Study On The Start-up And Operation Of Anammox System And The Effect Of Heavy Metals On Its Activity

As a kind of typical process for nitrogen removal, Anaerobic Ammonia Oxidation systemhas attracted the attention of theenvironmental protection workers at home and abroad. Due to the relative long bacteria doubling time and low cell yielding rate, the start-up of Anaerobic Ammonia Oxidation system is very slow.In view of this, this paper usedthe filled composite packing to enrichment and culture the anaerobic ammonia oxidation rapidaly. Menawhile, the purification performance, influencing factors and microbial structure during the strat-up and operation periods were studied. This study is supposed to provide theoretical basis and data support for the selection and application of the rapid start-up of anaerobic ammonium oxidation system. In addition, the individual and union effects of the typical heavy metals(Ni²⁺, Co²⁺ and Mn²⁺) were studied by the method of batch experiments. The major conclusionsare as follows:（1）The anammox bacteria can be successfully enriched and cultured by the UASB reactor filled with composite filler, in which the HRT and substrate concentration should be adjusted accordingly. At 116 day, NRR in the system reached 0.59 kg N·m-3·d-1, indicating the successful start-up of anaerobic ammonia oxidation system; in the operation process of the system, System instability caused by load shock. After 21 days of recovery, the nitrogen remove performance can not reach up to the level duringthe stable operation.（2）An excess of calcium and magnesium will affect anaerobic ammonia oxidation bacteria activity in the system. During 88-103 day, the system removal performance of nitrogen showed a downward trend, stop adding calcium and magnesium, the removal performance of nitrogen recoveried rapidaly in 3 days. This indicates that the inhabitation on the system of calcium and magnesium is a reversible process. However, the mechanism of inhibition on the anaerobic ammonia oxidation bacteria needs further study.（3）Through microbial analysis of the operation process of the system, we can find that the abundance and diversity of microorganisms reduced at the beging to the end of the start-up process. However, during the inorganic salt inhibition period, microbial abundance and diversityas well as functional bacteria changed abnormally; after the inorganic salt disinhibition, the abundance and diversity of microbialrapid declined; structure of microbial community changed grately at the phylum scale. With the accumulating of running time, the abundance of Proteobacteria decreased, but was still the main bacteria; Bacteroidetes and Firmicutes’ abundance declined as well; The abundance of planctomycetes, which is anaerobic ammonia oxidation bacteria, reached up to 9.81%, indicating that the anaerobic ammonia oxidation bacteria had been greatly enriched. AOB were detected at the genus level, the genus Nitrospira belonging to NOB existed only in the early start-up phase. Denitrifying bacteria existed in the whole start-up and operation process, whoes abundance remained in 1.38%- 1.43%. In the 5 genera of anaerobic ammonium oxidizing bacteria, at 79 day the Candidatus_Brocadia was detected and the abundance is 0.0075 which increased to 4.81% during the stable operation of the system.（4）The batch experiment results of the Ni²⁺, CO²⁺and Mn²⁺influence on the activity of ammonia oxidation bacteria shows: in high concentration, the effects of Ni²⁺, CO2+and Mn²⁺ on anaerobic ammonia oxidation bacteria were inhibitory effect. The IC50 value showed that among Ni²⁺, Co²⁺ and Mn²⁺ the strongest inhibition effect on anaerobic ammonium oxidizing bacteria was produced by Co²⁺. The union effect of Ni²⁺, Co²⁺ and Mn²⁺ on anaerobic ammonium oxidizing bacteria was investigated by orthogonal experiment. The results showed that Co²⁺ had the most significant inhibition effect on anaerobic ammonium oxidizing bacteria, Ni²⁺and Mn²⁺ had the generally significant inhibition effect on anaerobic ammonium oxidizing bacteria.