Potential of Novel Halotolerant and Psychrotrophic Strain of Planococcus sp. for Water Treatment

To screen multifunctional bacteria for water treatment,a chemical oxygen demand( COD)degradation and flocculation strain S2 A15 was obtained from the offshore sewage outfall at Weihai International Beach. Based on the phylogenetic characteristics,a novel strain was identified as a Planococcus species. Strain S2 A15 was determined to have the ability of flocculation and COD degradation. A series of experiments showed that the strain S2 A15 could be used for the treatment of four types of wastewater,including domestic wastewater( 400 mg/L and 800 mg/L) and high salt domestic wastewater( 400 mg/L and 800 mg/L). Among them,the best effect was exerted by the strain that reduced by 76.9% in domestic wastewater with 400 mg/L COD. The flocculation ratio reached 60.19%. The optimal treatment conditions are also discussed. We confirmed that the strain S2 A15 had salt tolerance and low temperature resistance. The best growth of S2 A15 at salt concentration of 6% and further confirmed that the strain could degrade COD at a low temperature.

Biodegradation of Ammonia Nitrogen Using a Novel Candida sp. Strain N6 Immobilization

Due to the high efficiency of ammonia nitrogen degradation,a novel Candida sp.strain N6 was applied for wastewater treatment by using immobilization technology.Immobilization conditions and corresponding ammonia removal capacity of immobilized N6 beads were investigated.The immobilized N6 beads were applied to degrade simulated ammonia nitrogen wastewater.Results showed that the optimum formula of immobilized materials was 9%polyvinyl alcohol,1.5%sodium alginate,and 2%calcium chloride,under which the ammonia nitrogen removal rate of the immobilized N6 beads reached 97.97%.The following immobilization conditions were observed to be optimal:the immobilization time was 24 h,the inoculum of N6 was 3%,and the pH was 8.The immobilized N6 beads exhibited excellent ammonianitrogen degradation ability in SBRs.The ammonia nitrogen removal rate was stable at 95%-99%in the SBRs.The results indicated that immobilized N6 beads possess good application prospects in the treatment of ammonia nitrogen wastewater.

Screening of Seawater Compound Bioflocculant Producing Bacterial Strains and Optimization of Their Culture Medium

Compared with single bioflocculant,compound bioflocculant(CBF)normally has more stable and higher flocculation efficiencies.In order to produce a new compound bioflocculant,four bacterial strains with relative high rate of flocculation were selected from the coastal zone sediment,all of which were determined as Pseudomonas sp.by 16S rRNA sequencing.Through compounding,the ideal proportion of compound bioflocculant consisting of two bacterial strains(F5∶M5)was determined as 1∶2,resulting in 6%increase in terms of flocculation rate.The significant fermentation factors in culture media and their limitations were investigated via single factor experiments and Plackett⁃Burman design,obtaining four key variables,MgSO_(4),(NH_(4))_(2)SO_(4),sucrose and peptone,which were further optimized by response surface methodology(RSM)for their optimal concentrations.Finally,the ideal culture medium was determined,containing(NH_(4))_(2) SO_(4)0.523 g,MgSO_(4)3.7 g,sucrose 12.82 g,K_(2)HPO_(4)4 g,KH_(2)PO_(4)3 g,NaCl 33 g,and deionized water 1 L.The flocculation rate of experimental data(88.92)agreed well with the model prediction,which was 16.60 higher than original rate.