Survey of treatment process in water treatment plant and the characteristics of flocs formed by two new coagulants

The relationship between pH, turbidity and COD of raw water with the residual Al in the filtrated water was investigated. The results indicated that the COD in raw water may have the maximum effects on the residual Al. The pH value of raw water had significant effects with the residual Al, but the relationship was not significant in the latter half of the year. The characteristics of water in the Yellow River had no significant relationship with the quality of filtrated water. In order to get better coagulation performances, two new coagulants (AS (Al-2(SO4)(3)) + Fe-TiO2 and AS (Al-2(SO4)(3)) + Al2O3) were applied to treat the raw water, and the characteristics of flocs were investigated. The results indicated that when nano particles (Fe-TiO2; Al2O3) were mixed with AS, they could significantly increase the floc size, and the recovery factor was also larger than using AS alone. The strength factor decreased if two new coagulants were used, and the results may be caused by the bridging effects formed by nano particles. (C) 2014 Elsevier B.V. All rights reserved.