Ordinary quartz sand has some defects such as smooth surface

small specific surface area and poor performance of attach microorganisms. To improve the surface texture of quartz sand and promote microorganism adhesion on the filter

it is an effective method to etch on the quartz sand with buffered oxide etch (BOE). The results of SEM shows that the morphology of the surface reconstructed quartz sand is obviously changed and the global morphology is grooved. Factorial experiment demonstrates that modified quartz sand has more grooves on the surface whose width is between 1.0-5.0 μm and the biomass increases from 9.3 nmol P·g-1 to 15.7 nmol P·g-1 after modification

under the condition of corrosive liquid concentration is 15%(mass)

the mass ratio of HF and NH4F is 1:1

the reaction temperature is 55℃

and the reaction time is 45 minutes. The result of FTIR reveals that the Si-O is transformed to Si-OH

the disappearance of organic characteristic peaks indicates the removal of organic material. After the surface modification

surface area of quartz sand increases from 0.427 m2·g-1 to 1.475 m2·g-1

and the removal rate of CODCr increased from 41.9% to 51.6%. Hence the modified quartz sand has a preferable microbiological compatibility.