity (%) OC (%) TKN (%) Av. P (mg kg 1) Av. K (mg kg 1) Av. Na (mg kg 1) Av. Ca (mg kg 1) Av. Mg (mg kg 1) Exch. Mn (mg kg 1) Exch. Zn (mg kg 1) Exch. Cu (mg kg 1) Exch. Ni (mg kg 1) Exch. Cd (mg kg 1) Exch. Cr (mg kg 1) Exch. Pb (mg kg 1) CaCO3 (%)

10.6–11.1 71 ± 6.5 0.14 ± 0.05 0.03 ± 0.006 0.08 ± 0.008 0.4 ± 0.04 2.4 ± 0.3 7.5 ± 0.7 1.9 ± 0.2 1.4 ± 0.2 0.62 ± 0.09 0.25 ± 0.04 ND ND 0.005 ± 0.001 0.15 ± 0.03 67 ± 7

6.0–7.3 80 ± 6.5 1.2 ± 0.3 5.6 ± 0.8 115.0 ± 8.9 105.9 ± 9.6 – – – 4.0 ± 0.6 1.5 ± 0.2 0.21 ± 0.04 0.04 ± 0.003 0.15 ± 0.06 0.01 ± 0.001 0.15 ± 0.002 –

succeeded to employ the organic mixtures of PMBS and PMLW as fertilizers for chilli and growth media for tissue cultured bamboo plants.

respectively. Urine free cow dung (CD), collected from a nearby dairy farm, was used as the organic source to initiate as well as expedite the biological conversion process. Juvenile, non-clitellated specimens of epigeic earthworm E. fetida, weighing about 200–250 mg, were obtained from our experimental vermiculture unit and used for composting of organically mixed PMBS and PMLW. 2.2. Experimental design and bioconversion techniques We have adopted two bioconversion techniques viz. aerobic composting and vermiconversion by following our previously standardized techniques (Goswami et al., 2013). Both PMBS and PMLW were mixed with cow dung in various ratios. The following mixtures were used for both aerobic composting and vermiconversion experimentations: PMBS only; PMBS + CD 1:1; PMBS + CD 2:1; PMLW + CD 1:2; PMLW + CD 1:3; PMLW + CD 1:4. The experiments were conducted for two months and the substrates were set aside in triplicate for each treatment combination. Elemental changes during the bioconversion processes were enumerated by drawing samples at 0, 30 and 60 d from each replicate. However, changes in the heavy metal content and growth of Nitrogen Fixing Bacteria (NFB) and Phosphate Solubilizing Bacteria (PSB) were estimated at 0 and 60 d after incubation.

2. Materials and methods 2.3. Tissue cultured bamboo, crop and soil study 2.1. PMBS, PMLW and earthworm species used for vermiconversion Samples were collected from Hindustan Paper Mill (HPCL), Jagiroad (Assam) and Sonabill Tea Garden, Tezpur (Assam)

Selected bioconverted mixtures of PMBS were applied to tissue cultured bamboo (Bambusa tulda). The well grown plantlets of were transferred into a greenhouse and kept for 30 d in a mist

Fig. 1. Changes in nutrient availability under various treatments during bio-composting process.

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height, leaf production and fruit yield of Capsicum, we have analyzed uptake of major nutrients (N and P) (Tandon, 1995), activity of Nitrate Reductase (NR) (Radin, 1974) and Chlorophyll content (Anderson and Boardman, 1964) in leaves. 2.5. Microbial analysis of vermicomposted materials The composted and vermicomposted PMBS and PMLW were analyzed for NFB and PSB after Parmer and Schmidt (1964) and all cultures were prepared in triplicate. Burk’s and Pikovskaya’s media were used to enumerate NFBs and PSBs respectively. 2.6. Statistical analysis We performed one-way ANOVA to analyze real differences between various treatments. Furthermore, for identifying optimum treatment combinations, least significant difference (LSD) test was implemented. 3. Results and discussion 3.1. Characteristics of PMBS and PMLW

Fig. 2. Impact of different treatments on nitrogen fixing (NFB) and phosphate solubilizing (PSB) bacterial population.

