Abstract:
The highly competitive and allergic weed Parthenium hysterophorus was introduced
to Ethiopia in 1970s. The weed has spread to the most parts of the country with high
infestation rates in grasslands and even in crop fields. It is a growing danger to smallscale
farmers: tef and sorghum grain yields are reduced; milk output from dairy cows is
decreasing to one third; the milk has sour taste; animals suffer from skin allergy and
reduction in weight; farmers suffer from skin allergy, itching, fever and asthma; intensive
labour input has to be made in order to clean the crop fields. So, Parthenium is a current
threat for further economic development in the rural areas of Ethiopia. Different
parthenium controlling methods were established, but no single method appeared
successful as each suffered with one or more limitations. This study presents the findings
of a study conducted to evaluate the biogas and fuel birquetting potential of parthenium
weed to manage the spread of parthenium weed through utilization. Parthenium was
mixed with cattle manure in different combinations at a level of 3:1 ,2:1 , 1:1 , 1:2
ratio, parthenium alone and cow dung alone and allowed to digest anaerobically at
ambient temperature in 2.5-litre batch digesters. The highest total gas yields were
obtained from 1:1combination as 9922 ml and the lowest was from cow dung alone as
3096ml., the highest biogas potential was observed for treatment 1:1 combination as
0.082308 m3 biogas kg-1VS added and the lowest biogas potential was observed from
treatment T1 as 0.03458 m3 biogas kg-1VS added. The highest COD removal efficiency
82.93% and biogas potential 0.1824 m3 biogas kg-1VS added was for treatment T3(1:1)
whereas the lowest COD removal efficiency 45.34% was for T6(3:1) . The highest
volatile solid VS) conversion efficiency 88.95 % was for T3 and the lowest conversion
efficiency 50.30% was for T1. The percentage of methane gas for treatment T4 obtained
was 47.2% and similarly, the methane percent of the biogas for treatment T3 and T5
obtained from gas chromatography and gas chromatography mass spectrometer was
greater than 50%. Among the best three treatments T3 (1:1) ratio was with highest peak
area and methane percent of the biogas. In this study Parthenium weed was also made
into fuel briquette and the moisture content, volatile matter, ash content, fixed carbon,
bulk density and calorific value of parthenium briquette were measured to be 4.10±0.06,
16.63±0.34,20.12±0.05,57.17±0.55,0.297±0.068,3907±0.88respectively.