Effects of micro-nano and non micro-nano MSWI ashes addition on MSW anaerobic digestion

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<ul><li><p>oechnih R</p><p>Anaerobic digestion</p><p>igattto-nanuldbi</p><p>3.5</p><p>able for the MSW anaerobic digestion particularly found in the micro-nano added bioreactors. 2012 Elsevier Ltd. All rights reserved.</p><p>been meated bn in Tae potene it als</p><p>the MSW anaerobic digestion (Lo et al., 2009). However, benecialfacilitation of MSW biodegradation by ash addition was still notwell understood. Similar investigations were also reported thatmetals of different levels might stimulate or inhibit the organicsubstrate anaerobic digestion and fermentation process (Fermosoet al., 2009; Chen et al., 2008; Yuan et al., 2009; Tan et al., 2009;Altas, 2009; Li and Fang, 2007; Lin and Shei, 2008; Yue et al.,</p><p>activated sludge anaerobic digestion. Nano-TiO2, nano-Al2O3 andnano-SiO2 in doses up to 150 milligram per gram total suspendedsolids (mg g1-TSS) showed no inhibitory effect, whereas nano-ZnO showed inhibitory effect with its dosages increased. The meth-ane generation was the same as that in the control when in thepresence of 6 mg g1-TSS of nano-ZnO, however, which decreasedrespectively to 77.2% and 18.9% of the control at 30 and150 mg g1-TSS. The released Zn2+ from nano-ZnO was an impor-tant reason for its inhibitory effect on methane generation. Luna-delRisco et al. (2011) found that particle size of CuO and ZnO could</p><p> Corresponding author. Tel.: +886 4 23323000x4469; fax: +886 4 23742365.</p><p>Bioresource Technology 114 (2012) 9094</p><p>Contents lists available at</p><p>T</p><p>elsE-mail address: hmlo@cyut.edu.tw (H.M. Lo).such as bottom ash (BA) and y ash (FA). MSWI BA and FA were re-ported to contain various metals and recalcitrant organic com-pounds such as polycyclic aromatic hydrocarbons (PAHs) andpolychlorinated dibenzodioxins/furans (PCDD/Fs). Both BA and FAcould be used as aggregate, backll, soil amendment and cementadditives after careful pretreatment, toxicity and TCLP test (Linand Chen, 2006).</p><p>Studies on BA or FA on co-disposal or co-digestion with MSWwere few (Lo et al., 2010, 2009; Lo and Liao, 2007; Boni et al.,2007). MSWI BA and FA addition might release various metals lev-els resulting to the potentially benecial or detrimental effects on</p><p>by microorganisms were also reported (Wyrzykowska et al., 2009;Lin et al., 2008; Yasuhara and Katami, 2007; Wang et al., 2010;Ham et al., 2008; Liu et al., 2008; Nam et al., 2005; Shitamuraet al., 2005; Oleszczuk, 2009).</p><p>Nanotechnology has been evolved to be an attractive option inengineering and environmental science. Mu and Chen (2011) hasreported that the presence of 1 mg g1-TSS of ZnO nanoparticles(NPs) did not affect methane production of waste activated sludge,but 30 and 150 mg g1-TSS of ZnO NPs induced 18.3% and 75.1% ofinhibition, respectively. Mu et al. (2011) has also investigated themetal oxide nanoparticles (TiO2, Al2O3, SiO2 and ZnO) on wasteMicro-nano scaleMetals</p><p>1. Introduction</p><p>Municipal solid waste (MSW) hasincinerator (MSWI) while partly trrecovery, composting and gasicatioreduce the MSW volume and have thet of the steam and