chamber in polythene pots filled with various vermicomposted and composted PMBS mixtures. The following treatments were used for the present study: B1 – vermicomposted PMBS; B2 – vermicomposted PMBS + CD 1:1; B3 – composted PMBS + CD 1:2; B4 – vermicomposted PMBS + CD 1:3; B5 – traditional vermicompost + chemical (Zn, Cu); and, B6 – traditional vermicompost + CD + cocopeat. The 30 d old plantlets in polythene pots were transferred to the mother bed in the semi-hardening chamber and growth pattern was noted for 45 d. Selected combinations of PMBS and PMLW were applied to experimental soil (typic endoaquepts; pH 5.85; organic C: 12.5 g kg 1; easily mineralizable N: 105 kg ha 1 and available P: 22.5 kg ha 1) with chilli as a test crop (Capsicum annum; variety: Pusa Jwala). The experiment was conducted in a randomized block design with three replicates during winter season. The treatment combinations used for the study on chilli are: C1 – 100% recommended NPK & vermicomposted PMBS @ 10 t ha 1; C2 – 100% recommended NPK & vermicomposted PMBS (1:1) @ 10 t ha 1; C3–100% recommended NPK & composted PMBS (2:1) @ 10 t ha 1; C4–100% recommended NPK & composted PMLW (1:2) @ 10 t ha 1; C5–100% recommended NPK & farmyard manure @ 10 t ha 1; and, C6–100% recommended NPK. 2.4. Bioconverted materials, soil and plant analysis N, P, K, metal and pH of PMBS, PMLW, experimental soil, compost and vermicompost samples were analyzed by following Page et al. (1982). Plant height, leaf number plant 1, leaf length were the main indicators for growth of tissue cultured B. tulda. Apart from

Table 1 represents few vital physico-chemical properties of PMBS and PMLW. Physical and chemical characteristics of these wastes largely depend on the raw materials used and recycling processes adopted for paper production. PMLW is the solid waste produced as part of the process that turns wood chips into pulp for paper. Extreme alkalinity due to high occurrence of Ca and Na is the major constraint for utilizing PMLW agriculture. However, liming property of these wastes was reported to reduce the bioavailability of heavy metal in soil upon application of these materials (Sthiannopkao and Sreesai, 2009). High organic carbon, N, P and K contents were the main characteristic features of PMBS (Table 1). 3.2. Effect of biocomposting on solubility of N, P, K and beneficial microorganisms Composition of macro nutrient elements viz. N, P and K in various mixtures of PMBS and PMLW significantly increased with respect to the inherently available status (Table 1) during the process of bioconversion (Fig. 1) (p < 0.01 in all the cases). Significant differences among the treatment combinations were observed under both the methods (P = 0.000). However, N mineralization increased significantly under vermiconverted PMLW + CD (1:4) followed by PMLW + CD (1:3) and PMBS + CD (1:1) combinations as compared to others (p = 0.000). This is well corroborated with Goswami et al. (2013). In general, the efficiency of vermicomposting was highly pronounced in the PMBS combinations as compared to PMLW combinations with respect to P solubility (Fig. 1). The LSD test suggested that P solubility was highest in PMBS followed by PMBS + CD (1:1) and PMBS + CD (2:1) under vermicomposting. Earthworm gut produces considerable amount of alkaline phosphatase, which facilitates P mineralization when waste materials pass through the worm intestine (Singh and Suthar, 2012). Significantly high P solubility was also recorded in composted PMLW + CD (1:3). However, composting was a slightly better option for increasing P solubility in the lime sludge. Loss of P by leaching or volatilization is nominal. Therefore, mass loss of lime mud (CaCO3) through leaching during the incubation period probably accelerated P release in the composted product. The efficiency of vermiconversion was relatively more evident in regard to potassium availability as compared to composting

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Fig. 3. Changes in heavy metal concentration under various treatments during bio-composting process.

Table 2 Nutrient uptake, nitrate reductase and total chlorophyll content in Bambusa tulada and Capsicum annum under different treatments. 1

)

Available P (mg kg

1

)

Nitrate reductase (lmol g

1

Treatments

Available N (mg kg

Bambusa tulada B1 B2 B3 B4 B5 B6 LSD at 0.05P

)

Total chlorophyll

67 ± 6 119 ± 7 85 ± 8 143 ± 8 79 ± 5 70 ± 7 6.8

57 ± 5 49 ± 8 58 ± 6 69 ± 4 38 ± 7 37 ± 9 4.3

148 ± 8 252 ± 10 110 ± 4 320 ± 9 240 ± 10 220 ± 8 8.9

0.01 ± 0.01 0.1 ± 0.1 0.02 ± 0.01 0.12 ± 0.05 0.01 ± 0.01 0.01 ± 0.02 0.01

Capsicum annum C1 C2 C3 C4 C5 C6 LSD at 0.05P

56.23 ± 4.5 122.12 ± 6.7 43.21 ± 5.5 99.11 ± 6.5 43.12 ± 6.6 29.24 ± 4.5 7.3

50.06 ± 4.4 70.44 ± 6.2 23.33 ± 3.2 39.22 ± 4.5 31.21 ± 6.6 28.48 ± 7.8 3.9

150.22 ± 11.22 745.55 ± 12.5 110.33 ± 7.9 580.43 ± 14.2 20.32 ± 2.2 80.33 ± 5.6 9.5

