Study On The Nitrogen Removal Efficiency By Light Bio-ceramics Carrier Fluidized Bed

Nitrogen is one of the mainly pollutants in water, which doesharm to environment and human health. How to remove and controlthe nitrogen pollution in water has been a question in academia forquite a long time. At this point, bio-fluidized bed is remarkable for itslow cost and high efficiency;and much of the research has been doneto its application on waste water treatment. However, there are stillsome questions to be trashed out or to be improved. Such as, thelack of carrier with high quality and low cost;the short of research onnitrogen removal;the absence of further study on operation system.As a consequence, the bio-fluidized bed is hard to apply in practice.Supported by the project of municipal water saving and sewagereuse technology, this subject was designed to solve the aboveproblems. By using the self-developed new granular biocarrier, theefficient light bio-ceramics, this research was initially focused on theperformance of three-phase bio-fluidized bed system with the carrierof efficient light bio-ceramics, the effect of RTDs on nitrogen removalefficiency, and that of sludge layer formed in the three-phraseseparation region. The experiment determined the dinitrificationperformance of carrier and fluidized bed system, discussed themicrocosmic mechanism of nitrification and denitrification in theaerobic region, and explored the macro mechanism of nitrificationand denitrification by RTDs and sludge effluent control in three-phaseseparation region. The results showed that:1. It was feasible to dispose organic sewage with the efficient lightbio-ceramics as carrier of bio-fluidized bed, a perfect removalefficiency of CODCr, NH4+-N and TN was gained. RTD tests showedthe bio-fluidized bed was a CSTR reactor, with the increase of bafflesin down-flow region, the number of tank-in-series was approaching 1,the back mixing was increased, the proportion of dead regiondecreased, and the volume utilization was then increased.2. The nitrobacteria suspended on the efficient light bio-ceramicswere reproduced in a high concentration CODCr after acclimation, theefficiency of NH4+-N was above 90%, the addition of baffles increasedthe turbulence and back mixing, the capacity of reactor, acceleratedthe bio-film renovation, at the same time, advanced the NH4+-Nremoval efficiency to 95%.3. There were all together three mechanisms of SND in thebio-fluidized bed reactor: a. the roughened microporous surface andthe special configuration of the efficient light bio-ceramics formed ananaerobic microenvironment, which improved the TN removal;b. thedead and stagnation region in bio-fluidized bed formed a localenvironment. With the addition of baffles, the TN removal fell down;c.the stable sludge layer in three-phase separation region provided amacroenvironment for the dinitrobacteria, with which increased theTN removal efficiency from 25~40% to 73.8~74.4%.This study chose the efficient light bio-ceramics as carrier for thefirst time, analyzed and compared nitrogen removal efficiency inbio-fluidized bed system, and obtained large numbers of data;RTDtests were performed firstly to detect the effect of mixing and capacityutilization on nitrification and denitrification, and gave a definition tolocal anaerobic environment for its functions to SND;first timementioned to advance the denitrification mechanism by optimizingthe three-phase separation region, and improved the TN removalefficiency to 73.8~74.4%.As a result, this research was carried out to solve those problemsexisting in bio-fluidized for the time being, provided valuableachievements, which definitely did contribution to the popularizationand application of bio-fluidized bed on its nitrogen removal.