A Hybrid Treatment System Combining Enforced Diatomite Process Followed by Biological Aerated Filters for Wastewater Treatment

A hybrid treatment system combining enforced diatomite process followed by biological aerated filters (BAF) was developed for treatment of municipal wastewater. Most pollutants, especially phosphorus, were removed in the enforced diatomite process and BAFs took a role of polishing process. New ceramic filter media and ceramisite agitator were used in two BAFs for comparison. The results showed that when the average influent CODcr was 347 mg/L, NH4+-N 49 mg/L and TP 6.1 mg/L, the removal efficiency was 92.6%, 99.8%, and 96.4% respectively at the operating conditions of precise diatomite dosage of 75 mg/L, the sludge reflux ratio 100%, the HRT of 30 min in diatomite enhanced primary treatment process and the HRT of 1.5 h in BAF.