| Acrylic fiber wastewater is typical high ammonia and low carbon industrial wastewater that is hard to treat.At present,traditional A/O processes are commonly used in engineering to treat high ammonia and low carbon wastewater.However,it has the disadvantages of large land space requirement and the need for an external carbon source,which then leads to the high overall cost.Thus how to remove nitrogen in such wastewater with high energy efficiency has become a hot research topic in recent years.The new partial nitrification-anaerobic ammonium oxidation (PN/A) process which is widely used to treat landfill leachate,fertilizer,slaughter wastewater,etc.Is an ideal popular low-cost denitrification technology popular these years.However,aeration is still required to convert half of the ammonia in the influent into nitrite to provide enough subsequent required by ANAMMOX process.Traditional mechanical aeration method has drawbacks due to clogging,damage,etc.Affecting the accuracy in DO (dissolved oxygen)control,which is crucial for the stable operation of PN/A process.Microalgae’s photosynthesis seems to be a good substitute for traditional mechanical aeration and the combination of algae and bacteria not only brings low operation cost and supplys continuous uniform oxygen but also increases the biological nitrogen removal (BNR) efficiency of sewage,which raised the attention of researchers.In this study,four 6.5L optical sequencing batch reactors were built to trlength,light intensity,and light-dark cycle on the biomass of Chlorella were tested by single factor method,and further impacts on the denitrification efficiency were investigated.On this basis,a 35L optical sequencing batch biofilm reactor was established to further optimize and verify the conditions above.The results suggested that optimizing the light source conditions can improve the denitrification load and operation stability,and can reduce energy consumption to a greater extent,hence cost down the acrylic fiber wastewater treatment cost.The results are shown below:(1)Batch tests were carried out on light conditions,the experimental results showed that: a.Under different light source wavelengths,the experimental results suggested that red light promotes the growth of algae cells most,white-blue light raking the 2nd and white light had the least effect.b.Under different light time conditions,since the light transmission rate of algae also affects the growth rate of chlorella,considering the energy consumption and the denitrification efficiency of the reactor,the optimal light-dark ratio was set to be 18h: 6h.c.Under different light intensity conditions,due to the inhibition effects of light,the total biomass of chlorella under 3500 lux was lower than 3000 lux.Considering the overheating problem of high-intensity illumination and the denitrification efficiency of the reactor,the optimal light intensity is set to be 3000 lux.(2)75 days after the algae-partial nitrification-ANAMMOX reactor start-up,a TN removal rate was observed (75%～78%),suggesting that the algae,AOB (Ammonia-oxidizing bacteria),ANAMMOX bacteria showed good symbiosis.And the reactor maintained stable operation.(3)Two red LED light tubes were mounted each side of the reactor as the light source,the light wavelength was set to be 3000 lux and the light-dark cycle was set to be 18h:6h.After applying the optimized illumination conditions above,both the NH4+-N and TN removal rate increased significantly.(4)Analyzed from the perspective of the structural diversity of microbial flora.The results showed that the dominant bacteria in the PN reactor were Nitrosomonas and Ottowia.The dominant bacteria in the MA-PN reactor is Actinobacter.The dominant bacteria in the MA-PN-ANA reactor were Candidatus Brocadia and Nitrospira. |
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