electricity whil0960-8524/$ - see front matter 2012 Elsevier Ltd. Ahttp://dx.doi.org/10.1016/j.biortech.2012.03.002ainly treated by MSWy landlling, resourceiwan. The MSWI couldtial co-generation ben-o produces the residues</p><p>2007; Kuo and Genthner, 1996; Gikas, 2007; Kida et al., 2001;Ma et al., 2009; Worm et al. 2009). Recently, Lo et al. (2012) haveincorporated the above research and reported the new results thatsuitable levels of several individual metals could enhance the MSWanaerobic digestion. On the other hand, PAHs and PCDD/Fs ofMSWI ashes and their release were investigated by severalresearchers and their adsorption by adsorbents and biodegradationMSWMSWI ashes</p><p>had the higher biogas production than the corresponding non micro-nano MSWI FA and BA added ones.Suitable MSWI ashes addition could improve the biogas production due to the released metals levels suit-Effects of micro-nano and non micro-nananaerobic digestion</p><p>H.M. Lo a,, H.Y. Chiu a, S.W. Lo a, F.C. Lo baDepartment of Environmental Engineering and Management, Chaoyang University of TbDepartment of Occupational Safety and Health, China Medical University, 91 Hsueh-Sh</p><p>a r t i c l e i n f o</p><p>Article history:Received 3 December 2011Received in revised form 29 February 2012Accepted 2 March 2012Available online 9 March 2012</p><p>Keywords:</p><p>a b s t r a c t</p><p>This study aims at invest(MSWI) y ash (FA) and bomicro-nano and non micro36, 60 and 120 g g1 VS) cofound to have the highest(193 mL g1 VS MSW, </p><p>Bioresource</p><p>journal homepage: www.ll rights reserved.MSWI ashes addition on MSW</p><p>ology, 168, Gifeng E. Rd., Wufeng District, Taichung 41349, Taiwan, ROCd., Taichung 40402, Taiwan, ROC</p><p>ing the effects of micro-nano municipal solid waste (MSW) incineratorm ash (BA) on the MSW anaerobic digestion. Results showed that suitableo MSWI ashes addition (FA/MSW 3, 6, 18 and 30 g g1 VS and BA/MSW 12,enhance the biogas production compared to the control. It was particularlyogas production at the micro-nano MSWI BA/MSW ratio of 36 g g1 VStimes to the control). Micro-nano MSWI FA and BA added bioreactors</p><p>SciVerse ScienceDirect</p><p>echnology</p><p>evier .com/locate /bior tech</p></li><li><p>1061110 and 111010000 nm after one day settlement respec-tively. As to micro-nano MSWI BA, Figure S-5B showed that parti-</p><p>Taiw</p><p>)</p><p>Cd (mg g1) 0.10 0.05 0.01 0.00</p><p>Techaffect the cattle manure anaerobic digestion. Biogas productionwas severely affected at concentrations of bulk and nanoparticlesover 120 and 15 mg L1 for CuO and 240 and 120 mg L1 for ZnO,respectively. EC50 concentrations for methane inhibition were esti-mated to be 129 mg Cu L1 for bulk CuO, 10.7 mg Cu L1 for nanoCuO, 101 mg Zn L1 for bulk ZnO and 57.4 mg Zn L1 for nano ZnO.</p><p>So far the investigations using BA or FA (containing metal oxi-des and other compounds) for co-digestion or co-disposal withMSW have rarely undertaken (Lo et al., 2009; Lo and Liao, 2007;Boni et al., 2007). Using metal oxides for co-digestion with organicsubstrate are also few. Only some anaerobic digestion of sludgeand manure with metal oxide addition were reported (Mu and</p><p>Cr (mg g1) 0.28 0.04 0.11 0.02Cu (mg g1) 0.12 0.03 0.20 0.04Ni (mg g1) 0.07 0.00 0.06 0.00Pb (mg g1) 2.53 0.10 0.07 0.00Zn (mg g1) 5.16 0.35 1.34 0.12Table 1Elemental values and carbon to nitrogen ratios between synthetic, Taichung city and</p><p>Analyzed items C (%) H (%) O (%) N (%</p><p>Synthetic MSW 46 6 41 1.4Taichung city MSW 20.55 3.06 18.53 0.50Taiwan MSW 17.38 0.47</p><p>Table 2Basic characteristics of organic MSW and anaerobic sludge seeding.