Clarified water then flows over effluent weirs to the excess-flow chlorine contact basin. At this basin, the flow is disinfected by sodium hypochlorite and dechlorinated with sodium bisulfite. It is then blended with treatment plant effluent and discharged to the Kansas River.
.....The microsand-solids mixture collected at the bottom of the sedimentation chamber is withdrawn and pumped to a hydrocyclone, which separates excess water and solids from microsand. The separated microsand is concentrated, discharged through the bottom of the hydrocyclone, and reinjected into the ballasted flocculation process. Most of the microsand is recycled in the ballasted flocculation basins for further flocculation. The solids separated by the hydrocyclone will flow by gravity back to the head of the plant to the influent pumping station, where they are treated by the main biological treatment process.

Mechanical Checkout and Performance Testing
After the ballasted flocculation basins were constructed, each basin was checked mechanically and tested for performance. The ideal time for process performance testing is during wet weather events, but it is difficult to predict when a storm event will occur. So, the project team developed a plan to simulate a storm event to test the system (see Table 2, p. 33). However, this plan proved to be unworkable because the influent pumping was being modified.
.....Furthermore, during ballasted flocculation basin testing, more than 50% of the primary basin capacity was out of service due to construction, so the primary basin effectiveness was low. Total suspended solids in the primary basin effluent were about 140 to 180 mg/L, which is in the anticipated range of influent flow to the ballasted flocculation basins, so primary basin effluent was used during mechanical equipment checkout, process optimization, and performance testing. The effluent was stored in the holding basin for excess-flow stormwater and pumped to the splitter—screening facility by temporarily installed pumps.
.....During testing, separated solids were pumped to
the liquid process streams downstream of the primary basins. If the chemically enhanced solids had been recycled during the performance test, the project team was concerned that they would enhance the polymer and ferric chloride dosages and skew the results.
.....After the ballasted flocculation equipment was completely field-tested, mechanical startup testing began. Because the ballasted flocculation basin is discharged directly into the Kansas River and this was the first sanitary sewer overflow facility of its kind, the project team designed two testing operations. In the first, the facilities were operated with a blend of nonpotable (disinfected plant effluent) and service water to alleviate any concerns about direct discharge into the