A study of start-up process and operation of anaerobic Digestion with coffee pulping waste water
Abstract
One of the major problems that occurs in the application of anaerobic
treatment to wastewater is the frequent failure to achieve startup.
The start-up period is the time upon which steady state conditions
are achieved after which the loading rate can be increased without
a deterioration of process efficiency until the maximum load is attained.
The main difficulty appears to be the development of the most suitable
microbial culture for the wastewater in question.
During the study, the start-up process of anaerobic digestion of
semi-continuous stirred tank reactors using coffee wastewater was
investigated. The start-up procedure involved wastewater analysis,
inoculation, stepwise increase of loading rate to a maximum and
monitoring the performance of the digesters during the loadi.ng
period. The COD of the pulping wastewater was in the range of
9980 to 14200 mg/l and the BOD/COD ratio was about 0.6.
Start-up periods based on steady state conditions were found to
be in the range of 33 to 44 days fer- biogas sludge and f r e s h
cowdunq as inoculum at the two operating temperatures. The loading
rates at the start of steady state were in the range of 1.4 to 2.7
kgCOD/m3/d. The maximum laoding rates achievable were 5.7 and
3.0 kgCOD/m3/d at 35°C and ambient temperatures in the range
18°-27°C respectively for biogas sludge. Daily gas production ,
was recorded to monitor the digesters performance. The gas yields
obtained at the start of steady state conditions were in the range
of 0.30 to 0.40 m3 / kgCOD removed. The average COD removal s
of over 70 percent were achieved at steady state conditions.
Sponsorhip
The University of NairobiPublisher
Department of Health