</p><p>Organic MSW Anaerobic sludge seeding</p><p>pH 7.90 0.22 6.86 0.09ORP (mV) 72.70 4.52 17.25 1.34EC (mS/cm) 0.34 0.01 1.96 0.05TS (%) 5.59 0.19 2.78 0.39VS (%) 3.96 0.34 0.74 0.40Ca (mg g1) 110.03 0.30 12.99 0.55Mg (mg g1) 7.84 0.13 2.25 0.15K (mg g1) 65.31 0.01 2.20 0.07Na (mg g1) 14.98 0.80 0.69 0.03</p><p>H.M. Lo et al. / BioresourceChen, 2011; Mu et al., 2011; Luna-delRisco et al., 2011).This work investigated the effects of various dose of micro-nano</p><p>and non micro-nano MSWI FA and BA on the anaerobic co-diges-tion of MSW and MSWI ashes that might provide the useful infor-mation for the MSW anaerobic digestion.</p><p>2. Methods</p><p>2.1. Materials</p><p>MSWI FA and BA were obtained from an incinerator located incentral Taiwan. Micro-nano (ground by ball mill, RETSCH, PM100) and non micro-nano MSWI ashes properties of metal com-pounds and image by XRD (PANalytical XPert Pro MRD) andFE-SEM (JEOL JSM-6700F) and micro-nano MSWI ashes distribu-tion by high performance particle sizer (HPPS, HPP5001, Malvern)can be found from Fig. S-1S-5, respectively. Figure S-1 showed theXRD plot of MSWI FA, micro-nano MSWI FA, MSWI BA and micro-nano MSWI BA. XRD plot of Figure S-1 showed to contain Al2O3,CaCO3, Ca(OH)2, SiO2, Ca3SiO5, CaMg(CO3)2, Ca2SiO4, PbO and ZnSfor all MSWI BA and FA. CaO, Al2O3, SiO2 were mostly found inMSWI FA and BA. Figure S-2 showed the FE-SEM image of un-ground MSWI FA and BA while Figure S-3 showed the FE-SEM im-age of ground micro-nano MSWI FA and BA. Results of FE-SEMshowed that ground micro-nano MSWI BA (Fig. S-3f) had the po-tential to agglomerate compared to unground ones (Fig. S-2f).Ground micro-nano MSWI FA (Fig. S-3c) had more needle shapethan unground ones (Fig. S-2c). Figure S-4B showed that particlecle size distributions of micro-nano MSWI BA were 68%, 0% and32% for 0.4106, 1061110 and 111010000 nm after immediatemeasurement respectively while Figure S-5D indicated that thoseof micro-nano MSWI BA were 55, 8% and 37% for 0.4106, 1061110 and 111010000 nm after one day settlement respectively.MSWI FA had higher amount of 0.4106 nm than MSWI BA.</p><p>Particle size distribution and chemical compositions such asmetal element, metal compounds and PAHs/PCDD(Fs) can be seenin Table S-1 and Table S-2. Table S-1 showed the particle size range(lm) and individual ratio (%) of BA and FA from some reports (Loet al., 2005; Wey et al., 2006; Huang and Huang, 2008). It also pre-sented the particle size distribution of micro-nano MSWI BA andMSWI FA investigated in this study. Table S-2 presented the metalscontent, LOI (loss of ignition), pH and PAHs by this investigationand dl-PCBs, PBDD/Fs, PCDD/Fs, PAHs and metals oxides from liter-atures as indicated in superscript number. Table S-3 indicated thebioreactors type, analyzed items and frequency and the requiredbioreactors for experiment. Table S-4 reported the metals levelsin the various ashes and control bioreactors that might affect theinhibition or stimulation of MSW anaerobic digestion.