0.015 ± 0.01 0.016 ± 0.01 0.013 ± 0.03 0.014 ± 0.04 0.012 ± 0.02 0.012 ± 0.02 0.01

B1 – vermicomposted PMBS; B2 – vermicomposted PMBS + CD (1:1); B3 – composted PMBS + CD (1:2); B4 – vermicomposted PMBS + CD (1:3); B5 – traditional vermicompost + chemical (Zn,Cu); B6 – traditional vermicompost + CD + cocopeat. C1 – 100% NPK & vermicomposted PMBS @ 10 t ha 1; C2 – 100% NPK & vermicomposted PMBS(1:1) @ 10 t ha 1; C3 – 100% NPK & composted PMBS(2:1) @ 10 t ha 1; C4 – 100% NPK & composted PMLW (1:2) @ 10 t ha 1; C5 – 100% NPK & farmyard manure @ 10 t ha 1; C6 – 100% recommended NPK.

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Fig. 4. Impact of biocomposted PMBS and PMLW on growth and yield of Bambusa tulda and Capsicum annum.

(Fig. 1). Moreover, LSD test suggests that vermicomposted PMBS + CD (1:1) and PMLW + CD (1:3) significantly contributed in enhancing K availability as compared to other combinations. This may be due to the action of endogenic and exogenic enzymes which hasten the waste mineralization rate under a vermicomposting system (Singh and Suthar, 2012). Significant differences among composted and vermicomposted series have been clearly observed in both NFB and PSB (Fig. 2: NFB: p = 0.001; PSB: p = 0.000). Among the vermicomposted samples T2 [PMBS + CD (1:1)] showed the highest PSB count. Therefore, T2 appeared to be the best substrate for PSB. This result strongly corroborates previous findings (Goswami et al., 2013). However, T3 [PMLW + CD (1:2)] showed highest count of NFB in both composting and vermicomposting systems. Such rise in NFBs could have largely attributed towards accelerated N mineralization in addition to other factors.

3.3. Trace elements in biocomposted PMBS and PMLW (Mn, Cu, Zn, Ni, Cd, Cr and Pb) Fig. 3 represents the concentration of different trace elements in various combinations under bioconversion. Bioavailability of Cu, Mn and Zn considerably increased in T2 [PMBS + CD (1:1)], T5 [PMLW + CD (1:2)] and T6 [PMLW + CD (1:3)] (LSD: Cu – 0.08; Zn – 0.09) due to vermicomposting [LSD-0.4]. Interestingly, bioavailability of Pb, Ni, Cr and Cd significantly decreased under vermiconversion in PMBS treatments. However, Ni and Cd concentrations increased in vermicomposted PMLW treatments, indicating a sluggish bioaccumulation activity of E. fetida in PMLW. These results are in good agreement with some previous findings (Nannoni et al., 2011; Goswami et al., 2013). Generally, bioaccumulation efficacy of earthworms is more pronounced for non-essential metals as compared to essential metals (Zn and Cu). This is because

