Membrane filtration for
removal of fine solids from aquaculture process water
R.C. Viadero Jr, J.A. Noblet-2002
Aquacultural Engineering, 26(3): 151-169
Abstract:
In recirculating aquaculture systems (RASs), fine
solids (diameters <20-25 µm) often escape conventional treatment
processes such as sedimentation and microscreen clarification and thus,
accumulate over time. Consequently, alternative means to remove fine solids
from RASs must be developed in an effort to improve water quality and fish
health, which is expected to enhance production yield and decrease cost.
Thus, the objective of this study was to assess the technical feasibility of
utilizing cross-flow microfiltration to remove fine particulate matter from
RASs. Based on tests conducted using a synthetic aquaculture process water
as a controlled feed solution in a dead-end filtration module, the 0.05 µm
membrane yielded the best water quality with >94% TSS rejection and 76%
biochemical oxygen demand rejection. In cross-flow membrane filtration using
a 0.05 µm pore size hollow fiber membrane, permeate flux increased with
increasing feed temperature. Flux also increased with and transmembrane
pressure up to a limit after which a pressure independent flux was observed.
On average, pressure independent flux was found to increase with cross-flow
rate approximately linearly. Based on a preliminary assessment of process
economics, it was determined that membrane filtration was not a cost
effective alternative to coarse solids removal processes such as microscreen
clarification. However, membrane filtration for fine solids removal has
potential niche applications in areas such as rearing high-value products.