The Study on the Operating Characteristics of Algae-Contaminated Reservoir Water UsingGAC-sand Dual Media Filter Flofilter

The problem of reservoir water quality caused by massive algae pollution keeps going serious, and the traditional solid-liquid separation technology generally fails to meet water quality standards. In the present study, GAC-sand-double-filtration flofilter was built to treat reservoir water derived from the Yellow River that has been polluted by high levels of algal biomass, with the running characteristics and operating results specifically investigated. The experimental results showed that, running effect was relatively superior when the dosage of PAFC was 4 mg/L (Al3+), the pressure of dissolved air was 0.4 Mpa, and the reflux ratio was 8%. Algal biomass fixed onto GAC and sand filter layer was mainly found in the carbon layer, which accounted for 97.4% of the total biomass (the highest value was 50.2 nmol p/g), and the biomass fixed onto carbon layer was 16.7 times of that fixed onto the sand layer (3.0 nmol p/g). Clearly, the removal of pollutants mainly occurred in the carbon layer. Also, the removal efficiency of particulate matter such as blue-green algae, turbidity, CODMn, UV254, NPOC, ammonia nitrogen was 96.48%, 92.40%, 92.56%, 57.40%, 52.50%, 51.60% and 75.67%, respectively. The odor was reduced from 4 to 0, and the content of geosmin and methylisoborneol was less than their detection limit, with the removal efficiency of chloroform and chlorodibromomethane as 60% and 55.1%, respectively. In general, the results showed that the flofilter process had imposed an efficient effect on the removal of algal biomass, odor substances and disinfection byproducts precursors.