Study On The Treatment Of Micro-polluted Water By Biological Aerated Filter

With the development of industrialization and improvement of living standard,pollution of the water environment has been a common problem in today’s world, moreand more attention has been paid on outspec level of organic pollution and amnionia insource water. Although the existing various processing techniques of micro-polluted rawwater of although, can achieve good treatment result, there are different restrictions thatbring difficulties to the actual operation and management. Therefore, we will have tofind a new processing technology to deal with this problem. Due to its good treatmentresult,less land usage, low costruction and operating costs. It is vital to employed forBiological Aerated Filter water treatment.This experiment used ceramic and zeolite by1:1volume ratio as the media of theBiological Aerated Filter, studyed on the treatment of micro-polluted water byBiological Aerated Filter, especially the removal of ammonia and COD_Mn. Through themedia of static adsorption test, determined the media to achieve adsorption saturationtime. Based on this, through the study of biological aerated filter‘s hydraulic loading、gas water ratio、packing height and other operating conditions, got the best operatingparameters of the biological aerated filter. On the best operating conditions, researchedthe Biological Aerated Filter resistance ammonia loading and organic loading capacity,in order to understand whether it could adapt to the micro-polluted water qualitysuddenly changes. Also studied the Biological Aerated Filter backwash cycle、strength、washing time and the recovery of the Biological Aerated Filter after backwash. Themain conclusions are as follows:①Though static adsorption experiment of mixed media, we can find, filter ofammonia adsorption capacity is0.478mg/g. Thus obtained, in this experimentalcondition, if used8L/h wastewater to flushing the Biological Aerated Filter byrepeatedly, media reached to the adsorption saturation time was about three days;②The biofilm of this test is inoculated biofilm, due to the media itself advantages aswell as high temperature and other factors, biofilm time was short, only10days, theammonia nitrogen removal rate was85.4%, the removal rate of COD_Mnwas16.7%. Thenext two days removal efficiency was stable, biofilm formation was successful;③By studying of the hydraulic conditions、the gas-water ratio、packing height andother operating conditions. The optimum operating parameters of the Biological Aerated Filter for hydraulic load was1.5m3（/m2h）、the gas-water ratio was1:1、packing heightwas90cm;④On the best operating conditions, researched Biological Aerated Filter resistanceammonia loading and organic loading capacity. The results show that: the ability ofBiological Aerated Filter resisted to ammonia shock loading and the organic load wasrelatively strong. When the concentration of ammonia nitrogen increased from1.7mg/Lto21.3mg/L, ammonia nitrogen removal rate was83.2%to92.5%, removal rate ofCOD_Mnwas29.8%to34.9%, removal efficiency was relatively stable. Theconcentration of COD_Mnincreased from5.49mg/L to22.68mg/L, removal rate ofCOD_Mntrended gradually upward, though ammonia nitrogen removal rate wasgradually declining trend, the minimum removal efficiency reached72.7%;⑤Backwash of this test was: first gas washing and then air-water joint backwashingthe final water rinse. On the best operating conditions, the backwash cycle was10days.After backwashing, the filter recovered rapidly, after24hours, the COD_Mnremovalrate reached35.33%, higher than15.8%before backwashing;⑥Compared with the single media of Biological Aerated Filter test, bofilmformation time of mixed media was shorter, the best hydraulic loading was larger;⑦For a water plant with everyday disposal quatity of20000t, the Biological AeratedFilter as a pretreatment process, the fixed investment cost of the pre-treatment process is94millions yuan，the running cost is0.17yuan per ton, so, used a mixture of zeolitesand ceramsite as the media of biological aerated filter, its investment and operatingcosts were low, therefore, it has a good prospect of application.The conclusion of this study shows, mixed filling BAF had good removal efficiencyto micro-polluted water pollutant, had great reference value and significance to theactual works. Its investment and operating costs low, has good application prospects.