Varying Alum
In the experiment, to investigate alum dosage at a given turbidity and length, we first planned to vary the alum dose over a large range, incrementing the dose in set intervals while holding the plant flow rate (shear), influent turbidity, and residence time constant.
Table 1 shows the alum ranges we tested for each flocculator length and influent turbidity:
TABLE 1: Alum dose ranges tested and the increment used (mg/L).
Flocculator Length (m) | 5 NTU | 25 NTU | 50 NTU | 100 NTU | 500 NTU |
|---|---|---|---|---|---|
28 | 10-50 | 10-50 | 10-66 | 20-60 | 10-90 |
Interval | 5 | 5 | 7 | 5 | 10 |
56 | 10-50 | 10-50 | 10-66 | 20-60 | 10-90 |
Interval | 5 | 5 | 7 | 5 | 10 |
84 | 10-50 | 10-50 | 10-66 | 20-60 | 10-90 |
Interval | 5 | 5 | 7 | 5 | 10 |
The alum dose was varied in process controller using the increment function shown in Figure 1:
FIGURE 1: Process Controller setpoints used to vary the alum dose.
The following Process Controller Files were used in our experiments:
5 NTU One Length Test File
5 NTU Three Length Test File
25 NTU One Length Test File
25 NTU Three Length Test File
50 NTU One Length Test File
50 NTU Three Length Test File
100 NTU One Length Test File
100 NTU Three Length Test File
500 NTU One Length Test File
500 NTU Three Length Test File