Research On Removal Of Low Concentration Ammonianitrogen Wastewater By A Combination Of Zeolite Biological Aerated Filter And Ceramsite Denitrification Filter Processes

Ammonia pollution has become one of the most serious environmental problems,the discharge of ammonia compound to soil and waters may adversely affect water resources in several ways including contribution to eutrophication,depletion of oxygen,and toxicity to aquatic environment.This study revealed that combination of natural zeolite integrated in“U-ZBAF”?Up-flow Zeolite Biological Aerated Filter?and ceramsite in“U-CBAF”?Up-flow Ceramsite Biological Anaerobic Filter?could be a feasible method to treat low concentration ammonia wastewater because of their extensive source,low-cost,and excellent treatment ability.The experiments were designed in pilot-lab scale,and could be used as effective pre-treatment method before its implement in a large-scale operation process.This study was based on biological wastewater treatment process,which consists of nitrification,biological regeneration?bio-regeneration?,and denitrification processes.The specific conclusions of this study are as follows:Natural zeolite were integrated in U-ZBAF can be a feasible way to remove low concentration ammonia nitrogen through the nitrification process.The effect of various HRTs and high-DO concentration?6.80-7.30 mg/L?has played a key role due to nitrification process.The optimal HRT was 2 h,with NH₄⁺-N removal efficiency reached 92.9%.At the same HRT of 2 h,NO₂^--N accumulate was detected with ratio of 85.1%,indicating the synergetic effects resulted by increasing of HRT and High-DO condition during the NH₄⁺-N removal process.However,high-DO condition was corresponding to promote high activity of NOB?nitrite oxidation bacteria?to oxidize NO₂^--N to NO₃^--N immediately when HRTs reduced from 1.0 to 0.75 and 0.50 h.The U-ZBAF process with highly enriched nitrifiers including Nitrosomonas,Nitrospira,and Nitrobacter indicated a consistency and stable growth of microbial population along flow direction in the reactor,and also played important role for excellent NH₄⁺-N removal under low temperature condition.Bio-regeneration can be considered as an advanced and supplementary process for recovering zeolite from the exhausted,the various temperature levels storage was chosen to evaluate the microorganism capability to oxidizing ammonia that has been liberated from the zeolite.During the bio-regeneration,the various temperature levels storage,storage time,and aeration process has played major role which could affect nitrate recovery rate,and the adaptability of microorganisms at low temperature?6-8 ^oC?.The experimental results showed that the NO₃^-recovery rate were increased from 0.20 mg/h to 1.51 mg/h after 36 h,whereas at normal temperature recovery rate were remained stable at the range of 1.70-2.17 mg/h after 24 h.The denitrifying in U-CBAF process revealed excellent NO₃^--N removal performance.The types of carbon source,the influencing factor,and microbial community of biofilm attached was the important factors to achieve complete denitrification in U-CBAF.The optimal C/N ratio was 5for glucose and methanol as carbon sources,with NO₃^--N removal efficiency of 85.8±1.63%and 90.9±1.43%,respectively.The differential intermediary production could be related to differential denitrification adaption to carbon source,thus leading to high NO₃^--N reduction and selective NO₂^--N production.Besides,the effect of HRT was important to succeed NO₃^--N removal in the reactor.The optimal HRT was 1.5 h for methanol,with NO₃^--N and TN removal efficiency of 83.2±1.87%and 81.0±2.03%,respectively,whereas the NO₃^--N and TN removals apparently decreased when the HRT adjusted higher than 1.5 h.The high-throughput sequencing analysis showed that the relative abundance of genus Pseudomonas and Streptococcus were played a major role and should be responsible for high TN removal in the U-CBAF.Finally,the removal of low nitrogen?NH₄⁺-N and NO₃^--N?wastewater by combination of U-ZBAF and U-CBAF processes was verified very satisfactorily.The characteristics of final treated water could meet grade A of the first level in“Discharge Standard of Pollutants for Urban Wastewater Treatment Plant of China?GB18918-2016?,especially in environmental sensitive areas.