A pilot-scale study of tertiary treatment of JIZHUANGZI Wastewater Treatment Plant by continuous preozonation-microflocculation-filtration process

A pilot-scale study of tertiary wastewater treatment of the JIZHUANGZI Muni cipal Wastewater Treatment Plant was carried out by preozonation, coagulati on and direct filtration process with the aim of producing wastewater suita ble for reuse. The proposed treatment scheme could produce a filtered water with lower turbidity, CODsigma and colour at lower ozone and coagulant dos ages. Ozone was added into the mixing tank with coagulant simultaneously an d postozonation was not cost effective. With the increase of ozone dosage, better CODsigma and colour removals were observed especially at the ozone d osage between 0.7-1.0 mg l(-1). Similarly, increasing ferric sulphate dosag e resulted in better removals of turbidity, CODsigma and colour in the filt ered water. In contrast, increasing polymer T-80 dosage seemed to improve c olour removal rather than turbidity and CODsigma. To achieve removal effici ency of 70% for turbidity, 45% for CODsigma and over 60% for colour, the op timum dosages of ozone, ferric sulphate and polymer T-80 should be 0.7-1.0 mg l(-1), 10.0-12.5 mg l(-1) and 0.7-1.0 mg l(-1), respectively.