Research On The Operational Characteristics Of Biological Aerated Filters With Porcelain And Ceramsite Carriers

In this experiment, two different carrier media, porcelain and ceramsite, were used to treat domestic wastewater in Biological Aerated Filter (BAF). Comparing the start-up and the operating characteristic with the two different carrier media, The main results were conducted as below:(1)The time needed for the start-up and biofilm formation of the two BAFs were different, because of stuffy aeration, for BAF with porcelain carrier, 37 days were needed. but for BAF with ceramsite carrier, 17 days were needed.(2)When the influent water temperature was 18～28℃, the gas to liquid ratio was 3:1, the influent CODcr concentration was 300mg/L,Cutting down HRT,the removal efficiency of porcelain BAF could be reduced. but there was no influence on ceramsite BAF. But the relation was not a linear relationship between hydraulic retention time and removal efficiency. For the porcelain BAF and ceramsite BAF,the best HRT was 10h.(3) When the influent water temperature was 27～33℃, HRT was 12h, the gas to liquid ratio was 3:1, Changing the influent CODcr was 400mg/L,300mg/L,200mg/L,100mg/L,With the influent organic loading decreased, the removal efficency of CODcr was reduced gradually. There was no influence on the removal efficiency of NH4+-N, The removal efficiency of NH4+-N was well.(4)When the influent water temperature was 12～22℃, HRT was 5h, the influent CODcr concentration was 300mg/L , the gas to liquid ratio rosed to 5:1 from 3:1, then decreased to 1:1. When the gas to liquid ratio was 5:1, the removal efficiency of CODcr and NH4+-N were the best in the porcelain BAF and ceramsite BAF. When the gas to water was 1:1, the removal efficiency of SS and TN were the best, on this condition, as well as the removal efficiency of CODcr and NH4+-N were better in the ceramsite BAF. Generally speaking, The ceramsite as carrier media, the removal efficiency of contamination was higher than porcelain BAF.(5)When the gas to liquid ratio was 3:1, HRT was 5h, the influent CODcr concentration was 300mg/L ,The best removal efficiency of CODcr occurred when the bed material height was 20cm～80cm. The best removal efficiency of NH4+-N occurred when the bed material height was 40cm～100cm.The best removal efficiency of SS occurred when the bed material height was 20cm. The SS removal efficiency rises slowly with the further increase of bed material height.(6)BAF had good function of nitrification. The NH4+-N removal efficiency with porcelain or ceramsite as carrier media was both well. There was no nitrite accumulation in BAF. Changing operating condition, the removal efficiency of TN was no marked by clear change and was misadventure. Because of not controlling for the factors of denitrification,if existing denitrification,then considering there was Simultaneous Nitrification and Denitrification in BAF. but the removal efficiency of TN was worse by means of Simultaneous Nitrification and Denitrification reaction. So the nitrification and denitrification and influencing factors in BAF need to be further studied.(7)When the CODcr concentration in influent was 280.59~319.22mg/L, the NH4+-N concentration in influent was 21.99~29.22mg/L, the SS concentration in influent was 86~121mg/L, the water temperature is 16~19℃, the ratio of gas to liquid ratio was 5:1 and HRT was 5h.Compared the contaminant removal performance of two carrier medias, the removal efficencies all were good. The NH4+-N removal efficiency was the best and was up to 95%, the removal efficiency of CODcr and SS all were up to 80%. Used porcelain as carrier media could also get higher removal efficiency, but as a whole the removal efficiency of porcelain exhibited a little decrease.