Study On The Treatment Of Low Strength Ammonia Nitrogen Water By Immobilized Nitrobacteria

So far, more research focus on the immobilized microorganism treatment of high concentration of ammonia wastewater, and few reports of the removing of low concentration of nitrogen-containing wastewater, so finding an efficient way to remove ammonia nitrogen in wastewater with low concentration is necessary. Use of nitrobacteria immobilized with polyvinyl alcohol (PVA) and sodium alginate (SA) for removal of ammonia nitrogen in wastewater, is the current hotspot.This paper focuses on treating wastewater containing low concentration of ammonia nitrogen with immobilized nitrobacteria which entrapped by PVA and SA as main entrapment carrier. The main contents included: nitrifying bacteria's isolation and screening; analysis of entrapment carriers'pore structure; discussion of the external conditions on the removal rate of ammonia nitrogen in wastewater; observation on the immobilized pellets with scanning electron microscope during the operation.The main results of the research were listed as follows: (1) One nitrifier strain called X-1 was isolated from five commercial microbial agents. Strain X-1 could remove 41.5% of 10 mg/L ammonia nitrogen in 72h.(2) Based on our previous research, we gradually optimized the carriers'proportion, and made fine immobilized pellets. Combined with the results from SEM, it was found that 4% PVA and 2% SA were the best material for PVA beads immobilized nitrifying bacteria. The beads had well mechanical intensity and diffusion characteristic.(3) The results showed considerable nitrification ability of immobilized bacteria when immobilized pellets were used to remove the ammonium nitrogen from breed aquatics water. Temperature, dissolved oxygen, pH and immobilized pellets dosage all could affect the nitrification ability. when temperature is 30℃,pH=8,DO=4mg/L , immobilized pellets dosage is 40g/L, The NH4+-N removal efficiency can reach 92.5% after 60h operation.In summary, results showed considerable nitrification ability when treat wastewater containing low concentration of ammonia nitrogen with immobilized nitrobacteria which entrapped by PVA and alginate as main entrapment carrier. What's more, the immobilized method is simple, economy, and provides a new method or craft for the solution of low concentration of nitrogen pollution.