</p><p>Physical and chemical components of MSW and anaerobicsludge seeding from Fu-Tien located in Taichung city were as de-scribed by Lo et al. (2009). Major elements of organic MSW suchas C, H, O, N etc. were measured by elemental analyzer (HeraeusvarioIII-NCH). C, H, O and N were measured to be about 46%, 6%,41% and 1.4% (C38.3H60O25.63N) respectively. MSW and sludge seed-ing were measured to have TS 5.5% (VS 4%) and TS 3% (VS1%) respectively. Table 1 and Table 2 showed the basic character-istics of MSW and sludge seeding. Table 1 showed that Taichungcity and Taiwan MSW had the close C(%), N(%), S(%), Cl(%) valuesof about 20.55 and 17.38, 0.50 and 0.47, 0.47 and 0.5, 0.0625 and0.07 respectively. C (46%) and N (1.4%) of synthetic MSW showedhigher compared to those of Taichung city and Taiwan MSW. How-ever, C/N ratios of Taichung city, Taiwan and synthetic MSW werefound to have close values in the order of 41.1, 39.68 and 32.86suitable for anaerobic digestion.</p><p>3. Experimental</p><p>Anaerobic reactors were 500 mL plastic bottle each containing350 mL MSW and 150 mL anaerobic sludge seeding admixture.size distributions of micro-nano MSWI FA were 83, 2 and 15% for0.4106, 1061110 and 111010000 nm after immediate measure-ment respectively. Figure S-4D indicated that particle size distribu-tions of micro-nano MSWI FA were 75%, 0% and 25% for 0.4106,</p><p>an MSW.</p><p>S (%) Cl (%) P (%) K (%) C/N ratio</p><p> 32.860.47 0.0625 0.1402 0.125 41.10.5 0.07 39.68</p><p>nology 114 (2012) 9094 91Adding ratios for MSWI FA (FA) and micro-nano FA (MNFA) were0.12, 3, 6, 18 and 30 g g1 VS while those for MSWI BA (BA) and mi-cro-nano BA (MNBA) were 0.6, 12, 36, 60 and 120 g g1 VS respec-tively. Anaerobic reactors without ashes addition were conductedas the control. All anaerobic reactors were carried out with dupli-cate. Briey speaking, 2 reactors (12 = 2) were used to measurethe biogas production per day while 12 reactors (62 = 12) for eachadded ratio were sacriced to analyze the pH, ORP, EC, salinity, VSand metals in ltrate at day 0, 10, 20, 30, 50 and 90. Detailed anal-ysis frequency can be seen in Table S-3. All anaerobic reactors were</p></li><li><p> an</p><p>A30</p><p>MNB</p><p>B</p><p>ed</p><p>Techperformed by batch mode without stirring and were maintained at35 C oven suitable for anaerobic process.</p><p>Biogas production was measured by gas collector with waterreplacement method. pH, ORP, EC, salinity, VS and metals in ltrate(after 100 mL admixture membrane ltration) were measured(Table S-3) according to standard methods for the examination ofwater and wastewater (AWWA, 1995). pH, ORP and EC and salinitywere measured by pH 207 (Lutron), pH meter SP-2300 (SUNTEX)</p><p>Various ashes added</p><p>MNFA</p><p>0.12MN</p><p>FA3MN</p><p>FA6</p><p>MNFA</p><p>18</p><p>MNFA</p><p>30FA</p><p>0.12</p><p>FA3</p><p>FA6</p><p>FA18</p><p>F</p><p>0</p><p>50</p><p>Fig. 1. Biogas accumulation in various ashes addioga</p><p>s ac</p><p>cum</p><p>ulat</p><p>ion,</p><p> mL </p><p>g-1 V</p><p>S</p><p>100</p><p>150</p><p>200</p><p>250Day 