Major Aspects of Microfiltration
Hardware
Process
Effect
Method
The present experimental study has highlighted potential operation problems, associated with the fibrous
nature of the sludge. In particular, there is a tendency for material to accumulate at restrictions in the
flow path, i.e. valves etc., and hence lead to blockages. The possibility of blockages developing is also a
concern voiced by Durban Corporation personnel. Hence, it would be necessary to engage in further
engineering development on a full-scale plant in order to identify and eliminate regions in the flow path
that could encourage the formation blockages. Other hardware aspects that need to be investigated
include the choice for the cleaning method. These would have to be addressed on a full-scale plant.
Back to top of page
It is desirable that the full-scale coupled process are automated and require minimum operator input.
Control and automation strategies would have to be developed on a full scale unit.
Back to top of page
If the biomass concentration in the digestor is increased, it would be a corresponding increase in the
viscosity of the digestor contents. This could possibly be detrimental to the flow distribution in the
digestor, leading to dead zones and poor mixing. Hence, it would be necessary to increase the
concentration of the full-scale digestor and monitor the effects on the flow distribution. This would be
done using tracer studies, i.e. the Residence Time Distribution technique. If any significant
maldistribution is identified, investigations will focus on whether these could be engineered out.
Back to top of page
A full-scale unit would be constructed in the workshop of the department of Chemical Engineering,
University of Natal. The unit is then to be relocated to the Northern Waste Water Treatment Works and
coupled to one of their two digestors. Equipment will be modified, if necessary, until consistent
blockage-free operation is achieved. In the second, stage the performance of the full-scale unit will be
compared to fluxes etc. achieved on the single tube tests. Discrepancies will be addressed until the
full-scale unit performs as per the design specifications. Thereafter the effects of the coupled process on
the digestor hydrodynamics would be investigated. The biomass concentration of the digestor would be
slowly and progressively increased. At increasing concentrations, the residence time distribution of the
digestor would be determined. Simultaneously, the flow distribution would be modeled using the
computational fluid dynamics (CFD) techniques. If any serious maldistributions occur as a result of the
increased concentration, effort will focus on developing engineering solutions, guided by predictions
from the CFD model. In the last stage, process automation and control will be addressed, thereafter the
process will be operated continuously as a demonstration unit.
Back to top of page
Previous Page