Methane Enhancement By Pretreatment And Co-digestion Of Corn Stover,Wheat Straw,Goose Manure And Chicken Manure

Agricultural lignocellulosic biomass is considered an abundant renewable energy resource found worldwide.However,the anaerobic digestion technology for the lignocellulosic biomass is not well developed as compared to the other livestock manure due presence of lignin and cellulosic crystallinity that leads it to poor anaerobic digestibility.Various pretreatment methods were reported to reduce this gap but still reluctance was observed by the commercial scale biogas plants to adopt it as anaerobic digestion feed.The five different pretreatment technologies developed in the present study for the lignocellulosic biomasses,hopefully,will share its portion to reduce this barrier.Dealing the anaerobic digestion of poultry manure on the industrial scale;the question of optimum C/N(mixing ratio)and OLR(daily feeding concentration)have significant importance still lack in literature.Therefore,pretreatment technologies were applied to corn stover and wheat straw and alkali solubilization and oxidative cleavage pretreatments were found optimum and most feasible to enhance their anaerobic digestibility.The pretreatment after effects was evaluated and consistent reduction in C/N ratio was found predominant.The pretreatment leads the cellulosic biomass to a significant methane enhancement.Moreover,Batch and CSTR co-digestion experiments of the chicken manure,goose manure,corn stover and wheat straw were carried out at mesophilic conditions.The C/N and OLR regression optimization models were also developed for their commercial scale usefulness.For the CSTR experimentation,three different OLRs of(1.5 g.VS/L.d),(3.0 g.VS/L.d)and(4.5 g.VS/L.d)were applied consequently,termed as Phase-?,Phase-? and Phase-? in the current study.Co-digestion of chicken manure with goose manure and wheat straw has reduced the ammonia inhibition effect to a greater extent.To truly elucidate the kinetics of the experimental methane production data;first order kinetics,transfer function model,cone model and modified Gompertz model was utilized and synergistic effects of the co-digestion of chicken manure,goose manure and pretreated wheat straw were evaluated.Modified Gompertz model had provided the best fitness and reliability with further kinetic predictions and explanations.Kinetic analysis and synergistic effect evaluations had confirmed the role of co-digestion in enhancing methane production.Furthermore,process biochemistry of the whole co-digestion process like total volatile fatty acids(TVFAs),alcohol production pattern,pH,soluble chemical oxygen demand(CODs),total available ammonia(TAN)and free available ammonia(FAN)were deeply monitored.[1]In the present study,thermo-chemical pretreatments(H2O2,Ca(OH)2,NaOH),ARP(ammonia recyclable percolation)and LA(liquid ammonia)were adopted to evaluate methane production potential from corn stover by co-digesting it with anaerobic activated sludge.All the pretreatments were carried out with two levels of concentration and found significant(P<0.05)to enhance lignocellulosic digestibility and methane production.The results indicated that the methane yield by H2O2-1,H2O2-2,and NaOH-2 treated corn stover were 293.52 ml/g.VS,310.50 ml/g.VS and 279.42 ml/g.VS which were 57.18%,66.27%and 49.63%higher than the untreated corn stover respectively.In the previous studies,pretreatment time was reported in days but the currently developed method had reduced it to about one hour.H2O2-2 and NaOH-2 treatments remained prominent to increase lignocellulosic degradation vigorously up to 45%and 42%respectively.ARP-2 pretreatment was proved as the optimum pretreatment with 50.69%,44.15%and 57.52%xylan,lignin removal and C/N reduction respectively as compared with the untreated corn stover.[2]Anaerobic co-digestion of corn stover and goose manure was also carried out in the present study at four composition levels.Corn stover was pretreated to enhance its lignocellulosic digestibility.The NaOH pretreatment effect on the chemical composition of the corn stover was also determined and the methane production from all the composition levels was found significant(P<0.05)as compared with the control.The cumulative methane production of treatment C2(0.6 CS:0.4 GM),C3(0.4 CS:0.6 GM)and C4(0.2 CS:0.8 GM)were 86.1%,92.1%and 83.1%enhanced as compared with the control respectively.On the basis of the experimental results,it was concluded that a C/N ratio between 20 and 30 was found optimum to enhance methane production.Asynchronism minimization was observed for all the treatments.Another experiment focused on carbon to nitrogen ratio(C/N)and organic loading rate(OLR)optimization of goose manure and wheat straw.The highest methane production was evaluated between the C/N of 20 to 30 during Batch experimentation while for CSTRs;the second applied OLR of(Phase-?,3.0 g.VS/L.d)was proved as the optimum with maximum methane production capability of 254.65 ml/g.VS for reactor B at C/N of 25.The C/N and OLR regression optimization models were developed for their commercial scale usefulness.[3]The present study emphasized the co-digestion of the thermal-H2O2 pretreated wheat straw and chicken manure with the waste activated sludge at four levels of C/N(35:1,30:1,25:1 and 20:1).All C/N compositions were found significant(P<0.05)to enhance methane generation and process stability during the anaerobic co-digestion of wheat straw and chicken manure.The experimental results revealed that the composition having C/N value of 20:1 was proved as optimum treatment with the methane enhancing capability of 85.11%,CODs removal efficiency of 48.55%and 66.83%VS removal as compared with the untreated wheat straw.The other compositions having C/N of 25:1,30:1 and 35:1 provided 75.85%,63.04%and 59.96%enhanced methane respectively as compared with the control.Pretreatment of the wheat straw reduced its C/N value up to 65%.The other experimental portion enhanced the research learning of co-digestion of chicken manure and pretreated wheat straw in semi-continuous stirring tank reactor(CSTR).The Phase-? of Reactor-B(C/N=20)proved as optimum with methane production capability of 296.90 ml/g.VS,68.19%VS removal and 59.87%CODs removal efficiency.Oxidative cleavage pretreatment was adopted for the wheat straw that had greatly enhanced its anaerobic digestibility.To truly elucidate the kinetics of the experimental methane production results,Gompertz model was applied to account the cumulative methane production curves for each experimental phase.[4]The current research also had investigated the effects of thermal-sonication pretreatment on anaerobic digestion of goose manure.The six CSTRs were run at three different organic loading rates:1.4 g-VS/L.day,2.9 g-VS/L.day and 4.4 g-VS/L.day,consequently termed as Phase-1,Phase-2,and Phase-3 respectively and five different sonication pretreatments levels:(25 min,45 min,60 min,90 min and 120 min)at 28 kHz were employed to optimize the anaerobic digestion process for goose manure to enhance methane production.The Phase-2 was proved as the optimum phase with maximum methane enhancement capability,CODs removal and VS removal efficiency.Due to thermal-sonication and organic loading management,methane enhancement up to 40.76%was evaluated for the reactor C during Phase-2 of the experiment.Another experiment dealing with the co-digestion of chicken manure,goose manure,and oxidative cleaved wheat straw was carried out with the basic objective of ammonia alleviation of chicken manure.The Phase-? of Reactor-B(C/N=25,3.0 g.VS/L.d)proved as optimum with methane production capability of 260.14 ml/g.VS,63.90%VS removal and 56.76%CODs removal efficiency.