10Day 30Day 50Day 70Day 90</p><p>92 H.M. Lo et al. / Bioresourceand Con 400 series (SUNTEX) respectively. TS and VS were mea-sured by 105 C oven (DS45, Deng Yng) and 550 C furnace (CMF304, Cheng Jang). Metals were analyzed by ICP-OES (IRIS IntrepidII, Thermal Electron Corporation). ICP-OES was set at the requiredoperational conditions. Incident energy was 1100W and reectiveenergy was </p></li><li><p>-100</p><p>TechVarious ashes added and control anaerobic reactors</p><p>MNFA</p><p>0.12</p><p>MNFA</p><p>3MN</p><p>FA6</p><p>MNFA</p><p>18</p><p>MNFA</p><p>30FA</p><p>0.12</p><p>FA3</p><p>FA6FA</p><p>18FA</p><p>30</p><p>MNBA</p><p>0.6</p><p>MNBA</p><p>12</p><p>MNBA</p><p>36</p><p>MNBA</p><p>60</p><p>MNBA</p><p>120BA0.6BA</p><p>12BA</p><p>36BA</p><p>60BA</p><p>120Con</p><p>trol</p><p>pH</p><p>4</p><p>5</p><p>6</p><p>7</p><p>8</p><p>9</p><p>10</p><p>11</p><p>EC</p><p>, mS</p><p>/cm</p><p>4</p><p>6</p><p>8</p><p>10</p><p>H.M. Lo et al. / Bioresource(Lo et al., 2012, 2010, 2009; Fermoso et al., 2009; Chen et al., 2008;Yuan et al., 2009; Tan et al., 2009; Altas, 2009; Li and Fang, 2007;Lin and Shei, 2008; Yue et al., 2007; Ma et al., 2009; Worm et al.,2009) as listed in Table S-4. Those levels in the control and ashesdosed bioreactors were found to have potential stimulation ratherthan inhibition particularly occurred in the ashes dosed bioreactors(MNFA3, MNFA6, MNFA18, MNFA30, FA3, FA6, FA18, FA30,MNBA12, MNBA36, MNBA60, MNBA120, BA12, BA36, BA60,BA120) (Fig. 1, Table S-4). The biogas accumulation and VS reduc-tion can also be found in Fig. S-7.</p><p>Some studies were reported that metal oxides nanoparticlessuch as TiO2, Al2O3, SiO2, ZnO and CuO could affect the activatedsludge and cattle manure anaerobic digestion (Mu and Chen,2011; Mu et al., 2011; Luna-delRisco et al., 2011). Mu and Chen(2011) reported that 30 and 150 mg g1-TSS of ZnO nanoparticlescould induce 18.3% and 75.1% anaerobic digestion inhibition ofwaste activated sludge, respectively. However, it showed no inhib-itory effect at 1 mg g1-TSS of ZnO. Mu et al. (2011) also reportedthat nano-TiO2, nano-Al2O3 and nano-SiO2 in doses up to150 mg g1-TSS and nano-ZnO 6 mg g1-TSS had no effect onanaerobic digestion. However, nano-ZnO 30 and 50 mg g1-TSS de-creased biogas production respectively to 77.2% and 18.9% of thecontrol. Released Zn level from nano-ZnO was thought to be thekey factor for the methane generation inhibition. Luna-delRiscoet al. (2011) indicated that biogas production was severely affectedat concentrations of bulk and nanoparticles over 120 and15 mg L1 for CuO and 240 and 120 mg L1 for ZnO, respectively.EC50 concentrations for methane inhibition were estimated to be129 mg Cu L1 for bulk CuO, 10.7 mg Cu L1 for nano CuO,</p><p>Various ashes added and control anaerobic reactors</p><p>MNFA</p><p>0.12MN</p><p>FA3MN</p><p>FA6</p><p>MNFA</p><p>18</p><p>MNFA</p><p>30FA</p><p>0.12</p><p>FA3</p><p>FA6FA</p><p>18FA</p><p>30</p><p>MNBA</p><p>0.6</p><p>MNBA</p><p>12</p><p>MNBA</p><p>36</p><p>MNBA</p><p>60</p><p>MNBA</p><p>120BA0.6BA</p><p>12BA</p><p>36BA</p><p>60BA</p><p>120Co</p><p>ntrol</p><p>0</p><p>2</p><p>Fig. 2. pH, ORP, EC and salinity in various ashes addedVarious ashes added and control anaerobic react...</p></li></ul>