poster - International Conference of Agricultural Engineering

For the positive control test, the microspheres presented more than 100% recovery. This
value can be considered acceptable and according to SANTOS et al. (2011), it is related to
the standardization of the inoculums used in the evaluation. In this test, the polystyrene
microspheres were not retained in the fabric, but in the final filtrate. Furthermore, some
factors as the batch experiments using a simplified system such as static reactors, the small
volume and the facility to observe the microspheres in the microscope allowed few losses
occurred, thus the recovery is greater when compared to full-scale systems, besides the use
of oocysts instead of microspheres decreases the chances of recovery. Figure 2 shows a
microscopic image of non-woven synthetic fabrics of the negative (FIGURE 2-A) and positive
control tests (FIGURE 2-B), demonstrating that the microspheres are not retained in both
wires of the fabric.
A
B
FIGURE 2: A - Microscopic image of non-woven synthetic fabric after negative control test. B
- Microscopic image of non-woven synthetic fabric after positive control test.
The turbidity values of the samples in the sampling intervals correspond to the same
reduction of microspheres relative to baseline values. The first point observed at the
beginning of the sampling obtained 85.5% reduction efficiency. During the sampling intervals
the efficiency increased and reached 95%.
In the negative control tests, the turbidity values exhibited the same behavior of the tests
carried out with coagulant and microspheres, as in this case there was the coagulant
Moringa oleifera, and therefore the floc formation and the turbidity reduction remained the
same. For the negative control test, the absence of coagulant Moringa oleifera proved
ineffective in reducing turbidity, as the reduction values of turbidity did not exceed 17%. The
turbidity values also confirm the importance of using the natural coagulant Moringa oleifera
for water treatment.
4. Conclusions
The coagulant based on the seeds of Moringa oleifera is the main responsible on the
aggregation of microspheres during the floc formation. The non-woven synthetic fabric helps
in retention the floc and therefore does not promote the passage of the microspheres in the
treated effluent. However, the use of the fabric without the natural coagulant does not
promote the retention of polystyrene microspheres, as shown in positive control test results,
so it is not considered an alternative treatment for reduction of polystyrene microspheres.