Screening of Psychrotrophic Bacteria and Their Application to Treatment of Livestock Wastewater

Abstract:

Fourteen psychrotrophic bacteria were isolated from swamp soil collected in Ruoergai plateau wetland, and their generation time and degrading ability of livestock wastewater CODcr was determined. The results showed that the generation time was within 4.9 h to 11.6 h. Based on the generation time, 9 psychrotrophic strains (NLJ1, NLJ6, NLJ7, NLJ9, NLJ10, NLJ11, NLJ12, NLJ13 and NLJ14), whose generation time was within 4.9 h to 5.6 h, were chosen to treat livestock wastewater. The results suggested that these 9 strains had different CODcr disposal ability when treating livestock wastewater singly at 6°C for 6 h, and strains NLJ6, NLJ7, NLJ9, NLJ10, NLJ11 and NLJ13 had good ability to degrade livestock wastewater, the CODcr degrading rate was about 60%~70%, hence, they were used as high efficient strains; However, the CODcr degrading rate of the other strains was less than 50%. After inoculating mixture culture of these six strains into the distilled livestock wastewater, after 6 h’s treating, the CODcr degrading rate reached to 85.42%. Furthermore, activated sludge collected from Yaan, Dujiangyan and Chengdu were inoculated by the mixture culture of those six strains, and used to treat livestock wastewater for 6 h. The results showed that the average CODcr degrading rate was 81.67%, 76.32% and 70.56%, respectively; Variance analysis showed that there was no significant differentiation between each treatment, which revealed that those six psychrotrophic strains had good adaptability to different source of activated sludge.

Key words:Psychrotrophic bacteria, Swampy soil, Livestock wastewater, CODcr