several of their products be screened in combinations if the individual poly- 

 mers produced pin-sized floes. The method for adding polymers in combination 

 is to add the cationic polymer first, as usual, and then to add the anionic 

 polymer at the end of the rapid mixing phase. The technical sales representa- 

 tives also provided cost information for the polymers selected for 

 optimization. 



23. Three forms of polymers were evaluated: liquid, emulsion, and dry. 

 Polymers were prepared for testing using the procedure outlined in Appendix A. 

 The screening procedures are outlined in Wang and Chen (1977). 

 Optimization of polymer dosage 



24. As a result of the initial screening process, 11 cationic and 



2 anionic polymers were selected for further evaluation in accordance with the 

 procedure detailed in Schroeder (1983). The test was similar to the screening 

 process except that the polymers were tested over a range of concentrations 

 where the optimum dosage was thought to occur. The suspended solids concen- 

 trations of the treated effluent were determined for each sample. Graphs of 

 supernatant suspended solids versus polymer dosage were plotted for each 

 polymer. 



12 



