Use of dewatered sludge and fly ash to prepare new fillers: Application and evaluation in wastewater treatment

Abstract

Fillers are core components of biofilm wastewater treatment systems and directly affect the pollutant removal efficiency. New fillers were prepared using a non-sintered process with dewatered sludge as the raw material. The structure of the new filler and the microbial community were investigated and the results showed that the new filler had a complex composition and nature, a large specific surface area and many attached microorganisms; the new filler was applied to the biological aerated filter (BAF) system and the amount of biofilm on the surface of the new filler was 102 mg/g during start-up. At an hydraulic retention time (HRT) of 6 h and a gas to water ratio of 7:1, the removal rates of COD, NH3-N and TN of the new BAF (biological aerated filter) system reached 74%, 73% and 32%, respectively. At different filler heights, the biofilm amount, biological activity, and pollutant removal effectiveness of the new filler were higher than those of the conventional filler. The microbial diversity and microorganism selectivity of the new filler BAF system were better and more abundant than those of the conventional filler. The study results could provide some scientific basis and technical support for applying the new filler in biofilm wastewater treatment systems.