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of inter-specific differences in the dietary intake of elements, in physiological and morphological characteristics, chemical species requirements, excretion and detoxification (Nannoni et al., 2011). Moreover, exposure to heavy metals induces synthesis of metallothionein isoform in earthworm intestines, which can detoxify metal ions (As, Cd, Hg, Si, Al, Fe) to a considerable extent (Maity et al., 2009). 3.4. Impact on nutrient uptake, Chlorophyll content and NR activity Uptake of N and P was maximum under vermicomposted PMBS + CD (1:1) + NPK100 treated chilli followed by PMLW + CD (1:3) + NPK100 and composted PMLW + CD (1:2) + NPK100 (Table 2). Whereas, B2 [vermicomposted PMBS + CD (1:1)] and B4 [vermicomposted PMBS + CD (1:3)] showed significantly promising result for B. tulda with respect to uptake of N and P. This may be due to rapid mineralization combined with enhanced enzymatic activity in the media. Two important physiological attributes viz. chlorophyll content and NR activity were evaluated in both the plant species (Table 2). In B. tulda, B3, B4 and B2 showed significant NR and chlorophyll concentration (LSD = 0.01). However, vermicomposted C2 [PMBS + CD (1:1) + NPK100] demonstrated significantly high concentration of NR in chilli followed by composted C4 [PMLW + CD (1:2) + NPK100] (LSD = 8.9). Moreover, C2 treated chilli plants recorded maximum total chlorophyll content. This may be due to increased uptake of N which expedited chlorophyll formation in leaves. Furthermore, accelerated microbial activity in the vermicompost enhanced enzyme activity in plants. 3.5. Effect of bioconverted PMBS and PMLW on plant growth and yield Fig. 4 presents the performance of biconverted PMBS and PMLW as growth promoters with regard to tissue cultured B. tulda and chilli (C. annum). Height of bamboo plantlets increased significantly over time under composted PMLW + CD (1:2) and vermicomposted PMBS from 30 to 45 DAI (P < 0.01). However, leaf length and production of B. Tulda most significantly increased under vermicomposted PMBS + CD (1:1) followed by PMLW + CD (1:3) (LSD: leaf number = 1.1; leaf length = 0.9). Plant height and leaf numbers in chilli plants increased significantly over time from 15 to 45 DAS (P < 0.01), after which the rate of increment gradually slowed down indicating cessation of vegetative growth (Fig. 4). Significant increase in height was recorded for vermiconverted PMBS + CD (1:1) + NPK100 (C2) followed by composted PMLW + CD (1:2) + NPK100 (C4) (LSD: chilli: height = 2.1; leaf production = 1.5). Concurrently, C2 recorded significantly high capsicum yield followed by composted C4 (LSD = 2.4). Enhanced nutrient uptake along with increased chlorophyll and NR activity under biconverted PMBS and PMLW treatments influenced plant growth in a holistic manner. All these factors together sustained balanced crop development and thus enhanced economic yield. 3.6. Effect of bioconverted PMBS and PMLW on cultivated soil The data on soil pH (Fig. 5) show that there was a slight increment in the pH of all the vermicomposted treatment combinations of PMBS, compared to the initial value. Such increment was highly prominent in soil under composted treatment of PMLW + CD (1:2) + NPK100 (T5). This may be due to high concentration of CaCO3 in the PMLW samples. Vermicomposted PMBS + CD (1:1) + NPK100 (T3) and composted PMLW + CD (1:2) + NPK100 (T5) significantly enhanced N mineralization and P solubility in soil compared to other combinations (LSD: N = 9.7; P = 2.3) (Fig. 5). Improvement in nitrogen

Fig. 5. Impact of different treatments on soil quality attributes.

mineralization of the soil may be attributed to gradual release of N from the organic component as well as enhanced activity of nitrogen fixing bacteria in these treatments. Singh and Suthar (2012) also suggested that considerable amount of P availability is contributed by earthworm gut phosphatase. Moreover, the liming effect of PMLW combinations may have augmented P solubility in soil. 4. Conclusions This study demonstrates that vermiconversion is a better option than aerobic composting with respect to nutrient composition in PMBS. In addition, heavy metal detoxification by E. fetida would reduce the risk of soil quality deterioration. However, efficiency of aerobic composting technology was marginally higher over vermicomposting with respect to bioconversion of PMLW. Furthermore, the results from crop experiments revealed that bioconverted PMBS and PMLW significantly contribute to the enhancement of both qualitative and quantitative aspects of plant growth. References Anderson, J.M., Boardman, N.K., 1964. Studies on greening of dark grown bean plants. Aust. J. Bios. Sci. 17, 93–101. Bhattacharya, S.S., Iftikar, W., Sahariah, B., Chattaopadhyay, G.N., 2012. Vermicomposting converts fly ash to enrich soil fertility and sustain crop growth in red and lateritic soils. Res. Conserv. Recycl. 65, 100–106. Goswami, L., Patel, A.K., Dutta, G., Bhattacharyya, P., Gogoi, N., Bhattacharya, S.S., 2013. Hazard remediation and recycling of tea industry and paper mill bottom ash through vermiconversion. Chemosphere 92, 708–713. Maity, S., Bhattacharya, S., Chaudhury, S., 2009. Metallothionein response in earthworms Lampito mauritii (Kinberg) exposed to fly ash. Chemosphere 77, 319–324. Nannoni, F., Protano, G., Riccobono, F., 2011. Uptake and bioaccumulation of heavy elements by two earthworm species from a smelter contaminated area in northern Kosovo. Soil Biol. Biochem. 43, 2359–2367. Page, A.L., Miller, R.H., Keeney, D.R., 1982. Methods of Soil Analysis. Part 2. Soil Sci. Soc. Am., Madison, WI. Parmer, D., Schmidt, E.L., 1964. Experimental Soil Micorbiology. Burgess Publication, Mineapolis, MN, USA. Radin, J.W., 1974. Distribution and development of nitrate reductase activity in germinating cotton seedlings. Plant Physiol. 53, 458–463.

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Efficacy of bioconversion of paper mill bamboo sludge and lime waste by composting and vermiconversion technologies.

Paper mill bamboo sludge (PMBS) and Paper mill lime waste (PMLW) are extensively produced as solid wastes in paper mills. Untreated PMBS and PMLW cont...
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