AN INNOVATIVE GREEN TECHNOLOGY FOR AGRICULTURAL WASTE UTILIZATION
Loading...
Date
2020-10
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
NAUNI,UHF
Abstract
ABSTRACT
In the present investigation, different agricultural wastes were collected from Himachal Pradesh and
their adjoining states i.e. Punjab and Haryana and an attempt had been made to utilize this waste as substrate for
its enzymatic degradation to enhance their saccharification and bioconversion to ethanol by co-fermentation
with ethanologens. Based upon the chemical composition of mixed agricultural waste and large availability of
rice straw, these were finally selected for further study. Different physico-chemical pretreatment methods
applied to rice straw/mixed waste, where maximum reducing sugars i.e. 46.98 and 44.45 mg/g from rice
straw/mixed waste respectively were obtained in microwave pretreatment. After optimization of different
process parameters by one factor at a time (OFAT) approach for enzymatic saccharification under SmF, highest
reducing sugars reported from untreated and pretreated rice straw/mixed waste were 34.40 and 56.70 mg/g; 38.0
and 63.50 mg/grespectively, at enzymatic ratio of 3.5:1.5, 50oC temperature, 5.5 pH, incubation period 72 h and
7.5% biomass loading followed by CCD of RSM by varying temperature, pH and incubation time. SEM
analysis revealed that the surface structure of rice straw/mixed waste was significantly changed after
pretreatment and enzymatic hydrolysis. The reducing sugars so obtained were analyzed using HPLC technique.
In 2nd mode i.e. SSF (biological degradation), two fungal strains selected P. chrysoporium and P. ostreatus
fungal strains had showed maximum amount of reducing sugars produced i.e. 55.70 and 49.05 mg/g by using
microwave pretreated rice straw and mixed waste respectively. After optimization of process parameters
through OFAT and RSM maximum reducing sugars from untreated and pretreated rice straw (450 watt) /mixed
waste (600 watt) had the critical values as 51.12 and 37.98 mg/g; 71.99 and 73.10 mg/g respectively, at 30 and
25oC temperature and incubation period 10 days respectively. Among two processes of ethanol fermentation
evaluated in the present study, SHF was found to be the best in terms of highest ethanol productivity with S.
cerevisiae I+ P. stipitis as best fermenting microorganism from enzymatic saccharified and fungal degraded
sugary syrup. Estimation of bioethanol production after enzymatic saccharfied/ biological degrdaded microwave
pretreated rice straw/mixed waste hydrolysate fermented by co-culture of S. cerevisae I and P. stipitis was done
with the help of GC-MS. Scale up of ethanol fermentation using 7.5 l stirred tank bioreactor, batch conversion
of rice straw/mixed waste enzymatic saccharified hydrolysate to ethanol was carried out by co-culture of S.
cerevisiae I + P. stipitis under SHF. The highest ethanol yield of 52.14 and 46.89 g/l with 88.12 and 80.01 % of
fermentation efficiency was achieved after 48 and 36 h of fermentation with an agitation speed of 200 rpm and
aeration rate of 0.05vv, pH 6 at 25 ±2°C and inoculating the bioreactor with 24 h old co-culture of yeasts (S.
cerevisiae I + P. stipitis). Also to combat the pollution problem, value addition of agricultural waste for
cultivation of mushroom supplemented with apple pomace had emerged as an ecofriendly technique with higher
yield and better utilization substrate.