| Wastewater treatment by biofilm is an new wastewater treatment technology developed in recent years, featured with high biomass, multiple dominant species, high efficiency, small establishment area and little sludge. Preparation of filler immobilizing microorganism is the key to this new technology. According to the installation mode,fillers used in wastewater treatment are divided into the following categories: fixed filler, suspended filler, dispersed filler and new biological filler. Traditional fillers have varying degrees of disadvantage, such as uneven air distribution, poor biocompatibility, thus the hydrophilic filler, biocompatible filler and magnetic filler are developing in the future.Phosphorite wasterwater is generated in gelatin production process after recycling calcium hydrogen phosphate(CaHPO4), the amount is about 50 ton per ton gelatin.Large amount, high chloride, high calcium, high protein and acidic are the main charactristics of the waterwater,thus its treatment is difficult and expensive.Currently gelatin wastewater is treated by the following methods :physical treatment, chemical treatment and biochemical approach. Phosphorite wasterwater is acidic, so it is often used to neutralize the alkaline water produced in other process and hardly been treated separately from effluent However, that phosphorite wasterwater mixed with water produced in other process will bring more difficulties to gelatin production wastwater treatment .Photosynthetic bacteria's application in wastwater treatment areas become increasingly widespread because of its better ability in decomposition of organic waste with high concentration and resistance to shocks, salt and also in recent years.In this paper, under laboratory conditions, different fillers were used as carriers.Their surface were attached by biofilm mainly composing of photosynthetic bacteria. Phosphorite wasterwater was treated independently by bio-contact oxidation, the performance of different carriers'biofilm was investigated in the course of the experiment .The results showed that:Because of its features ,the treatment of phosphorite wasterwater was not successful when biofilm reactor was started and domesticated only with phosphorite wasterwater.So a certain amount of nutrient solution must be added into reator ,at the meantime, proportion of phosphorite wasterwater content shoud gradually increase and biofilm was also gradually domesticated. Only in this way can biofilm reactor be started and domesticated. The experiment's results show that the concentration of Ca2+ and Cl- and pH value of wastewater were three dominant factors that infuence the effect of membrane culturing carrier.After biofilm was mature, the results of phosphorite wastewater treament showed the following traits in brush carrier reactor and fiber carrier reactor respectly:COD value of effluent was stable below 200 mg/L in brush carrier, while it failed in fiber carrier reactor, sometimes there were substantial fluctuations .Analyzing other water indicators, effluent of brush carrier reactor was better than that of fiber carrier reactor.The nature of carriers had led to different treatment effects of two reactors. Analyzing results of two carriers by SEM,we found that brush carriers own rough surface, large surface area, certain biological affinity and its filaments had certain flexibility and excellent light penetration, these physical traits were benefit for microbial attachment to carrier surface ,and then biofilm formate easily. While,fiber carrier surface was very smooth, its filaments was slender and easy to twine, these traits not only easily intercept CaCO3 particles among wastewater but also work against biofilm formation and mass transfer between microbes.In this paper, theoretical analysis in kinetics of brush carrier reactor was made and kinetic constant of the reactor was obtained on the basis of the experimentresults. : Umax=82501mg/(h·m2)=82.501g/(h·m2), Ks=1078mg/L... |
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