| The significant demand in energy utilization especially in rapidly developing countries has generated interest to develop alternate fuels.Biomass is a primary feedstock for production of alternative fuels and alternative fuel precursors.The use of biomass as a potential renewable energy source,not only to reduce dependence on petroleum fuels,but also to improve upon the harm caused by fossil fuels to the environment.Considerable amount of waste by-products materials is being generated through agricultural practices,mainly from various agro-based industries.Unfortunately,much of the biomass is often disposed by burning,which is not restricted to developing countries alone.The Sugarcane Industry is responsible for production of different types of organic wastes.Cane straw left in the field after harvesting,bagasse,and filter mud.Bagasse and a small share of straw have already been used as solid fuel in cogeneration systems in general.Meanwhile,the filter mud has been completely unused from the energy point of view.One of the bioprocess techniques used for recovering the energy from biomass residues is anaerobic digestion that has as a primary result the production of biogas.The process of anaerobic digestion is a biochemical one,involving the hydrolases of organic compounds such as carbohydrates,proteins and fats to biogas through the actions of several groups of microorganisms under oxygen free conditions.Keeping in view all these facts,this research work was carried out to produce biogas by utilizing sugarcane bagasse and filter mud as a substrate.For this purpose,batch and semi-continuous flow stirred tank reactors(CSTR)was used under mesophilic conditions(37±1?).The feedstock was added to the reactor along with water in such ratio that maintains total solids(TS)at 6%.Different pre-treatment methods and co-digestions,to enhance biogas production from sugarcane bagasse and filter mud were conducted.The results are generalized as following:1.The effect of individual and combined microwave-alkaline pre-treatments at various range of power and residence time on sugarcane bagasse composition and subsequent aerobic digestion in batch mesophilic digesters.All pre-treatments were effective in the biodegradation of the lignocellulosic sugarcane bagasse structure.The most lignin removal 86.02%and 58.55%of the cellulose and 11.08%of the hemicellulose remained within the bagasse was observed in pre-treatment by NaOH 1N for 45 min.Pre-treatments with microwave and alkaline achieved 6,560 and 20,384 mg L-1 chemical oxygen demand solubilisation(COD),respectively.However,combined microwave-alkaline pre-treatment synergistically enhanced sugarcane bagasse solubilisation and achieved 30,616 mg L-1,682.61%greater than the untreated(3,912 mg L-1).Moreover,the highest cumulative biogas production 117.77±2.10,158.60±3.75 and 196.96±2.44 mL g.VS-1 and its respect bio-methane content 54.57%,53.03%and 58.89%were found on microwave,alkaline and microwave-alkaline pre-treatment,respectively.The results show that microwave-alkali pre-treatment is effective in increasing biodegradability of sugarcane bagasse.2.Sugar cane filter mud pre-treated by combined ultrasound-alkaline pre-treatment at different NaOH loading(0.25 to 6%)and pre-treatment time(5 to 60 min)were performed in batch reactors.Central Composite Design(CCD)was used to assess the effects on the chemical oxygen demand(COD)solubilisation,volatile fatty acid(VFA)concentration and methane yield.All pre-treatments were found significant(P<0.01)to enhance methane yield(up to 39.49%)compared to the untreated filter mud,as there is no significant difference between pre-treated samples.Pre-treatment also increased the CODs solubilisation as well as VFA concentration,but the optimal Initial CODs and VFA of 12,212 and 5,830 mg L-1,as determined by response surface methodology were noted on T9.Finally,modified Gompertz model was applied successfully to study kinetic of biogas production data,and showed an excellent fit.3.To enhance the co-digestion of degradation and improve bio-methane production potential,sugar cane bagasse and filter mud were pre-treated by sodium hydroxide NaOH 1N at 100? for 15,30,and 45 minutes,respectively.Bio-methane generation from 1-litre batch reactor was studied at five levels of mixing proportion with and without pre-treatment.The results demonstrate that co-digestion of filter mud with bagasse produce more bio-methane than fermentation of filter mud as single substrate,even co-digested substrate composition presented a better balance of nutrients(C/N ratio of 24.70)when co-digestion ratio between filter mud and bagasse was 25:75 in comparison to filter mud as single substrate(C/N ratio 9.68).All the pre-treatments tested led to solubilisation of the organic matter,with a maximum lignin reduction 86.27%and cumulative yield of bio-methane(158.60 mL gVS-1,digestion of pre-treated bagasse as single substrate)obtained after 45 minutes of cooking by NaOH 1N at 100?.Under this pre-treatment condition,significant increase in cumulative methane yield was observed(126.20 mL gVS-1)at co-digestion ratio of 25:75 between filter mud and bagasse by increased 81.20%from untreated composition.4.The anaerobic digestion of sugarcane filter mud and the option of co-digestion with bagasse,wheat straw and chicken manure in two mixing ratios were investigated.Experiments were carried out in mesophilic semi-continuously stirred tank reactor(CSTR)at hydraulic retention times(HRT)of 15,10 and 7 days.While the main anaerobic digestion process parameters monitored.The HRT of 15 days was proved as the optimum with maximum biogas production capability of 700±44 ml Ld-1 for digestion of filter mud,and slightly reduce in biogas production when the HRT was reduced to 10 and 7 days.The VS removal efficiency at all HRTs was about 3.80%,and the highest average of COD removal efficiencies was 25.23%in HRT of 15 days.Regardless the co-digestion of filter mud with wheat straw in 1:1 ratio presented higher biogas yield(811.11±30 ml Ld-1)than co-digestion with other waste in all proportions during steady-state condition of 15 days HRT. |
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