MSc

Fruits are highly perishable commodities and generate huge amount of
waste.Besides loss of freshfruits,waste is also generated during the processing
stage. Fruits and vegetable processing industries generate waste up to the extent of
25-40 per cent of raw materials used. Disposal and proper management of these
fruit waste has become a serious problem to agro-entrepreneurs. Biological
conversion of biomass to methane has received increased attention during recent
years
So the proposed study entitled “Production and effective utilization of
biogas from fruit waste” was conducted at College of Horticulture to envisages the
standardization of biogas production from fruit waste and the effect of biogas
slurry on the germination of mango stones. The broad objective was to enable the
agro-entrepreneurs to effectively utilize the fruit waste from processing factories.
In order to determine the optimum ratio of cow dung and fruit waste for
maximum biogas production, the floating drum biogas digesters of 0.5 m3 capacity
were used. The experiment was conducted in completely randomized design and
consists of six treatments and three replications (T1 : Cow dung alone, T2 : Fruit
waste alone, T3 : Cow dung + Fruit waste (1:0.5), T4 : Cow dung + Fruit waste (1:1),
T5 : Cow dung + Fruit waste (1:1.5), T6 : Cow dung + Fruit waste (1:2). The results
indicated that mixing cow dung and fruit waste in a proportion of 1:1.resulted in the
generation of biogas with 65.30 % methane and 32 % carbon dioxide which was
closely followed by T5 (Cow dung: fruit waste,1:1 ratio) . Fruit waste alone was
loaded to the biogas plants which were found to be comparatively inferior in
methane generation. The treatment T5 (Cow dung: fruit waste, 1:1 ratio) also
produced the highest volume of gas (0.44 m3/day) within 17 days Hydraulic
Retention Time (HRT). The pH of the slurry varied from 6.4-8.0 and EC between
0.52-0.79 and total solids ranged between 2.10-6.55 per cent and organic carbon
content to 19.83 to 26.09 %. The highest C/N ratio was in Fruit waste alone (27.19)
and lowest in Fruit waste and cow dung 1:1 ratio (9.48). The best combination in
view of maximum manurial value was cow dung and fruit waste in 1:2 ratio (2.58 %
N, 0.81 % P and 2.23 % K) which was selected for the second experiment.
The experiment to evaluate the effect of biogas slurry on germination of
mango seed stones was done in CRD consisting of seven treatments and three
replications. Two varieties (Moovandan and Bangalora) were made use of. The
germination per cent and vigour index was found to be maximum for pre soaking
with fruit waste slurry (T7 )which was closely followed by presoaking with cow
dung slurry (T5) for both the varieties. After germination the reducing sugar content
of mango stones of both the varieties were found to be was found to be increased
compared to the initial content. The nutrient uptake for almost all the nutrients was
higher with presoaking treatments with the slurry. There was significant decrease in
available soil nutrient contents after the experiment as compared to the initial
contents in potting mixture used for the study due to crop uptake.